Shape-selective adsorption mechanism of CS-Z1 microporous molecular sieve for organic pollutants

A self-made microporous molecular sieve CS-Z1 has been found to have excellent adsorption performance for small molecular nitrile and pyridine pollutants in acrylonitrile production wastewater. In order to explore its adsorption mechanism, the adsorption kinetics, isotherms and thermodynamics of CS-Z1 for eight nitrile and pyridine organic pollutants with different structures and properties were investigated. Meanwhile, the analysis of molecular dynamics simulation based on density functional theory was conducted to revel the adsorption-diffusion process of different organic pollutants on the surface and in the pores of CS-Z1. Both the experimental and simulated results verified the shape-selective adsorption mechanism of CS-Z1 for these organic pollutants. The adsorption processes of CS-Z1 for these pollutants were spontaneous physical adsorption, and the adsorption efficiency of CS-Z1 mainly depended on the molecular size of pollutant. Benefitting from the flexible crystalline structure of CS-Z1 and the breathing vibration of CS-Z1 orifices, it could adsorb some pollutants with slightly larger size than its pore diameter. Molecular dynamics simulation results visually display the shape-selective adsorption process of CS-Z1 for these pollutants through the respiratory effect of CS-Z1 molecular sieve orifices.