Adsorptive of vanadium and palladium ions using chitin-extracted from shrimp shell wastes: genetic programming modeling

In this study, chitin was extracted from shrimp shells (SS) and characterized by scanning electron microscopy, X-ray diffraction, and Fourier transforms infrared spectroscopy. And investigate the adsorption of vanadium (V) and palladium (Pd) toxic metals onto the chitin. The effect of parameters such as the concentration of V and Pd, contact time, solution pH, adsorbent dose, cations, and anions were studied on the adsorption process. Kinetic, isotherm, and thermodynamic models were investigated. Genetic programming (GP) is used to obtain an appropriate equation showing the relationship between the variables. Experimental optimum conditions were found in the V and Pd concentrations of 25 mg/L, pH of 9, an adsorbent dose of 0.8 g/L and a contact time of 15 minutes. The maximum adsorption capacities (qm) of 13.15 and 12.65 mg/g were obtained for V and Pd, respectively. Among the anions and cations examined in this study, Ca2+ and SO42- had the greatest effect on the absorption of V and Pd on chitin. The adsorption kinetics followed a pseudo-second-order kinetic model and the equilibrium data showed a good fit of the Langmuir model and demonstrated a monolayer and favorable physisorption process. The thermodynamic analysis depicted that the process of adsorbing V and Pd using chitin was endothermic and spontaneous. Findings also presented GP as a potential tool for identifying the behavior of V and Pd adsorption. It can be concluded that chitin extracted from SS wastes, as a nontoxic and cheap adsorbent, could efficiently remove V and Pd from aqueous solutions.