Metal tolerance and sequestration of Ni(II), Zn(II) and Cr(VI) ions from simulated and electroplating wastewater in batch process: Kinetics and equilibrium study

Abstract

In the present study, total eight filamentous fungal strains were isolated from metal plating effluent discharged soil. Among the tested isolates, four fungal strains namely Aspergillus niger, Aspergillus sydoni, Penicillium janthinellum and Trichoderma viride were exhibited greater tolerance to Ni(II) > Zn(II) > Cr(VI) ions. The mycelium growth order of the fungal strains was observed as A. niger > T. viride > A. sydoni > P. Janthinellum. Fungal strain A. niger is the highly tolerant strain and found minimum inhibitory concentration for Cr(VI) 3.5 mg/mL, Ni(II) 4.5 mg/mL and Zn(II) 3.0 mg/mL. Maximum dry weight of A. niger was observed 4.59 g/L in Cr(VI), 5.09 g/L in Ni(II) and 5.01 g/L in Zn(II) ions at initial concentration 50 mg/L in broth medium. Further sorption study was carried out to sequestration of Ni(II), Zn(II) and Cr(VI) ions from simulated and real electroplating wastewater with mycelia of A. niger. The sorption performance was evaluated by equilibrium and kinetic studies. After sorption process, the bound metal ions were eluted with 0.1 M HCl solution for reusability of the biosorbent. Functional groups and cell surface morphology were analyzed using Fourier Transform Infrared Spectrometer (FTIR) and Scanning Electron Microscopy (SEM).