Biosorption of thallium(I) and cadmium(II) with the dried biomass of pestalotiopsis sp. FW-JCCW: Isotherm, kinetic, thermodynamic and mechanism

Abstract

In this study, the dried biomass of strain Pestalotiopsis sp. FW-JCCW was employed as an adsorbent for the biosorption of thallium (Tl) and cadmium (Cd). Influential factors including reaction pH, initial concentration of Tl+ and Cd2+, agitation speed, reaction temperature and contact time on the biosorption capacity of Tl+ and Cd2+ were investigated. Isotherm tests showed that the Langmuir model provides the best fit for equilibrium data of both metals, with maximum biosorption capacity of 99.80 mg/g for Tl+ and 98.01 mg/g for Cd2+. In addition, the pseudo-second-order model described biosorption kinetics more effectively than the pseudo-first-order model. Thermodynamic parameters indicated that biosorption of Tl+ and Cd2+ is a spontaneous and endothermic process. In addition, the biosorbent was characterized through Brunauer Emmett Teller analysis (BET), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and energy disperse spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrate that functional groups (C-O,-OH or-NH,-CN and-COOH) on the surface of the strain contribute to the biosorption. In conclusion, Pestalotiopsis sp. FW-JCCW can be used as an effective biosorbent for removing Tl+ and Cd2+ from wastewater.