Equilibrium, kinetic and thermodynamic studies of the biosorption of copper onto Luffa Cylindrica Cords.

This study explores the possibility of using Luffa Cylindrica Cords to remove Copper from aqueous effluents. The removal of copper was investigated in both batch and continuous processes. Batch mode adsorption studies were performed by varying parameters such as contact time, pH, initial copper concentration and temperature. The different adsorption models Langmuir, Freundlich, Elivoch and Temkin were used for the mathematical description of the adsorption equilibrium, and it was found that the very well - equipped experimental data for the Langmuir model (R2=0.961), the pseudo - first - order and pseudo - second - order kinetic models were applied to the experimental data. The experimental data fitted very well the pseudo-second-order kinetic model (R2= 0.965) and also followed the model of intra particle diffusion for concentrations between 5 and 50 mg/L), whereas diffusion is not the only rate - control step. Finally the thermodynamic parameters for the adsorption of copper onto cords were also determined. The negative sign of S° shows the decreased randomness at the solid - solution interface during adsorption, and the negative sign of H° indicates that the adsorption process is exothermic. The negative sign of G° confirms the spontaneous nature of the adsorption process, physical reaction. [ABSTRACT FROM AUTHOR]