The enhancement of ozone–liquid mass transfer performance in a PTFE hollow fiber membrane contactor using ultrasound as a catalyzer

Abstract

A comprehensive assessment of a polytetrafluoroethylene (PTFE) hollow fiber membrane contactor and ultrasound for intensifying ozone–liquid mass transfer was conducted simultaneously. The initial part of the study concentrates on the systematic analysis of the previous literature related to the reinforcement on the ozone–liquid mass transfer. In this paper, the introduction of a membrane contactor and ultrasound as a catalyzer that increased the mass transfer coefficient (K_La) may be partially attributed to the increase of the net surface area and the decrease of the mass transfer resistance, thus leading to the enhancement of the ozone mass transfer rate and acceleration of the ozone decomposition in solution. Results revealed that the maximum value of the K_La value was 0.7858 min⁻¹ in the PTFE hollow fiber membrane contactor in the presence of the ultrasound, while only 0.5154 min⁻¹ in a single ozone aeration at an intake flow of 300 L h⁻¹, ozone dosage of 32.38 mg L⁻¹ and operating temperature of 293.15 K. A 52.46% improvement of the K_La value was obtained in the presence of the ultrasound. In addition, the dosage of sodium chloride appeared to have a positive correlation with K_La, but a negative correlation with the concentration of dissolved ozone. The sulfolane destruction by ozonation, ultrasound and the combination between the ozonation and ultrasound were performed to further verify the enhancement of the ozone mass transfer performance. It has been established that the O₃/US combined process was a promising method, giving the maximum degradation of sulfolane (96.5%) with the synergistic index as 2.41.