Journal articles: 'Specific surface area packing'

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B, Narandalai, W. G. Shim, M. S. Balathanigaimani, and H. Moon. "Influence of compressing pressure on macro void formation of carbon monolith for methane adsorption." Mongolian Journal of Chemistry 18, no. 44 (February 13, 2018): 24–35. http://dx.doi.org/10.5564/mjc.v18i44.934.

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Carbon monoliths for adsorbed natural gas (ANG) storage were prepared from Mongolian anthracite-based activated carbons using carboxy-methyl cellulose as a binder under different compressing pressures. Nitrogen adsorption/desorption experiments were carried out to obtain the specific surface area, pore volume, and pore size distribution of the monoliths. Methane adsorption experiments on the carbon monoliths were conducted at different temperatures and pressures up to around 3.5 MPa in a high pressure volumetric adsorption apparatus. As expected, adsorption results indicated that the methane adsorption capacity of the carbon monoliths increased with increasing specific surface area and packing density. The maximum volumetric adsorption of methane was observed as 163 V/V at 293 K and 3.5 MPa on a carbon monolith sample, PMAC1/2-3-65, that does not have the highest specific surface area but relatively high packing density comparing with other monoliths, which implies that two physical properties contribute contradictorily to the methane adsorption capacity. Based on experimental results, the carbon monoliths prepared from Mongolian anthracite-based activated carbons can be promising media for ANG storage application.

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Woudberg, S., J. Van Jaarsveld, and E. Dumont. "Predicting the pressure drop of a biofilter and the specific surface area of the packing material." Powder Technology 342 (January 2019): 233–45. http://dx.doi.org/10.1016/j.powtec.2018.09.059.

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Cimerman, Richard, Mária Cíbiková, Leonid Satrapinskyy, and Karol Hensel. "The Effect of Packing Material Properties on Tars Removal by Plasma Catalysis." Catalysts 10, no. 12 (December 17, 2020): 1476. http://dx.doi.org/10.3390/catal10121476.

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Plasma catalysis has been utilized in many environmental applications for removal of various hydrocarbons including tars. The aim of this work was to study the tars removal process by atmospheric pressure DBD non-thermal plasma generated in combination with packing materials of various composition and catalytic activity (TiO2, Pt/γAl2O3, BaTiO3, γAl2O3, ZrO2, glass beads), dielectric constant (5–4000), shape (spherical and cylindrical pellets and beads), size (3–5 mm in diameter, 3–8 mm in length), and specific surface area (37–150 m2/g). Naphthalene was chosen as a model tar compound. The experiments were performed at a temperature of 100 °C and a naphthalene initial concentration of approx. 3000 ppm, i.e., under conditions that are usually less favorable to achieve high removal efficiencies. For a given specific input energy of 320 J/L, naphthalene removal efficiency followed a sequence: TiO2 > Pt/γAl2O3 > ZrO2 > γAl2O3 > glass beads > BaTiO3 > plasma only. The efficiency increased with the increasing specific surface area of a given packing material, while its shape and size were also found to be important. By-products of naphthalene decomposition were analyzed by means of FTIR spectrometry and surface of packing materials by SEM analysis.

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Chen, Zhi Li, Kai Sheng Xiong, Wan Tu Zhang, Wen Biao Wang, Wen Ping Chen, Hua Qiao, Yi Yang, and Wei Ping Gu. "On the Development and Performance Test of Combined Packing Integrated Device for Treating Domestic Sewage Aboard Ships." Applied Mechanics and Materials 66-68 (July 2011): 2153–57. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.2153.

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This paper elaborates on the development of elastic combined packing and an integrated device for treating domestic sewage aboard ships, analyzes the growth of combined packing microorganisms, the speed of membrane forming as well as the impact of raw water quality on membrane forming, and conducts a simulation experiment of treating domestic sewage by membrane bio-reactors. Researches show that elastic combined packing features high specific surface area and high speed of membrane forming and that this integrated domestic sewage treatment device performs well and can be widely applied.

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Cambedouzou, Julien, and Olivier Diat. "Measuring the specific surface area of mesoporous silica using x-ray scattering." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C599. http://dx.doi.org/10.1107/s2053273314094005.

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The development of porous silica or carbon material with high specific surface area raises a high interest in the field of materials science given their potential interest in a wide range of applications including catalysis, water treatment or drug delivery. Among these mesoporous structures, those consisting of one-dimensional pores aligned along a compact hexagonal packing are of prime importance and can be referred to as "hexagonal mesoporous materials" (HMPM). The most famous silica structures of this kind are MCM-41 and SBA-15. The same symmetry can be found in carbon mesoporous materials, for example in FDU-15 structures. The precise characterization of HMPM is necessary for most of the applications envisioned for these materials (pore size, pore density, specific surface and sometimes thickness of the functionalization layer). Small angle X-ray scattering techniques offer the opportunity to determine the mean structural parameters of HMPM. Although different approaches can be found in the literature in order to numerically reproduce the experimental data obtained on HMPM or hexagonal liquid crystals, when the sample is a powder, fitting the experimental data in absolute scale with numerical models becomes necessary. However, with a large scattering contribution of grain at low q vector as well as short range correlation contribution at large q, the analysis is not so simple. In this paper, we propose a comprehensive study [1] devoted to the quantitative interpretation of small-angle scattering patterns of HMPM in terms of structure and specific surface estimation based on the formalism proposed by Spalla et al. [2]. In the case of two real samples, namely a SBA-15 and a MCM-41 powder, the specific surface area of the mesopores is estimated and is discussed in the light of gas adsorption measurements.

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Potapov, Vadim, Roman Fediuk, and Denis Gorev. "Hydrothermal SiO2 Nanopowders: Obtaining Them and Their Characteristics." Nanomaterials 10, no. 4 (March 27, 2020): 624. http://dx.doi.org/10.3390/nano10040624.

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The technological mode of obtaining amorphous SiO2 nanopowders based on hydrothermal solutions is proposed in this study. Polycondensation of orthosilicic acid as well as ultrafiltration membrane separation, and cryochemical vacuum sublimation were used. The characteristics of nanopowders were determined by tunneling electron microscopy, low-temperature nitrogen adsorption, X-ray diffraction, and small-angle X-ray scattering. The scheme allows to adjust density, particle diameters of nanopowders, specific surface area, as well as diameters, area and volume of the pore. Thus, the structure of nanopowders is regulated—the volume fraction of the packing of spherical particles in aggregates and agglomerates, the size of agglomerates, and the number of particles in agglomerates. The pour densities of the nanopowders depend on the SiO2 content in sols, which were 0.02 to 0.3 g/cm3. Nanoparticles specific surface area was brought to 500 m2/g by low temperature polycondensation. Nanoparticle aggregates specific pore volume (0.2–0.3 g/cm3) weakly depend on powders density. The volume fraction of the packing of SiO2 nanoparticles in aggregates was 0.6–0.7. Solid samples of compacted nanopowders had a compressive strength of up to 337 MPa. Possible applications of hydrothermal SiO2 nanopowders are considered.

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Zhang, Qian Qian, Jian Zhong Liu, and Jia Ping Liu. "Influence of Ground Slag on the Rheology of Mortar." Applied Mechanics and Materials 438-439 (October 2013): 67–71. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.67.

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The effects of ground slag with different specific surface area on the rheology of mortar at water-binder ratio of 0.25, 0.28 and 0.30 were investigated, and the combined effects of packing density and solid surface area on the rheology of mortar were evaluated in terms of the water film thickness. The results show that with the increasing of specific surface area of slag (220 m2/kg-784 m2/kg), plastic viscosity and yield stress decrease. The correlations of yield stress and plastic viscosity to the water film thickness are basically linear with high correlation R2 values. The action of the ground slag on the rheology of mortar can be characterized by water film thickness, and with the increasing of water film thickness the rheological parameters decrease.

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Gun'ko, V. M. "Features of the morphology and texture of silica and carbon adsorbents." Surface 13(28) (December 30, 2021): 127–65. http://dx.doi.org/10.15407/surface.2021.13.127.

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The morphological and textural characteristics of various silicas (93 fumed silicas and 56 porous silicas), different carbons (230), and porous polymers (53) are analyzed using probe (nitrogen, argon, benzene, n-decane, water) adsorption, small angle X-ray scattering (SAXS), and transition (TEM), scanning (SEM) electron and atom force (AFM) microscopies. There are certain correlations between pore volume (Vp) and specific surface area (SSA, SBET) for these materials. Synthesis and treatment temperatures affect this relationship since a linear Vp - SBET approximation scatter decreases with decreasing these temperatures. Silicas are composed of nonporous nanoparticles (NPNP), but activated carbons (AC) are composed of porous nanoparticles (PNP). For different materials, NP are weakly or strongly packed in secondary structures. However, there are general features of pore size distributions (PSD) for NP-based materials, e.g., minimal contribution of narrow mesopores of 3-5 nm in radius due NP-packing effects. For AC produced using the same chars and activation agents but with varied activation time, the textural characteristics demonstrate smooth changes with increasing burn-off degree: nanopores partially transform into narrow mesopores with opposite PSD shifts of broad mesopores and macropores. Comparison of adsorption (open pores accessible for probes) and SAXS (both open and closed pores) data for carbons shows that the difference decreases with increasing burn-off degree due to decreasing contribution of closed pores. Most clear pictures on the particulate morphology and texture could be obtained in parallel analysis using adsorption, SAXS, and microscopic methods with appropriate data treatments.

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Avili, Mohammad Ghomi, Javad Karimi Sabet, and Seyyed Mohammad Ghoreishi. "Experimental characterization of a random packing with high specific surface area in a small diameter cryogenic distillation column." Progress in Nuclear Energy 106 (July 2018): 417–24. http://dx.doi.org/10.1016/j.pnucene.2018.03.014.

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Nikiema, Josiane, and Michèle Heitz. "The Use of Inorganic Packing Materials during Methane Biofiltration." International Journal of Chemical Engineering 2010 (2010): 1–8. http://dx.doi.org/10.1155/2010/573149.

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The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This result is probably due to its high specific surface area and to its good surface properties as compared to the other 2 tested porous materials. The influence of the nonirrigation with the nutrient solution of the biofilter is also investigated. It has been found that nonirrigation of biofilter causes the biofilter performance to decrease significantly (e.g., 45% decrease in 1 week) even with the humidification of the gas phase prior to its introduction into the biofilter.

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Wang, Haijun, Xiaogang Sun, Jianwen Wang, Yun Duan, Changsuo Zhang, Jingping Qiu, and Zhenbang Guo. "Effect of Tailings Fine Content on the Properties of Cemented Paste Backfill from the Perspective Packing Density." Advances in Civil Engineering 2021 (June 1, 2021): 1–10. http://dx.doi.org/10.1155/2021/9947620.

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In order to quantitatively study the influence of tailings fine content on the properties of cemented paste backfill (CPB) and further understand the mechanism of tailings fine content acting, the concept of packing density was introduced in this study. The packing density of each tailings sample was measured by the wet packing method after the samples with various fine contents were prepared. Moreover, CPBs with different tailings fine contents were tested by the mini slump test, rheological test, uniaxial compressive strength (UCS) test, and mercury intrusion porosimetry test. The results demonstrated that the flow spread and UCS both increase first and then decrease with the increase of tailings fine content, while the yield stress shows an opposite trend. The fine content of tailings affects the flowability of fresh CPB mainly through the packing density. When the fine content is high, the influence of the specific surface area of tailings cannot be ignored. The packing density is an important factor affecting the strength of CPB, and there is an obvious linear relationship between the packing density and UCS. The pore structure of CPB samples with different tailing fine contents is significantly different, and the macroscopic packing density changes the strength of CPB by affecting the microscopic pores.

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Ueyama, Tamotsu, and Youichi Machii. "Influence of particle diameter of alumina and specific surface area of glass flux on the packing density of green sheets." Journal of the Japan Society of Powder and Powder Metallurgy 35, no. 6 (1988): 517–20. http://dx.doi.org/10.2497/jjspm.35.517.

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Zheng, Chao, Xufeng Zhou, Hailiang Cao, Guohua Wang, and Zhaoping Liu. "Synthesis of porous graphene/activated carbon composite with high packing density and large specific surface area for supercapacitor electrode material." Journal of Power Sources 258 (July 2014): 290–96. http://dx.doi.org/10.1016/j.jpowsour.2014.01.056.

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Li, Miao Wan, Yan Zhen Yu, and Lei Cheng. "The Performance Test of Composite Zeolite Filter." Advanced Materials Research 610-613 (December 2012): 522–25. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.522.

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Use natural zeolite to prepare spherical composite zeolite filter material. With range analysis, the composite zeolite filter material’s packing density is 674Kg/m3, cylinder compressive strength is 4.32MPa, and apparent porosity is 59.02%. Compared with ceramsite, composite zeolite filter whose surface roughness has larger specific surface area and higher porosity. At the start of biofilm formation and stability of the operational phase, composite zeolite filter Biological Aerated Filter (BAF)’s ammonia removal is better than ceramsite BAF, and its Biofilm biomass is higher, thus more proper to be the carrier of BAF.

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CAMPOS, H. F., T. M. S. ROCHA, G. C. REUS, N. S. KLEIN, and J. MARQUES FILHO. "Determination of the optimal replacement content of Portland cement by stone powder using particle packing methods and analysis of the influence of the excess water on the consistency of pastes." Revista IBRACON de Estruturas e Materiais 12, no. 2 (April 2019): 210–32. http://dx.doi.org/10.1590/s1983-41952019000200002.

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Abstract Cement is considered the basic component with the highest environmental impact in construction, in terms of CO2 emissions. As for the aggregates, the process of comminution of rocks, in addition to artificial sand, generates stone powder that ends up being stored outdoors, generating environmental damages. Thus, the replacement of cement by stone powder appears as an attractive alternative towards the sustainable concretes. In this context, the objective of this paper is to determine the maximum packing density in Portland cement, silica fume and stone dust pastes, to determine the optimal cement substitution content for the stone powder. In addition, it is intended to verify the influence of excess water on the consistency of the mixtures produced. The substitution was done in contents equal to 0%, 7%, 14% and 21% by volume and, for each content, the packing density was determined analytically by CPM model and combinations were reproduced experimentally. Excess water was checked by the mini Kantro cone test. The results showed that the higher cement substitution content of the stone powder obtained the higher packing density, experimental and analytical, and the higher workability, allowing economic and environmental advantages. Analyzing each material, the stone powder resulted in the highest packing density and silica fume is the lowest one. Therefore, finer particles resulted in lower packaging densities, due to the greater specific surface area, which demands more water. The agglomeration resulted in more empty gaps between the grains. In addition, mixtures flowability increased with the increase of the stone powder content. As the excess water is responsible for mixture lubrication, a higher packing density for a given volume of water improves the flowability.

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Janas, T., K. Nowotarski, W. I. Gruszecki, and T. Janas. "The effect of hexadecaprenol on molecular organisation and transport properties of model membranes." Acta Biochimica Polonica 47, no. 3 (September 30, 2000): 661–73. http://dx.doi.org/10.18388/abp.2000_3987.

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The Langmuir monolayer technique and voltammetric analysis were used to investigate the properties of model lipid membranes prepared from dioleoylphosphatidylcholine (DOPC), hexadecaprenol (C80), and their mixtures. Surface pressure-molecular area isotherms, current-voltage characteristics, and membrane conductance-temperature were measured. Molecular area isobars, specific molecular areas, excess free energy of mixing, collapse pressure and collapse area were determined for lipid monolayers. Membrane conductance, activation energy of ion migration across the membrane, and membrane permeability coefficient for chloride ions were determined for lipid bilayers. Hexadecaprenol decreases the activation energy and increases membrane conductance and membrane permeability coefficient. The results of monolayer and bilayer investigations show that some electrical, transport and packing properties of lipid membranes change under the influence of hexadecaprenol. The results indicate that hexadecaprenol modulates the molecular organisation of the membrane and that the specific molecular area of polyprenol molecules depends on the relative concentration of polyprenols in membranes. We suggest that hexadecaprenol modifies lipid membranes by the formation of fluid microdomains. The results also indicate that electrical transmembrane potential can accelerate the formation of pores in lipid bilayers modified by long chain polyprenols.

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Wang, Jingyu, Jian Yang, Bengt Sunden, and Qiuwang Wang. "Numerical study of flow inhomogeneity and heat transfer enhancement in structured packed beds." Thermal Science 24, no. 6 Part A (2020): 3533–42. http://dx.doi.org/10.2298/tsci200323274w.

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Packed beds are widely used in engineering applications due to their high specific surface area and good heat transfer characteristics. A grille-sphere composite packed bed is proposed previously and has been proved to have higher overall heat transfer coefficient than the simple cubic packing structure. In the present paper, the flow inhomogeneities in both the grille-sphere composite packed bed and the simple cubic packing are studied and the relationship between the flow inhomogeneity and the heat transfer characteristics is revealed by numerical simulations. The simulations are performed on ANSYS FLUENT software. The turbulence flow is modelled by the renormalization group k- model. Both dispersion of the velocity distribution and the residence time distribution are employed to assess the flow maldistribution. When the inlet velocity equals 2.17 m/s, the variance of the residence time distribution of the composite packed bed is 5.91% smaller than that of the simple cubic packing while the Nusselt number is 10.64% higher. The results indicate that less flow maldistribution can lead to heat transfer enhancement.

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Mehdipour, Iman, and Kamal H. Khayat. "Effect of particle-size distribution and specific surface area of different binder systems on packing density and flow characteristics of cement paste." Cement and Concrete Composites 78 (April 2017): 120–31. http://dx.doi.org/10.1016/j.cemconcomp.2017.01.005.

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Kouznetsova, T. F., V. Е. Agabekov, A. I. Ivanets, E. V. Karpinchik, and J. D. Sauka. "Synthesis of mesoporous silica with ordered nanostructural morphology from natural quartz sand." Doklady of the National Academy of Sciences of Belarus 64, no. 5 (November 5, 2020): 544–50. http://dx.doi.org/10.29235/1561-8323-2020-64-5-544-550.

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Silica with ordered nanostructured morphology characteristic of mesoporous molecular sieves with cubic packing of cylindrical pores and a three-dimensional porous structure is obtained from natural quartz sand. It was shown by X-ray diffraction, scanning electron microscopy, and low-temperature nitrogen adsorption-desorption that the obtained silica material is thermally stable, amorphous, consists of submicron grains, has a high specific surface area of 1396 m2/g, a pore volume of 0.780 cm3/g and an average diameter of 2.2 nm with a narrow size distribution of mesopores.

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Mijaylova Nacheva, P., and G. Moeller Chávez. "Wastewater treatment using a novel bioreactor with submerged packing bed of polyethylene tape." Water Science and Technology 61, no. 2 (January 1, 2010): 481–89. http://dx.doi.org/10.2166/wst.2010.838.

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The performance of a novel aerobic bioreactor with a specially designed submerged packing bed of high specific surface area density, made of polyethylene tape, was studied for the treatment of domestic wastewater. The reactor has a volume of 0.71 m3 and the specific area of the packing bed was 1,098 m2/m3. The operation was performed with and without effluent recycling, applying different organic loads in the range of 4.0–17.6 g COD m−2 d−1. No back-washings were carried out. Overall BOD5 removals of 90–95% were obtained with organic loads of 4.0–17.6 g COD m−2 d−1 and HRT of 0.2–1.1 h. Overall TN removal of 69–72% was obtained at loads of 0.8–4.6 g TN m−2 d−1 when effluent recycling was used. The reactor allowed obtaining high quality water for urban reuse and demonstrated an effective process performance and resistance to load variations. The developed biofilm was completely penetrated by the organic matter, ammonia and oxygen, providing high removal rates. Large biomass quantities, up to 13 g dry VS/m2, were reached in the reactor and the determined sludge yield coefficient was relatively low, of 0.25 g VSS/g COD. These results allow obtaining compact treatment systems with low sludge production and make the technology a suitable option for small wastewater treatment plants.

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Ji, Yan Liang, Zhen Ping Sun, and Min Pang. "The Influence of Various Gypsum Dosage, Specific Area of Cement and Water Reducers on Bleeding of Fresh Cement Paste Using Low-Field NMR." Materials Science Forum 1036 (June 29, 2021): 255–62. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.255.

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Based on the low-field NMR, this study inveitigated bleeding property of the fresh cement pastes mixed with various gypsum dosage, specific area of cement and water reducers. Results showed that the gypsum dosage between 3 % and 5 % will cause an decrease bleeding and a lower bleeding velocity, while a 1 % gypsum dosage will increase the bleeding as a function of time. The increase of the cement surface will lead to a less bleeding rate. This can be explained that the finer particle will contribute to the packing which will form a low permeability of the cement paste, as a result less bleeding water is observed. The PCEs-made sample has smaller hot zone area which indocated the PCEs has good bleeding stability when varing water cement ratio. Furthermore, bying comparing with the NPE, it was found the ACS type water reducer has higher bleeding sensitivity when high water cement ratios were used.

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Ramirez-Lopez, E. M., A. Montillet, J. Comiti, and P. Le Cloirec. "Biofiltration of volatile organic compounds – application to air treatment." Water Science and Technology 41, no. 12 (June 1, 2000): 183–90. http://dx.doi.org/10.2166/wst.2000.0268.

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A hydrodynamic study and an ethanol biodegradation were carried out in an experimental biofilter using wood bark as packing material. The Comiti and Renaud model was used in order to determine, from pressure drop measurements, the tortuosity and the dynamic specific surface area of the packing material, and its structural parameters, considering the wall effect corrections. The pressure drop was used as a qualitative measure of the growth of native wood bark microorganisms. The aerobic biodegradation with a concentration of 1 g of ethanol m–3 was studied. An air superficial velocity of 100 m h–1, an air flow rate of 20 m3 h–1 and an empty bed residence time of 37 seconds with a true residence time of 19.5 s were the operational conditions in the biofilter. The ethanol concentration, pH, temperature and the pressure drop at different heights of the biofilter were measured. Performances of this process were presented.

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Athmaselvi, K. A., Pandian Jenney, C. Pavithra, and Ishita Roy. "Physical and Biochemical Properties of Selected Tropical Fruits." International Agrophysics 28, no. 3 (July 29, 2014): 383–88. http://dx.doi.org/10.2478/intag-2014-0028.

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Abstract This study was conducted to determine the physical and biochemical properties of guava, sapota, and papaya. The physical properties studied were: dimensions, shell ratio, surface area, bulk and true density, porosity, sphericity, packing coefficient, aspect ratio, and roundness index. The specific heat at various mass fractions, biochemical properties like pH, titratable acidity, total soluble solids, and colour analysis were studied for fruit pulps. The viscosity of fruits was studied at various mass fractions. The high sphericity of guava and sapota indicated that those fruits had high rolling capability, which is an important factor for designing hoppers. Biochemical analysis showed that sapota was the sweetest fruit amongst the three studied.

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Jones, Scott B., Wenyi Sheng, and Dani Or. "Dielectric Measurement of Agricultural Grain Moisture—Theory and Applications." Sensors 22, no. 6 (March 8, 2022): 2083. http://dx.doi.org/10.3390/s22062083.

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Moisture content is a critical variable for the harvesting, processing, storing and marketing of cereal grains, oilseeds and legumes. Efficient and accurate determination of grain moisture content even with advanced nondestructive techniques, remains a challenge due to complex water-retaining biological structures and hierarchical composition and geometry of grains that affect measurement interpretation and require specific grain-dependent calibration. We review (1) the primary factors affecting permittivity measurements used in practice for inferring moisture content in grains; (2) develop novel methods for estimating critical parameters for permittivity modeling including packing density, porosity, water binding surface area and water phase permittivity and (3) represent the permittivity of packs of grains using dielectric mixture theory as a function of moisture content applied to high moisture corn (as a model grain). Grain permittivity measurements are affected by their free and bound water contents, chemical composition, temperature, constituent shape, phase configuration and measurement frequency. A large fraction of grain water is bound exhibiting reduced permittivity compared to that of free water. The reduced mixture permittivity and attributed to hydrophilic surfaces in starches, proteins and other high surface area grain constituents. The hierarchal grain structure (i.e., kernel, starch grain, lamella, molecule) and the different constituents influence permittivity measurements due to their layering, geometry (i.e., kernel or starch grain), configuration and water-binding surface area. Dielectric mixture theory offers a physically-based approach for modeling permittivity of agricultural grains and similar granular media.

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Yang, Yibo, Baixi Chen, Yan Su, Qianpu Chen, Zhiji Li, Wenying Guo, and Hengchang Wang. "Concrete Mix Design for Completely Recycled Fine Aggregate by Modified Packing Density Method." Materials 13, no. 16 (August 11, 2020): 3535. http://dx.doi.org/10.3390/ma13163535.

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The undesirable properties of conventional recycled fine aggregate (RFA) often limit its application in the construction industry. To overcome this challenge, a method for preparing completely recycled fine aggregate (CRFA), which crushes all concrete waste only into fine aggregate, was proposed. The obtained CRFA had high apparent density, and its water absorption was lower than that of the conventional RFA. To take advantage of the CRFA, this paper introduced the modified packing density method for the CRFA concrete mix design. The modified packing density method took account of the powder with a particle size of smaller than 75 μm in the CRFA and balanced both the void ratio and the specific surface area of the aggregate system. Concrete (grade C55) was prepared using the CRFA to validate the feasibility of the proposed method. The unit price of the prepared CRFA concrete was around 12.7% lower than that of the natural aggregate concrete. Additionally, the proposed procedure for the concrete mixture design could recycle all concrete waste into the new concrete and replace all the natural fine aggregate in the concrete mixture.

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Serenko, Olga, Kirill Skupov, Artem Bakirov, Nina Kuchkina, Zinaida Shifrina, and Aziz Muzafarov. "Porosity of Rigid Dendrimers in Bulk: Interdendrimer Interactions and Functionality as Key Factors." Nanomaterials 11, no. 10 (October 2, 2021): 2600. http://dx.doi.org/10.3390/nano11102600.

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The porous structure of second- and third-generation polyphenylene-type dendrimers was investigated by adsorption of N2, Ar, and CO2 gases, scanning electron microscopy and small-angle X-ray spectroscopy. Rigid dendrimers in bulk are microporous and demonstrate a molecular sieve effect. When using CO2 as an adsorbate gas, the pore size varies from 0.6 to 0.9 nm. This is most likely due to the distances between dendrimer macromolecules or branches of neighboring dendrimers, whose packing is mostly realized due to intermolecular interactions, in particular, π–π interactions of aromatic fragments. Intermolecular interactions prevent the manifestation of the porosity potential inherent to the molecular 3D structure of third-generation dendrimers, while for the second generation, much higher porosity is observed. The maximum specific surface area for the second-generation dendrimers was 467 m2/g when measured by CO2 adsorption, indicating that shorter branches of these dendrimers do not provide dense packing. This implies that the possible universal method to create porous materials for all kinds of rigid dendrimers is by a placement of bulky substituents in their outer layer.

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Davies, P. D., and A. D. Wheatley. "Pilot plant study of alternative filter media for rapid gravity filtration." Water Science and Technology 66, no. 12 (December 1, 2012): 2779–84. http://dx.doi.org/10.2166/wst.2012.517.

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Sand has been the main filter media used in rapid gravity filtration since its introduction. The dominance of sand has been due to its low cost and availability. Extensive experience has led to sand filters with a dependable and predictable performance. Sand remains the preferred filter medium but usually with a larger sized anthracite capping to reduce the onset of head loss. Other approved filter media are now commercially available and this paper compares sand with recycled glass, Filtralite® and slate at pilot scale. The results have reaffirmed the basic importance of particle size on head loss and turbidity performance rather than surface activity or specific surface area. The results did suggest, however, that particle shape and packing exerted a stronger influence on performance than previously acknowledged. These could be used to improve the design and the contribution to sustainability made by rapid gravity filters.

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Tsibranska, Sonya, Anela Ivanova, Slavka Tcholakova, and Nikolai Denkov. "Structure and Undulations of Escin Adsorption Layer at Water Surface Studied by Molecular Dynamics." Molecules 26, no. 22 (November 13, 2021): 6856. http://dx.doi.org/10.3390/molecules26226856.

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The saponin escin, extracted from horse chestnut seeds, forms adsorption layers with high viscoelasticity and low gas permeability. Upon deformation, escin adsorption layers often feature surface wrinkles with characteristic wavelength. In previous studies, we investigated the origin of this behavior and found that the substantial surface elasticity of escin layers may be related to a specific combination of short-, medium-, and long-range attractive forces, leading to tight molecular packing in the layers. In the current study, we performed atomistic molecular dynamics simulations of 441 escin molecules in a dense adsorption layer with an area per molecule of 0.49 nm2. We found that the surfactant molecules are less submerged in water and adopt a more upright position when compared to the characteristics determined in our previous simulations with much smaller molecular models. The number of neighbouring molecules and their local orientation, however, remain similar in the different-size models. To maintain their preferred mutual orientation, the escin molecules segregate into well-ordered domains and spontaneously form wrinkled layers. The same specific interactions (H-bonds, dipole–dipole attraction, and intermediate strong attraction) define the complex internal structure and the undulations of the layers. The analysis of the layer properties reveals a characteristic wrinkle wavelength related to the surface lateral dimensions, in qualitative agreement with the phenomenological description of thin elastic sheets.

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Cabiscol, Ramon, Jan Finke, Harald Zetzener, and Arno Kwade. "Characterization of Mechanical Property Distributions on Tablet Surfaces." Pharmaceutics 10, no. 4 (October 12, 2018): 184. http://dx.doi.org/10.3390/pharmaceutics10040184.

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Powder densification through uniaxial compaction is governed by a number of simultaneous processes taking place on a reduced time as the result of the stress gradients within the packing, as well as the frictional and adhesive forces between the powder and the die walls. As a result of that, a density and stiffness anisotropy is developed across the axial and radial directions. In this study, microindentation has been applied to assess and quantify the variation of the module of elasticity ( E m o d ) throughout the surface of cylindrical tablets. A representative set of deformation behaviors was analyzed by pharmaceutical excipients ranging from soft/plastic behavior (microcrystalline cellulose) over medium (lactose) to hard/brittle behavior (calcium phosphate) for different compaction pressures. The results of the local stiffness distribution over tablet faces depicted a linear and directly proportional tendency between a solid fraction and E m o d for the upper and lower faces, as well as remarkable stiffness anisotropy between the axial and radial directions of compaction. The highest extent of the stiffness anisotropy that was found for ductile grades of microcrystalline cellulose (MCC) in comparison with brittle powders has been attributed to the dual phenomena of overall elastic recovery and Poisson’s effect on the relaxation kinetics. As a reinforcement of this analysis, the evolution of the specific surface area elucidated the respective densification mechanism and its implementations toward anisotropy. For ductile excipients, the increase in the contact surface area as well as the reduction and closing of interstitial pores explain the reduction of surface area with increasing compaction pressure. For brittle powders, densification evolves through fragmentation and the subsequent filling of voids.

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Bordoloi, Ankur, Miguel Sanchez, Heshmat Noei, Stefan Kaluza, Dennis Großmann, Yuemin Wang, Wolfgang Grünert, and Martin Muhler. "Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation." Journal of Catalysts 2014 (October 1, 2014): 1–9. http://dx.doi.org/10.1155/2014/807545.

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Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA) process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.

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Markov, Sergey, Maxim Tyulenev, Stefan Vöth, and Vasiliy Klintsov. "Analysis of physical properties of granular materials on their numerical models (2D case)." E3S Web of Conferences 315 (2021): 01018. http://dx.doi.org/10.1051/e3sconf/202131501018.

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The paper describes a method for determining the density and specific surface of the package of rock particles represented by discs with the size corresponding to the size of the rock fragments of real dump massifs (2D case). The packing method of the particles corresponds to the schemes of dumping used in open-pit mining - areal and peripheral ones. The influence of boundaries, in which the dump is located, on the physical characteristics of this massif - density and porosity - is revealed. It was revealed that the way of formation of the bulk of particles affects its density, especially at the boundaries of the massif. The massif of particles formed in accordance with the area technology of dumping has a denser composition and is less affected by the effect of its boundaries than the massif formed in accordance with the peripheral technology of dumping. The applied method of determining the physical characteristics of the bulk medium differs from the statistical methods (e.g., Monte Carlo) and is well-proven for static media, such as dumps and filtering massifs in open-pit mining.

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32

Quan, Xue Jun, Qing Hua Zhao, Jin Xin Xiang, Zhi Liang Cheng, and Fu Ping Wang. "Mass Transfer Mechanism of a Water-Sparged Aerocyclone Reactor." Advanced Materials Research 396-398 (November 2011): 279–83. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.279.

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Air stripping of ammonia is a widely used process for the pretreatment of wastewater. Scaling and fouling on the packing surface in packed towers and a lower stripping efficiency are the two major problems in this process. New patented equipment that is suitable for the air stripping of wastewater with suspended solids has been developed. Air stripping of ammonia from water with Ca(OH)2, was performed in the newly designed gas-liquid contactor, a water-sparged aerocyclone (WSA). The mechanism of the mass transfer process in the WSA was investigated using a CO2—NaOH rapid pseudo first order reaction system. The results indicated that there is a critical gas phase inlet velocity Ug. When Ug is lower than this value, the increase of the inlet velocity has a double function of both intensifying the liquid side film mass transfer coefficient kL and increasing the specific mass transfer area a; whereas when Ug is larger than this value, the major function of Ug increase is to make the water drops in the WSA broken, increasing the mass transfer area of gas-liquid phases.

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Xu, Hui, Qun Shao, Jia Zhou, and Xiao Cheng Ma. "Study on Preparation of Water Treatment Ceramic Particles by Using Sludge and Fly Ash and the Ceramic Particles’ Application." Advanced Materials Research 356-360 (October 2011): 1876–81. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1876.

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Water treatment ceramic particles were prepared using dewatered life sludge in Huainan No.1 Sewage treatment plant and power plant fly ash as main materials and clay as the bond. Through the L9 (43) orthogonal test, we obtained the best conditions of the preparing process. The product can be used as water treatment packing ceramic particles and simulated adsorption experiment with the wastewater including Pb2 + was conducted. The results indicate that ceramic particles (used as wastewater treatment filler) bibulous rate is 25.0%, the loose density is 690kg/m3, the particle density is 1240kg/m3, specific surface area is 5.997m2/g, the compressive strength is 9.40MPa and the adsorptive performance is excellent. The toxic metal leaching experimental result shows that the concentration of toxic heavy metals in leaching solution is in the range of GB specification and the performance of product is stable which will not cause second pollution.

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Sankaranarayanan, Kamatchi, M. Kalaiyarasi, B. Sreedhar, B. U. Nair, and A. Dhathathreyan. "Ionic Liquid Doped β Lactoglobulin as Template for Nanoclusters of Nickel Oxide." International Journal of Nanoscience 13, no. 01 (February 2014): 1450006. http://dx.doi.org/10.1142/s0219581x14500069.

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In this work, Langmuir films of organized assemblies of β-lactoglobulin (βLG) with 1-ethyl-3-methyl imidazolium ethyl sulfate (IL-emes) have been characterized at air/water interface using surface pressure-specific area isotherms and dilational rheology. The protein in the IL-mediated assembly shows excellent packing at the interface and is stable as seen in circular dichroic spectroscopy. These spread films on nickel chloride were transferred as Langmuir–Schaffer films of βLG and βLG+IL-emes and used as template for designing nanoclusters of nickel oxide. The nanoclusters have been characterized using transmission electron microscopy (TEM) and powder XRD. While pure protein template gives needle-shaped structures, the IL-mediated template gives spherical shapes of hexagonal nickel oxide in the range 30 nm to 40 nm. Presence of ionic liquid seems to slow down the growth of the cluster and also prevents aggregation of the clusters.

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35

Lee, Bum Han, and Sung Keun Lee. "Effects of specific surface area and porosity on cube counting fractal dimension, lacunarity, configurational entropy, and permeability of model porous networks: Random packing simulations and NMR micro-imaging study." Journal of Hydrology 496 (July 2013): 122–41. http://dx.doi.org/10.1016/j.jhydrol.2013.05.014.

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Mendes, T. M., W. L. Repette, and P. J. Reis. "Effects of nano-silica on mechanical performance and microstructure of ultra-high performance concrete." Cerâmica 63, no. 367 (September 2017): 387–94. http://dx.doi.org/10.1590/0366-69132017633672037.

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Abstract The use of nanoparticles in ultra-high strength concretes can result in a positive effect on mechanical performance of these cementitious materials. This study evaluated mixtures containing 10 and 20 wt% of silica fume, for which the optimum nano-silica content was determined, i.e. the quantity of nano-silica that resulted on the higher gain of strength. The physical characterization of raw materials was done in terms of particle size distribution, density and specific surface area. Chemical and mineralogical compositions of materials were obtained through fluorescence and X-ray diffraction. The mechanical performance was evaluated by compressive strength, flexural strength and dynamic elastic modulus measurements. The microstructural analysis of mixtures containing nano-silica was performed by X-ray diffraction, thermogravimetry, mercury intrusion porosimetry and scanning electron microscopy. Obtained results indicate an optimum content of nano-silica of 0.62 wt%, considering compressive and flexural strengths. This performance improvement was directly related to two important microstructural aspects: the packing effect and pozzolanic reaction of nano-silica.

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Yun-lu, Tang, Liu Dong-fang, Meng Xian-rong, Yu Jie, Wang Jin, Liu Yu-xing, Li Ke-xun, and James Lander. "Performance of a modified RBC system in simulated municipal wastewater treatment." Water Science and Technology 66, no. 9 (November 1, 2012): 2014–19. http://dx.doi.org/10.2166/wst.2012.412.

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A new method based on rotating biological contactor (RBC) was employed for solving the problems of long hydraulic retention times (HRT) low specific surface area and organic loading rates (OLR) in conventional RBCs. The system showed its particular adsorption ability of microorganisms in the biofilm-attaching period. Microbes on the first cage were observed in comparison with the second one. Packing biodisc also had a good shock load tolerance. It was observed that the system performance improved at higher HRTs, while at the increased level of input OLR, the removal performance worsened slightly. The positive role of rotational speed in the treatment of municipal wastewater was more pronounced in the range of 10–12 rpm. Chemical oxygen demand (COD) removal rate achieved 94% under the optimal operating conditions, which were HRT of 1.5 h, rotational speed of 9.9 rpm. The modified RBC system is highly beneficial to engineering application for better system performance and lower energy consumption.

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Park, T. J., K. H. Lee, D. S. Kim, and C. W. Kim. "Petrochemical wastewater treatment with aerated submerged fixed-film reactor (ASFFR) under high organic loading rate." Water Science and Technology 34, no. 10 (November 1, 1996): 9–16. http://dx.doi.org/10.2166/wst.1996.0233.

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An aerated submerged fixed-film reactor (ASFFR) was developed to treat a petrochemical wastewater with high organic loading rate, where stationary submerged biofilms were attached to net-type media (SARAN 1000D) under diffused aeration. The specific surface area of SARAN 1000D was 400 m2/m3 approximately. The organic removal ability of the reactor was tested in three lab-scale ASFFRs. The reactor demonstrated 91.8-96.6% removal efficiencies of soluble chemical oxygen demand (SCOD) and exhibited efficient and stable performance at organic loadings of 1.02-6.21 kg COD/m3 day. When the media packing ratio increased the COD removal efficiency increased, while the effluent COD and SS concentrations were stable. The organic removal rates were dependent on the effluent SCOD concentration and the reaction orders were the same as or lower than 0.5. Based on the experimental results, the ASFFR should be very suitable for treating petrochemical wastewater with relatively high organic loading rate.

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Chong, Samantha, Tom Hasell, Jamie Culshaw, Marc Little, Marc Schmidtmann, Daniel Holden, Linjiang Chen, Kim Jelfs, and Andrew Cooper. "Exploiting weak supramolecular interactions to assemble organic cage materials." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C632. http://dx.doi.org/10.1107/s205327331409367x.

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Intensive research into microporous materials has been driven by potential applications in areas such as catalysis, gas separation, storage, and sensing. Recently, a new class of purely organic molecular cage materials has emerged, which can exhibit significant porosity arising from the internal molecular cavity as well as extrinsic porosity from packing in the crystal structure [1]. Unlike extended frameworks, porous molecular materials lack strongly directional interactions to drive their assembly, complicating the crystal engineering possible for isoreticular metal-organic frameworks [2], for example. Our work has focused on covalent imine-linked cages, which exhibit diverse crystal chemistry. The connectivity of the pore network is derived from the cage packing: Therefore, the crystal structure directly affects the observed porosity. The imine cages synthesised so far lack strongly hydrogen bonding groups. Thus, the solid state supramolecular assembly of cage molecules is governed by the aggregate of weak interactions, such as van der Waals forces. By identifying robust `tectons', that is, regularly occurring supramolecular motifs, progress toward designing the crystal structure and therefore controlling the physical properties of organic cage materials becomes possible. Here, we report exploiting robust supramolecular motifs, comprising either cage modules or host and guest molecules to gain control over the porosity of the bulk material. We demonstrate how formation of a desired void network topology can be driven by hosting a specific guest in preferred sites which maximise weak host-guest interactions [3]. Subsequent guest removal can produce stable polymorphs, one of which exhibited double the Brunauer-Emmett-Teller surface area with respect to the originally observed polymorph. We also examine how the interaction between gas phase guests and cage host is important in the application of porous organic cages in rare gas separation.

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Kim, Woo Chang, and Jong Kook Lee. "Effect of Powder Characteristics on Slip Casting Fabrication of Dental Zirconia Implants." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5385–89. http://dx.doi.org/10.1166/jnn.2020.17610.

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Dense zirconia compacts were fabricated by slip casting and sintering of nanoscale zirconia powders, and the effect of the powder characteristics (crystallite size, specific surface area, yttria content, and agglomeration) on the slurry and sintered properties was investigated. Three types of commercial 3 mol% yttria-stabilized tetragonal zirconia polycrystals powders were used as the starting powders after the powder characteristic analysis. A zirconia slurry for slip casting was prepared by mixing zirconia powder (solid loading of 60, 65, and 70 wt.%), distilled water, and a dispersant of Darvan C. The green compacts obtained from slip casting were cold isostatic pressed to enhance the close packing and densified by sintering at 1450 °C for 2 h. Highly dense zirconia compacts with a relative density of 99.5% and grain size of 350 nm were obtained based on the powder type and solid loading in the slurry. The microstructure and mechanical hardness of the sintered specimen after slip casting were dependent on the yttria content in the 3 mol% yttria-stabilized tetragonal zirconia polycrystal powder and the solid loading within the slurry.

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Shankle, W. R., Michael S. Rafii, Benjamin H. Landing, and James H. Fallon. "Approximate Doubling of Numbers of Neurons in Postnatal Human Cerebral Cortex and in 35 Specific Cytoarchitectural Areas from Birth to 72 Months." Pediatric and Developmental Pathology 2, no. 3 (May 1999): 244–59. http://dx.doi.org/10.1007/s100249900120.

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From 1939 to 1967, J.L. Conel quantitatively studied the microscopic features of the developing human cerebral cortex and published the findings in eight volumes. We have constructed a database using his neuroanatomical measurements (neuronal packing density, myelinated large fiber density, large proximal dendrite density, somal breadth and height, and total cortical and cortical layer thickness) at the eight age periods (0 [term birth], 1, 3, 6, 15, 24, 48, and 72 postnatal months) he studied. In this report, we examine changes in neuron numbers over the eight age-points for 35 von Economo areas for which Conel gave appropriate data. From birth to 3 months postnatal age, total cortical neuron number increases 23–30%, then falls to within 3.5% of the birth value at 24 months, supporting our previous work showing that the observed decrease in the number of neurons per column of cortex under a 1-mm2 cortical surface from birth to 15 months is almost entirely due to cortical surface expansion. The present study also shows a 60–78% increase in total cortical neuron number above the birth value from postnatal ages 24 to 72 months. The generalization, to humans at least, of the finding of no postnatal neurogenesis in rhesus macaques, a species belonging to a super-family that diverged from that of Homo sapiens more than 25 million years ago, is not warranted until explicitly proven for humans. The data of the present study support the existence of substantial postnatal neurogenesis in humans for the 35 cortical areas studied.

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Li, Tianpeng, Jing Fan, and Tingting Sun. "Acid red G dye removal from aqueous solutions by porous ceramsite produced from solid wastes: Batch and fixed-bed studies." Green Processing and Synthesis 9, no. 1 (December 29, 2020): 770–82. http://dx.doi.org/10.1515/gps-2020-0068.

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AbstractA novel porous ceramsite was made of municipal sludge, coal fly ash, and river sediment by sintering process, and the performance of batch and fixed-bed column systems containing this material in the removal of acid red G (ARG) dye from aqueous solutions was assessed in this study. The results of orthogonal test showed that sintering temperature was the most important determinant in the preparation of porous ceramsite, and it possesses developed pore structure and high specific surface area. Batch experiment results indicated that the adsorption process of ARG dye toward porous ceramsite was a spontaneous exothermic reaction, which could be better described with Freundlich–Langmuir isotherm model (R2 > 0.992) and basically followed the pseudo-first-order kinetic equation (R2 > 0.993). Column experiment results showed that when the porous ceramsite was used as packing material, its adsorption capacity was roughly improved by 3.5 times compared with that in batch system, and the breakthrough behavior was simulated well with Yoon–Nelson model, with R2 > 0.954. This study suggested that the novelty man-made porous ceramsite obtained from solid wastes might be processed as a certain cost-effective treatment material fit for the dye removal in aqueous solutions.

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Schmierer, Eric N., and Arsalan Razani. "Self-Consistent Open-Celled Metal Foam Model for Thermal Applications." Journal of Heat Transfer 128, no. 11 (April 11, 2006): 1194–203. http://dx.doi.org/10.1115/1.2352787.

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Many engineering applications require thermal cycling of granular materials. Since these materials generally have poor effective thermal conductivity various techniques have been proposed to improve bed thermal transport. These include insertion of metal foam with the granular material residing in the interstitial space. The use of metal foam introduces a parasitic thermal capacitance, disrupts packing, and reduces the amount of active material. In order to optimize the combined high porosity metal foam-granular material matrix and study local thermal nonequilibrium, multiple energy equations are required. The interfacial conductance coefficients, specific interface area, and the effective thermal conductivities of the individual components, which are required for a multiple energy equation analysis, are functions of the foam geometry. An ideal three-dimensional geometric model of open-celled Duocell® foam is proposed. Computed tomography is used to acquire foam cell and ligament diameter distribution, ligament shape, and specific surface area for a range of foam parameters to address various shortcomings in the literature. These data are used to evaluate the geometric self-consistency of the proposed geometric model with respect to the intensive and extensive geometry parameters. Experimental thermal conductivity data for the same foam samples are acquired and are used to validate finite element analysis results of the proposed geometric model. A simple relation between density and thermal conductivity ratio is derived using the results. The foam samples tested exhibit a higher dependence on relative density and less dependence on interstitial fluid than data in the literature. The proposed metal foam geometric model is shown to be self-consistent with respect to both its geometric and thermal properties.

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MENDES, T. M., and W. L. REPETTE. "Effect of nano-silica on Portland cement matrix." Revista IBRACON de Estruturas e Materiais 12, no. 6 (December 2019): 1383–89. http://dx.doi.org/10.1590/s1983-41952019000600009.

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Abstract The use of nano-particles is a current trend that may play an important role for improving the mechanical performance of Portland cement. The aim of this study is to evaluate the effect of nano-silica on Portland cement matrix. The particle size distribution of Portland cement matrix was modified by the incorporation of 11, 6.2, 3.1, 1.7, 0.85 and 0.42 wt.% of nano-silica. The water demand and the consumption of dispersant were adjusted, and the rheological properties of suspensions were analyzed through rotational rheometry. The mechanical performance of studied mixtures was evaluated by the compressive strength. The pore size distribution was measured by mercury intrusion porosimetry (MIP), and the hydration was analyzed through X-ray diffractometry. The rheological behavior presented a considerable changed, as a consequence of high specific surface area of nano-particles. The optimum content of nano-silica, or the smaller quantity of nano-particles, that leads to the maximum strength gain, varied according to the water to solids ratio. An increasing on the hydration and a pore refinement were obtained due to the use of silica nanoparticles. The particle’s packing and the pozzolanic reaction were the two main effects of nano-silica on the microstructure of Portland cement matrix.

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Yu, Q. J., H. Xu, D. Yao, and P. Williams. "Development of a two-stage flexible fibre biofilm reactor for treatment of food processing wastewater." Water Science and Technology 47, no. 11 (June 1, 2003): 189–94. http://dx.doi.org/10.2166/wst.2003.0604.

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Biofilm (or attached growth) reactors can be effectively used to treat organic wastewater from various industries such as food processing industry. They have a number of advantages including high organic loading rates (OLRs) and improved operational stability. A flexible fibre biofim reactor (FFBR) has been developed for efficient and cost effective treatment of food processing wastewater. In the process, simple flexible fibre packing with a very high specific surface area is used as support for microorganisms. The COD removal efficiencies for a range of OLRs have been studied. The FFBR can support an increasingly high OLR, but with a corresponding decrease in the COD removal efficiency. Therefore, a two-stage FFBR was developed to increase the treatment efficiency for systems with high OLRs. Experimental results indicated that a high overall COD removal efficiency could be achieved. At an influent COD of about 2700 mg/L and an OLR of 7.7 kgCOD/m3d, COD removal efficiencies of 76% and 82% were achieved in the first and the second stage of the reactor, respectively. The overall COD removal efficiency was 96%. Therefore, even for wastewater samples with high organic strength, high quality treated effluents could be readily achieved by the use of multiple stage FFBRs.

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Sapiee, Nurul Haiza, Nurul Atiqah Izzati Zulkifly, and Noor Fitrah Abu Bakar. "Development and potential applications of gelatine, honey, and cellulose electrospun nanofibres as a green polymer." Malaysian Journal of Chemical Engineering and Technology (MJCET) 4, no. 2 (October 31, 2021): 90. http://dx.doi.org/10.24191/mjcet.v4i2.13333.

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Nanofibres have emerged as a brilliant technology to be applied in various areas due to their excellent properties that include having a great flexibility, prominent specific surface area and structural strength. Electrospinning is one of the most effective and favourable methods to fabricate nanofibres mainly because electrospun nanofibres have been demonstrated to possess small pore sizes, large specific surface area, and can be produced with different functions to fill the need of various applications in industries. Due to their remarkable properties, electrospun nanofibres have been proven to be suitable for applications in food packaging, medical, pharmaceutical and even in tissue engineering. Currently, there have been numerous research utilising both electrospun synthetic and natural polymers. Natural or green polymers are considered more favourable due to their biodegradable properties and potential biocompatibility. Therefore, there has been a shift to include more research regarding these green polymers. Green polymers can source from both plant polysaccharides and animal protein. Considering the different characteristics of synthetic polymers, the processing and fabrication methods may differ and must be adjusted accordingly. To well summarise the development of these green polymer nanofibres, we review fabrication methods of gelatine, honey and cellulose-based nanofibre and their potential applications in industries. There are indeed numerous promising areas for the usage of these green polymers which are based on their splendid individual properties especially when combined to form nanofibres via electrospinning. We hope this will promote continuous research and development for the applications in various industries including but not limited to tissue engineering, biomedical, food and pharmaceutical industries.

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Chen, Jing, Bo Zhang, Ming Quan Wei, Jun Men, and Guang Wu Miao. "The Optimum of Preparation and Characterization of Aerogels like Hydrophobic Titania by Ambient Pressure Drying." Advanced Materials Research 1120-1121 (July 2015): 264–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.264.

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The influence of different factors in the alcogel preparation process and ambient pressure drying process on packing density of hydrophobic TiO2 aerogel synthesized by ambient pressure drying (APD) and the optimum preparation conditions were investigated by the orthogonal test with four-factor and three-level L9(34), respectively. The morphology and structural properties of hydrophobic TiO2 aerogels with different density were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetry (TG), N2 adsorption-desorption measurement and Scanning Electron Microscope (SEM). The results showed that the most important factors in the preparation process for TiO2 aerogels with low-density under ambient pressure are aging time, the volume ratio of C2H5OH to TBT, ethanol immersion time and hydrophobic modification time. The optimized preparation conditions are that aging time is 24 h, the volume ratio of C2H5OH to TBT is (7+7) : 5, the volume ratio of H2O to TBT is 1.7 : 5, the volume ratio of HAc to TBT is 1.7 : 5, ethanol immersion time is 24 h, hydrophobic modification time is 48 h, hexane solvent replacement time is 24 h and the drying temperature is 393 K. TiO2 aerogels with density of 460 kg/m3 was obtained at the optimized conditions. TiO2 aerogel with lower density displays higher specific surface area, porosity and pore volume as well as the larger pore size.

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Đaković, Marijana, Željka Soldin, Vesna Petrović Peroković, Ivan Kodrin, and Zora Popović. "Exploring the structural landscape in nia derivatives and their Cd(II) complexes." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C645. http://dx.doi.org/10.1107/s2053273314093541.

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Constant need for design of new materials with desired and pre-determined bulk properties necessitates much improved understanding of competition and balance between non-covalent interactions. In order not to rely on serendipity when targeting synthesis of new solids with pre-determined connectivity and topology, as this offers a path towards the design of materials with pre-determined bulk properties, it is imperative to map out the reliability and robustness of supramolecular synthons. In this contribution, we want to delineate the effect of the counter ion accommodation in the supramolecular assembly on the synthon formation. We opted for positively charged pyridine-based organic molecules that are encoded with two functionalities, caboxamide and carboxylic acid moieties, which both proved as robust and reliable self-complementary reagents, accompanied with one of the three halide counter ions (Cl-, Br-, I-). The study thus focuses on the competition and hierarchy of supramolecular synthons in organic systems of the ligands themselves as well as in the Cd(II)-containing architectures (upon the ligand coordination) depending on the polarizability of the present halide ion. Furthermore, the most prominent intermolecular contacts in the crystal structures will be visualized by Hirshfeld surface analysis and their contributions to the Hirshfeld surface area will be determined. Bader's QTAIM (Quantum Theory of Atoms in Molecules) analysis will be used to characterize the nature and strength of intermolecular interactions based on the DFT calculations started from X-ray determined geometries. The computationally determined data will be compared with the experimental results to get unbiased analysis about the role of specific intermolecular interactions on crystal packing of examined compounds.

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Saremi, Raha, Nikolay Borodinov, Amine Mohamed Laradji, Suraj Sharma, Igor Luzinov, and Sergiy Minko. "Adhesion and Stability of Nanocellulose Coatings on Flat Polymer Films and Textiles." Molecules 25, no. 14 (July 16, 2020): 3238. http://dx.doi.org/10.3390/molecules25143238.

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Renewable nanocellulose materials received increased attention owing to their small dimensions, high specific surface area, high mechanical characteristics, biocompatibility, and compostability. Nanocellulose coatings are among many interesting applications of these materials to functionalize different by composition and structure surfaces, including plastics, polymer coatings, and textiles with broader applications from food packaging to smart textiles. Variations in porosity and thickness of nanocellulose coatings are used to adjust a load of functional molecules and particles into the coatings, their permeability, and filtration properties. Mechanical stability of nanocellulose coatings in a wet and dry state are critical characteristics for many applications. In this work, nanofibrillated and nanocrystalline cellulose coatings deposited on the surface of polymer films and textiles made of cellulose, polyester, and nylon are studied using atomic force microscopy, ellipsometry, and T-peel adhesion tests. Methods to improve coatings’ adhesion and stability using physical and chemical cross-linking with added polymers and polycarboxylic acids are analyzed in this study. The paper reports on the effect of the substrate structure and ability of nanocellulose particles to intercalate into the substrate on the coating adhesion.

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Mishakov, I. V., S. D. Afonnikova, Yu I. Bauman, Yu V. Shubin, M. V. Trenikhin, A. N. Serkova, and A. A. Vedyagin. "Carbon Erosion of a Bulk Nickel–Copper Alloy as an Effective Tool to Synthesize Carbon Nanofibers from Hydrocarbons." Kinetics and Catalysis 63, no. 1 (February 2022): 97–107. http://dx.doi.org/10.1134/s0023158422010049.

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Abstract:

Abstract Carbon erosion of bulk metals and alloys in a carbon-containing atmosphere can be used as an effective tool for the targeted synthesis of carbon nanomaterials. In this study, a set of bulk Ni0.89Cu0.11 (11 at % Cu) alloys has been synthesized by the mechanochemical alloying of metal powders in an Activator 2S planetary mill. The synthesized samples have been studied as precursors of catalyst for the synthesis of carbon nanofibers (CNFs) from ethylene at 550°C. The effect of the activation time on the particle morphology and phase composition of the alloys, the kinetics of growth, and the carbon product yield in C2H4 decomposition has been studied. For the most active samples, the CNF yield has exceeded 100 g/gcat within 30 min of reaction. The early stage of carbon erosion of a bulk Ni0.89Cu0.11 alloy has been studied by electron microscopy methods. It has been found that the nucleation of carbon fiber growth active sites occurs during a short-term contact of the sample with the reaction mixture (less than 1 min); the complete disintegration of the alloy is observed in a few minutes. The carbon product is represented by nanofibers having a submicrometer diameter and characterized by a dense “stacked” and coaxial-conical packing of graphene layers. The material has a developed specific surface area (140–170 m2/g) and a low bulk density (less than 30 g/L).

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Journal articles on the topic 'Specific surface area packing'

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