Green removal of aromatic organic pollutants from aqueous solutions with a zeolite–hemp composite

Abstract

A composite based on zeolite L nanocrystals (LTL-type structure) and hemp fibers was prepared. The intimate growth of zeolite nanocrystals in the hemp fibers is achieved by direct hydrothermal crystallization. The crystalline phase, particle size distribution, porosity and zeolite loading in the composite are measured by X-ray diffraction, dynamic light scattering, thermo-gravimetric analysis, and nitrogen sorption. Further, the composite is used for the removal of aqueous aromatic organic pollutants (benzene, toluene and chlorobenzene), and the sorption ability is studied by IR and UV spectroscopy. The zeolite–hemp composite exhibited a high removal degree (above 80%), and a high flux of 19.3 kg m⁻² h⁻¹, 20.9 kg m⁻² h⁻¹ and 19.9 kg m⁻² h⁻¹ for benzene, toluene and chlorobenzene, respectively. Also, the zeolite–hemp composite shows substantially higher water flux than that of pure zeolite. The better performance of the composite is explained by an improved absorption ability of the zeolite–hemp material coupled with higher dynamic separation efficiency. A kinetic model based on the sorption ability of the composite and solubility of the contaminants in water is proposed. Both the zeolite L nanocrystals and the natural hemp fibers are environmentally friendly compounds, which make the composite particularly appropriate for water purification.