Preparation and characterization of composite adsorbent LiCl/zeolite 13X for adsorption system

Abstract

A novel composite adsorbent with high adsorption capacity, stable cycle performance and structure is developed. LiCl/zeolite 13X composite adsorbents with different LiCl content were synthesized by double solvents impregnation with alcohol and ethanol. The textural properties of composite adsorbents were characterized by nitrogen adsorption and scanning electron microscopy (SEM). The water adsorption performance of the composite adsorbents was tested, and the dynamic and equilibrium adsorption characteristics of the composite adsorbents were simulated by Polanyi potential theory and LDF model, respectively. Research on nitrogen adsorption suggested that because of the impregnated salt, composite adsorbents presented different pore structure pure. As the salt concentration of the LiCl solution increases, more salt is immersed into the pore channels of zeolite 13X, resulting in the LiCl content in the adsorbents increasing simultaneously. Water adsorption capacity of the composite adsorbent is not enhanced consistently with the increase in LiCl loading amount. After LiCl modification process, the water adsorption capacity increases little when the salt load is low, and then, the water adsorption capacity increases significantly with the increase in the salt load and finally decreases slightly. The sorption performance of CS30 with salt content of 16.7 wt% was optimal, and the maximum sorption capacity was 0.7 g/g, nearly 3.3 times than properties of zeolite 13X 0.21 g/g. As the number of cycles increases, the adsorption capacity of the composite adsorbent decreases slightly. The tenth cycle is only reduced by 8.67% compared to the first cycle.