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Distinguishing kaolinites and Smectite Clays from Central and Eastern Uganda Using Acidity, pH, Colour and Composition

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American Journal of Analytical Chemistry 2015年第1期6卷 58-70页

作者： I. Z. Mukasa-Tebandeke P. J. M. Ssebuwufu S. A. Nyanzi A. Schumann M. Ntale G. W. Nyakairu F. Lugolobi Department of Chemistry Makerere University Kampala Uganda Department of Geology Makerere University Kampala Uganda Department of Earth Sciences Wesleyan University Middletown USA

The Langmuir isotherms of 1-aminobutane in isohexane slurries showed increase in clay acidity with increase in concentration of mineral acid used to leach the clay as well as the temperature at which the clay was thermally activated prior to experimentation involving adsorption of 1-aminobutane. The values of acidity for Central Uganda were low ranging from 0.07 mol/g to 0.32 mol/g yet those for clays from Eastern Uganda were high ranging from 0.1 mol/g to 1.85 mol/g. Based on acidity, pH, elemental and mineral compositions, the clays from Central Uganda were found to be kaolinites or halloysites, yet Eastern Uganda clays were resolved to contain nontronite and kaolinite.

关键词： Surface Acidity Adsorption 1-Aminobutane pH Isotherms kaolinite Smectite

Physico-Chemical Study of the Adsorption of Carotenoids from Carrots on Raw and Modified kaolinites

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Advances in Chemical Engineering and Science 2023年第2期13卷 132-148页

作者： Orléans Ngomo Etienne Dongo Joseph Sieliechi Department of Organic Chemistry Faculty of Sciences University of Yaoundé I Yaounde Cameroon Department of Applied Chemistry The National School of Agro-Industrial Sciences University of Ngaoundere Ngaoundere Cameroon

This study focuses on the adsorption at temperatures below 70℃, of carotenoids from carrots on clay materials such as kaolinite in the raw state, activated with a 0.5 M HCl solution or treated with a sodium solution of Al+. The kinetic study of carotenoid adsorption shows that equilibrium is reached after 30 minutes and the temperature has little influence on carotenoid adsorption. On the other hand, the quantities adsorbed at equilibrium increase with the initial concentration of carotenoids. The kinetic model that best describes the experimental data is that of the pseudo-second order, adsorption is made in two time. For the carotenoid adsorption isotherms, the best correlation is obtained with the Freundlich model. The low values of the Freundlich constants indicate that the adsorption is probably of a physical type. This conclusion is confirmed by the effective desorption of carotenoids observed during desorption experiments.

关键词： kaolinite Carrots Antioxidant Cosmetic Adsorption

Sorption and cosorption of the nonionic herbicide mefenacet and heavy metals on soil and its components

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Journal of Environmental Sciences 2012年第3期24卷 427-434页

作者： Zhenyu Liu Huiqin Guo Huan He Cheng Sun State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210046China Shanghai Pudong New Area Environmental Monitoring Station Shanghai 200135China

Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals （copper and silver） on black soil and its components （kaolinite and humic acid） were investigated. It was found that because of their different valences and properties, Cu2＋and Ag＋ presented different effects on the sorption of mefenacet. Due to the competition of Cu2＋, along with the shells of dense water formed by its surface complexation, for sorption surface area with mefenacet, the addition of Cu2＋ decreased the sorption amount of mefenacet on soil and its components, especially on humic acid. However, the addition of Ag＋ significantly enhanced the sorption of mefenacet, which was attributed to the softness of the cation that weakened the hydrophilicity of the local region around Ag＋-complexed functionalities, and thus mitigated the competitive sorption of water. In addition, the sorption of mefenacet on soil with or without the two metals was generally decreased with increasing pH, which was caused by the hydrolysis of carbonyl and carboxyl groups on the surface of the sorbents, π-π interaction between mefenacet and the soil organic matter, and so on. On the other hand, the presence of mefenacet seemed to have little effect on the sorption of Cu2＋ and Ag＋, indicating that Cu2＋ and Ag＋ might be sorbed strongly on the tested sorbents and the mefenacet added was too low in concentration to affect the sorption of the metals.

关键词： mefenacet copper silver soil kaolinite humic acid adsorption pH

Study on kinetics of thermal decomposition of low LOI goethetic hematite iron ore

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International Journal of Mining Science and Technology 2017年第6期27卷 1031-1036页

作者： Beuria P.C. Biswal S.K. Mishra B.K. Roy G.G. Mineral Processing Department CSIR–Institute of Minerals and Materials TechnologyBhubaneswar 751013India Indian Institute of Technology Kharagpur 721302India

In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical *** estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.

关键词： Loss on ignition Goethite kaolinite Gibbsite Roasting Pellet feed Kinetic analysis

Modes of occurrence and pre-concentration of rare earth elements in No.17 coal in Liupanshui coalfield,China

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Journal of Rare Earths 2022年第8期40卷 1323-1332页

作者： Bo Yang Chen Cheng Yuanxin Li Wei Cheng Jingkun Zang Xiangping Lai Xiaorui Wang College of Mining Guizhou UniversityGuiyang 550025China National&Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas Guiyang 550025China Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources Guiyang 550025China Guizhou Panjiang Clean Coal Co. Ltd.Liupanshui 553000China

Rare earth elements(lanthanide and yttrium,abbreviated as REY) provide important support for national security,energy production,environmental protection and economic *** recent years,many studies have shown that the content of REY in some coal or coal by-products is close to or even higher than that in traditional REY ore,which makes coal a potential source of *** study took the No.17 coal of Panzhou mining area in Liupanshui coal field as the research object,and the content and occurrence modes of REY in raw coal and 7 density fraction samples were *** results show that the content of REY in the raw coal reaches 220.67 μg/g,which is significantly higher than the average REY content in the world coal and Chinese coal as reported in the *** separation has a certain pre-enrichment effect on REY and the fraction sample> 1.8 g/cm~3 has the highest REY of 426.27 μg/g(equal to rare earth oxide 0.1%).Study on correlation between REY and ash yields reveals that the organic affinity of the light rare earth is higher than that of the medium rare earth and the heavy rare *** shown by X-ray diffraction(XRD) and X-ray flouresence spectroscopy(XRF),the major minerals in coal are kaolinite,quartz and calcite,and the content of REY in coal is significantly related to Al,Si and kaolinite,which implies that REY occur mainly in *** ablation inductively coupled plasma mass spectroscopy(LA-ICP-MS) was adopted to determine chemical composition of micro-zone in kaolinite in coal and the results show that there is no obvious correlation between REY and the contents of Al and *** indicates that the REY occur probably in the form of *** research results provide a scientific reference for the potential extraction of the associated REY in the coal.

关键词： Coal Rare earth elements Occurrence mode kaolinite Pre-concentration

The effect of interaction between Bacillus subtilis DBM and soil minerals on Cu(Ⅱ) and Pb(Ⅱ) adsorption

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Journal of Environmental Sciences 2019年第4期31卷 328-337页

作者： Jun Bai Yuanqing Chao Yanmei Chen Shizhong Wang Rongliang Qiu School of Environmental Science and Engineering Sun Yat-sen University School of Public Health Southwest Medical University Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology Sun Yat-sen University Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation Sun Yat-sen University

The effects of interaction between Bacillus subtilis DBM and soil minerals on Cu(Ⅱ)and Pb(Ⅱ)adsorption were *** combination with DBM,the Cu(Ⅱ)and Pb(Ⅱ)adsorption capacities of kaolinite and goethite improved compared with the application of the minerals *** modeling results of potentiometric titration data proved that the site concentrations of kaolinite and goethite increased by 80%and 30%,respectively after combination with ***,the involvement of functional groups in the DBM/mineral combinations resulted in lower concentrations of observed sites than the theoretical values and led to the enhancement of desorption rates by NH_4NO_3 and EDTA-Na_*** DBM-mineral complexes might also help to prevent heavy metals from entering DBM cells to improve the survivability of DBM in heavy metal-contaminated *** the combination process,the extracellular proteins of DBM provided more binding sites for the minerals to absorb Cu(Ⅱ)and Pb(Ⅱ).In particular,an especially stable complexation site was formed between goethite and phosphodiester bonds from EPS to enhance the Pb(Ⅱ)adsorption ***,we can conclude that the DBM–mineral complexes could improve the Cu(Ⅱ)and Pb(Ⅱ)adsorption capacities of minerals and protect DBM in heavy metal-contaminated environments.

关键词： Bacillus subtilis DBM Goethite kaolinite Cu Pb

Flux mechanism of compound flux on ash and slag of coal with high ash melting temperature

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1200-1206页

作者： Chengli Wu Beibei Wang Jiuqiang Zheng Hanxu Li School of Chemical Engineering Anhui University of Science and Technology

The melting temperature of Z coal ash was reduced by adding calcium–magnesium compound flux(WCaO/WMgO=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction(XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases,and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy(XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral [AlO4] and hexacoordinated aluminoxy octahedral [AlO6] change with the temperature changing. The addition of Ca2+ and Mg2+ destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon;and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca2+ and Mg2+ are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.

关键词： Coal ash and slag Compound flux X-ray photoelectron spectroscopy Transformation of mineral structure Structure of kaolinite and mullite

Clay mineralogy affects the efficiency of sewage sludge in reducing lead retention of soils

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Journal of Environmental Sciences 2019年第6期31卷 45-57页

作者： Giovana Clarice Poggere Vander Freitas Melo Beatriz Monte Serrat Ant?nio Salvio Mangrich Amanda Araújo Fran?a Rodrigo Stuart Corrêa Julierme Zimmer Barbosa Soil Science and Agricultural Engineering Department Federal University of Paraná State Chemistry Department Federal University of Paraná StateCentro Politécnico Institute of Criminalistic Civil Police

Recent studies have shown the feasibility of using of sewage sludge for the remediation of heavy metal-contaminated soils. However, there are no researches to check the influence of clay mineralogy on the efficiency of the sewage sludge to remediation of contaminated soils with heavy metals. For this purpose, we use two contrasting soils:Oxisol rich in hematite and gibbsite and Inceptisol rich in kaolinite. Thermal-treated sludge was applied to Pb-contaminated soil samples and incubated for 40 days. The soil samples were submitted to seven sequential extractions: soluble-Pb, exchangeable-Pb,precipitated-Pb, organic matter-Pb, Fe and Mn oxide-Pb, gibbsite and kaolinite-Pb, and residual-Pb. The reduction of soluble Pb forms by thermal sludge application was more pronounced in the Oxisol than in the Inceptisol because of the conversion of soluble-Pb into more stable forms, such as precipitated-Pb and oxides-Pb. For Inceptisol was necessary to apply high rates of thermal sludge to reach a significant reduction in soluble-Pb contents. The addition of humic fractions in the form of thermal sludge increased the concentration of organic matter-Pb. In confined area, the use of sewage sludge to reduce the heavy metals levels in soils must be better considered, mainly in more weathered soils.

关键词： Sequential extraction Humic fraction Fe oxides Gibbsite kaolinite

Performance evaluation for selectivity of the flocculant on hematite in selective flocculation

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1123-1129页

作者： Lopamudra Panda Pradip K.Banerjee Surendra Kumar Biswal R.Venugopal N.R.Mandre Research and Development Tata Steel Ltd. Institute of Minerals and Materials Technology (Council of Scientific and Industrial Research) Indian School of Mines University

Increased demand for iron ore necessitates the utilization of low-grade iron ore fines, slimes, and existing tailings. Selective flocculation can be an alternative physico-chemical process for utilizing these low-grade fines, slimes, and tailings. In selective fiocculation, the most critical objective is the selection of proper reagents that will make fioc of desired minerals. In present study, selective flocculation was applied to ultra-fine synthetic mixtures of hematite and kaolinite, and the Fe value was upgraded up to 65.78% with the reduction of Al2O3 and SiO2 values to 2.65% and 3.6670, respectively. Here, degraded wheat starch was used as a *** this process, separation occurs on the basis of the selectivity of the flocculant. The selectivity of the fiocculant can be quantified in terms of separation efficiency. Here, an attempt was also made to develop a correlation between separation efficiency and major operating parameters such as flocculent dose, pH value, and solid concentration to predict the separation performance.

关键词： hematite kaolinite selective fiocculation modeling iron ores tailings