Study on the adsorption of low-concentration VOCs on zeolite composites based on chemisorption of metal-oxides under dry and wet conditions

Abstract

Adsorption is a classical process applied to eliminate air pollutants with low-concentration of volatile organic compounds (VOCs). The evaporation induced self-assembly (EISA) method was used to efficiently load metal-oxide nanoparticles on the NaY zeolite to improve the adsorption capacity for VOCs. Dynamic and static adsorption experiments were applied to investigate the adsorption of toluene, isopropanol and acetone by Y@MxOy (M = Ni, Co, Cu, Mn) under dry (RH = 0) and wet (RH = 50%) conditions. Compared with NaY zeolite, Y@MxOy with uniformly dispersed nanoparticles of metal-oxide significantly improved the adsorption capacity of VOCs, and Y@CoO exhibited the optimal adsorption performance for isopropanol (189 mg/g) and acetone (124 mg/g) under RH = 50%, yet Y@MnO2 showed the best adsorption capacity for toluene (50 mg/g). Several important properties of the Y@MxOy composites were determined by XRD, N2 adsorption–desorption isotherm, SEM, TEM and EDS. Moreover, density functional theory (DFT) was used to systematically calculate the adsorption system and explored the mechanism of the weakening of competitive adsorption between VOCs and water molecules. The chemisorption of metal-oxides with the oxygen functional groups of VOCs greatly improves the adsorption capacity, which provides a new way to develop a neoteric adsorbent for VOCs.