Threshold Flux and Membrane Fouling Analysis of the Hybrid Pre-ozonation and CNTs Membrane Modification Process

Abstract

Polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotubes (CNT). Hybrid pre-ozonation and CNT modification were investigated by experimentally manipulating the ozonation process, threshold flux, and membrane fouling. The results showed that the threshold fluxes of the unmodified membrane and hybrid process were 45 L·(m2·h)-1 and 81 L·(m2·h)-1, respectively. Additionally, the fouling rate of the hybrid process was about 0.00137 kPa·min-1·L-1·m2·h, which was notably lower compared to other process. The results showed that the filtration volume under threshold flux was higher than that under critical flux with the same CNT loading mass and ozone dosage. This comparison indicated that membrane fouling was alleviated under threshold flux and that the corresponding operation period was extended. Through the carbon balance experiment, the fouling capacity and recoverability improved remarkably after CNT modification. Additionally, ozonation could enhance the recoverability of membranes. The hybrid process examined in this study could dramatically improve the permeability and extend the operation time of the ultrafiltration membrane.