Removal of Cd(II) ion from aqueous solution by powdered leaf biomass of Boehmeria listeri: equilibrium and kinetic studies

The adsorptive efficiency of leaf powder of Boehmeria listeri to remove Cd(II) from aqueous solution was investigated as a function of contact time, initial metal ion concentration of cadmium ion, solution pH, and biosorbent dosage, using batch method at room temperature. Batch biosorption experiments showed that leaves of B. listeri used in this study proved to be suitable for the removal of cadmium from dilute solutions where a maximum adsorption capacity of 45.5 mg g−1 was obtained for optimum conditions at an equilibrium time of 70 min, biosorbent dosage of 0.5g and pH 6. Cadmium biosorption on B. listeri were found to be highly pH dependent. The equilibrium adsorption data were fitted to Langmuir, Freundlich, and Temkin adsorption isotherm models and the model parameters were evaluated. From the model parameters obtained, the Freundlich isotherm model was found to be best fitted with a correlation coefficient value of 0.838. The kinetic study showed that the pseudo-second-order kinetic model better described the biosorption process in comparison to pseudo-first-order and Elovich kinetic model with a correlation coefficient range of 0.998–0.999 for the entire concentration range. FT-IR spectrum analysis revealed that hydroxyl, carbonyl, carboxyl, amide, aliphatic amine, thiol, and sulfahydral groups present in the adsorbent were the primary cadmium ion-binding groups.