Picolinic acid enhances ultrafiltration performance in surface water treatment by promoting the...

The widespread application of ultrafiltration processes is largely hindered by membrane fouling and insufficient removal of emerging pollutants. To address these challenges, a novel pre-oxidation system based on the activation of peroxymonosulfate by Mo(IV) and picolinic acid (PMS/PICA/MoS₂) was developed, and its performance and underlying mechanisms were systematically investigated. The results demonstrated that under the optimal conditions of the PMS/PICA/MoS₂ system, the normalized flux after pre-oxidation increased from 0.20 to 0.86, while the degradation rate of carbamazepine (CBZ) reached 80.36 %. Free radical identification and quenching experiments elucidated that high-valent molybdenum oxygen species (Mo^VI=O), singlet oxygen (¹O₂), sulfate radicals (SO₄^•-), and hydroxyl radicals (•OH) were the primary reactive oxygen species involved in the system. The contribution of each ROS to membrane fouling reduction was determined as 40.45 %, 33.45 %, 14.95 %, and 11.15 %, respectively, while their contributions to CBZ degradation were 34.95 %, 32.95 %, 16.74 %, and 15.36 %, respectively. Correlation analysis indicated that the reduction of UV₂₅₄ absorbance, along with an increase in zeta potential and particle size, played a crucial role in mitigating membrane fouling. Moreover, membrane fouling layer characterization and fouling model analysis revealed that cake filtration and intermediate pore blockage were the dominant fouling mechanisms. According to the extended Derjaguin-Landau-Verwey-Overbeek theory, the PMS/PICA/MoS₂ system enhanced the repulsive forces between the membrane and pollutants, thereby reducing pollutant adhesion to the membrane surface. This study presents an innovative pre-oxidation strategy for alleviating membrane fouling and removing emerging contaminants, offering valuable theoretical support for the practical application of metal-based pre-oxidation technologies.