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Sehliselo Ndlovu,Geoffrey S. Simate,Kudzai A. Mchibwa,Alejandra Giaveno 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
In this study, Acidianus spp., a thermophilic archae which can oxidize sulphide minerals was used to produce ferric sulphate solutions from pyrite. The ferric sulphate solutions were aged through a forced hydrolysis process at different pH conditions to yield a variety of iron oxide and basic sulphate precipitates which were subsequently characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and Branauer–Emmett–Teller (BET) analysis. The results showed that potassium jarosite was formed as the main phase when ageing was done under acidic conditions. Various other iron oxides and oxyhydroxides were precipitated when ageing was done under neutral to basic pH conditions. For example, maghemite was precipitated as the main phase at a pH of 6–7, and magnetite was the main phase from a pH of 7–9. The spherical globular aggregates of magnetite nanoparticles formed were of high purity and had a surface area of 20.77 m2/g. Hematite nanoparticles were then produced via an oxidative transformation of the precursor magnetite nanoparticles at 600 ℃. Since various precipitates were formed under different pH conditions, this knowledge can be used to control the solubility of the ferric ion in bioleaching and other industrial systems where iron removal is problematic.
The removal of heavy metals in a packed bed column using immobilized cassava peel waste biomass
Geoffrey S. Simate,Sehliselo Ndlovu 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Several studies on the removal of heavy metals in batch systems using cassava waste biomass have beenreported in literature. However, for practical and large scale operations, packed bed columns arepreferred. This study investigated the biosorption of heavy metals (Cr3+, Co2+ and V3+) onto immobilizedcassava peel waste in a packed bed column. Experiments were conducted with 100 mg/L of combinedmetal ion solutions under different flow rates (0.83–1.61 mL/s) and bed depths (5–15 cm). The dynamicbehaviour of the process was described in terms of the breakthrough curves. The results showed that theremoval efficiency was favoured by low flow rate and high bed depth. Biosorption efficiency was foundto increase in the order V3+ > Cr3+ > Co2+ for all conditions tested. Amongst the two well-establishedcolumn models tested, the bed depth service time (BDST) model with biosorption capacities of 99.6,116.2 and 132.8 mg/L for Co2+, Cr3+ and V3+, respectively, fitted experimental data very well. The columnwas regenerated and reused six times consecutively without significant loss in biosorbent capacitysignifying its appropriateness for commercial application.