臭氧-CNT膜改性联用工艺阈通量及膜污染分析

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

采用碳纳米管(carbon nanotube,CNT)对聚偏氟乙烯(polyvinylidene fluoride,PVDF)中空纤维超滤膜进行改性,结合臭氧预氧化技术,考察了臭氧-CNT膜改性联用工艺的阈通量及膜表面污染情况.结果表明,原膜阈通量为45 L·(m^2·h)^(-1),联用工艺下阈通量为81 L·(m^2·h)^(-1),联用工艺相对原膜阈通量提高了约80%;且联用工艺的污染速率最低,约为0. 001 37k Pa·min-1·L-1·m^2·h.相同臭氧投量与CNT负载量下,对比联用工艺阈通量与临界通量运行情况,得出阈通量下运行过水量高于临界通量运行,表明阈通量下运行能够缓解膜污染,延长膜组件的运行时间.膜污染碳平衡实验结果表明,采用CNT对膜改性后,膜组件的纳污能力与可恢复性得到明显提高,臭氧氧化能够进一步提高CNT改性膜组件的可恢复性,大幅提高其过水性能和使用时间.

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. 001 37 k Pa·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.