Adsorption kinetics of Rhodamine-B on used black tea leaves

Rhodamine b (rh-b) is one of the most common pollutants in the effluents of textile industries effluents indeveloping countries. this study was carried out to evaluate the applicability of used black tea leaves (ubtl) for theadsorptive removal of rh-b from aqueous system by investigating the adsorption kinetics in batch process. theeffects of concentration and temperature on adsorption kinetics were examined. first-, second- and pseudo-secondorder kinetic equations were used to investigate the adsorption mechanism. the adsorption of rh-b on ubtlfollowed pseudo-second order kinetics. the equilibrium amount adsorbed and the equilibrium concentration werecalculated from pseudo-second-order kinetic plots for different initial concentrations of rh-b to construct theadsorption isotherm. the adsorption isotherm was well expressed by langmuir equation. the maximum adsorptioncapacity of ubtl to rh-b was found to be 53.2 mg/g at ph = 2.0. the equilibrium amount adsorbed, calculatedfrom pseudo-second-order kinetic plots, increased with temperature increase. the positive value of enthalpy ofadsorption, ?hads = 31.22 kj/mol, suggested that the adsorption of rh-b on ubtl at ph = 2.0 is an endothermicprocess.