Kinetic and equilibrium modelling of MTBE (Methyl tert-butyl ether) adsorption on ZSM-5 zeolite: Batch and column studies

Abstract

The intensive use of methyl tert-butyl ether (MTBE) as a gasoline additive has resulted in serious environmental problems due to its high solubility, volatility and recalcitrance. The feasibility of permeable reactive barriers (PRBs) with ZSM-5 type zeolite as a reactive medium was explored for MTBE contaminated groundwater remediation. Batch adsorption studies showed that the MTBE adsorption onto ZSM-5 follows the Langmuir model and obeys the pseudo-second-order model with an adsorption capacity of 53.55 mg·g-1. The adsorption process reached equilibrium within 24 h, and MTBE was barely desorbed with initial MTBE concentration of 300 mg·L-1. The mass transfer process is found to be primarily controlled by pore diffusion for MTBE concentrations from 100 to 600 mg·L-1. pH has little effect on the maximum adsorption capacity in the pH range of 2-10, while the presence of nickel reduces the capacity with Ni concentrations of 2.5-25 mg·L-1. In fixed-bed column tests, the Dose-Response model fits the breakthrough curve well, showing a saturation time of ~320 min and a removal capacity of ~18.71 mg·g-1 under the conditions of this study. Therefore, ZSM-5 is an extremely effective adsorbent for MTBE removal and has a huge potential to be used as a reactive medium in PRBs.