CuO@carbon nanofiber as an efficient peroxymonosulfate catalyst for mitigation of organic matter fouling in the ultrafiltration process

Abstract

Persulfate oxidation has been increasingly integrated with membrane separation for water purification, whereas the oxidizing ability of persulfate is relatively limited, and appropriate activation methods are urgently required. In this work, a novel catalyst of carbon nanofiber (CNF) supported CuO (CuO@CNF) was synthesized for peroxymonosulfate (PMS) activation. The micro-morphology showed that CuO nanoparticles were well dispersed on the CNF support, which solved the agglomeration problem of nanoparticles and improved the catalytic ability. Furtherly, PMS oxidation activated by CuO@CNF was proposed as a pre-processing means for improving ultrafiltration (UF) water purification efficiency and mitigating membrane fouling. The prepared CuO@CNF was more efficient than individual CNF and CuO in activating PMS for the reduction of various typical natural organic matter, improving permeation flux, and mitigating membrane fouling. The fouling control efficiencies were also verified by characterizing the membrane surface functional groups. The CuO@CNF catalyst could signally promote the oxidative capacity by generating a series of reactive oxygen species, thus enhancing the removal of organics with varying species and molecular weight ranges in surface water. With respect to the fouling condition, the specific permeation flux after filtration was improved from 0.25 to 0.61, with the removal rate of reversible fouling resistance reached 89.6%. The fouling mechanism was apparently altered, with both standard and complete blocking dominated throughout the filtration process. The findings are beneficial for the development of new strategies to improve membrane-based water purification efficiency.