The sorption of cationic and anionic heavy metal species on the biosorbent of Aspergillus terreus: Isotherm, kinetics studies

摘要

In this study, the capacity of Aspergillus terreus fungus biomass to remove Cr (VI) and Cd from aqueous solution was investigated. The present experimental study employed the shake flask method to cultivate fungal biomass. For the preparation of adsorbent, after inoculation of Aspergillus terreus in PDA medium, it was placed on a shaker at 150 rpm, at 25 degrees C for 4 days. After separation of living biomass, it was boiled in a 0.5% NaOH solution. The ability of the biomass to remove of Cr (VI) and Cd from aqueous solution was examined under conditions including initial concentrations of (20-120 mg/L); pH of 3, 5, 7, and 9; contact times of 15-120 min; and the adsorbent doses of 0.1, 0.2, 0.5, 1, and 2 g. The concentration of the heavy metals was determined by an atomic absorption device. The results showed that in the optimum conditions of the input variables; contact time of 90 min, pH of 7, the initial metal concentration of 20 mg/L, and the adsorbent dose of 1 g, the removal efficiency of Cd and Cr (VI) was 94 and 89%, respectively. The processes of Cd and Cr (VI) adsorption were successfully described by Freundlich isotherm with R-2 = 0.9463 and R-2 = 0.9949, respectively, and well-followed pseudo-first-order kinetic with R-2 = 0.9935 and R-2 = 0.9718, respectively. Due to the high adsorption capacity of this biomass in removing metals in comparison to other adsorbents, it can be proposed as a suitable adsorbent in treatment processes.