A systematic study of enhanced ozone mass transfer for ultrasonic-assisted PTFE hollow fiber membrane aeration process

The ozone mass transfer efficiency based on deionized water of both the PTFE hollow fiber membrane aeration and ultrasonic-assisted PTFE hollow fiber membrane aeration processes have been studied and described by mass transfer coefficient (K(L)a). Bubble size distributions were also investigated via an image-technology to analyze mass transfer processes. All the PTFE hollow fiber membranes were hydrophobic and had an asymmetrical structure. Results showed that the maximum value of K(L)a (0.438 min(-1)) was obtained at an intake flow rate of 300 L/h with 1(#) membrane (0.22 mu m) in single membrane aeration system. This gas-liquid mass transfer was strongly dependent on pressure. After the introduction of ultrasonic power, the K(L)a value reached 0.632 min(-1) with an ultrasonic power of 1000 W. This enhancement was related to the periodical replacement of local liquid at the interface between the bulk solution and the liquid with high concentration of ozone. The degradation of sulfonated phenolic resin (SMP) confirms that its mineralization was promoted by the enhanced gas-liquid mass transfer of ozone and the generation of center dot OH in the bulk solution.