Removal of the hazardous dye rhodamine B through photocatalytic and adsorption treatments

This paper reports on photocatalytic and adsorptive treatment of a hazardous xanthene dye, Rohdamine B, in wastewater. The photocatalytic degradation was carried out in the presence of the catalyst TiO2 and the effects of pH, concentration of the dye, amount of TiO2, temperature and electron acceptor H2O2 on the degradation process were observed. It was found that photocatalytic degradation by TiO2 is an effective, economical and faster mode of removing Rohdamine B from aqueous solutions. Attempts were also made to utilize activated carbon and rice husk as potential adsorbents to remove Rhodamine B from wastewater. The adsorption studies were carried out at 40, 50 and 60 degrees C. and the effects of pH, temperature, amount of adsorbents, concentration of adsorbate, etc., on the adsorption were measured. On the basis of adsorption data the Langmuir and Freundlich adsorption isotherm models were also confirmed. The adsorption isotherm constants thus obtained were employed to calculate thermodynamic parameters like Gibb's free eneray, change in enthalpy and entropy. In order to observe the quality of wastewater COD measurements were also carried out before and after the treatments. A significant decrease in the COD values was observed, which clearly indicates that both photocatalytic and adsorption methods offer good potential to remove Rhodamine B from industrial effluents. (C) 2006 Elsevier Ltd. All rights reserved.