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Dissolution kinetics of kaolin mineral in acidic media for predicting optimal condition for alum production

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Journal of Central South University 2017年第2期24卷 318-324页

作者： Folahan A.ADEKOLA Alafara a.baba Sadisu GIRIGISU Department of Industrial Chemistry University of Ilorin

The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.

关键词： kaolin alum sulphuric and fluosilicic acid leaching kinetic model mixed control

A review on phorate persistence, toxicity and remediation by bacterial communities

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Pedosphere 2022年第1期32卷 171-183页

作者： Mohd ADAR Zahoor Ababa Garima KAUSHIK Department of Environmental Science School of Earth sciencesCentral University of RajasthanBandarSindriAjmer 305801India Biofertilizer Research Laboratory Division of Basic Science and HumanitiesWaduraSher-e-Kashmir University of Agricultural Sciences and TechnologySopore 193201India

Pesticides are an integral part in maintaining agriculture and horticultural productivity and play a vital role in meeting the increasing food, fiber, and fuel needs of the growing population. Globally, organophosphate pesticides(OPPs) are among the most common pesticides used due to their high proficiency and relatively low persistence in the environment. However, recent studies have reported problems due to pesticide use, e.g., phorate contamination of aquatic ecosystems(fresh and groundwater), sediments, fruits and vegetables, and forage crops. This review highlights many cases where phorate has been detected above its respective maximum residue limit values. Organophosphate pesticides, including phorate, have negative impacts on both the environment and human health. The ecological and public health concerns of recurrent pesticide utilization have encouraged the research related to environmental fate of *** is an effective, eco-friendly, and financially viable approach for the decontamination and degradation of toxic OPPs from the environment,compared to the costly, unecological, and time-consuming physicochemical approaches, which lead to the generation of byproducts of higher *** have recognized that a wide range of microbes, mainly bacteria, can degrade this extremely hazardous pesticide. Therefore, this review discusses the present pesticide scenarios, especially phorate contamination, its toxicity, biodegradation, and metabolic products via bacterial communities, both in India and globally. The latest and up-to-date literatures on the use, contamination, and bacterial application of phorate degradation are also summarized. This article offers national and international food safety organizations and public health authorities the ability to be involved in preventing the risks associated with the use of food and nutrition products contaminated with extremely toxic phorate pesticide. This article would also enable research

关键词： biodegradation bioremediation contamination organophosphate pesticide residue

Hydrometallurgical application for treating a Nigerian chalcopyrite ore in chloride medium:Part *** kinetics assessment

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International Journal of Minerals,Metallurgy and Materials 2013年第11期20卷 1021-1028页

作者： Alafara a.baba Kuranga I.Ayinla Folahan A.Adekola Rafiu B.Bale Malay K.Ghosh Abdul G.F.Alabi Abdul R.Sheik Ismael O.Folorunso Department of Industrial Chemistry University of IlorinP.M.B.1515 Department of Chemistry Institute of Basic and Applied SciencesKwara State PolytechnicP.M.B.1375 Department of Geology and Mineral Sciences University of IlorinP.M.B.1515 Hydro & Electrometallurgy Department Institute of Minerals and Materials Technology Department of Materials & Metallurgical Engineering University of IlorinP.M.B.1515

The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy （Ea） of 32.92 ***1-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.

关键词： chalcopyrite hydrometallurgy leaching, hydrochloric acid dissolution ore treatment

Bioleaching of Zn(Ⅱ) and Pb(Ⅱ) from Nigerian sphalerite and galena ores by mixed culture of acidophilic bacteria

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Transactions of Nonferrous Metals Society of China 2011年第11期21卷 2535-2541页

作者： Alafara a.baba Folahan A.ADEKOLA Rasaq F.ATATA Risikat N.AHMED Sandeep PANDA Department of Chemistry University of Ilorin Department of Biological Sciences Fountain University Department of Microbiology University of Ilorin Bioresources Engineering Department Institute of Minerals and Materials Technology

Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic *** influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were *** result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn（Ⅱ） and Pb（Ⅱ） from sphalerite and galena,*** was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced *** oxidation equilibrium for sphalerite and galena took 3 and 4 d,*** 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn（Ⅱ） and 89.0% Pb（Ⅱ） were recovered in 5 d,*** unleached residual products were examined by X-ray diffraction for sphalerite,revealing the presence of elemental sulphur（S）,zinc sulphate（ZnSO4） and few traces of calcium aluminate（Ca3Al2O6）.The XRD pattern also indicates the presence of elemental sulphur（S）,lead sulphate（PbSO4） and few traces of itoite [Pb（S,Ge）（O,OH）4] and cobalt lead silicate [Pb8Co（Si2O7）3] in the unleached galena ore.

关键词： sphalerite galena zinc(Ⅱ) lead(Ⅱ) oxidation acidophilic bacteria

The effects of storage time on fuel properties of Jatropha biodiesel blends

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Journal of Bioresources and Bioproducts 2018年第3期3卷 101-106页

作者： Ajimotokan H.Adewale Rabiu a.baba Lawal A.Rilwan Department of Mechanical Engineering Faculty of Engineering and TechnologyUniversity of IlorinIlorinNigeria LPG Plant PPMC/NNPC DepotTunfure GombeGombe StateNigeria

This study investigates the effects of storage time on fuel properties of biodiesel made from Jatropha oil and its blends with mineral diesel at different percentage *** influence of storage stability on selected fuel properties such as kinematic viscosity,density,pour,cloud and flash points for Jatropha biodiesel and its blends at varying storage times were investigated using standard test *** biodiesel obtained through trans-esterification of Jatropha oil was blended with mineral diesel to obtain fractional samples of B20(20%biodiesel blend),B40(40%biodiesel blend),B60(60%biodiesel blend)and B100(100%neat biodiesel).Results show that kinematic viscosity and density increase for each blend over the 12 weeks of storage ***,cloud and pour points decrease for each blend over the period of study.B20 was observed to be the optimum blend mix as its fuel properties were relatively unchanged over the storage period when compared to that of mineral *** can be implied from the research that while properties like kinematic viscosity and density deteriorate with time;flash,cloud and pour points are observed to have improved with storage time.

关键词： Biodiesel storage stability kinematic viscosity density flash point pour point Cloud point