Biosorptive removal of Hg(II) ions by Rhizopus oligosporus produced from corn-processing wastewater

Abstract

In this study, corn processing wastewater was used as a new low-cost substrate to produce Rhizopus oligosporus. Dried biomass of R. oligosporus was evaluated as a biosorbent for treatment of synthetically contaminated waters with Hg(II) ions. The biosorption process was carried out in a batch process and the effects of contact time (1 to 48 h), initial pH (2.0 to 7.0), initial metal ion concentration (20 to 100 mg/L) and temperature (20 to 38°C) on the biosorption were investigated. Hg(II) ions concentration were measured with ICP-MS. The maximum adsorption capacity was determined at pH 6.0. The isothermal data of dried fungal biomass could be described well by the Langmuir equations
and the Langmuir monolayer capacity had a mean value of 33.33 mg/g. Experimental results indicated that the pseudo-second order reaction model provided the best description of the data with a correlation coefficient 0.99 for different initial metal concentrations. This result indicates that chemical sorption might be the basic mechanism in this system.

Keywords: Biosorption, corn-processing wastewater, mercury, Rhizopus oligosporus