Biosorption of hexavalent chromium and Congo red dye onto Pleurotus mutilus biomass in aqueous solutions

Abstract

With the significantly increasing pharmaceutical and antibiotics industry in Algeria, the elimination of biomass is of utmost importance since the latter represents a large part of waste from the manufacturing process. In this work, the elimination of hexavalent chromium Cr (VI) and Congo red dye is part of the Pleurotus mutilus biomass recovery process. Thus, biosorption has been studied in a discontinuous system. Optimal conditions were estimated by variations in contact time, temperature, initial pollutant concentrations, and simultaneous removal of both pollutants. The greatest uptake capacities achieved were 36.68 mg/g of and 15.08 mg/g of Cr(VI). The initial concentrations of both pollutants being equal to 50 mg/l, for a duration time of 180 min and a temperature of 300 K. Based on the values of the coefficient of determination R2, χ2, and ARE, the isothermal equilibrium data were better represented by Freundlich, Temkin, and Dubinin-Radushkevich models. The kinetic biosorption of the two pollutants was well described using the pseudo-first-order model. The biosorption process is controlled by external mass transfer. The physical process in nature of Cr(VI) and (CR) biosorption has been justified based on the values obtained of ΔG° and ΔH°. Globally, this work demonstrates the considerable potential of Pleurotus mutilus for the elimination of anionic pollutants. Research results indicate that this biomass, a waste material, first destined for incineration, was recovered without any treatment. Due to its low cost, it could serve as an inexpensive source for recovering heavy metals and dyes from dilute contaminated water.