Mechanism elucidation and adsorbent characterization for removal of Cr(VI) by native fungal adsorbent

Abstract

Mechanism of Cr(VI) bio-removal from mine drainage was studied using a native fungal isolate. The Cr(VI) tolerant species, from chromite mining at Sukinda mine water fungus characterized as Aspergillus fumigatus Fresenius was applied after inactivation in an autoclave, to optimize the parameters of biosorption. Maximum uptake of 48.2 mg Cr(VI) g−1 of inactivated biomass at pH 5.5, 35 °C and 1% sorbent/solution (w/v) ratio was obtained (> 96% sorption) in 120 h from 50 mg L−1 Cr(VI) solution. The chemisorption mechanism involved the functional groups of treated biomass which was elucidated by the Fourier-transform infrared spectroscopy, X-ray powder diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy studies. The XRD phase analysis of the biosorbed material confirmed the limited reduction of Cr(VI) to Cr(III) unlike previous studies. Actual mine drainage containing Cr(VI) and Co(II) was treated with the fungal biomass and was effectively eluted with 0.5 M HCl solution. The study demonstrates the potential application of native fungal isolate to remediate Cr(VI) from the chromite mine drainage. Keywords: Chromite ore, Mine drainage, Hexavalent chromium, A. fumigatus Fresenius, Biosorption