Biosorption Of Cr (Ⅵ) By Fungal Biomass Of Mucor Racemosus

It is very expensive and ineffective to remove metal ionsfrom wastewaters using conventional methods when the initialconcentration is low (1-100 mg/l). Thus, it is very necessaryto develop alternative technologies and elucidate itsmechanism now. A large portion of current research has beenoriented towards the removal of heavy metal cations fromwastewater, whereas the importance of anions (e.g. Cr, V, Se,Mo) has become a growing concern in many fields.In the study we established the main optimum conditions of theremoval of Cr (â…¥) on the Mucor racemosus, such as pH, biomassdose, initial Cr(â…¥) concentration and contact time. The totalresidual Cr was determined at the optimum conditions. Theequilibrium data were fitted in to the Langmuir and theFreundlich isotherm models and the correlated coefficientswere gained from the models, h Fourier transform infraredspectra was employed to elucidate clearly the possible removalmechanism as well.The metal removal by the biomass was strongly affected bypH. The optimum pH ranged from 0.5 to 1.0. At biosorbent dose 6g/l, almost all the Cr (â…¥) was removed in optimum conditions.Higher removal percentage was observed at lower initialconcentrations of Cr (â…¥) ions, while the removal capacity q_tof the biomass linearly depended on the initial Cr (â…¥)concentration. More than half of Cr (â…¥) ions were diminishedwithin 1 h of contact and removal process reached a relativeequilibrium in approximately 8h. Almost all of the Cr (â…¥) ionswere removed in 24h when initial concentrations were below 100mg/l. Thermodynamical isotherms for the biosorption of Cr (â…¥)on the fungal biomass were developed and the equilibrium datawere found be fitted well to the Langmuir and the Freundlichisotherm models. The correlated coefficients were 0.998 and0.996, respectively, which showed that Langmiur model was moresuitable. The total residual Cr was determined. It was foundthat dichromate reduction occurred at a low very low pH value.The FTIR analysis also elucidated the possible biosorptionmechanism -it is the protonated amido of protein and theN-acetyl glucosamine polymer of chitin that are mainly involvedin the binding of chromium during Cr (â…¥) biosorption.