Equilibrium studies on sorption of an anionic dye onto acid activated water hyacinth roots

Abstract

The inappropriate disposal of dyes in wastewater constitutes an environmental problem and can cause
damage to the ecosystem. Present investigation deals with the utilization of water hyacinth roots (collected from the ponds) as adsorbent for the removal of anionic dye from its aqueous solutions. Batch studies were conducted to evaluate the adsorption capacity of the dye, Congo red on the sorbent with respect to the variations in initial pH, contact time and initial dye concentration and the adsorbent. The effective pH for better adsorption of Congo red on water hyacinth roots was found to be 6.0.
Equilibrium was reached in about 3 h contact time. Equilibrium isotherms for the adsorption of Congo
red on water hyacinth root were analyzed by the Freundlich, Langmuir and Redlich–Peterson isotherm
equations. Results showed that Redlich–Peterson isotherm best-fits with the Congo red adsorption
isotherm data on all initial dye concentrations. The Freundlich isotherm also showed comparable fit.