Equilibrium kinetics and thermodynamic studies on biosorption of heavy metals by metal-resistant strains of...

This study was aimed at finding the metal sorption potential of six indigenous Trichoderma strains by using batch experiments for Cd (II), Cr (VI), Cu (II), and Pb (II). Trichoderma atrobrunneum showed maximum metal biosorption potential at 800 mg L^-1 of initial concentration. Two adsorption isotherm models, (1) Langmuir (2) Freundlich models, were employed on the biosorption data obtained at various initial metal concentrations (10 mg L^-1-200 mg L^-1) and pseudo-first (PSI) and pseudo-second (PSII) order equilibrium kinetic models were subjected to data of agitation time (3-7 days). A maximum correlation coefficient value (R²) of ≤ 1 was observed for the Langmuir and PSII model. Results revealed that pH 6-7 was the best for metal sorption, while metal removal efficiency was increased by increasing temperature (298 K, 303 K, 308 K, 313 K). The results of thermodynamic study parameters (∆G°, ∆H°, ∆S°) indicated that heavy metal biosorption by Trichoderma strains was an endothermic, spontaneous, and feasible process. Moreover, surface characterization analysis through SEM, BET, FTIR, and XRD showed that T. atrobrunneum and Trichoderma sp. could adsorb more metal ions when grown in high metal concentrations. The results indicate that living biomass of T. atrobrunneum and Trichoderma sp. is an effective multi-metal biosorbent that can be used for efficacious bioremediation of bio-treatment of heavy metal polluted wastewater.