Removal Of Heavy Metals From Aqueous Solution By Non-living Penicillium Simplicissimum

It was found that inactive microorganisms can absorb heavy metal ions, even better than living cells. Dead cells could combine metal ions with functional groups on the surface.There is no literature on removing metal ions by Penicillium simplicissimum, a new material for biosorption. Penicillium simplicissimum is widely exist in soil and other environment system. Therefore, freeze-dried Penicillium simplicissimum cells were applied in removing of Pb²⁺, Cd²⁺ and chromium(â…¥) in this work.At present, the researches on biological treatment mainly focus on heavy metal cations. But a lot of virulent metals exist in the form of anion in waste water. Therefore, the research on anion has important realistic meanings. The experiment involved removal of Cr(â…¥).The present study is about removal of heavy metal ions by Penicillium simplicissimum. It is studied with respect to the effects of the does of sorbent, pH, contact time, co-ions and so on. The results showed that the optimum adsorption pH for Pb²⁺ and Cd²⁺ was individually 5.0 and 3.0 using dead Penicillium simplicissimum. Biosorption equilibrium was all established within about 4h for Pb²⁺ and Cd²⁺ adsorbed by Penicillium simplicissimum. The uptake were 36.65 mg/g and 26.5 mg/g for Pb²⁺ and Cd²⁺. The uptake of Pb²⁺ and Cd²⁺ decreased when co-ions existed. The adsorption data was fit to Langmuir isotherm model for Pb²⁺ and Freundlich model for Cd²⁺. The desorption rates of Pb²⁺ and Cd²⁺ by 1 mol/L HNO3 were calculated, as 92.3% and 88.5%.The potential of inactive Penicillium simplicissimum to remove chromium was also studied in different conditions, including pH, pretreatment and co-ions. And the mechanism of removal of Cr(â…¥) was discussed. The results showed that Cr(â…¥) was completely removed from aqueous solution, and Cr(â…¢) appeared in aqueous solution which was not initially present. The Cr(â…¥) removal rate inceased with a decrease in pH. The total chromium uptake increased when it contacted with the pretreated biomass, that of 1M HCl pretreated cells being 64.7% total chromium at pH 4.0. The main mechanism of Cr(â…¥) removal was the reduction between Cr(â…¥) and functional group, especially the carboxyl. Positive Cr(â…¢) is the main form binding to the biomass because high pH benefit the total chromium sorption. The presence of Cu²⁺ stimulated Cr(â…¥) reduction and the rate of Cr(â…¥) reduction increased with increasing copper concentration. Energy dispersive X-ray spectra of cells (EDX) showed that chromium was absorbed mainly by ion exchange.