Sodium Hypochlorite

Reverse osmosis (RO) membrane technol. encounters challenges such as membrane biofouling and oxidation during practical use, which significantly hinders its further development and application.To improve the chlorine and biofouling resistance of RO membrane, we suggest a method that modifies the mass ratios of zwitterionic and quaternary ammonium copolymers in the mussel-inspired coating layer.This method successfully controls the hydrophilicity and pos. charge of the membrane surface, enhancing its overall performance.The plate counting results indicate that the bacterial killing efficiency of the blended modified TFC membrane (50:50) against E. coli and S. aureus is ≥98%.Thanks to the combined effects of the anti-adhesion zwitterionic copolymer and the antibacterial quaternary ammonium copolymer, the blended modified TFC membrane (50:50) demonstrates superior anti-biofouling performance in dynamic biofouling tests.Furthermore, the desalination performance of the blending modified TFC membrane (50:50) remains stable after long-term exposure to 60,000 ppm·h of active chlorine, while the desalination performance of the pristine TFC membrane significantly declines.In conclusion, our advancements in chlorine-tolerant and anti-biofouling RO membranes could enhance the reliability of RO technol.

To overcome conventional membrane challenges in eliminating natural organic matter (NOM) from natural water, we successfully integrated β-iron hydroxide oxide (β-FeOOH) nanorods onto a PAA-PVDF blend membrane fabricated from poly(acrylic acid) (PAA) and polyvinylidene fluoride (PVDF).Contact angle assessments with various fluids confirmed the strong organic matter adsorption property of the membrane, with a dispersion component of surface energy at 26.7 mJ/m² for β-FeOOH@PAA-PVDF.This membrane consistently removed over 80% of dissolved organic matter in the cross-flow filtration of water containing 50-150 ppm fulvic acid (FA) under neutral conditions.Such remarkable performance is attributed to the interactions between the Fe-OH groups and the carbonyl (2.960 eV) and phenolic (2.864 eV) groups of FA, overcoming the size sieving limits.Under acidic conditions, zeta potential tests revealed effective ferric coagulation, resulting in over 90% FA (50 ppm) removal.We thoroughly investigated that common cations (e.g., K⁺ and Ca²⁺) have impacts on FA removal using β-FeOOH@PAA-PVDF.The used membranes regained nearly original fluxes after washing with trace hydrogen peroxide (H₂O₂) under UV light illumination, outperforming traditional washing with sodium hypochlorite (NaClO).ESR spectrometry elucidated the cleaning mechanism of β-FeOOH@PAA-PVDF was superoxide anion radical (^·O^-₂) and singlet oxygen (¹O₂) active species.In summary, β-FeOOH@PAA-PVDF showed a superior adsorption capacity (2200 mg/m²) and efficient photocatalytic degradation towards NOM in natural water, providing an efficient cleaning technol. for membrane reuse.