Utilization of Quaternized Rice Hull as Low-Cost Adsorbent for the Removal of Congo Red from Aqueous Solution

In this study, the ability of quaternized lice hull to remove Congo Red from synthetic dye solution was investigated. The percentage uptake of Congo Red by quaternized rice hull was close to 50 % and this corresponds to an enhancement of 6.6 folds as compared to natural rice hull. The effect of contact time, kinetic study, sorption isotherm, agitation rate and adsorbent dosage were studied under various experimental conditions. Batch studies revealed that adsorption was depended on contact time and concentration. For Congo Red with the concentration of 50 mg/L, equilibrium was attained around 2 h whereas at higher concentration it requires a longer time. The adsorption of Congo Red onto quaternized rice hull followed pseudo-second order kinetic model with higher correlation coefficients as compared to pseudo-first order kinetic Model. The maximum adsorption capacity of quaternized rice hull calculated using Langmuir model is 30.03 mg/g.