Enhanced adsorption of o-phenylphenol on zeolites: A combing pore filling and hydrophobic effects

Abstract

Abstract O-phenylphenol (OPP) is an important fungicide and surface disinfectant, widely used in industry, agriculture and daily life, and is severe risk to ecological environment and physical health. In this study, the adsorption mechanism of OPP on zeolites with varied pore sizes and SiO2/Al2O3 ratios was investigated. The zeolites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 physical adsorption and X-ray fluorescence (XRF). Ultra-stable Y zeolite (USY) presented a prominent capacity for OPP adsorption with Kd value of 105–103 L kg−1, indicative of a strong adsorption affinity between OPP and USY. Batch adsorption results along with characterization of zeolites indicated that pore filling and hydrophobic effect were the main mechanisms for OPP adsorption on zeolites. The adsorption isotherm of OPP on USY could be well fitted by Freundlich model and Dubinin-Astakhov (D-A) model, indicating that the adsorption process was a multiple layer adsorption with high adsorption energy of 57.37 kJ mol−1. Adsorption kinetics showed that the adsorption equilibrium of OPP on USY was fast, and the equilibrium was established within only 20 min at an initial concentration of 76 mg L−1. Various solution chemistry conditions such as ionic strength, pH and dissolved humic acid (HA) were also carried out to assess their effects on USY for OPP adsorption. Moreover, the used USY could be effectively regenerated and reused, and presented stable adsorption performance after seven consecutive adsorption-desorption cycles.