The influence of ZSM-5 structure on As(V) adsorption performance: pseudomorphic transformation and grafting of rare-earth Ce onto ZSM-5

ZSM-5 has been regarded as one of the potential materials for separating substances from the mixture; however, their micropore channel is not favorable to load new active sites and adsorbate species. Herein, the pseudomorphic transformation method was used to convert high-aluminum-content micropore ZSM-5 into mesoporous structure (ZSM-5K). The samples of ZSM-5 and ZSM-5K were modified by Ce-2(SO4)(3) via the same impregnation route, and the obtained samples were used to adsorb As(V) from aqueous solution. The As(V) removal percentage and the X-ray diffraction data indicate that Ce-2(SO4)(3) was the effective adsorption site due to the high affinity between As(V) species and Ce. The N-2 adsorption-desorption isotherms show that the linear connection between As(V) removal and BET surface of adsorbents was been obtained. The transmission electron microscopy results showed that mesoporous structure was more favorable to disperse the adsorption sites. In addition, the As(V) equilibrium adsorption data were fitted well by the Langmuir isotherm, and the maximum adsorption capacity was found as 31.63 mg/g, which was larger than that of the conventional alumina, carbon, iron oxide, etc. The adsorption kinetics under different initial concentration obeyed the pseudo-second-order model.