Modeling of Adsorption Isotherms and Kinetics of Organic Pollutants onto Three Tunisian Clays

This work aims to study the kinetics and the adsorption models of organic pollutants in a real textile effluent on three different raw Tunisian clays [Rommanna green clay (RGC), Tabarka white clay (TWC), and Mednine red clay (MRC)]. Since the used effluent is real, the dye concentration is unknown, and the kinetics study and the adsorption isotherms are constructed based on the chemical oxygen demand (COD). The initial COD of the effluent is 3750 mg L−1. The low COD concentrations are obtained by dilution. According to the calculated model parameters from the slopes and intercepts of the linear models and the correlation coefficients R2, the adsorption obeys to the pseudo-second-order kinetic model for the three different clays. Moreover, adsorption isotherms are all L-type, and according to R2 values (R2 ~ 1), both models of Langmuir and Freundlich describe well the adsorption phenomena.