Preparation of a Fe-ZSM-5 Adsorbent and Its Selective Adsorption of p-Xylene Performance Exploration

In the purified terephthalic acid wastewater treatment process, a large amount of wastewater containing p-xylene (PX), Co2+ and Mn2+ would be by-produced and PX needs to be recycled to avoid affecting the subsequent treatment process. Fe3+-modified ZSM-5 zeolites were prepared for selective adsorption of PX, which were better than H-ZSM-5 zeolites and ZSM-5 zeolites. Moreover, the selectivity factors of PX to Co2+ and PX to Mn2+ attained on Fe-ZSM-S can approach to 5365.97 and 5038.70, respectively, and the saturated capacity can reach 125.0 mg.g(-1). Experimental data obtained from batch studies provided a good fit for the Langmuir isotherm model. The adsorption process was a spontaneously exothermic physisorption, and the adsorption of PX on Fe-ZSM-5 followed the pseudo-second-order rate expression. Production of granular Fe-ZSM-5 was further explored, and the fixed bed adsorption experiment was carried out. The adsorption capacity of granular Fe-ZSM-5 to PX can reach 45.64 mg.g(-1) under better process conditions, which is superior to ZSM-5 zeolites and activated carbon. It shows that Fe-ZSM-S can be used as a highly efficient adsorbent to selectively remove PX from wastewater with industrial prospects.