Journal articles: 'Citric acid; calcite'

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Al-Khaldi, M. H., H. A. Nasr-El-Din, S. Mehta, and A. D. Al-Aamri. "Reaction of citric acid with calcite." Chemical Engineering Science 62, no. 21 (November 2007): 5880–96. http://dx.doi.org/10.1016/j.ces.2007.06.021.

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Alkhaldi, Mohammed H., Hisham A. Nasr-El-Din, and Hemanta K. Sarma. "Kinetics of the Reaction of Citric Acid With Calcite." SPE Journal 15, no. 03 (September 1, 2010): 704–13. http://dx.doi.org/10.2118/118724-pa.

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Alkhaldi, Mohammed H., Hemanta K. Sarma, and Hisham A. Nasr-El-Din. "Diffusivity of Citric Acid During its Reaction With Calcite." Journal of Canadian Petroleum Technology 49, no. 08 (August 1, 2010): 43–52. http://dx.doi.org/10.2118/139570-pa.

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Zhu, Dong, Jiao, Qin, and Wei. "Use of Sodium Hexametaphosphate and Citric Acid Mixture as Depressant in the Flotation Separation of Scheelite from Calcite." Minerals 9, no. 9 (September 16, 2019): 560. http://dx.doi.org/10.3390/min9090560.

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The floatability of scheelite and calcite in the presence of single depressant (SHMP or H3Cit) and mixed depressant (SHMP/H3Cit) was studied by microflotation experiments and artificial mixed mineral experiments. Solution chemical calculation, zeta potential tests, thermodynamic analysis and XPS analysis were used to explain the relevant depressive mechanism. Mixed depressant (SHMP/H3Cit) exhibited excellent selective depressive effect on calcite. The optimal molar ratio of SHMP to H3Cit was 1:4. The depressant SHMP and H3Cit can be chemically bonded with Ca2+ to form CaHPO4 and Ca3(Cit)2 at pH 8. The CaHPO4 was more easily formed than Ca3(Cit)2 on the mineral surface, which indicated that the depressive effect of SHMP was stronger than H3Cit. The SHMP and H3Cit of the mixed depressant were co-adsorbed on the calcite surface, while the H3Cit of the mixed depressant was weakly adsorbed on the scheelite surface. The mixed depressant can significantly improve the separation efficiency of scheelite from calcite.

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Wei, Qian, Liuyang Dong, Fen Jiao, and Wenqing Qin. "Use of citric acid and Fe(III) mixture as depressant in calcite flotation." Colloids and Surfaces A: Physicochemical and Engineering Aspects 578 (October 2019): 123579. http://dx.doi.org/10.1016/j.colsurfa.2019.123579.

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Westin, K. J., and Å. C. Rasmuson. "Crystal growth of aragonite and calcite in presence of citric acid, DTPA, EDTA and pyromellitic acid." Journal of Colloid and Interface Science 282, no. 2 (February 2005): 359–69. http://dx.doi.org/10.1016/j.jcis.2004.03.029.

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Silveira de Araujo, Isa, and Zoya Heidari. "Quantifying Interfacial Interactions Between Minerals and Reservoir/Fracturing Fluids." Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 63, no. 6 (December 1, 2022): 658–70. http://dx.doi.org/10.30632/pjv63n6-2022a6.

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Chemical interactions between the injected fluids and the minerals during the fracturing process can affect fluid flow and production. However, there is still a need to understand the impact of geochemistry on the interactions at the rock-fluid interface and how these interactions affect the wettability of the rock and fluid flow in organic-rich mudrocks. In this paper, we quantify the mineral-fluid affinity by performing adsorption calculations. Molecular dynamics simulations (MDS) are carried out to (i) quantify the adsorption of fracturing fluids on the surface of minerals, (ii) perform sensitivity analysis on the composition of fracturing fluid and reservoir temperature on adsorption and mobility, and (iii) analyze the spatial distribution of water and chemicals on mineral surfaces. The minerals evaluated include illite and calcite, and the fracturing-fluid components are methanol, citric acid, sodium chloride, and water. We evaluate the effect of each chemical separately. First, systems composed of mineral surfaces in contact with brine are generated. Then, we analyze the mineral in contact with a solution containing brine and methanol and with a solution composed of brine and citric acid. MDS are carried out in the canonical (NVT) ensemble at the temperature of 330 K to evaluate the adsorption of the fracturing fluid. To quantify the impacts of reservoir temperature, we carry out MDS at a temperature of 360 K. Results suggest that methanol does not have a strong effect on water adsorption and the ion spatial distribution on the mineral’s surface. We found that citric acid tends to form aggregates and that some cations present in the solution might participate in these aggregates. When methanol or citric acid is added to the brine solution, the mobility of both sodium and water on the illite surface decreases. The effects of each additive on the affinity between the mineral and fracturing fluids were also investigated. We found that the number of hydrogen bonds between illite and the fluid did not change when additives were added. However, the number of hydrogen bonds between calcite and the fluid was affected when methanol was added to the system. The quantification of adsorption in the molecular scale provides a fundamental understanding of the electrochemical interactions between the rock surface and the fracturing/reservoir fluids at reservoir conditions, which enables the enhanced design of fracturing-fluid composition for different reservoir types. This information can also be used to quantify the impacts of injected and reservoir fluids on the wettability of the rocks.

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Prempeh, Clement Owusu, Steffi Formann, Thomas Schliermann, Hossein Beidaghy Dizaji, and Michael Nelles. "Extraction and Characterization of Biogenic Silica Obtained from Selected Agro-Waste in Africa." Applied Sciences 11, no. 21 (November 4, 2021): 10363. http://dx.doi.org/10.3390/app112110363.

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Increased amounts of available biomass residues from agricultural food production are present widely around the globe. These biomass residues can find essential applications as bioenergy feedstock and precursors to produce value-added materials. This study assessed the production of biogenic silica (SiO2) from different biomass residues in Africa, including cornhusk, corncob, yam peelings, cassava peelings and coconut husks. Two processes were performed to synthesize the biogenic silica. First, the biomass fuels were chemically pre-treated with 1 and 5% w/v citric acid solutions. In the second stage, combustion at 600 °C for 2 h in a muffle oven was applied. The characterization of the untreated biomasses was conducted using Inductively coupled plasma—optical emission spectrometry (ICP-OES), thermal analysis (TG-DTA) and Fourier-transform infrared spectroscopy (FTIR). The resulting ashes from the combustion step were subjected to ICP, nitrogen physisorption, Energy dispersive X-ray spectroscopy (EDX) as well as X-ray diffraction (XRD). ICP results revealed that the SiO2 content in the ashes varies between 42.2 to 81.5 wt.% db and 53.4 to 90.8 wt.% db after acidic pre-treatment with 1 and 5 w/v% acid, respectively. The relative reductions of K2O by the citric acid in yam peel was the lowest (79 wt.% db) in comparison to 92, 97, 98 and 97 wt.% db calculated for corncob, cassava peel, coconut husk and cornhusk, respectively. XRD analysis revealed dominant crystalline phases of arcanite (K2SO4), sylvite (KCl) and calcite (CaCO3) in ashes of the biomass fuels pre-treated with 1 w/v% citric acid due to potassium and calcium ions present. In comparison, the 5 w/v% citric acid pre-treatment produced amorphous, biogenic silica with specific surface areas of up to 91 m2/g and pore volumes up to 0.21 cm3/g. The examined biomass residues are common wastes from food production in Africa without competition in usage with focus application. Our studies have highlighted a significant end-value to these wastes by the extraction of high quality, amorphous silica, which can be considered in applications such as catalyst support, construction material, concrete and backing material.

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Dong, Liuyang, Qian Wei, Wenqing Qin, and Fen Jiao. "Effect of iron ions as assistant depressant of citric acid on the flotation separation of scheelite from calcite." Chemical Engineering Science 241 (September 2021): 116720. http://dx.doi.org/10.1016/j.ces.2021.116720.

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Xu, Yanbo, Longhua Xu, Houqin Wu, Jia Tian, Zhoujie Wang, and XiaoChuan Gu. "The effect of citric acid in the flotation separation of bastnaesite from fluorite and calcite using mixed collectors." Applied Surface Science 529 (November 2020): 147166. http://dx.doi.org/10.1016/j.apsusc.2020.147166.

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Wang, Yu, Xi Zhang, Jie Zhang, and Wei Zhao. "Utilization of Citric Acid to Improve the Depressive Efficiency of Sodium Silicate on the Flotation of Calcite and Fluorite." Mining, Metallurgy & Exploration 39, no. 2 (February 27, 2022): 855–62. http://dx.doi.org/10.1007/s42461-022-00577-1.

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Moghal, Arif Ali Baig, Mohammed Abdul Lateef, Syed Abu Sayeed Mohammed, Kehinde Lemboye, Bhaskar C. S. Chittoori, and Abdullah Almajed. "Efficacy of Enzymatically Induced Calcium Carbonate Precipitation in the Retention of Heavy Metal Ions." Sustainability 12, no. 17 (August 28, 2020): 7019. http://dx.doi.org/10.3390/su12177019.

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This study evaluated the efficacy of enzyme induced calcite precipitation (EICP) in restricting the mobility of heavy metals in soils. EICP is an environmentally friendly method that has wide ranging applications in the sustainable development of civil infrastructure. The study examined the desorption of three heavy metals from treated and untreated soils using ethylene diamine tetra-acetic acid (EDTA) and citric acid (C6H8O7) extractants under harsh conditions. Two natural soils spiked with cadmium (Cd), nickel (Ni), and lead (Pb) were studied in this research. The soils were treated with three types of enzyme solutions (ESs) to achieve EICP. A combination of urea of one molarity (M), 0.67 M calcium chloride, and urease enzyme (3 g/L) was mixed in deionized (DI) water to prepare enzyme solution 1 (ES1); non-fat milk powder (4 g/L) was added to ES1 to prepare enzyme solution 2 (ES2); and 0.37 M urea, 0.25 M calcium chloride, 0.85 g/L urease enzyme, and 4 g/L non-fat milk powder were mixed in DI water to prepare enzyme solution 3 (ES3). Ni, Cd, and Pb were added with load ratios of 50 and 100 mg/kg to both untreated and treated soils to study the effect of EICP on desorption rates of the heavy metals from soil. Desorption studies were performed after a curing period of 40 days. The curing period started after the soil samples were spiked with heavy metals. Soils treated with ESs were spiked with heavy metals after a curing period of 21 days and then further cured for 40 days. The amount of CaCO3 precipitated in the soil by the ESs was quantified using a gravimetric acid digestion test, which related the desorption of heavy metals to the amount of precipitated CaCO3. The order of desorption was as follows: Cd > Ni > Pb. It was observed that the average maximum removal efficiency of the untreated soil samples (irrespective of the load ratio and contaminants) was approximately 48% when extracted by EDTA and 46% when extracted by citric acid. The soil samples treated with ES2 exhibited average maximum removal efficiencies of 19% and 10% when extracted by EDTA and citric acid, respectively. It was observed that ES2 precipitated a maximum amount of calcium carbonate (CaCO3) when compared to ES1 and ES3 and retained the maximum amount of heavy metals in the soil by forming a CaCO3 shield on the heavy metals, thus decreasing their mobility. An approximate improvement of 30% in the retention of heavy metal ions was observed in soils treated with ESs when compared to untreated soil samples. Therefore, the study suggests that ESs can be an effective alternative in the remediation of soils contaminated with heavy metal ions.

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Yusiharni, B. E., H. Ziadi, and R. J. Gilkes. "A laboratory and glasshouse evaluation of chicken litter ash, wood ash, and iron smelting slag as liming agents and P fertilisers." Soil Research 45, no. 5 (2007): 374. http://dx.doi.org/10.1071/sr06136.

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Standard AOAC methods of chemical analysis have been used to characterise the industrial byproducts partly burnt chicken litter ash (CLA), totally burnt chicken litter ash (CLAT), wood ash (WA), and iron smelting slag, for use as a combined liming agent and phosphate (P) fertiliser. These materials are effective liming agents with calcium carbonate equivalence of 93–99%. Total P concentrations of CLA (3.6% P), CLAT (4.75% P), slag (0.26% P), and WA (0.44% P) indicate that they would function as P fertilisers when applied at the high rates required for liming soils. The form of P in slag is unknown; CLA and CLAT consist mostly of mixtures of the phosphate mineral apatite with calcite and quartz. WA consists mostly of calcite, quartz, and various salts. For long extraction times, total P dissolved increased in the sequence CA (citric acid) > NAC (neutral ammonium citrate) > AAC (alkaline ammonium citrate). Little apatite persisted in residues of CLA and CLAT after 120 h of CA extraction but considerable amounts of apatite remained in NAC and AAC residues. A glasshouse P-response experiment was carried out with ryegrass on an acid lateritic soil with the application of various levels of phosphate as chicken litter ash, iron smelting slag, and wood ash. Monocalcium phosphate (MCP), dicalcium phosphate (DCP), and rock phosphate (RP) were included for comparison purposes. Based on plant yield data, the relative agronomic effectiveness (RE) of DCP compared to MCP was 57%, 72%, 73%, and 94%, respectively, for 4 successive harvests, for RP was 24%, 34%, 70%, and 56%, for chicken litter ash was 13%, 16%, 33%, and 39%, for slag was 8%, 9%, 16%, and 10%, for WA was 6%, 9%, and was effectively zero for the final 2 harvests. For no extraction time was the P soluble in the 3 citrate extractants a reliable predictor of the agronomic effectiveness of these materials as P fertilisers established by plant growth measurements.

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Moghal, Arif Ali Baig, Mohammed Abdul Lateef, Syed Abu Sayeed Mohammed, Munir Ahmad, Adel R. A. Usman, and Abdullah Almajed. "Heavy Metal Immobilization Studies and Enhancement in Geotechnical Properties of Cohesive Soils by EICP Technique." Applied Sciences 10, no. 21 (October 27, 2020): 7568. http://dx.doi.org/10.3390/app10217568.

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Soil treatment methods to cope with ever-growing demands of construction industry and environmental aspects are always explored for their suitability in different in-situ conditions. Of late, enzyme induced calcite precipitation (EICP) is gaining importance as a reliable technique to improve soil properties and for contaminant remediation scenarios. In the present work, swelling and permeability characteristics of two native Indian cohesive soils (Black and Red) are explored. Experiments on the sorption and desorption of multiple heavy metals (Cd, Ni and Pb) onto these soils were conducted to understand the sorptive response of the heavy metals. To improve the heavy metal retention capacity and enhance swelling and permeability characteristics, the selected soils were treated with different enzyme solutions. The results revealed that EICP technique could immobilize the heavy metals in selected soils to a significant level and reduce the swelling and permeability. This technique is contaminant selective and performance varies with the nature and type of heavy metal used. Citric acid (C6H8O7) and ethylene diamine tetra-acetic acid (EDTA) were used as extractants in the present study to study the desorption response of heavy metals for different EICP conditions. The results indicate that calcium carbonate (CaCO3) precipitate deposited in the voids of soil has the innate potential in reducing the permeability of soil up to 47-fold and swelling pressure by 4-fold at the end of 21 days of curing period. Reduction in permeability and swell, following EICP treatment can be maintained with one time rinsing of the treated soil in water to avoid dissolution of precipitated CaCO3. Outcomes of this study have revealed that EICP technique can be adopted on selected native soils to reduce swelling and permeability characteristics followed by enhanced contaminant remediation enabling their potential as excellent landfill liner materials.

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Shkromada, Oksana, Tatiana Fotina, Yevheniia Dudnyk, Roman Petrov, Viktoriya Levytska, Vadym Chivanov, Nadiya Bogatko, Alina Pikhtirova, and Olexandr Bordun. "Reducing the biogenic corrosion of concrete in a pigsty by using disinfectants." Eastern-European Journal of Enterprise Technologies 4, no. 6(118) (August 31, 2022): 57–66. http://dx.doi.org/10.15587/1729-4061.2022.263310.

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The object of this study is the regularity of changes in the biogenic destructive effect of microorganisms on the concrete structural elements of livestock facilities due to the use of the original liquid phase mixture of disinfectant based on aldehyde and surfactant. Microorganisms use construction materials as a substrate for growth and nutrition; they produce citric acid, which leads to a change in the composition and morphology of hydrated cement new formations. The composition of the microflora of the pigsty has been determined, and the minimum concentration of disinfectant based on glutaraldehyde and didecyl dimethyl ammonium chloride was found. By the TPD MS method, a decrease in the intensity of carbon dioxide (CO2) release in concrete samples during the heating of the sample to 900 °C was proved, compared to the control intact corrosion sample. Electron microscopy of concrete samples shows the presence of destructive changes and colonies of micromycetes. It was established that calcite was intensively released in the control sample of concrete, which retained its integrity and was not subjected to corrosion when heated to a temperature of 600 °C. Electron microscopy confirms the preservation of the homogeneous structure of concrete. The use of a disinfectant based on glutaraldehyde and didecyl dimethyl ammonium chloride at a concentration of 1 % destroys colonies of micromycetes, 2 % – the shell of microorganisms, and 3 % – biofilm. Treatment of concrete with a disinfectant at a concentration of 3 % destroys microorganisms Aspergillus fumigatus and Penicillium oxalicum, inhibits the process of biological corrosion of concrete, and strengthens the structure of concrete. The results of the experiment can be applied to inhibit the corrosion of concrete and extend the life of building structures made of concrete through the use of a disinfectant based on aldehyde and didecyl dimethyl ammonium chloride at a concentration of 3 %.

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Liu, Pei Ya, Huan Liu, Yu Jiao Li, and Chang Xun Dong. "Remediation of Arsenic Contaminated Soils and Treatment of Washing Effluent Using Calcined Mn-Fe Layered Double Hydroxide." Advanced Materials Research 955-959 (June 2014): 2014–21. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.2014.

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Arsenic contaminated soil is a serious worldwide problem nowadays, and soil washing technique is one of hottest topics in the area of remediating arsenic contaminated soils, while treatment of the washing effluent is still an urgent problem. In this study, in order to select the best washing extractants for arsenic contaminated soil of the Xiangxi Autonomous Prefecture, nine kinds of extractants (citric acid, oxalic acid, malic acid, tartaric acid, H3PO4, KH2PO4, KOH, NH4Ac and ultra-pure water) were studied. Innovatively, a new material (calcined Mn-Fe Layered double hydroxide) was firstly introduced and fully applied to the adsorption of arsenic washing effluents. Results showed citric acid, oxalic acid and KH2PO4 were the optimal extractants for arsenic contaminated soil, considering the extraction rate and environmental perspective. When the concentrations were 200, 300, 300 mmol/ L , solution soil ratios were 10, 10, 20 mL/g , extraction times were 12,12,12 h, the citric acid, oxalic acid and KH2PO4, respectively, achieved the maximum extraction rate of 39%, 65% and 29%. Calcined Mn-Fe LDH used in this work was characterized by SEM and FT-IR, indicating the unique structure and high phase purity of the synthetic samples. For the 28mg/L arsenic effluent washing by citric acid, calcined Mn-Fe LDH showed the most effective capacity as adsorbent under neutral or weak base condition as well as 2 h absorption time.

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Wang, Yi, and Jia Chen Liu. "Synthesis of Amorphous Al₂O₃-ZrO₂ Powders Prepared by Citric Acid Gel Process." Key Engineering Materials 512-515 (June 2012): 73–76. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.73.

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AmorphousAl2O3ZrO2powders were synthesized by citric acid gel process. The effects of molar ratio of citric acid to total metal ions concentration and the calcined powders with CA/M=2:1 were investigated through XRD and SEM analysis. Thermal behavior of the dried gel with CA/M=2:1 was studied by DSC/TG. Amorphous Al2O3-ZrO2 powders with particle size of about 3μm were obtained.

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Demir, Fatih, Oral Laçin, and Bünyamin Dönmez. "Leaching Kinetics of Calcined Magnesite in Citric Acid Solutions." Industrial & Engineering Chemistry Research 45, no. 4 (February 2006): 1307–11. http://dx.doi.org/10.1021/ie0507629.

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Velazco, G., J. M. Almanza, D. A. Cortés, J. C. Escobedo, and J. I. Escalante-Garcia. "Effect of citric acid and the hemihydrate amount on the properties of a calcium sulphoaluminate cement." Materiales de Construcción 64, no. 316 (December 1, 2014): e036. http://dx.doi.org/10.3989/mc.2014.03513.

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Karbalaei Saleh, Danyal, Hadi Abdollahi, Mohammad Noaparast, and Alireza Fallah Nosratabad. "Dissolution of aluminium from metakaolin with oxalic, citric and lactic acids." Clay Minerals 54, no. 2 (May 27, 2019): 209–17. http://dx.doi.org/10.1180/clm.2019.28.

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AbstractThis study examines the leaching of aluminium from calcined kaolin (metakaolin) with citric, oxalic and lactic acid and binary combinations of these organic acids. The investigated parameters were the pulp density, acid concentration, pH, agitation speed, temperature and contact time. The kinetics of aluminium dissolution from metakaolin in binary organic acid mixtures were determined and scanning electron microscopy examination and energy-dispersive spectrometry mapping of Si and Al of untreated kaolin and residual solids were also carried out. Aluminium dissolution increased with temperature, time, acid concentration, pulp density and acidity. At maximum dissolution, citric–oxalic (1:4 w/w) and lactic–oxalic (1:4 w/w) mixtures dissolved 77% and 78% aluminium, respectively, from metakaolin in 11 h. The activation energy ranged from 57.8 to 74.6 kJ/mol. The most effective parameter in the dissolution of aluminium was the temperature, indicating that the reaction was not diffusion-controlled. It was concluded on the basis of the activation energy values and the sensitivity of the reaction to temperature that the dissolution was under chemical-reaction control.

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Ren, Xue Jiao, Ju Pei Xia, Gui Qin Zi, Chao Qin Yang, Zhao Shu Zhang, Guo Bin Li, and Jing Xia Chao. "Effect of Leaching Conditions on Dissolution Rate of Potassium from K-Feldspar Calcined Sample." Advanced Materials Research 734-737 (August 2013): 911–15. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.911.

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Potassium feldspar, phosphogypsum and coke are used as raw materials to obtain soluble salts of calcined sample through mechanical grinding, roasting activation and leaching with acid. A study has been conducted on the factors that affect the leaching ratio of K2O of calcined samples, such as the type and concentration of leaching medium, temperature, time, liquid-solid ratio. The experiments show under the conditions that concentration of citric acid of 2% (wt%), liquid-solid ratio of 4, leaching for 4 hours at room temperature, potassium dissolution rate can reach 76.81%.

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Wang, Min, Li Fang Zhang, and Hai Yan Luan. "Synthesis and Photocatalytic Property of FeVO4 Photocatalyst by Sol-Gel Method." Advanced Materials Research 328-330 (September 2011): 1507–11. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1507.

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FeVO4 photocatalysts were synthesized by complexing Sol-Gel method using citric acid as chelate and characterized with X-ray diffraction (XRD), scanning electron microsoope(SEM, specific surface area (BET). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under visible light. It was found that the sample prepared with the molar ratio of citric acid to metal inons be 2:1, pH=7 and calcinated under 750°C for 4 hours was pure triclinic FeVO4 phase. In the experimental conditions used, the FeVO4 calcined at 750°C had highest photocatalytic activity with the photodegradation rate was about 85% or so in 150min under 250W halogen lamp.

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Thongtem, Titipun, Sulawan Kaowphong, and Somchai Thongtem. "Synthesis and Analysis of Nano-Crystalline LiNiVO₄." Materials Science Forum 510-511 (March 2006): 1142–0. http://dx.doi.org/10.4028/www.scientific.net/msf.510-511.1142.

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LiNiVO4 was synthesized using Li2CO3, NH4VO3 and Ni(CH3COO)2.4H2O as starting reagents and citric acid as a chelating agent. Mole ratios of metals to citric acid used for the preparation were 1 : 1 - 1 : 4. Carboxylate precursors were calcined at high temperatures to form powder. TGA data showed weight loss due to the evaporation and decomposition processes. FTIR showed the stretching bands of VO4 tetrahedron at 642, 713 and 813 cm-1. For 1 : 3 and 1 : 4 mole ratios, nano-crystals of inverse spinel LiNiVO4 (produced at 450 oC calcination for 6 h) were detected by XRD, electron diffraction, SEM and TEM.

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Vahdati, Nima, and Arman Sedghi. "Synthesis of nano Mn-Zn ferrites by gel combustion method with three different fuels and investigation of their structure and properties." Materials Science-Poland 38, no. 2 (June 1, 2020): 350–58. http://dx.doi.org/10.2478/msp-2020-0037.

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AbstractThe purpose of studying the properties of zinc-manganese nanoferrite was to compare organic fuels that were produced in conditions created by the auto gel combustion method, using citric acid, glycine, and urea with different pH values: (citric acid = 6, glycine = 3 and urea = 0). The samples were prepared in stoichiometric ratios to gain Mn0.5Zn0.5Fe2O4, and all the samples were calcined in the same condition (500 °C and 30 minutes). It should be noted that the entire process of synthesis was photographed to analyze the effect of fuels during the combustion process. Combustion reactions were studied by simultaneous thermal analysis (STA), FT-IR spectroscopy, and X-ray diffraction (XRD), also the Rietveld method was used to determine the type and amount of crystalline phases. Magnetic properties of the samples were measured by vibration sample magnetometer (VSM), and their morphology and powder agglomeration was observed by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Superior magnetic properties of the sample synthesized with glycine were achieved. Urea gave the smallest particle size, while citric acid produced intermediate properties.

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Wang, Min, Qiong Liu, and Hai Yan Luan. "Preparation, Characterization and Photocatalytic Preoperty of BiVO₄ Photocatalyst by Sol-Gel Method." Applied Mechanics and Materials 99-100 (September 2011): 1307–11. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.1307.

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Bismuth vanadate (BiVO4) powders were synthesized by complexing Sol-Gel method using citric acid as chelate,calcined at different temperature and characterized with X-ray diffraction (XRD), scanning electron microsoope（SEM）and specific surface area (BET). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under visible light. It revealed that temperature values can influence significantly on the morphologies and structures of the products.It also found that the sample prepared with the molar ratio of citric acid to metal inons be 2:1, pH=7 and calcinated under 400°C for 5 hours was pure monoclinic BiVO4 phase.In this conditions, the sample had highest photocatalytic activity with the photodegradation rate was about 94% or so in 20min under 250W halogen lamp.

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Song, Yuan, Guang Hui Cheng, Jiang Guo, and Xiao Le Li. "Study on the Method and Factors of Preparating Cobalt Blue Pigment from Waste Cobalt Acid Lithium Battery." Applied Mechanics and Materials 687-691 (November 2014): 4192–96. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4192.

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In the solution of sulfuric acid and hydrogen peroxide dissolved waste cobalt acid lithium battery income as raw material, the process and its influence factors of preparation of nanocobalt blue pigment are studied in the paper. The results show that: under the condition of pH 6, metal ion and citric acid ratio was 1:1 dry gel prepared at 135°C calcination, then calcined at 800°C uniform particle size, good dispersion and spinel structure of nanocobalt blue pigment can be directly synthetized.

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Arif, Ayesha, Ming Xu, Jamshaid Rashid, Chaudry Sajed Saraj, Wei Li, Bilal Akram, and Binbin Hu. "Efficient Recovery of Lithium Cobaltate from Spent Lithium-Ion Batteries for Oxygen Evolution Reaction." Nanomaterials 11, no. 12 (December 9, 2021): 3343. http://dx.doi.org/10.3390/nano11123343.

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Owing to technological advancements and the ever-increasing population, the search for renewable energy resources has increased. One such attempt at finding effective renewable energy is recycling of lithium-ion batteries and using the recycled material as an electrocatalyst for the oxygen evolution reaction (OER) step in water splitting reactions. In electrocatalysis, the OER plays a crucial role and several electrocatalysts have been investigated to improve the efficiency of O2 gas evolution. Present research involves the use of citric acid coupled with lemon peel extracts for efficient recovery of lithium cobaltate from waste lithium-ion batteries and subsequent use of the recovered cathode material for OER in water splitting. Optimum recovery was achieved at 90 °C within 3 h of treatment with 1.5 M citric acid and 1.5% extract volume. The consequent electrode materials were calcined at 600, 700 and 800 °C and compared to the untreated waste material calcined at 600 °C for OER activity. The treated material recovered and calcined at 600 °C was the best among all of the samples for OER activity. Its average particle size was estimated to be within the 20–100 nm range and required a low overpotential of 0.55 V vs. RHE for the current density to reach 10 mA/cm2 with a Tafel value of 128 mV/dec.

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Wang, Min, Qiong Liu, and Hai Yan Luan. "Preparation and Photocatalytic Preoperty of Cu₁₁O₂ (VO₄)₆ Photocatalyst by Sol-Gel Method." Advanced Materials Research 361-363 (October 2011): 1598–601. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.1598.

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Cu11O2 (VO4)6 powders have been synthesized by complexing Sol-Gel method using citric acid as chelate, calcined at different temperature without using any template. Techniques of X-ray diffraction (XRD) and scanning electron microscope (SEM) have been employed to characterize the as-synthesized materials. The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under UV-light. It revealed that temperature values can influence significantly on the morphologies and structures of the products.It also found that the sample prepared with the molar ratio of citric acid to metal inons be 2:1, pH=7 and calcinated under 500°C for 4 hours was pure triclinic Cu11O2 (VO4)6 phase.In this conditions, the sample had highest photocatalytic activity with the photodegradation rate was about 78.9% or so in 60min under 20W ultraviolet lamp.

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Osman, Nafisah, Nur Athirah Abdullah, and Sharizal Hasan. "Chelating Agent Role in Synthesizing Cerate-Zirconate Powder by a Sol-Gel Method." Advanced Materials Research 896 (February 2014): 112–15. http://dx.doi.org/10.4028/www.scientific.net/amr.896.112.

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In this study, powders of BaCe0.54Zr0.36Y0.1O2.95 (BCZY) were synthesized by a sol-gel method assisted with three different groups of chelating agents. The chelating agents used were citric acid, tartaric acid, glycolic acid from carboxylic group, tryelthylenetetraamine (TETA) from polyamino group, nitriloaacetic acid (NTA) and ethylenediaaminetetraacetic acid (EDTA) from polyamino carboxylic group. The samples were dried at 325 °C and calcined at a series of temperatures. The solution and resulting powder properties were studied using Fourier transform Infrared (FTIR) spectroscopy. FTIR spectra showed all the samples exhibit different characteristics of absorption bands after being treated at various temperatures. Such behavior indicates that the chelation process took place before the formation of metal oxide. The chelating agent from polyamino group that consists of N-donor atoms, which is TETA showed no characteristics peak of carbonates was detected after the sample was calcined at 1100 °C. Therefore, TETA gave a significant role in reducing calcination temperature for synthesizing cerate-zirconate powder.

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30

Tai, Lone-Wen, and Paul A. Lessing. "Modified resin–intermediate processing of perovskite powders: Part II. Processing for fine, nonagglomerated Sr-doped lanthanum chromite powders." Journal of Materials Research 7, no. 2 (February 1992): 511–19. http://dx.doi.org/10.1557/jmr.1992.0511.

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Nonagglomerated ceramic precursor for Sr-doped lanthanum chromite powder was prepared by a modified resin–intermediate process using equimolar citric acid, ethylene glycol, and metallic nitrates. Pure and well-crystallized submicron powders with a narrow particle-size distribution were calcined from an optimally pulverized resin at a temperature of 750 °C for 2 h in flowing air. The material cost for organics used in the investigated process was considerably lower than the original Pechini process.

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Ayu Lestari, Riani, Muthia Elma, Erdina Lulu Atika Rampun, Anna Sumardi, Adhe Paramitha, Aptar Eka Lestari, Sadidan Rabiah, Zaini Lambri Assyaifi, and Gesit Satriaji. "Functionalization of Si-C Using TEOS (Tetra Ethyl Ortho Silica) as Precursor and Organic Catalyst." E3S Web of Conferences 148 (2020): 07008. http://dx.doi.org/10.1051/e3sconf/202014807008.

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Silica network was tailored configuring siloxane (Si-O-Si) and silanol (Si-OH) groups which are essential to produce porous-structured materials. As silanols are hydrophilic, react with water to form fouling. This research address to actualize strategy for synthesizing highly functionalized silica carbon (Si-C) using hybrid organic-inorganic structures as the primary method for improving hydro-stability by employing precursor TEOS and organic catalyst through a sol-gel process. Catalysis employs citric acid or citric acid-ammonia whereas carbon templated into silica network. The synthesis scheme involves: a) sol-gel process at 0°C and b) calcination. Silica sol dried into xerogels were prepared and calcined at 200°C and 250°C. Characterization of xerogels showed the infrared band areas of the organic groups to evaluate the thermal stability. For xerogel employed single (pH 5.5) and dual (pH 7.65) catalyst, infrared spectra showed mostly look similar Si-C area at similar wavelength. Silica xerogel is more effectively prepared from TEOS with one-step single acid catalyst including calcination.

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32

Abdullah, Nur Athirah, Sharizal Hasan, and Nafisah Osman. "Role of CA-EDTA on the Synthesizing Process of Cerate-Zirconate Ceramics Electrolyte." Journal of Chemistry 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/908340.

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The role of a combination between citric acid (CA) and ethylenediaminetetra acetic acid (EDTA) as chelating agents in preparation of BaCe0.54Zr0.36Y0.1O2.95powder by a modified sol-gel method is reported. The precursor solutions were prepared from metal nitrate salts (M+), chelating agents (C), and ethylene glycol (EG) at molar ratio of M+ : C : EG = 3 : 2 : 3. Chemical and phase transformation of samples during thermal decomposition were analyzed by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. TGA results show that the sample prepared by a combination of CA-EDTA exhibited the lowest thermal decomposition temperature,Ttdsince there was no significant weight loss after 750°C. After calcined at 1100°C, the carbonates residue remained in the samples as proven by FTIR results. It was found that the used combination of CA-EDTA acts as a better combustion reagent to increase the reaction rate and influence the thermal decomposition behaviour compared to a single citric acid and EDTA, respectively. Apparently, calcination temperatures above 1100°C are needed to produce a pure perovskitic BaCe0.54Zr0.36Y0.1O2.95.

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Lim, H. H., and R. J. Gilkes. "Beneficiation of apatite rock phosphates by calcination: effects on chemical properties and fertiliser effectiveness." Soil Research 39, no. 2 (2001): 397. http://dx.doi.org/10.1071/sr00005.

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Apatitic rock phosphates (RP) are commonly calcined to remove impurities and to increase phosphorus (P) concentration but calcination decreases the agronomic effectiveness of RPs used for direct application to soils. This study investigated the effect of calcination on 6 apatite RPs (Christmas Island A-ore, Egypt, Morocco, North Carolina, Queensland, and Sechura). RPs were uncalcined (25°C) and calcined at 500°C, 900°C, and 1100°C. They were evaluated by X-ray diffraction (XRD) and BET-N 2 surface area technique. P dissolution in 2% citric acid with a 128 h extraction time was measured. Chemical results were compared with those from a plant growth experiment, where wheat was fertilised with the calcined RP products. Calcination at 1100°C reduced the agronomic effectiveness of apatite RPs by about 90%, by altering the crystal properties and the particle size of the RPs. Unit-cell a dimension increased from values of 9.324—9.375 Å to approximately 9.38 Å, indicating that the carbonate containing apatite RPs altered to less-soluble fluorapatite. Apatite average crystal size (coherently diffracting zone) more than doubled and BET-N 2 specific surface area decreased by 95%, due to crystal growth and sintering. Consequently, the extent of dissolution in 2% citric acid and agronomic effectiveness decreased substantially. Calcination at 500°C and 900°C produced similar but smaller changes in mineral properties. It is concluded that beneficiation of apatitic RP by calcination will adversely affect the agronomic effectiveness of RP used for direct application to soils.

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Chaves, A. C., Hélio Lucena Lira, G. A. Neves, L. L. M. Sales, D. M. A. Melo, and Bráulio Silva Barros. "Study Morphologic and Microstructural of the System CeO₂-NiO Obtained by Polymeric Precursor Method." Materials Science Forum 727-728 (August 2012): 491–96. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.491.

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Cerium oxide has a high potential to be apply in removing pollutants combustion powders, organic materials from waste water and in the technology of fuel cells. Nickel oxide is an attractive material due to its excellent chemical stability, and their optical, electrical and magnetic proprieties. In this work, CeO2-NiO systems on molar ratios of 1:1, 1:2 and 1:3 citric metal-acid were synthesized by using Pechinis method. The change in compositions and calcined temperature were studied by different techniques such as: XDR and SEM. It was also done a microstructural study by Rietvelds method, whose routine was designed to run in the Fullprof Suite program, and analyzed by pseudo-Voigt function. It has noticed that the molar ratio between metal-citric acid in the system CeO2-NiO 1:1, 1:2 and 1:3 has a strong influence on microstructural proprieties, crystallite size and cell micro-deformations and can be used to control these proprieties.

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35

Riaz, Madeeha, Rehana Zia, Snudia Aslam, Alliya Qamar, Tousif Hussain, and Safia Anjum. "Low temperature synthesis of wollastonite using sol–gel combustion method: In vitro bioactivity evaluation." International Journal of Modern Physics B 33, no. 10 (April 20, 2019): 1950081. http://dx.doi.org/10.1142/s0217979219500814.

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In this paper, low temperature, economical sol–gel combustion method was adopted to synthesize wollastonite ceramic. Calcium nitrate tetrahydrate and tetraethyl orthosilicate were taken as source for Ca and Si, while citric acid and nitric acid were used as chelating/combustion agents. The yielded powder calcined at 600[Formula: see text]C for 4 h was characterized by FTIR, XRD and SEM techniques. Results showed that the citrate combustion method was the most efficient method to prepare wollastonite at low temperature. Moreover, in vitro bioactivity test performed in simulated body fluid (SBF) showed good bioactivity of synthesized wollastonite ceramics.

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Sun, Yuan, Xiu Juan Zhao, Guo Jun Li, and Rui Ming Ren. "Synthesis of LiFePO₄ Cathode Materials by a Chemical Method." Advanced Materials Research 197-198 (February 2011): 1049–52. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1049.

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The olivine-type LiFePO4powder was prepared by a chemical method using the synthesized FePO41.78H2O, LiOH, citric acid and PEG as raw materials. The synthesized FePO41.78H2O precursor powder was obtained by co-precipitation method. LiFePO4powder was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA)/differential scanning calorimetry (DSC). The results showed that the calcined LiFePO4was in a single phase when fabricated by using the synthesized FePO41.78H2O powder at pH of 3.5 in argon atmosphere.

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da Silva, Mirele Costa, Hélio Lira Lucena, and Normanda Lino de Freitas. "Influence of the Citric Acid and Metal Cation Ratio on the Structural and Morphological Characteristics of Aluminum Oxide Synthesized by Pechini Method." Materials Science Forum 798-799 (June 2014): 133–38. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.133.

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Given the opportunities that aluminas present in relation to the broad field of applications to which they refer, the literature has reported great diversity in methodology to obtain these materials in the search of generating the best properties. In this way, the aim of this work is to evaluate the use of different citric acid and metallic cation ratio on the structural and morphological characteristics of the alumina synthesized by Pechini method and calcined at 1100°C. The samples were characterized by X-ray diffraction, thermal analysis, particle size and scanning electron microscopy. The results showed a large amount of loss of mass after pyrolysis. The α-alumina phase was achieved for the two studied ratio reaching values for crystallite size of 41.4 and 52.5 nm, crystallinity of 88 and 91.2%, agglomerates size of 12.3 and 14μm, for the synthesized samples 2:1 and 3:1, respectively. According to the SEM images, the changes in the citric acid: metallic cation ratio did not significantly modify the morphology of the alumina.

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Zhang, Li Li, Jie Sun, and Yong Tan. "Synthesis and Microwave Electromagnetic Property of Nano-Sized Mn_0.5Zn_0.5Fe₂O₄ Spinel-Type Ferrite." Advanced Materials Research 160-162 (November 2010): 484–87. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.484.

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The nano-sized Mn0.5Zn0.5Fe2O4 spinel-type ferrite was synthesized by sol-gel auto-combustion method using citric acid as the chelating agents. The analysis methods of FT-IR, XRD, wave-guide were used to character the gel and the products after calcining. From the results, it was shown that the homogeneous organic complex base salts were formed in the process of gelation formation. The crystalline sizes of as-synthesis powders, calcined at 700°C for 2h and calcined at 1000°C for 2h were 15nm, 21nm and 25nm, respectively. The nanocrystalline had both dielectric loss and magnetic loss in the frequency range of measurement. The electron transportation of Fe2+↔Fe3+ can make the resistivity reduce to result in a certain amount of dielectric loss.

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39

Barati, M. R., S. A. Seyyed Ebrahimi, and A. Badiei. "Influence of Different Calcination Conditions on the Microstructure and Phase Constitution of Nickel-Zinc Ferrite Nanocrystalline Powders Prepared by a Sol-Gel Auto-Combustion Method." Key Engineering Materials 368-372 (February 2008): 598–600. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.598.

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In this work, nickel-zinc ferrite nanocrystalline powder has been prepared by a sol-gel autocombustion technique using nitrate-citrate gel obtained from metal nitrates and citric acid solution. Characterization of the nitrate-citrate gel, as-burnt powder and calcined powder at different calcination conditions were investigated by using XRD, FTIR and SEM techniques. The results revealed that the nitrate-citrate gel exhibits a self-propagating behavior after ignition and showed that the different calcination conditions affect the crystallite size of the synthesized powder as well as its phase constitution.

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Zhou, Dong Xiang, Guo Hua Huang, Zhi Ping Zheng, Jian Mei Xu, and Shu Ping Gong. "Synthesis of (1-x) Ca_0.4Sm_0.4TiO₃ – xLi_0.5Nd_0.5TiO₃ Ceramic Powders via Citric Acid Precursor." Key Engineering Materials 280-283 (February 2007): 683–86. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.683.

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Using citric acid (CA) as a chelating agent, (1-x)Ca0.4Sm0.4TiO3 –xLi0.5Nd0.5TiO3 (CSLNT) (x = 0.3) ceramic powders were synthesized by the Pechini method. The CSLNT precursor and derived oxide powders were characterized by differential thermal analysis, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. Only perovskite CSLNT (x=0.3) phase appeared when the CSLNT precursor was calcined at 1050°C for 3 h. Compared with the conventional solid-state reaction method, microwave dielectric ceramics with better properties could be prepared by the Pechini method at lower sintering temperature.

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Yan, Bing, Peng Zhao Gao, Dong Yun Li, and Guang Lei Tian. "Influence of the Preparation Process on the Electrochemical Properties of xLiFePO₄·yLi₃V₂(PO4)₃/C Nano-Sized Composite Cathode Materials." Key Engineering Materials 680 (February 2016): 238–43. http://dx.doi.org/10.4028/www.scientific.net/kem.680.238.

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In this paper, a series of xLiFePO4·yLi3V2(PO4)3/C (x/y = 1:0, 7:1, 5:1, 3:1, 1:1, 1:3 and 0:1, ratio in mol) nano-sized composite cathode materials were successfully prepared via the solid reaction method. Influence of x/y ratio, calcination temperatures and the content of citric acid on the composition, microstructure and electrochemical properties of the materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical measurements, et al. results showed that the xLFP·yLVP/C (x and y ≠ 0) composites were composed of olivine LiFePO4 and monoclinic Li3V2(PO4)3, both of which featured slight structural distortions as the formation of V-doped LFP/C and Fe-doped LVP/C, respectively; With the increase of calcination temperatures, the crystallinity and particles size of the 7LFP·LVP/C composites increased, when calcined at 700°C, the initial charge/discharge specific capacity of the composites reached a maximum value of 145.6 mAh/g, and the voltage drop values between charge/discharge platform possessed the minimum value(0.04 V), suggesting the minimum polarization of the composites in charge/discharge process. Content of citric acid did not affect the compositions of the composites, with the increase of the molar ratio of citric acid to V3+, the discharge specific capacities of 7LFP·LVP/C increased first and then decreased, when it equaled to 1.0:1.0, the discharge specific capacity of the relative composites was 119.18 mAh/g, with a capacity retention rate of 93.9 % after 50 cycles, owning the excellent electrochemical stability.

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RAVAL, ANAND, NITAL PANCHAL, and RAJSHREE JOTANIA. "STRUCTURAL PROPERTIES AND MICROSTRUCTURE OF COBALT FERRITE PARTICLES SYNTHESIZED BY A SOL-GEL AUTO COMBUSTION METHOD." International Journal of Modern Physics: Conference Series 22 (January 2013): 558–63. http://dx.doi.org/10.1142/s2010194513010660.

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Synthesis and characterization of Cobalt ferrite powders by a sol gel combustion process is focused in the present work. The prepared precursors was calcined at 950° C for 4 hours in order to get cobalt ferrite powder. The effect of metal nitrates/citric acid ratio (referred as x) of CoFe2O4 on structural and micro-structural properties was investigated. The structural characterization on CoFe2O4 ferrite samples were carried out using the X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. Phase identification and crystallite size of calcined powder were determined using XRD analysis. The formation of the ferrite is confirmed by FTIR results. The morphology of prepared CoFe2O4 ferrite samples (with x = 0.5, 1.0, 1.5 and 2.0, where x is metal to citrate ratio) was studied using a scanning electron microscopy.

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Lestari, Aptar E., Muthia Elma, Sadidan Rabiah, Erdina Lulu Atika Rampun, Aulia Rahma, and Amalia Enggar Pratiwi. "Performance of Mesoporous Organo Silica Membrane for Desalination." Materials Science Forum 1000 (July 2020): 285–92. http://dx.doi.org/10.4028/www.scientific.net/msf.1000.285.

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Clean water is essential source for household purpose. However, many surface water contain high salt concentration was found. In this work, membrane was made using tetraethyl orthosilicate (TEOS) as silica precursors and citric acid as single organo catalyst. Membranes were calcined at 200 and 250 °C using Rapid thermal processing (RTP). All membranes were tested via pervaporation. Pervaporation processes allow membrane to separate salt from water as vapour phase with vacuum condition required. Permeate was collected in the cold trap after condenses. This study focus to the performance of organo silica membrane in variance of refluxed 0 and 50 °C and feed concentrations (0.3, 3.5 and 5wt% NaCl) at room temperature (~25 °C). Optimum condition was obtained at reflux 50 °C with high siloxane and Si-C bonds. Carbon content from citric acid promote silica network more strength. The good performances in variance feed concentration were also showed at reflux 50°C with 0.3324 kg.m-2.h-1 (0.3 wt%), 0,2290 kg.m-2.h-1 (3.5 wt%) and 0.2168 kg.m-2.h-1 (5 wt%). These membranes are categorized as mesoporous and achieve excellent salt rejection >95%.

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Thongchanthep, Chanyaphak, and Sarawut Thountom. "Effect of the Fuel Type on the Synthesis of Barium Strontium Titanate by Sol-Gel Combustion Method." Advanced Materials Research 802 (September 2013): 149–53. http://dx.doi.org/10.4028/www.scientific.net/amr.802.149.

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The ferroelectric ceramic, Barium Strontium Tinanate (Ba0.7Sr0.3TiO3), was prepared by the sol-gel combustion method using citric acid, urea, and glycine as the fuel for reduce the calcination temperature. The molar ratio of sol powderto fuel was 1:1. All of the samples were calcined at 450, 550, 650, 750, 850 and 950°C for 2 h. Then,Ba0.7Sr0.3TiO3powders were applied with acid treatment process. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM) analysis were used to characterize the crystal structure and microstructure. The perovskite phases of BST and the pyrochlore (BaCO3,SrCO3) were obtained after the calcinations temperature of 550°C. BST powders were applied with acid treatment process.The XRD result showed the pure perovskite phase without the phase of pyrochlore in all of the samples. Ba0.7Sr0.3TiO3was in cubic structure, corresponding to JCPDS 34-0411. SEM analysis of BST powders calcined at 750°C.The particles were spherical morphology and had agglomerates while the particles sizes were larger corresponding with the increase of calcinations temperature.The results for TEM analysis of the BST powders prepared by using urea as the fuel had a smaller particles,and the average of particle size was about 47 nm.

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Guan, Xiang Feng, Yan An Wang, He Ping Zhou, and Li Hua Zhou. "Synthesis of Nanocrystalline Ce_0.8Sm_0.2O_1.9 by Citrate Gel Method." Key Engineering Materials 368-372 (February 2008): 247–49. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.247.

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A citrate gel method was applied to synthesize Ce0.8Sm0.2O1.9 powders by using cerium and samarium nitrates as raw materials and citric acid as complexing agent. It was shown that Ce0.8Sm0.2O1.9 phase was formed when the decomposition of the dried gel completed at 500 °C. The crystallite size of the synthesized powders calcined at 500 °C for 2 h is 5-10 nm. The powders can be easily sintered in air to yield over 97 % relative density at 1250 °C, which is significantly lower than sintering temperature of over 1500°C required by the doped ceria powders prepared via conventional ceramic techniques.

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da Silva, Mirele Costa, Hélio Lira Lucena, and Normanda Lino de Freitas. "Effect of Calcination Temperature in the Aluminum Oxide Synthesized by Pechini Method in the Citric Acid: Metal Cation Ratio of 2:1." Materials Science Forum 798-799 (June 2014): 139–44. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.139.

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Through the constant search by researchers to obtain materials with improved properties, literature has presented an annual increase in the number of articles that seek to optimize in the methodology used to prepare nanopowders. In this way, the aim of this work is to study how the calcined temperature (500, 600, 700, 800, 900, 1000, 1100 and 1200oC) changes the final properties of the alumina synthesized by Pechini method with citric acid: metallic cation ratio of 2:1. The alumina was characterized by thermal analysis, X-ray diffraction, particle size analysis and scanning electron microscopy. The results showed a total of mass loss of 61.6%. The alumina phase appear at 800°C of temperature, however the α-alumina only appear at 1100oC. The increase in the calcined temperature increases the crystallite size and the crystallinity of the alumina and the great value reached for the agglomerates diameter was 13μm for the alumina calcined at 1200oC. In relation to the morphology of the alumina, it was observed heterogeneous particles with different size and irregular geometry, with aspect of high density.

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Huda, N., E. Lulu Atika Rampun, R. Ayu Lestari, Y. Raharjo, D. Heri Yuli Yanto, and M. Elma. "Membrane pervaporation performance applied for brackish water prepared by vacuum impregnation method." IOP Conference Series: Materials Science and Engineering 1195, no. 1 (October 1, 2021): 012056. http://dx.doi.org/10.1088/1757-899x/1195/1/012056.

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Abstract Coating method and number of membrane layer are crucial factors on membrane performance. Through a vacuum impregnation method allows a sol solution uniformly fill into membrane support and it is required only less solution. The aim of this study is to apply vacuum impregnation method through vacuum calcination and air calcination during fabrication of silica membranes and to investigate the effect of layer variations on silica membranes performance to apply for brackish water. The sol solution was made from TEOS as silane precursor, ethanol and dual catalysts (citric acid + ammonia). Alumina membrane support was coated by vacuum impregnation method and calcined the membrane under air and vacuum condition. From the FTIR result, it indicates that silica membranes calcined in air and vacuum calcination have Si-O-Si and Si-OH. The vacuum impregnation obtained smoother surface membranes. The silica membrane calcined via vacuum calcination performs excellent water fluxes and salt rejection of 22.01 kg.m− 2.h−1 and 98.98 %. If compare to silica membranes calcined in air, the water flux (19.11 kg.m− 2.h−1) and salt rejection (98.75 %). It also found the two layers silica membrane is better than three layers for the membrane performance result.

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Zhou, Chuan, Dachuan Zhu, and Daji Wang. "Synthesis and Characterization of Cerium Dioxide Nanoparticles Obtained by a Novel Soft Mechanochemical Method Combined with Sol–Gel Method." Nano 12, no. 02 (February 2017): 1750020. http://dx.doi.org/10.1142/s1793292017500205.

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After mechanochemical reaction of hydrous cerium (III) chloride and citric acid with a little of ethanol followed by a subsequent calcination process at different temperature, cerium dioxide nanoparticles with fluorite structure were successfully prepared. Then the obtained ceria powders were characterized by means of X-ray diffractometer, specific surface area analyzer, scanning electron microscope, transmission electron microscopy and laser particle analyzer. It was found that the degree of particle aggregation passed through a minimum with the calcination temperature rising from 400[Formula: see text]C to 800[Formula: see text]C, accompanied with growth of particle size. The ceria powders calcined at 500[Formula: see text]C had an average aggregated particle size of 59.8[Formula: see text]nm with uniform spheroidal morphology, while their crystallite sizes ranged from 10[Formula: see text]nm to 20[Formula: see text]nm. Yet the product calcined at 400[Formula: see text]C had the maximum specific surface area of 109.6[Formula: see text]m2/g. In polishing experiment, the ceria powders calcined at 500[Formula: see text]C showed great polishing performances.

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Mirzaei, Ali, Kamal Janghorban, Babak Hashemi, Seyyed Hosseini, Maryam Bonyani, Salvatore Leonardi, Anna Bonavita, and Giovanni Neri. "Synthesis and characterization of mesoporous α-Fe2O3 nanoparticles and investigation of electrical properties of fabricated thick films." Processing and Application of Ceramics 10, no. 4 (2016): 209–17. http://dx.doi.org/10.2298/pac1604209m.

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In this work, ?-Fe2O3 nanoparticles (NPs) have been synthesized by using a simple Pechini sol-gel method from iron nitrate, citric acid as complexing agent and ethylene glycol as polymerization agent. The calcined ?-Fe2O3 NPs were fully characterized by different techniques. It was confirmed that ultrafine and highly crystalline ?-Fe2O3 NPs with high purity and mesoporous nature can be obtained after calcination at 550?C for 3 h. In addition, the results of electrical resistance measurements of the fabricated Fe2O3 thick films showed that ?-Fe2O3 thick films have stable electrical properties which are beneficial for electrical applications such as gas sensing and field effect transistors.

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Indira, R., V. Jaisankar, and S. C. Vella Durai. "A study on the development of scaffold fabrication using citric acid polyester – nanohydroxyapatite composite." Bulletin of the Chemical Society of Ethiopia 36, no. 4 (August 30, 2022): 923–34. http://dx.doi.org/10.4314/bcse.v36i4.17.

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ABSTRACT. Nano hydroxyapatite (n-HAp) and its composites have shown a great development in the field of tissue regeneration and in controlled drug delivery due to its good biocompatibility and bioactivity behavior. Furthermore, HAp-based nanocomposites enhance mechanical properties. These synthetic HAp nanocomposites can also be tailored to fabricate scaffold with controlled porosity which facilitate the growth of the cell in the field of tissue engineering. In this paper, we focus on the synthesis of nano hydroxyapatite (n-HAp) by sol-gel method. The synthesized nano powders were calcined at 500 oC and characterized by FT-IR, XRD and TEM. We have also described the synthesis of citric acid-based polyester by melt polycondensation method without adding catalyst. The monomers used were citric acid, 1,6-hexane diol and sebacic acid. The corresponding synthesized n-HAp/polyester composite have potential application in soft tissue engineering. The structures of polyester and its nanocomposite were studied by FT-IR and 1H NMR spectral studies. The thermal and mechanical properties of polyester, composites and cytotoxicity activity (MTT assay) using vero cells were also studied. Porous scaffold of the nano HAp/Polyester was fabricated by solvent-casting particulate leaching technique which is useful in the development of tissue engineering applications. SEM and TEM studies were carried out for nano HAp, polyester, composites and scaffold. KEY WORDS: Cytotoxicity, Polycondensation, Sol-gel, Solvent-casting, Tissue engineering Bull. Chem. Soc. Ethiop. 2022, 36(4), 923-934. DOI: https://dx.doi.org/10.4314/bcse.v36i4.17

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Journal articles on the topic 'Citric acid; calcite'

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