Adsorption of Cadmium and Nickel by Modified Agricultural Byproducts

An agricultural byproduct, wheat straw, was chemically modified by alkaline treatment and succinylation, followed by sodium carbonate treatment as the adsorbents for cadmium and nickel. The adsorption capacities were calculated under different conditions. The experimental parameters such as adsorbent dose, initial metal concentrations, and solution pH, were studied. The adsorbents were characterized by FTIR (Fourier-Transform Infrared Spectroscopy) to investigate the changes of surface functional group. The optimum adsorption percentage of cadmium (> 99.0%) and nickel (> 98.0%) was achieved when using 5 g/L as adsorbent dose and 50 mg/L as initial concentration. The adsorption competition between cadmium and nickel was investigated. The result shows that cadmium affected nickel adsorption more than nickel did on cadmium. The kinetic study shows that the adsorption of cadmium and nickel on modified wheat straw follows the pseudo-second order kinetics and the adsorption isotherm follows the Langmuir mono-layer adsorption model