Removal efficiency of chromium (VI) ions from aqueous solution by adsorption of rice husk and saw dust ash as a homogeneous composite

The present study was conducted to determine the chromium (VI) removal efficiency from aqueous solution by using agricultural wastes like rice husk and saw dust ash as a homogeneous mixture. The proximate analysis showed that the amount of fixed carbon and ash content of rice husk was greater than saw dust and on the other hand, the moisture content and volatile content of saw dust were higher than that of rice husk. The study was conducted by using batch adsorption experiment and it was done at room temperature (25°C). Amount of chromium (VI) adsorbed under different conditions was evaluated by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The foremost factors which have effect on the adsorption capacity of Cr (VI) like pH and contact time of the solution were also studied. It was found that, removal efficiency was high at certain pH value 2 and adsorption efficiency was dependent on time. The efficiency of chromium (VI) removal was found satisfactory and the percentages were about 92% and 85% respectively for two initial concentrations of 50 mg/L and 10 mg/L. Pseudo second order kinetic model was established and the correlation coefficient (R²) was also satisfactory for the adsorption of Cr (VI) ions.