Biosorption of azoimide on almond integument: Kinetics, isotherm and thermodynamics studies

Hospital effluents are a serious problem in waterways due to azoimide that provides physical and health hazards. The removal of azoimide using powdered almond integument was studied in batch mode. Hydroxyl, carbonyl and carboxyl on the biosorbent surface were measured by titration method. The biosorption of azoimide was found to depend on the initial concentrations, pH and contact time. The equilibrium data was analyzed by using a non-linear form of Langmuir, Freundlich, Toth and Redlich–Peterson isotherm models. The fitness of data was evaluated using three error functions and correlation coefficient value (R2). The error analysis showed three parameters models described the best biosorption in comparison of two parameters models such as Langmuir and Freundlich. The pseudo-first order, pseudo-second order and Elovich kinetic models were applied to study the kinetic behavior, and revealed applicability of the pseudo-second order model. The evaluation of thermodynamic parameters showed that biosorption process was endothermic and spontaneous.