Adsorption of dyes on rice husk ash

Rice Husk Ash, a waste from rice mills has been used as an adsorbent for th e removal of chemical oxygen demand from aqueous solutions of textile dyes. The adsorption capacity of rice husk ash for five aqueous acid dye solutio ns has been determined by adsorption isotherm. The adsorption data have bee n fitted to Freundlich isotherm and Langmuir isotherm by the least square m ethod and the values of the constants k, n, C-m and b have been obtained. T he effect of contact time, pH, adsorbent concentrations and rate constants for each dye have been calculated.