Batch cadmium(II) biosorption by an industrial residue of macrofungal biomass (Clitopilus scyphoides)

An industrial waste of Clitopilus scyphoides (Pleurotus mutilus) fungal biomass collected from an antibiotic production plant was tested as a biosorbent for Cd(II) cations. The residue was first characterized by SEM observations, TGA and XRF analyses, and acid–base potentiometric titration. It contained 13.5% (w/w) mineral matter in which Ca, Si and P elements prevailed. Modeling of the potentiometric data showed that amino, phosphate and carboxyl groups were the main functional groups present in the biosorbent. Batch biosorption experiments were then performed to assess the optimal pH for cadmium(II) removal and the biosorption efficiency at varying biosorbent (X) and metal (C0) concentrations. Cadmium uptake by fungal particles was fast, equilibrium being reached within 15 min. The biosorption capacity increased and the biosorption yield decreased with increasing C0/X ratio. A maximum capacity around 200 mg metal g−1 residue was obtained at optimal pH and high C0/X ratio. The biosorption kinetics obeyed the pseudo-first and -second order models as well as the intraparticle diffusion model. Metal biosorption data at equilibrium were well fitted by a 3-parameter equation derived from the BET isotherm model characterizing a multilayer adsorption process. Metal recovery and biosorbent reusability were also investigated using acidic eluent.

► Cadmium removal by abundant, low cost and easily collected macrofungal biomass.
► Exhaustive biosorbent characterization (SEM, TGA, XRF, IR, potentiometric titration).
► Fast metal uptake (<15 min) and high biosorption capacity (up to 200 mg g−1).
► Data best fitted by the pseudo-first-order kinetic and the BET isotherm models.
► Biosorbent reusability demonstrated using nitric acid as eluent.