Recovery of Rhodium(III) from Solutions and Industrial Wastewaters by a Sulfate-Reducing Bacteria Consortium

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• 作者：Nonhlanhla Ngwenya ; Chris G. Whiteley
• 刊名：Biotechnology Progress
• 出版年：2006
• 出版时间：December 2006
• 年：2006
• 卷：22
• 期：6
• 页码：1604 - 1611
• 全文大小：452K
• 年卷期：v.22,no.6(December 2006)
• ISSN：1520-6033

文摘

A quantitative analysis of the rate of removal of rhodium(III) by a resting sulfate-reducing bacteria(SRB) consortium under different initial rhodium and biomass concentrations, pH, temperature,and electron donor was studied. Rhodium speciation was found to be the main factor controllingthe rate of its removal from solution. SRB cells were found to have a higher affinity for anionicrhodium species, as compared to both cationic and neutral species, which become abundantwhen speciation equilibrium was reached. Consequently, a pH-dependent rate of rhodium removalfrom solution was observed. The maximum SRB uptake capacity for rhodium was found to be66 mg of rhodium per gram of resting SRB biomass. Electron microscopy studies revealed atime-dependent localization and distribution of rhodium precipitates, initially intracellularly andthen extracellularly, suggesting the involvement of an enzymatic reductive precipitation process.When a purified hydrogenase enzyme was incubated with rhodium chloride solution underhydrogen, 88% of the rhodium was removed within 1 h, whereas with a soluble extract fromSRB 77% was removed within 10 min. Due to the low pH of the industrial effluent (1.31), theenzymatic reduction of rhodium by the purified hydrogenase was greatly limited, and it wasapparent that an industrial effluent pretreatment was necessary before the application of anenzymatic treatment. In the present study, however, it was established that SRB are goodcandidates for the enzymatic recovery of rhodium from both aqueous solution and industrialeffluent.