Journal articles on the topic 'Second-order growth kinetics'
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1
Idi, Ahmad. "DENITRIFICATION KINETICS OF PSEUDOMONAS STUTZERI AZ101." International Journal of Research -GRANTHAALAYAH 7, no. 7 (July 31, 2019): 247–55. http://dx.doi.org/10.29121/granthaalayah.v7.i7.2019.758.
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Nitrogen removal from environment is significant due to its effect on health and the whole ecosystems. Hence a highly nitrogen tolerant aerobic denitrifier, Pseudomonas stutzeri AZ101 was isolated from aquaculture wastewater and characterized using 16S rRNA analysis. The ability of the isolate to carry out simultaneously nitrification and denitrification (SND) was investigated. Different initial concentrations of nitrate and ammonium were used to determine the rate of SND. The denitrification data fitted well with the second order reaction kinetics with correlation coefficient between 0.923-0.9588. The nitrification data does not fit to both first and second order reaction kinetic but progressive shifts in the logarithm phase of the growth were observed at different initial concentrations. The kinetics data provide a significant insight to nitrogen removal from the wastewater.
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Stefanovich, L. I., and É. P. Fel’dman. "Kinetics of formation and growth of antiphase domains during second-order phase transitions." Journal of Experimental and Theoretical Physics 86, no. 1 (January 1998): 128–33. http://dx.doi.org/10.1134/1.558477.
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Balagurov, Anatoly M., Nataliya Yu Samoylova, Ivan A. Bobrikov, Sergey V. Sumnikov, and Igor S. Golovin. "The first- and second-order isothermal phase transitions in Fe3Ga-type compounds." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, no. 6 (November 9, 2019): 1024–33. http://dx.doi.org/10.1107/s2052520619013106.
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Structural features and kinetics of the transition between ordered metastable b.c.c.-derived D03 and equilibrium f.c.c.-derived L12 phases of Fe–xGa alloys (x = 27.2% and 28.0%) have been analyzed by in situ real-time neutron diffraction during isothermal annealing in the temperature range 405–470°C. It has been revealed that the transition proceeds with alternation of the first- and second-order phase transformations according to a D03 → A2 → A1 → L12 scheme, where A2 and A1 are disordered b.c.c. and f.c.c. structures. Deformations of the crystal lattice that arise due to these transitions are determined. The kinetics of the L12 phase nucleation and growth were analyzed in the frame of the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model; however, only the early stage of the D03 → L12 transition is well described by the JMAK equation. The value of the Avrami exponent corresponds to the constant growth rate of the new L12 phase and decreasing nucleation rate in the Fe–27.2Ga alloy and indicates the presence of pre-existing nucleation centres of the L12 phase in the Fe–28.0Ga alloy.
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Bergwerff, Luke, and Leon A. van Paassen. "Review and Recalculation of Growth and Nucleation Kinetics for Calcite, Vaterite and Amorphous Calcium Carbonate." Crystals 11, no. 11 (October 28, 2021): 1318. http://dx.doi.org/10.3390/cryst11111318.
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The precipitation of calcium carbonate is well studied in many fields of research and industry. Despite the fact that, or perhaps because of the fact that, it is well studied in many fields, different approaches have been used to describe the kinetics of the precipitation process. The aim of this study was to collect and compare the data available in the literature and find a consistent method to describe the kinetics of growth and nucleation of the various polymorphs of calcium carbonate. Inventory of the available data showed that a significant number of the literature sources were incomplete in providing the required information to recalculate the kinetic constants. Using a unified method, we obtained a unique set of parameters to describe the kinetics for growth for calcite, vaterite and amorphous calcium carbonate (ACC) and nucleation for vaterite and ACC. Recalculation of the kinetic constants demonstrated that calcite confirmed there are two growth mechanisms within one polymorph, namely pure spiral growth and spiral growth mixed with surface nucleation. The spiral growth does not show second-order growth, which is typically attributed to it. Re-evaluation of the available nucleation data confirmed the suggested existence of a second pure ACC polymorph with a solubility product between 10−5.87 and 10−5.51 mol2 kgw−2.
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Ramesh Kumar, G., and S. Gokul Raj. "Growth and PhysioChemical Properties of Second-Order Nonlinear Optical L-Threonine Single Crystals." Advances in Materials Science and Engineering 2009 (2009): 1–40. http://dx.doi.org/10.1155/2009/704294.
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The present aim of the paper is to grow and to study the various properties of L-threonine amino acid single crystal in various aspects. Crystal growth of L-threonine single crystals has been carried out with the help of crystallization kinetics. pH and deuteration effects on the properties of the grown crystals have been studied and the results presented in a lucid manner. The various second-order NLO parameters were evaluated using anharmonic oscillator model. Particle and ion irradiation effects on structural, optical, and surface properties of the crystals have also been studied in detail.
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Zhang, Shiying, Chen Lai, Kun Wei, and Yingjun Wang. "Kinetic Studies on the Synthesis of Hydroxyapatite Nanowires by Solvothermal Methods." Australian Journal of Chemistry 60, no. 2 (2007): 99. http://dx.doi.org/10.1071/ch06117.
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Hydroxyapatite nanowires with a high axial ratio have been synthesized in reverse micelle solutions that consist of cetyltrimethylammonium bromide (CTAB), n-pentanol, cyclohexane, and the reactant solution by solvothermal methods. This paper focusses on the kinetic studies of the solvothermal reaction and the linear growth of hydroxyapatite nanowires. When the reaction was carried out at low temperatures (65°C), the experimental results showed that the reaction rate was of zero order since the whole reaction was diffusion controlled with constant diffusion coefficients. In the middle to high temperature range (130–200°C), the kinetics were characterized by second order reaction kinetics. Since the controlling factor was activation energy and the apparent activation energy was large, the reaction rate was more sensitive to the temperature. Therefore, the exponent of the reaction rate constant increased by two when the temperature was increased from 130 to 200°C. By calculating the yields of products and the specific surface areas at different times, the linear and overall growth rate equations of the hydroxyapatite nanowires could be obtained. The experimental effective growth order of the crystals was 11. The larger growth order indicated that the crystal could grow more effectively in one direction because of the induction of the surfactant in the experiment system.
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Mendes, Elton, Elidio Angioletto, Erlon Mendes, Raquel Ternus, Kelly Regina Betiatto, Riss Heloisa, Karine Testa, Raquel Piletti, Humberto Gracher Riella, and Márcio Antônio Fiori. "Kinetics Modelling of the Adsorption Process of Zinc Ions by Glass Microparticles." Materials Science Forum 930 (September 2018): 556–61. http://dx.doi.org/10.4028/www.scientific.net/msf.930.556.
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The oligodynamic property is a lethal effect which some atoms exert over bacteria, fungi and other microorganisms. The oligodynamic property can be promoted by glass microparticles doped by zinc ionic specimens utilizing the ionic exchange processes. This study is aimed at modelling the behavior of adsorption mechanisms of the zinc ions on glass microparticles absorbent, with potential use as antimicrobial material. Aqueous solutions of zinc nitrate were used as the ionic supplying of zinc ions. The amount of zinc adsorbed on the glass was determined by spectroscopy of atomic absorption and with a mass balance analysis for each adsorption conditions. The experimental data were modeled by three Eq.s employed in adsorption kinetics studies: pseudo first order, pseudo second order and Elovich Eq.. The pseudo second order data model presented the better adjust condition. A sample of zinc glass microparticles, prepared at the finest conditions established by the kinetic model of pseudo second order, was submitted to microbiological analysis: agar diffusion test with Pseudomonas aeruginosa and Staphylococcus aureus and with Candida albicans. The glass doped with ionic zinc inhibited the growth of microorganisms in every conducted analysis.
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Helfenritter, Christoph, and Matthias Kind. "Determination of Crystal Growth Rates in Multi-Component Solutions." Crystals 12, no. 11 (November 3, 2022): 1568. http://dx.doi.org/10.3390/cryst12111568.
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Many solid forming processes involve crystallization from multi-component solutions. In order to predict final phase assemblages, multi-component phase transfer kinetics must be known. It is not sufficient to have the kinetics of only one crystallizing component in the presence of other entities; the kinetics of concurrent crystallizing components are of interest as well. However, methods for their determination are currently lacking. We propose a new method comprising desupersaturation measurements of a 150 µm film of supersaturated solution in contact with a planar crystalline substrate. We show that concentration measurement at a single point in the film is sufficient to retrieve the phase transfer kinetics. For this, we use a confocal micro-Raman spectroscope, which is able to distinguish between different components and has a high spatial resolution. We chose crystallization of Na2SO4 and Na2CO3 decahydrate from aqueous solution as our model system because of its well-known phase equilibrium. In binary experiments, we demonstrate the mode of operation and its ability to reproduce known kinetics from the literature. In ternary experiments, we successfully distinguish two courses of crystallization, the first of which is a preferential crystallization of one component and the second a simultaneous crystallization of both crystallizing components. In both cases, the parameters for simple power law kinetics are determined. If sodium carbonate decahydrate crystallizes while sodium sulfate remains in solution, the mean mass transfer coefficient is revealed to be kg,CO3=6×10−7ms−1, which is about an order of magnitude lower compared to binary crystallization. If sodium carbonate decahydrate crystallizes concurrently with sodium sulfate decahydrate, the crystallization kinetics are similar to binary cases. The other component tends to be significantly slower compared to its binary crystallization.
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Jia, Zhigang, Cong Han, Rui Chang, and Daqing Zhang. "Synthesis of carbon dots-assisted MgAl-LDH hollow microspheres with hierarchical structure for the effective removal of Congo red from wastewater." E3S Web of Conferences 269 (2021): 02003. http://dx.doi.org/10.1051/e3sconf/202126902003.
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Hierarchical hollow Mg-Al layered double hydroxide microspheres (HHMs) are successfully prepared by hydrothermal treatment in the presence of carbon dots (CDs). Morphology and structure of the as-prepared samples are characterized using XRD, SEM, FT-IR, and TEM techniques. The growth process of HHMs has been investigated in detail, and Ostwald ripening mechanism is suggested for the hierarchical growth of HHMs. Adsorption isotherms and adsorption kinetics of HHMs for congo red (CR) are investigated. Langmuir and Temkin model are more fitted to the experimental data of CR isotherm adsorption. Adsorption kinetic data obeys the pseudo-second-order kinetic model. Moreover, thermodynamic parameters (ΔGo, ΔHo and ΔSo) show that the CR adsorption onto HHMs is an endothermic and spontaneous process. The as-prepared HHMs could be a potential adsorbent for wastewater treatment containing anion dyes.
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Castle, Brian T., David J. Odde, and David K. Wood. "Rapid and inefficient kinetics of sickle hemoglobin fiber growth." Science Advances 5, no. 3 (March 2019): eaau1086. http://dx.doi.org/10.1126/sciadv.aau1086.
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In sickle cell disease, the aberrant assembly of hemoglobin fibers induces changes in red blood cell morphology and stiffness, which leads to downstream symptoms of the disease. Therefore, understanding of this assembly process will be important for the treatment of sickle cell disease. By performing the highest spatiotemporal resolution measurements (55 nm at 1 Hz) of single sickle hemoglobin fiber assembly to date and combining them with a model that accounts for the multistranded structure of the fibers, we show that the rates of sickle hemoglobin addition and loss have been underestimated in the literature by at least an order of magnitude. These results reveal that the sickle hemoglobin self-assembly process is very rapid and inefficient (4% efficient versus 96% efficient based on previous analyses), where net growth is the small difference between over a million addition-loss events occurring every second.
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Chen, Ruinan, Qinghua Chen, Xu Huang, Qingsong He, Jian Su, Bin Tan, Chao Xu, Huahong Deng, and Qingwei Dai. "Effect of Al Content on the Microstructural and Grain Growth Kinetics of Magnesium Alloys." Metals 12, no. 11 (November 15, 2022): 1955. http://dx.doi.org/10.3390/met12111955.
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In order to control the grain size in thermomechanical processing, the grain growth behavior of hot extruded Mg–xAl–1Zn (x = 3, 6, 9) alloys and their relationship with second phase particles and solutes were investigated. The growth rate of AZ61 is greater than that of AZ31 and AZ91 at 300 °C, 350 °C, 400 °C, and 450 °C under isothermal annealing. The average grain growth exponents n of Mg–xAl–1Zn (x = 3, 6, 9) alloys were 2.26, 2.33, and 2.53 at 300–400 °C, respectively. The deviation from the theoretical value of 2 was attributed to the hindrance of grain boundary migration of Al-rich second phase particles and solute Al. Microscopic observations show that the grain size of the annealed samples is closely related to the shape, volume fraction, size, and distribution position of the second phase particles. Significantly, the pinning effect is stronger for lamellar and network-like second phase particles. In addition, the pinning effect of Al-rich second phase particles plays a more important role in grain refinement than the dragging of solute Al. The growth of abnormal grains in the microstructure is attributed to the high energy difference between the preferentially oriented <112¯0> grains and the surrounding grains, which drives the grain boundaries to overcome the same pinning force of the second phase particles.
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Schwartzkopf, Matthias, Volker Koerstgens, Ezzeldin Metwalli, Gunthard Benecke, Kai Schlage, André Rothkirch, Ralf Roehlsberger, Peter Mueller-Buschbaum, Rainer Gehrke, and Stephan Roth. "From Atoms to Layers: Gold Cluster Growth Kinetics during Sputter Deposition." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1183. http://dx.doi.org/10.1107/s2053273314088160.
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The adjustment of the size-dependent catalytic and optoelectronic properties of gold cluster assemblies is a very significant topic in modern applied nanotechnology [1]. For an efficient and controlled production of active nanostructured cluster surfaces, sputter deposition plays an important role [2]. In order to characterize the self-organization during nanocluster film formation, it is mandatory to understand how growth kinetics influences the cluster film morphology during sputter deposition. The first real-time investigations of gold nanocluster growth kinetics into a gold layer are enabled by combining sputter deposition and surface sensitive X-ray scattering (GISAXS). High frame-rate 2D X-ray detectors in combination with the high photon flux of micro beam spot size, available at the PETRA III beamline P03, enables a non-invasive in situ and real-time investigation of gold growth during sputter deposition. With an acquisition throughput of 67 frames per second, we were able to identify 4 different stages of growth including their thresholds with sub-monolayer resolution and concomitant phase transitions. Each stage can be characterized by a predominant surface process and its intrinsic kinetic: nucleation, diffusion, adsorption and grain growth. Moreover we introduced a flexible geometrical model to extract morphological real space parameters, such as cluster size, correlation distance, layer porosity and surface coverage, directly from the reciprocal space scattering data. The model allowed simulating, visualizing and interpreting gold cluster growth kinetics in terms of nanoscopic processes. Furthermore, we were able to deduce wetting angle on the nanoscale and onset of long-range connectivity during the deposition process [3]. This approach is a prerequisite for future investigations of the influence of different process parameters on thin metal film morphology, which is essential for optimization of manufacturing parameters, saving energy and resources.
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Li, Y. S., Z. Chen, Y. L. Lu, and Y. X. Wang. "Coarsening kinetics of intermetallic precipitates in Ni75AlxV25−x alloys." Journal of Materials Research 22, no. 1 (January 2007): 61–67. http://dx.doi.org/10.1557/jmr.2007.0013.
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The precipitation kinetics of growth and coarsening of γ′(Ni3Al) and θ (Ni3V) in Ni75AlxV25−x alloys were investigated by microscopic phase-field simulation incorporated with elastic interactions. For the elastic interactions, γ′ aligned along the 〈001〉 direction and θ aligned along the [100] direction, which resulted in plate shape. For the lower (x < 4, at.%) and higher (x > 6) content regions, the growth of first precipitates was dominant at the initial stage and then coarsening was dominant, but the growth and coarsening proceeded simultaneously for the second precipitates. The growth and coarsening of γ′ and θ were dominant, respectively, at the initial and late stages for middle content regions. In addition, dynamic scaling was analyzed in the two-phase systems. It was shown that the dynamic scaling regimes were attained simultaneously at late-stage coarsening for γ′ and θ, despite the different precipitation order.
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Perrone, Ítalo Tuler, João Pablo Fortes Pereira, Isis Rodrigues Toledo Renhe, Júlia D’Almeida Francisquini, Rodrigo Stephani, and Antônio Fernandes De Carvalho. "Monitoramento da cristalização da lactose em soro concentrado." Revista do Instituto de Laticínios Cândido Tostes 72, no. 4 (May 23, 2017): 215–26. http://dx.doi.org/10.14295/2238-6416.v72i4.647.
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The kinetics of lactose crystal growth in concentrated whey were studied in two stages. The first took place in a bench-top crystallizer and the second in an industrial crystallizer using concentrated whey obtained by vacuum evaporation, consisting of 3 treatments: crystallization by primary nucleation, by secondary nucleation with the addition of 0.05% and with the addition of 0.1% microcrystalline lactose. The average size of the crystals remained between 60.7 mm and 63.8 mm. The percentage of crystallization was greater in the secondary nucleation process than in the primary nucleation, where crystallization stabilized first. Mathematical equations which independently related crystallization times of the concentrated whey to the concentrations of soluble solids, crystallization percentage and mass of lactose in water were established, that can be used in the industrial setting to process whey. The kinetics of lactose crystal growth was not well described by models of first or second order reactions.
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Milonopoulou, V., K. M. Forster, J. P. Formica, J. Kulik, J. T. Richardson, and D. Luss. "Influence of oxygen partial pressure on the kinetics of YBa2Cu3O7−x formation." Journal of Materials Research 9, no. 2 (February 1994): 275–85. http://dx.doi.org/10.1557/jmr.1994.0275.
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The YBa2Cu3O7−x formation kinetics from a spray-roasted precursor powder containing Y2O3, BaCO3, and CuO was followed via in situ, time-resolved x-ray diffraction as a function of gas atmosphere and temperature. In inert atmospheres, BaCO3 and CuO form BaCu2O2 which subsequently reacts with Y2O3 to form YBa2Cu3O6. However, YBa2Cu3O6 decomposes at temperatures exceeding 725 °C with Y2BaCuO5 being one of the decomposition products. In oxidizing atmospheres, YBa2Cu3O7−x formation involves the BaCuO2. At high temperatures (800–840 °C), oxygen increases the yield of YBa2Cu3O6. A nuclei growth model assuming two-dimensional, diffusion-controlled growth with second-order nucleation rate fits the experimental data.
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Wei, Yuan, Shu Lin An, and Su Ran Liao. "Research on the Reaction of IPDI and PPG with Organo-Tin Mixed Catalyst." Advanced Materials Research 430-432 (January 2012): 399–403. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.399.
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The kinetics of the reaction is essential for the synthesis of polyurethane. In this study, the reaction kinetics and polymerization conditions in two-step process of isophorone diisocyante (IPDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by chemical titration. The results showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of IPDI and PPG reaction at 50, 60 and 70°C were 0.0161, 0.0373 and 0.0806 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 74.25 kJ•mol-1. The polyurethane with number molecular weight 38721 was synthesized and was characterized by Fourier transform infrared (FTIR).
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Khoshhesab, Zahra Monsef, Katayon Gonbadi, and Gholamreza Rezaei Behbehani. "Removal of Reactive Red 74 Dye from Textile Industrial Waste using Zinc Oxide Nanoparticle." JOURNAL OF ADVANCES IN CHEMISTRY 6, no. 3 (December 7, 2010): 1077–84. http://dx.doi.org/10.24297/jac.v6i3.2645.
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Global population growth and industrial activities in recent decades has been caused to enter excessive amount of pollutants to water resources. Industrial textile dyes are an important class of the pollutants in the sewage system. Disposal of the dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Considering the toxicity of the pollutants, their removal from water resources is necessary. In this research, removal of reactive red 74, RR47, from aqueous solution by zinc oxide nanoparticles was investigated and the affecting parameters such as pH, contact time and adsorbent mass on removal efficiency were determined. Langmuir and Freundlich isotherms were studied and the results indicated that the adsorption process obey the Langmuir and Freundlich isotherms. The experimental results also showed that the pseudo-second order kinetic equation could nicely describe the sorption kinetics.
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Zhang, Ming Yi, Kun Yang, and Zheng Chen. "Kinetics of Order-Disorder Transition of Antiphase Domain Boundary Formed between DO22 Phases: Microscopic Phase-Field Study." Advanced Materials Research 160-162 (November 2010): 996–1000. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.996.
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Based on the microscopic phase-field model, the precipitation process of Ni75Al4.3V20.7 alloy at 1190K is simulated, and the kinetics of order-disorder transition at antiphase domain boundary (APDB) formed between DO22 (Ni3V) phases is investigated. After the ordered APDB formed by the impingement of growing DO22 (Ni3V) domains, the order-disorder transition at APDB is happened. Accompanied with the enrichment of Ni and Al at the APDB, the ordered APDB transforms into a thin disordered phase layer. The second phase L12 nucleates at the order-disorder interface between DO22 and disordered phases, and grows along the disorder phase layer quickly. The order-disorder transition at the ordered APDB accelerates the nucleation and growth of L12 phase at the APDB. The disordered phase caused by the order-disordered transition can be considered the transient phase during the precipitation process of L12 phase.
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Carvalho, G., I. Nopens, J. M. Novais, P. A. Vanrolleghem, and H. M. Pinheiro. "Modelling of activated sludge acclimisation to a non-ionic surfactant." Water Science and Technology 43, no. 7 (April 1, 2001): 9–17. http://dx.doi.org/10.2166/wst.2001.0377.
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A model is proposed to describe activated sludge acclimatisation to a non-ionic surfactant. The model was calibrated automatically, using WEST, a specific software environment for wastewater treatment model building, simulation and parameter estimation. The assays have been performed in a sequencing-batch reactor (SBR), using a non-ionic surfactant as sole carbon source and non-acclimatised sludge. The best fitting model was based on the assumption of three sequentially degraded COD fractions, where the second fraction is a metabolite of the original molecule and the third fraction is a more slowly biodegradable metabolite resulting from the secondary degradation. For primary degradation, hydrolysis with no associated growth was assumed. The growth of microorganisms responsible for degradation of the second and third COD fractions was presumed to follow Haldane and first order kinetics, respectively. The model was able to fit four consecutive assays of the same acclimatisation process, using Brij 30 as carbon source, with different food/microorganism ratios. The parameters obtained showed that the (self-)inhibition of the growth on the second COD fraction decreased along acclimatisation.
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Occhiuto, Ilaria Giuseppina, Maria Angela Castriciano, Mariachiara Trapani, Roberto Zagami, Andrea Romeo, Robert F. Pasternack, and Luigi Monsù Scolaro. "Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin." International Journal of Molecular Sciences 21, no. 11 (June 3, 2020): 4001. http://dx.doi.org/10.3390/ijms21114001.
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Under acidic conditions and at high ionic strength, the zinc cation is removed from its metal complex with 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4) thus leading to the diacid free porphyrin, that subsequently self-organize into J-aggregates. The kinetics of the demetallation step and the successive supramolecular assembly formation have been investigated as a function of pH and ionic strength (controlled by adding ZnSO4). The demetallation kinetics obey to a rate law that is first order in [ZnTPPS4] and second order in [H+], according to literature, with k2 = 5.5 ± 0.4 M−2 s−1 at 298 K (IS = 0.6 M, ZnSO4). The aggregation process has been modeled according to an autocatalytic growth, where after the formation of a starting seed containing m porphyrin units, the rate evolves as a power of time. A complete analysis of the extinction time traces at various wavelengths allows extraction of the relevant kinetic parameters, showing that a trimer or tetramer should be involved in the rate-determining step of the aggregation. The extinction spectra of the J-aggregates evidence quite broad bands, suggesting an electronic coupling mechanism different to the usual Frenkel exciton coupling. Resonance light scattering intensity in the aggregated samples increases with increasing both [H+] and [ZnSO4]. Symmetry breaking occurs in these samples and the J-aggregates show circular dichroism spectra with unusual bands. The asymmetry g-factor decreases in its absolute value with increasing the catalytic rate kc, nulling and eventually switching the Cotton effect from negative to positive. Some inferences on the role exerted by zinc cations on the kinetics and structural features of these nanostructures have been discussed.
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Meng, Wanyao, Sijie Wang, Haifeng Lv, Zhenxing Wang, Xuewen Han, Zijing Zhou, and Junwen Pu. "Porous cellulose nanofiber (CNF)-based aerogel with the loading of zeolitic imidazolate frameworks-8 (ZIF-8) for Cu(II) removal from wastewater." BioResources 17, no. 2 (March 21, 2022): 2615–31. http://dx.doi.org/10.15376/biores.17.2.2615-2631.
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A novel biobased porous aerogel was synthesized using physical mixing, freeze-drying, and in-situ growth methods. Zeolitic imidazolate frameworks-8 (ZIF-8) were grafted onto the surface of the CS/CNF solid composite to form a ZIF-8@CS/CNF aerogel. The structural characteristics and the adsorption potential of the ZIF-8@CS/CNF aerogel were investigated. It was found that the specific surface area of the ZIF-8@CS/CNF aerogel was 206 m2/g, and the water stability of the CNF aerogel was enhanced by incorporating the CS. Meanwhile, the adsorption isotherm and kinetics of the composite aerogel fit the pseudo-second-order kinetic model (R2 = 0.96) and the Langmuir isotherm model (R2 = 0.97) with the copper(II) oxide (Cu(II)) theoretical adsorption capacity of 245 mg/g, respectively. Furthermore, this aerogel, which combined metal-organic frameworks (MOFs) and CNF, was easy to fabricate and it was biodegradable. These characteristics suggest it has a broad potential for wastewater treatment.
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Vidya, Y. S., and B. N. Lakshminarasappa. "Preparation, Characterization, and Luminescence Properties of Orthorhombic Sodium Sulphate." Physics Research International 2013 (December 24, 2013): 1–7. http://dx.doi.org/10.1155/2013/641631.
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A highly efficient thermoluminescence Na2SO4 phosphor with thenardite polymorphic structure was prepared by simple slow evaporation technique followed by subsequent calcination at 200°C, 400°C, and 600°C for 4 h and the resultant crystals were characterized by various analytical techniques. All the samples exhibited thermodynamically stable thenardite phase and the grain growth was increased for the calcined samples. SEM analysis indicated the fine distribution of twinned orthogonal prism and pyramidal structure without any agglomeration. The electron spin resonance spectroscopy showed the existence of SO4- radicals as trap centre. The thermoluminescence behavior suggested the charge carrier recombination dynamics in the thenardite sample followed second-order kinetics. The trapping parameters such as activation energy (E), order of kinetics (b), and frequency factor (s) have been determined using Chen’s peak shape method. Further fading of the TL intensity of Na2SO4 showed that thenardite is quite suitable for radiation dosimetry even up to 15 days. The photoluminescence band of Na2SO4 reduced in its intensity after γ-irradiation, suggesting that defects are unstable and decay rapidly.
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Engberg, Göran, Ida Kero, and Karin Yvell. "Modeling Microstructure Development during Hot Working of an Austenitic Stainless Steel." Materials Science Forum 753 (March 2013): 423–26. http://dx.doi.org/10.4028/www.scientific.net/msf.753.423.
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A number of physically based models are combined in order to predict microstructure development during hot deformation. The models treat average values for the generation and recovery of vacancies and dislocations, recrystallization and grain growth and the dissolution and precipitation of second phase particles. The models are applied to a number of laboratory experiments made on 304 austenitic stainless steel and the model parameters are adjusted from those used for low alloyed steel mainly in order to obtain the right kinetics for the influence of solute drag on climb of dislocations and on grain growth. The thermodynamic data are obtained using Thermo-Calc© to create solubility products for the possible secondary phases. One case of wire rolling has been analyzed mainly concerning the evolution of recrystallization and grain size. The time, temperature and strain history has been derived using process information. The models are shown to give a fair description of the microstructure development during hot working of the studied austenitic stainless steel.
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Janke, Wolfhard, Suman Majumder, and Subir K. Das. "Universal finite-size scaling function for coarsening in the Potts model with conserved dynamics." Journal of Physics: Conference Series 2122, no. 1 (November 1, 2021): 012009. http://dx.doi.org/10.1088/1742-6596/2122/1/012009.
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Abstract We study kinetics of phase segregation in multicomponent mixtures via Monte Carlo simulations of the q-state Potts model, in two spatial dimensions, for 2 ≤ q ≤ 20. The associated growth of domains in finite boxes, irrespective of q and temperature, can be described by a single universal finite-size scaling function, with only the introduction of a nonuniversal metric factor in the scaling variable. Our results show that although the scaling function is independent of the type of transition, the q-dependence of the metric factor hints to a crossover at q = 5 where the type of transition in the model changes from second to first order.
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Molavi, Roya, Majid Baghernejad, Reza Ghasemi-Fasaei, and Mehdi Zarei. "Release characteristics of potassium from native reserves of some calcareous soils of Iran and their relationship with yield and potassium uptake by ryegrass (Lolium perenne L.)." Soil Research 58, no. 8 (2020): 770. http://dx.doi.org/10.1071/sr20181.
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Information on the release of potassium (K) reserves in soils can improve K-fertiliser management. The purpose of this study was to investigate the available K-release capacity of soils and its relationship with plant responses in three soil orders. Six consecutive ryegrass cultivations were conducted on nine soil samples from surface (0–30 cm) horizons of Vertisols, Alfisols, and Inceptisols of three sites with different temperature and precipitation under greenhouse conditions. The K release was investigated using 0.2 M sodium tetraphenylboron extractant during 0.2–144 h. The cumulative release of K ranged within 243–895 mg kg–1 at 0.2 h and 620–1788 mg kg–1 at 144 h. Kinetics of K release from soils at two time intervals (0.2–2 and 2–144 h) were described well by power function and pseudo second-order equations. The growth of ryegrass was somewhat stunted after six consecutive cultivations. Significant correlations were observed between dry matter and K uptake of ryegrass. The parameters of the best fitted kinetic models were significantly correlated with plant responses, especially the uptake of K by ryegrass.
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Boukarma, Latifa, Rachid Aziam, Said Baroud, Elhassane Eddaoudi, Fouad Sinan, Issam Sadki, Saida Tahrouch, and Mohamed Chiban. "Kinetic and equilibrium isotherm studies for the removal of acid blue 113 dye by dried corallina officinalis alga as a novel eco-friendly adsorbent." E3S Web of Conferences 240 (2021): 02004. http://dx.doi.org/10.1051/e3sconf/202124002004.
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Water pollution is an alarming problem in developing countries. Dried algae can be considered as potential and suitable bio-sorbents due to their fast and easy growth and high availability. The special surface properties of these algae allow them to adsorb different types of organic and inorganic pollutants from solutions. In this context, the removal of anionic acid blue 113 dye (AB113) from aqueous solutions by dried Corallina officinalis alga as low-cost bio-sorbent was chosen as a case study of a typical remediation process of water contaminants. The effect of various environmental and physicochemical parameters has been studied. The results show that the equilibrium adsorption was established within 120 min. The sorption phenomenon was investigated by determining the process kinetics at different concentrations and the adsorption isotherms at different temperatures. The kinetics results showed that the pseudo second-order kinetics model generates the best agreement with the experimental data. The modeling results showed that linear Langmuir and Freundlich models appear to fit the adsorption data better than Temkin model for the adsorption of AB113 onto dried C. officinalis alga. It can be concluded that C. Officinalis alga can be successfully used as adsorbent.
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Llusco, Aleksei, Mario Grageda, and Svetlana Ushak. "Kinetic and Thermodynamic Studies on Synthesis of Mg-Doped LiMn2O4 Nanoparticles." Nanomaterials 10, no. 7 (July 19, 2020): 1409. http://dx.doi.org/10.3390/nano10071409.
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In this work, a first study on kinetics and thermodynamics of thermal decomposition for synthesis of doped LiMn2O4 nanoparticles is presented. The effect of Mg doping concentration on thermal decomposition of synthesis precursors, prepared by ultrasound-assisted Pechini-type sol–gel process, and its significance on nucleation and growth of Mg-doped LiMn2O4 nanoparticles was studied through a method based on separation of multistage processes in single-stage reactions by deconvolution and transition state theory. Four zones of thermal decomposition were identified: Dehydration, polymeric matrix decomposition, carbonate decomposition and spinel formation, and spinel decomposition. Kinetic and thermodynamic analysis focused on the second zone. First-order Avrami-Erofeev equation was selected as reaction model representing the polymer matrix thermal decomposition. Kinetic and thermodynamic parameters revealed that Mg doping causes an increase in thermal inertia on conversion rate, and CO2 desorption was the limiting step for formation of thermodynamically stable spinel phases. Based on thermogravimetry experiments and the effect of Mg on thermal decomposition, an optimal two-stage heat treatment was determined for preparation of LiMgxMn2−xO4 (x = 0.00, 0.02, 0.05, 0.10) nanocrystalline powders as promising cathode materials for lithium-ion batteries. Crystalline structure, morphology, and stoichiometry of synthesized powders were characterized by XRD, FE-SEM, and AAS, respectively.
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Alvarado, Karen, Ilusca Janeiro, Sebastian Florez, Baptiste Flipon, Jean-Michel Franchet, Didier Locq, Christian Dumont, Nathalie Bozzolo, and Marc Bernacki. "Dissolution of the Primary γ′ Precipitates and Grain Growth during Solution Treatment of Three Nickel Base Superalloys." Metals 11, no. 12 (November 28, 2021): 1921. http://dx.doi.org/10.3390/met11121921.
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Second phase particles (SPP) play an essential role in controlling grain size and properties of polycrystalline nickel base superalloys. The understanding of the behavior of these precipitates is of prime importance in predicting microstructure evolutions. The dissolution kinetics of the primary γ′ precipitates during subsolvus solution treatments were investigated for three nickel base superalloys (René 65, AD730 and N19). A temperature-time codependency equation was established to describe the evolution of primary γ′ precipitates of each material using experimental data, the Thermo-Calc software and the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model. The dissolution kinetics of precipitates was also simulated using the level-set (LS) method and the former phenomenological model. The precipitates are represented using an additional LS function and a numerical treatment around grain boundaries in the vicinity of the precipitates is applied to reproduce their pinning pressure correctly. Thus, considering the actual precipitate dissolution, these simulations aim to predict grain size evolution in the transient and stable states. Furthermore, it is illustrated how a population of Prior Particle Boundaries (PPB) particles can be considered in the numerical framework in order to reproduce the grain size evolution in the powder metallurgy N19 superalloy. The proposed full-field strategy is validated and the obtained results are in good agreement with experimental data regarding the precipitates and grain size.
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Li, Yongmei, Arthur Karlin, John D. Loike, and Samuel C. Silverstein. "Determination of the Critical Concentration of Neutrophils Required to Block Bacterial Growth in Tissues." Journal of Experimental Medicine 200, no. 5 (September 6, 2004): 613–22. http://dx.doi.org/10.1084/jem.20040725.
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We showed previously that the competition between bacterial killing by neutrophils and bacterial growth in stirred serum-containing suspensions could be modeled as the competition between a first-order reaction (bacterial growth) and a second-order reaction (bacterial killing by neutrophils). The model provided a useful parameter, the critical neutrophil concentration (CNC), below which bacterial concentration increased and above which it decreased, independent of the initial bacterial concentration. We report here that this model applies to neutrophil killing of bacteria in three-dimensional fibrin matrices and in rabbit dermis. We measured killing of 103–108 colony forming units/ml Staphylococcus epidermidis by 105–108 human neutrophils/ml in fibrin gels. The CNC was ∼4 × 106 neutrophils/ml gel in the presence of normal serum and ∼1.6 × 107 neutrophils/ml gel in the presence of C5-deficient serum. Application of our model to published data of others on killing of ∼5 × 107 to 2 × 108 E. coli/ml rabbit dermis yielded CNCs from ∼4 × 106 to ∼8 × 106 neutrophils/ml dermis. Thus, in disparate tissues and tissuelike environments, our model fits the kinetics of bacterial killing and gives similar lower limits (CNCs) to the neutrophil concentration required to control bacterial growth.
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JUNEJA, VIJAY K., SUDARSAN MUKHOPADHYAY, DIKE UKUKU, CHENG-AN HWANG, VIVIAN C. H. WU, and HARSHAVARDHAN THIPPAREDDI. "Interactive Effects of Temperature, pH, and Water Activity on the Growth Kinetics of Shiga Toxin–ProducingEscherichia coli O104:H4†." Journal of Food Protection 77, no. 5 (May 1, 2014): 706–12. http://dx.doi.org/10.4315/0362-028x.jfp-13-387.
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The risk of non-O157 Shiga toxin–producing Escherichia coli strains has become a growing public health concern. Several studies characterized the behavior of E. coli O157:H7; however, no reports on the influence of multiple factors on E. coli O104:H4 are available. This study examined the effects and interactions of temperature (7 to 46°C), pH (4.5 to 8.5), and water activity (aw; 0.95 to 0.99) on the growth kinetics of E. coli O104:H4 and developed predictive models to estimate its growth potential in foods. Growth kinetics studies for each of the 23 variable combinations from a central composite design were performed. Growth data were used to obtain the lag phase duration (LPD), exponential growth rate, generation time, and maximum population density (MPD). These growth parameters as a function of temperature, pH, and aw as controlling factors were analyzed to generate second-order response surface models. The results indicate that the observed MPD was dependent on the pH, aw, and temperature of the growth medium. Increasing temperature resulted in a concomitant decrease in LPD. Regression analysis suggests that temperature, pH, and aw significantly affect the LPD, exponential growth rate, generation time, and MPD of E. coli O104:H4. A comparison between the observed values and those of E. coli O157:H7 predictions obtained by using the U.S. Department of Agriculture Pathogen Modeling Program indicated that E. coli O104:H4 grows faster than E. coli O157:H7. The developed models were validated with alfalfa and broccoli sprouts. These models will provide risk assessors and food safety managers a rapid means of estimating the likelihood that the pathogen, if present, would grow in response to the interaction of the three variables assessed.
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Chen, Ya, Ruifeng Shan, and Xiaoyin Sun. "Adsorption of cadmium by magnesium-modified biochar at different pyrolysis temperatures." BioResources 15, no. 1 (December 11, 2019): 767–86. http://dx.doi.org/10.15376/biores.15.1.767-786.
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Metal pollution in soil is an increasing concern. Cadmium poses significant risks to ecosystems, and methodologies for its removal, including adsorption, have been researched. There are several environmentally friendly adsorbing materials (such as Biochar) for Cd removal. In this study, to improve the adsorptive capacity of Cd, coconut and peanut shells were used as raw materials to prepare Biochar at 300 °C and 600 °C. The effects of the pyrolysis temperature and material type on the physicochemical properties of the adsorbents were investigated by elemental analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. Magnesium-loaded BC was synthesized to determine its Cd2+ absorptivity. The adsorption characteristics and mechanisms of Cd2+ in an aqueous phase were studied through batch adsorption experiments. The results demonstrated that the pseudo-second-order kinetics model accurately described the adsorption kinetics of adsorbents of Cd2+. The adsorption behavior of the Cd2+ adsorbent conforms to the single layer adsorption described by the Langmuir model. Adsorption of Cd2+ involves a spontaneous endothermic process. The initial pH of the solution greatly influenced the adsorption of Cd2+ and showed a trend of rapid growth and then slow growth. Thus, magnesium-modified biomass carbon has good potential for applications in pollutant remediation.
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Alhindawy, Elshehy, El-Khouly, Abdel-Monem, and Atrees. "Fabrication of Mesoporous NaZrP Cation-Exchanger for U(VI) Ions Separation from Uranyl Leach Liquors." Colloids and Interfaces 3, no. 4 (October 8, 2019): 61. http://dx.doi.org/10.3390/colloids3040061.
Full textAbstract:
As the demand for uranium production-based energy worldwide has been increasing in the last decades to maintain nuclear growth for electricity production, there are great efforts towards developing an easy and inexpensive method for uranium extraction and separation from its ores. For this purpose, mesoporous inorganic cation exchangers provide an efficient separation technology that can help streamline production and lower overall cost. This study describes the development of nano-structured mesoporous sodium zirconium phosphate (NaZrP-CEX) for separation and extraction of uranyl ions from real samples. The fabricated NaZrP-CEX was well characterized by various techniques such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), N2 adsorption/desorption, Dynamic light scattering (DLS) and zeta potential). The kinetics/thermodynamic behaviors of uranyl ion adsorption into NaZrP-CEX from an aqueous solution were minutely studied. The kinetic studies showed that the pseudo-second order model gave a better description for the uptake process. The negative value of ΔG indicate high feasibility and spontaneity of adsorption. Finally, mesoporous NaZrP-CEX can be regenerated using both of HNO3 (0.05 M) or HCl (1 M) up to seven cycles of operation.
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Ortiz-Domínguez, M., O. A. Gómez-Vargas, G. Ares de Parga, G. Torres-Santiago, R. Velázquez-Mancilla, V. A. Castellanos-Escamilla, J. Mendoza-Camargo, and R. Trujillo-Sánchez. "Modeling of the Growth Kinetics of Boride Layers in Powder-Pack Borided ASTM A36 Steel Based on Two Different Approaches." Advances in Materials Science and Engineering 2019 (October 7, 2019): 1–12. http://dx.doi.org/10.1155/2019/5985617.
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An indispensable tool to choose the suitable process parameters for obtaining boride layer of an adequate thickness is the modeling of the boriding kinetics. In this work, two mathematical approaches were used in order to determine the value of activation energy in the Fe2B layers on ASTM A36 steel during the iron powder-pack boriding in the temperature range of 1123–1273 K for treatment times between 2 and 8 h. The first approach was based on the mass balance equation at the interface (Fe2B/substrate) and the solution of Fick’s second law under steady state (without time dependent). The second approach was based on the same mathematical principles as the first approach for one-dimensional analysis under non-steady-state condition. The measurements of the thickness (Fe2B), for different temperatures of boriding, were used for calculations. As a result, the boron activation energy for the ASTM A36 steel was estimated as 161 kJ·mol−1. This value of energy was compared between both models and with other literature data. The Fe2B layers grown on ASTM A36 steel were characterized by use of the following experimental techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray Spectroscopy (EDS). Finally, the experimental value of Fe2B layer’s thickness obtained at 1123 K with an exposure time of 2.5 h was compared with the predicted thicknesses by using these two approaches. A good concordance was achieved between the experimental data and the simulated results.
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Mukherjee, Smita, Marie-Claude Fauré, Michel Goldmann, and Philippe Fontaine. "Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth." Beilstein Journal of Nanotechnology 6 (December 15, 2015): 2406–11. http://dx.doi.org/10.3762/bjnano.6.247.
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In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal–organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters.
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Hamed, Mostafa M., I. M. Ahmed, and M. Holiel. "Retention behavior of anionic radionuclides using metal hydroxide sludge." Radiochimica Acta 107, no. 12 (November 26, 2019): 1161–72. http://dx.doi.org/10.1515/ract-2019-0010.
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Abstract With the speedy growth of nuclear power production, the removal and disposal of radioactive nuclides such as 129I, 99Tc, 79Se, 36Cl, 93Mo, and 137Cs become major environmental security issues. Retention of these radionuclides, especially anionic species such as 129I (t1/2 1.7 × 107 years), 93Mo (t1/2 4 × 103 years) and 79Se (t1/2 3.27 × 105 years) has been challenging. 129I, 93Mo and 79Se bind very weakly to most sorbents and deposits. This study has examined the sorption potential of Metal hydroxide sludge (MHS) for 125I (t1/2 60.2 days), 99Mo (t1/2 2.75 days) and 75Se (t1/2 120 days) as a surrogate for 129I, 93Mo and 79Se, respectively. MHS has been characterized by different techniques and the factors affecting the sorption processes were investigated. The experimental data were analyzed using kinetic models and thermodynamic parameters. The results showed that the kinetics of sorption of 125I and 99Mo on MHS proceeds according to the pseudo-first-order, on the contrary of 75Se sorption follows pseudo second-order kinetic model. The maximum sorption capacity of MHS was found to be 51.2 mg/g, 46.5 mg/g and 40.2 mg/g for 125I, 99Mo and 75Se, respectively. It can be concluded that, in the case of release of anionic radionuclide species to the surroundings the MHS could act as a succeeded and economical sorbent material for retention of different anionic radionuclides such as 133, 129I, 79Se, 36Cl, 93, 99Mo, and 99Tc. To avoid the release of such anionic species from the stored nuclear wastes to the environment.
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Teng, Chun Yu, Yun Fu, Zhan Yong Ren, Yong Hong Li, Yun Wang, and Wen Li Ouyang. "Phase Field Simulation of Grain Growth with Particle Pinning." Key Engineering Materials 724 (December 2016): 8–11. http://dx.doi.org/10.4028/www.scientific.net/kem.724.8.
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The properties of alloys depend on its microstructure, such as the size of grains. In general, the balanced mechanical properties of alloys can be obtained with small grain size. While the grain size of alloys may increases under heat treatment, thermal mechanical processing and service condition of high temperature, i.e., the grain growth is inevitable. The effort of most research is to control the rate of grain growth and avoid abnormal grain growth. For example, pinning the grain boundary and reduce its mobility with the second phase particles in order to prevent grain growth. Therefore, the properties of the alloys will not decreases dramatically and the structure retains a high degree of integrity. The details of grain growth with particle pinning were investigated by phase field simulations in the present paper. It is found that, with the same size of pinning particles, the pinning effect increases with the increases of the pinning particle number. With the same pinning particle number, the pinning effect increases with the increases of pinning particle size. Under the same total volume of pinning particles while different particle size and number, the pinning effect is complicated and it will be discussed in details. The pinning effect decreases with the increases of grain boundary energy. These findings could shed light on the understanding of the grain growth kinetics with particle pinning.
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Leigh, William J., Ileana G. Dumbrava, and Farahnaz Lollmahomed. "Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution." Canadian Journal of Chemistry 84, no. 7 (July 1, 2006): 934–48. http://dx.doi.org/10.1139/v06-107.
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Photolysis of 1,3,4-trimethyl-1-phenylgermacyclopent-3-ene (5) in hydrocarbon solvents containing isoprene, methanol, or acetic acid affords 2,3-dimethyl-1,3-butadiene (DMB) and the expected trapping products of methyl phenylgermylene (GeMePh) in chemical yields exceeding 90%. The germylene has been detected in hexane solution by laser flash photolysis as a short-lived species (τ ~ 2 µs) exhibiting a UV-vis absorption spectrum centered at λmax = 490 nm. It decays with second-order kinetics and a rate constant close to the diffusion-controlled limit, with the concomitant growth of a second longer-lived transient (λmax = 420 nm) that is assigned to a mixture of (E)- and (Z)-1,2-dimethyl-1,2-diphenyldigermene (4). Absolute rate constants have been determined for the reactions of the germylene with primary and tertiary amines (n-BuNH2 and Et3N, respectively), acetic acid (AcOH), a terminal alkyne and alkene, isoprene, DMB, CCl4, and the group 14 hydrides Et3SiH and Bu3SnH. GeMePh is slightly more reactive than GePh2 towards all the reagents studied in this work; both are significantly less reactive than GeMe2 toward the same substrates. Absolute rate constants for the reactions of 4 have also been measured or assigned upper limits in every case and are compared to previously reported values for tetraphenyl- and tetramethyl-digermene with the same reagents.Key words: germylene, digermene, kinetics, laser flash photolysis, germirane, germirene, vinylgermirane, complex, UV–vis spectrum, insertion, addition.
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Li, Fan, Thomas Shean Yaw Choong, Soroush Soltani, Luqman Chuah Abdullah, and Siti Nurul Ain Md. Jamil. "Kinetic Study of Fenton-Like Degradation of Methylene Blue in Aqueous Solution Using Calcium Peroxide." Pertanika Journal of Science and Technology 30, no. 2 (March 14, 2022): 1087–102. http://dx.doi.org/10.47836/pjst.30.2.13.
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The textile industry is one of the fastest-growing industries that significantly contribute to the economic growth in Malaysia. Dyeing wastewater is one of the more difficult to control in industrial wastewater. Methylene blue is a widely used dye in the textile industry, which cannot be discharged directly into the natural environment without treatment. The present study involves the degradation of methylene blue by a Fenton-like system using calcium peroxide (CaO2, CP). The process of degradation was recorded spectrophotometrically. The field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) were measured for testing the purchased commercial calcium peroxide. The effect of pH, the initial dosage of CaO2, and temperatures were studied with kinetics modeling, respectively. The results indicated that 97.07% removal of methylene blue took place at the optimum condition (pH=3.0, initial CaO2, dosage=3.0 g, 65°C, 150 rpm, contact time=60 minutes). Over four models (zero-order, first-order, second-order, Behnajady, Modirshahla, and Ghanbary (BMG) model) applied in this study, the BMG model with the R2=0.9935 was in accordance with the experimental data.
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Gawhane, Supriya. "Scavenging of Nickel(II) from Aqueous Wastes by Adsorption with Granular Activated Carbon (GAC)." Applied Mechanics and Materials 612 (August 2014): 187–92. http://dx.doi.org/10.4028/www.scientific.net/amm.612.187.
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Due to explosive growth of industrial and agricultural activities, there is rise in pollutants in water including heavy metals and toxic elements. In light of increasing pollution load of environment it is imperative to address this problem by different approaches and means.Of the numerous unit processes, evaluated to control pollution, to a degree, adsorption by GAC is one of the best available broad spectrum technologies. Scavenging of a precious metal such as Nickel, present in aqueous systems can be carried out with or without use of carrier such as 8-hydroxyquinoline (Oxine) and its derivatives on various grades of as received activated carbons. The carrier improves uptake of metal ions by GAC. The adsorption process agrees with the Langmuir and Freundlich models and also obeys pseudo-second order kinetics.
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Shantz, N. C., R. Y. W. Chang, J. G. Slowik, J. P. D. Abbatt, and W. R. Leaitch. "Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site." Atmospheric Chemistry and Physics Discussions 9, no. 3 (June 23, 2009): 13775–99. http://dx.doi.org/10.5194/acpd-9-13775-2009.
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Abstract. Growth rates of water droplets were measured with a static diffusion cloud condensation chamber in May–June 2007 at a rural field site in Southern Ontario, Canada, 70 km north of Toronto. Observations were made during periods when the winds were from the south and the site was impacted by anthropogenic air from the US and Southern Ontario as well as during a 5-day period of northerly wind flow when the aerosol was dominated by biogenic sources. The growth of droplets on anthropogenic size-selected particles centred at 0.1 μm diameter and composed of approximately 40% organic and 60% ammonium sulphate (AS) by mass, was delayed on the order of 1 second compared to a pure AS aerosol. Simulations of the growth rate indicate that a lowering of the water mass accommodation coefficient from αc=1 to an average of αc=0.044 is needed (assuming an insoluble organic with hygroscopicity parameter, κorg, of zero). In contrast, the growth rate of the aerosol of biogenic character, consisting of >80% organic, was similar to that of pure AS. Simulations of the predominantly biogenic aerosol show agreement between the observations and simulations when κorg=0.05–0.2 and αc=1. Inhibition of water uptake by the anthropogenic organic applied to an adiabatic cloud parcel model in the form of a constant low αc increases the number of droplets in a cloud compared to pure AS. If the αc is assumed to increase with increasing liquid water on the droplets, then the number of droplets decreases which could diminish the indirect effect. The slightly lower κorg in the biogenic case decreases the number of droplets in a cloud compared to pure AS.
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Hamoudi, Souhila Ait, Boualem Hamdi, and Jocelyne Brendlé. "Tetracycline Removal from Water by Adsorption on Geomaterial, Activated Carbon and Clay Adsorbents." Ecological Chemistry and Engineering S 28, no. 3 (September 1, 2021): 303–28. http://dx.doi.org/10.2478/eces-2021-0021.
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Abstract The use of antibiotics for breeding and for humans increased considerably in recent years, as a dietary supplement to enhance animal growth. This frequent use leads to the detection of residues in water and wastewater. Thus, the emergence of new strains of bacteria resistant to these antibiotics and, can lead to incurable diseases of livestock, and can lead to a possible transmission of these strains to humans. The purpose of this work is to develop new materials based on treated Maghnia clay, activated carbon, cement, and PVA polymer, named geomaterials. These materials were intended for the containment of hazardous wastes in landfills. The removal of tetracycline from aqueous solution was tested by adsorption onto synthesised geomaterials and their mineral constituents. Adsorption kinetics revealed that tetracycline was rapidly retained by GM and ATMa. This was confirmed by the relatively short equilibrium time of 30 min. The pseudo-second-order and intraparticle models well fitted the adsorption kinetic of the TC-adsorbent studied systems. It was noticed that the adsorption kinetic passes through several mechanisms, was demonstrated by the multi-linearity on the plot of qt against the square root of t. The adsorption capacity (Qa ) of TC onto GM is pH-dependent. Indeed, Qa reaches a maximum value (Qa = 12.58 mg ∙ g–1 at a very acidic pH of 2, then the adsorbed amount decreases to reach a minimum value at pH of 8, and for basic pHsQa increases up to 10 mg ∙ g–1.
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Velázquez-Carriles, Carlos, María Esther Macías-Rodríguez, Omar Ramírez-Alvarado, Rosa Isela Corona-González, Adriana Macías-Lamas, Ismael García-Vera, Adriana Cavazos-Garduño, Zuamí Villagrán, and Jorge Manuel Silva-Jara. "Nanohybrid of Thymol and 2D Simonkolleite Enhances Inhibition of Bacterial Growth, Biofilm Formation, and Free Radicals." Molecules 27, no. 19 (September 20, 2022): 6161. http://dx.doi.org/10.3390/molecules27196161.
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Due to the current concerns against opportunistic pathogens and the challenge of antimicrobial resistance worldwide, alternatives to control pathogen growth are required. In this sense, this work offers a new nanohybrid composed of zinc-layered hydroxide salt (Simonkolleite) and thymol for preventing bacterial growth. Materials were characterized with XRD diffraction, FTIR and UV–Vis spectra, SEM microscopy, and dynamic light scattering. It was confirmed that the Simonkolleite structure was obtained, and thymol was adsorbed on the hydroxide in a web-like manner, with a concentration of 0.863 mg thymol/mg of ZnLHS. Absorption kinetics was described with non-linear models, and a pseudo-second-order equation was the best fit. The antibacterial test was conducted against Escherichia coli O157:H7 and Staphylococcus aureus strains, producing inhibition halos of 21 and 24 mm, respectively, with a 10 mg/mL solution of thymol–ZnLHS. Moreover, biofilm formation of Pseudomonas aeruginosa inhibition was tested, with over 90% inhibition. Nanohybrids exhibited antioxidant activity with ABTS and DPPH evaluations, confirming the presence of the biomolecule in the inorganic matrix. These results can be used to develop a thymol protection vehicle for applications in food, pharmaceutics, odontology, or biomedical industries.
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Zhang, Yanyan, Hao Liu, Junyan Cui, Xiaosong Bai, Daoyuan Yang, Huiyu Yuan, and Baoming Wang. "Research on the Thickness and Microstructure of Plate-like TiO2 by the Nanosheet-Seeding Growth Technique." Coatings 12, no. 11 (November 4, 2022): 1673. http://dx.doi.org/10.3390/coatings12111673.
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The nanosheet-seeding growth (NSG) technique is an interesting synthesis method for preparing two-dimensional (2D) materials by employing ultrathin nanosheets as templates. In this work, the synthesis of 2D TiO2 nanoplates using Ti0.87O2 nanosheets via the NSG process is thoroughly studied to achieve a better understanding of this process. The influence of various synthesis conditions on the morphology and phase composition has been carefully examined. The study of synthesis time reveals that the TiO2 grows in the Stranski–Krastanov mode on the templates and the growth follows second-order kinetics. It is also found that the concentration of precursors and the synthesis time are the effective parameters in controlling the thickness of TiO2 nanoplates. The phase of the sample changes from anatase TiO2 to NH4TiOF3 and the morphology changes from flake to disk with the increase in the precursor concentration. The synthesis temperature has a large influence on the morphology and thickness of the sample but has little effect on the phase composition. However, the synthesis temperature changes the color of the sample, and a high temperature enlarges the light absorption range of the sample.
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Badea, Gabriela Elena, Lotfi Aleya, Petronel Mustatea, Delia Mirela Tit, Laura Endres, Simona Bungau, and Gabriela Cioca. "Chlorate Electrochemical Removal from Aqueous Media Based on a Possible Autocatalytic Mechanism." Revista de Chimie 70, no. 1 (February 15, 2019): 185–89. http://dx.doi.org/10.37358/rc.19.1.6878.
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The electrochemical chlorate reduction at the Pt electrode in 0.5 M H2SO4 deaerated solutions has been studied using potentiostatic steady-state voltammetry. The kinetics parameters (Tafel slope, charge transfer coefficient, current density, and reaction order) were evaluated in function of chlorate concentration (1x10-4 � 0.2 M KClO3). The process of chlorate reduction is a complex one that implies two charge transfer controlled steps with formation of free radicals and an extent potential region controlled by the concentration polarization. The current density dependence of chlorate concentration tends to an exponential growth at concentration � 0.1 M KClO3 and becomes exponential in the conditions of the catalyst system presence. In the second charge transfer, a surface reaction between free radical �Cl-2 and platinum electrode with formation of complex anions PtCL42- and PtCL62- is responsible for the rapid increase of the reaction rate.
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Li, Shifeng, Yanming Shen, Min Xiao, Dongbin Liu, Lihui Fan, and Zhigang Zhang. "Simultaneous Intercalation of 1-Naphthylacetic Acid and Indole-3-butyric Acid into Layered Double Hydroxides and Controlled Release Properties." Journal of Nanomaterials 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/862491.
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Controlled release formulations have been shown to have potential in overcoming the drawbacks of conventional plant growth regulators formulations. A controlled-release formulation of 1-naphthylacetic acid (NAA) and indole-3-butyric acid (IBA) simultaneous intercalated MgAl-layered double hydroxides (LDHs) was prepared. The synthetic nanohybrid material was characterized by various techniques, and release kinetics was studied. NAA and IBA anions located in the gallery of MgAl-LDHs with bilayer arrangement, and the nanohybrids particles were of typical plate-like shape with the lateral size of 50–100 nm. The results revealed that NAA and IBA have been intercalated into the interlayer spaces of MgAl-LDHs. The release of NAA and IBA fits pseudo-second-order model and is dependent on temperature, pH value, and release medium. The nanohybrids of NAA and IBA simultaneously intercalated in LDHs possessed good controlled release properties.
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Wu, Yangwei, Aijun Li, Su Lei, Qian Deng, and Hong Yao. "Synthetic Effects and Economic Accounting of Low-temperature Pyrolysis Process of Typical Medical Waste based on Kinetics Analysis." E3S Web of Conferences 350 (2022): 03010. http://dx.doi.org/10.1051/e3sconf/202235003010.
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The thermogravimetric (TG) analysis was adopted to study the pyrolysis characteristics of two typical medical wastes at different heating rates (10, 20, and 50 °C/min), and the kinetic parameters were analyzed by the Coats-Redfern method. Finally, the economic evaluation of the technology was carried out. The results showed that the two typical medical wastes both have only one weight loss peak. The syringes and bamboo sticks pyrolysis ranged from 264.80 to 554.07 °C and from 205.66 to 487.05 °C, respectively. With the increase of the heating rate, the initial, final and peak temperatures of the two raw materials shifted to higher values. The pyrolysis reaction mechanisms of the syringes and bamboo sticks were summarized as the nucleation growth model (A2.5) and the second-order model (F2). The total investment of medical waste pyrolysis project is 59 million yuan, and the annual net gain is 11.85 million yuan. The investment recovery period of the project takes five years.
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Diaz-Uribe, Carlos, Barni Angulo, Karen Patiño, Vincent Hernández, William Vallejo, Euler Gallego-Cartagena, Arnold R. Romero Bohórquez, Ximena Zarate, and Eduardo Schott. "Cyanobacterial Biomass as a Potential Biosorbent for the Removal of Recalcitrant Dyes from Water." Water 13, no. 22 (November 10, 2021): 3176. http://dx.doi.org/10.3390/w13223176.
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The accumulation of cyanobacteria produced due to eutrophication processes and the increment of different pollutants in water as a result of industrial processes affects aquatic environments such as the ocean, rivers, and swamps. In this work, cyanobacterial biomass was used as a biosorbent for the removal of a commercial dye, methylene blue (MB). Thus, MB was removed from biomass obtained from cyanobacterial samples collected from the swamp located in the Colombian Caribbean. Spectroscopical techniques such as FTIR, SEM, EDX measurements were used for the physico-chemical characterization of the bio-adsorbent material. Furthermore, we present the effect of various adsorption parameters such as pH, MB dose, time, and adsorbent concentration on the adsorbent equilibrium process. Three different isotherm models were used to model the MB adsorption on biomass. The functional groups identified on biomass suggest that these models are suitable for the characterization of the sorption of cationic dyes on the surfaces of the biomass; in addition, an SEM assay showed the heterogeneous surface of the biomass’ morphology. The equilibrium tests suggested a multilayer type adsorption of MB on the biomass surface. The kinetics results show that a pseudo-second order kinetic model was suitable to describe the MB adsorption on the biomass surface. Finally, the herein obtained results give an alternative to resolve the eutrophication problems generated by cyanobacterial growth in the swamp “Ciénaga de Malambo”.
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Huang, Zhong-Sheng, and Tian-Zu Yang. "Comparative Study on Refractory Gold Concentrate Kinetics and Mechanisms by Pilot Scale Batch and Continuous Bio-Oxidation." Minerals 11, no. 12 (November 29, 2021): 1343. http://dx.doi.org/10.3390/min11121343.
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Most studies conducted have focused on the pulp density, Fe3+ concentration and sulfuric acid concentration, etc., of bio-oxidation, and few have reported on the influence of different bio-oxidation methods on kinetics. In this study, a comparative investigation on refractory gold concentrate by batch and continuous bio-oxidation was conducted, with the purpose of revealing the kinetics influence. The results showed that improving the removal rates of the gold-bearing pyrite (FeS2) and arsenopyrite (FeAsS) yielded the best results for increasing gold recovery. The removal rates of S, Fe and relative gold recovery linearly increased when compared to the second-order equation increase of the As removal rate in both batch and continuous bio-oxidation processes. The removal kinetics of S and Fe by continuous bio-oxidation was 12.02% and 12.17% per 24 h day, approximately 86.64% and 51.18% higher than batch bio-oxidation, respectively. The higher removal kinetics of continuous bio-oxidation resulted from a stepwise increase in microbe growth, a larger population and higher dissolved Fe3+ and H2SO4 concentration compared to a linear increase by batch bio-oxidation. The cyanidation gold recovery was as high as 94.71% after seven days of continuous bio-oxidation, with the gold concentrate sulfur removal rates of 83.83%; similar results will be achieved after 13 days by batch bio-oxidation. The 16sRNA sequencing showed seven more microbe cultures in the initial residue than Acid Mine Drainage (AMD) at genus level. The quantitative real-time Polymerase Chain Reaction (PCR) test showed the four main functional average microbe populations of Acidithiobacillus, Leptospirillum, Ferroplasma and Sulfobacillus in continuous bio-oxidation residue as 1.08 × 103 higher than in solution. The multi-microbes used in this study have higher bio-oxidation activity and performance in a highly acidic environment since some archaea co-exist and co-contribute.
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Toffolon-Masclet, Caroline, Clara Desgranges, Carolina Corvalan-Moya, and Jean Christophe Brachet. "Simulation of the β→α(O) Phase Transformation due to Oxygen Diffusion during High Temperature Oxidation of Zirconium Alloys." Solid State Phenomena 172-174 (June 2011): 652–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.652.
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The EKINOX numerical code, formerly developed to simulate high temperature oxidation of Ni alloys, has been recently adapted to solve out the issue of high temperature oxidation of Zirconium alloys. This numerical code is a one dimensional model that simulates the growth of an oxide layer using a specific algorithm for moving boundaries problem. In order to simulate the oxygen diffusion inside Zr alloys, an adaptation of the EKINOX code was necessary. It consisted in adding, first, a non-null oxygen equilibrium concentration in the substrate and second, a new interface in order to simulate the β/α(O) phase transformation due to oxygen diffusion. In this study, EKINOX has also been coupled with the thermodynamic database for zirconium alloys ZIRCOBASE (thermocalc formalism) in order to obtain accurate concentrations values in each phases (considering local equilibrium at each interface). The present paper illustrates the simulation ability of the code by comparing experimental and calculated oxygen diffusion profiles corresponding to different cases, from isothermal oxidations at high temperature (900 < T < 1250°C) to the study of dissolution kinetics of a pre-transient oxide layer under a neutral environment. The influence of pre-hydriding from a few hundreds up to thousands weight-ppm is also derived from the calculations.
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Liao, Su Ran, Yuan Wei, Yu Qi Zhang, Meng Zhang, and Gao Fei Feng. "Study on the Reaction of TDI and PPG with Organo-Tin Mixed Catalyst." Advanced Materials Research 418-420 (December 2011): 13–17. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.13.
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The study of polyurethanes are of continuing interest due to their excellent physical properties. In this study, the reaction kinetics and polymerization conditions in two-step process of toluene diisocyante (TDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by di-n-butylamine back-titration. It was showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of TDI and PPG reaction at 50, 60 and 70°C were 0.0922, 0.3373 and 0.5828 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 71.63 kJ•mol-1. The number average molecular weight (Mn) and molecular-weight distribution (Mw/Mn) of the polyurethane were 45175 and 1.53, respectively, and the content of hydrogen bonding in the N-H group from Fourier transform infrared spectrum (FTIR) was 80.75%, which manifested that the large amount of N-H were present in hydrogen bonding.