Novel H2O2–MnO2 system for efficient physico-chemical cleaning of fouled ultrafiltration membranes by simultaneous generation of reactive free radicals and oxygen

Abstract

The novel H2O2–MnO2 system was developed to achieve highly efficient membrane cleaning for both fouled PVDF and PES membranes in this study. Compared with conventional chemical cleaning process in which the whole membrane module had to be soaked in highly concentrated solution of chemical reagent for long period of time, the H2O2–MnO2 cleaning process conducting for only 5 min in 0.5 wt% H2O2 solution could achieve more than 95% recovery of permeate flux and almost total removal of the irreversible foulants. More importantly, the permeate flux and filtration efficiency of the membrane could be still kept stable after 6 runs of consecutive fouling and cleaning. Based on the systematic microscopic analyses, Electron Spin Resonance (ESR), Fourier Transform Infrared Spectroscopy (FTIR), as well as the quenching experiments with different free radical scavengers, the outstanding performance of H2O2–MnO2 system was attributed to the generation of both free radicals and abundant oxygen simultaneously, leading to the physico-chemical membrane cleaning. Conclusively, the newly developed H2O2–MnO2 system demonstrated noteworthy advantages on efficient membrane cleaning, and exhibited highly potential for the wide application in practical water treatment process.