Sequential Separation-Catalysis Membrane For Enhanced Removal Of Multiple Micropollutants

Efficient reuse and resource reclamation of wastewater is considered to be a promising way in response to clean water scarcity.However,industrial wastewater contains a wide variety of pollutants with complex compositions and variable water quality,and thus being hard to meet reuse standards by single traditional wastewater treatment process.Here,a conception of efficient removal for multiple pollutants in complex matrix by integrating separation and catalysis in controlled spatial sequencing was proposed.A sequential separation-catalysis membrane with high catalytic activity,high stability,and anti-interference properties was fabricated by inner pores filling and in-situ prolysis methods.The removal performance on multiple pollutants in complex water matrix has been investigated and the interference sheilding and mass-transfer enhancement effects have been revealed.And a sequential-separation-catalysis-membrane-based combined process with catalytic ultrafiltration membrane and nanofiltration membrane was proposed for efficient wastewater reuse of actual effluents in the chemical industrial park to obtain clean water resources.（1）Highly active nanocatalysts are prerequisites of catalytic activity membranes for water reuse technology.By regulating the growth process and composition distribution of silicon and ZIF-67 composite nanoparticles,catalytic nanoreactors with a uniformly Si O₂/C/Co₃O₄dispersed and core-shell structure was prepared.The presence of silicon improved the electron-donating ability of cobalt active sites and increased the hydrophilicity of the material.Bisphonel-A with high concentration(20 mg L^-1)was efficient degraded within 2 min under regular reaction conditions.The reaction kinetic constant was 2.38 min^-1,nearly 20 times higher than that of catalysts derived directly from ZIF-67(0.126 min^-1).The degradation process was dominated by a free radical process with main species of SO₄^●–.Moreover,after 5cycles of testing,no huge decline in catalytic performance was observed,indicating the good cyclic stability.（2）The practical applications of nanocatalysts were hindered from their easy loss,poor reusability,and inferior adaptability in complex aqueous matrices.By loading highly active nanocatalysts into finger-like pores of ultrafiltration membrane below the separation layer,a sequential separation-catalysis membrane was prepared and achieved the sequential integration of membrane separation and AOPs at a membrane interface.The loading amount of nanocatalysts can reach 56.3 wt%,providing the membrane with abundant catalytic active sites.Such a sequenced structure design successfully overcome the diminished performance in complex aqueous matrices by pre-intercepting large molecular interferents with seletive separation layer,which exhibits excellent decontamination performance toward multi-pollutants by filtering the water matrices containing HA and BPA.100%rejection of HA and95%catalytic degradation of BPA were achieved in a single pass under lower pressure of 0.14MPa and an ultra-high flux of 229 L m^-2 h^-1,corresponding retention time of 3.1 s.In addition,the flow-through process demonstrated significant enhancement of BPA degradation kinetics,which is 21.9 times higher than that of a conventional batch reactor.Moreover,the sequential separation-catalysis membrane has good stability and anti-fouling performance.（3）A conductive Co/N co-doped carbon hollow fiber ultrafiltration membrane derived from ZIF-67@AF was prepared by in-situ pyrolysis method.This membrane can be a platform to introduce electrodriven process into AOPs in membrane reactors.The MOF-derived catalytic center has high intrinsic activity and intensified by confinement effect and mass transfer enhancement in narrow membrane nanochannel effect.Under external electric field assistance,charge repulsion improved membrane retention performance（95%rejection on HA）providing interference shielding for subsequent AOPs,and catalysis reaction rate also has been accelerated by enhancing electron transfer（three times higher kinetic constant）.In addition,the active cobalt species were cycled via electroreduction thus showing exceptional sustainability with nearly zero Co leaching even after 24 h.（4）A sequential-separation-catalysis-membrane-based combined process with catalytic ultrafiltration membrane and nanofiltration membrane was designed and compared with conventional nanocatalysis-ultrafiltration-nanofiltration serial processes and microfiltration-reverse osmosis dual-membrane treatment for advanced treatment of actual secondary effluent from chemical industrial parks to compare their water reuse performance.The sequential separation-catalytic membrane overcome the limitation on conventional nanocatalysis-ultrafiltration processes of nanocatalysts lossing and diminished performance.The treated effluent meets the A1 level reuse water standard（GB/T 19772,well irrigation）in the“Water Reuse Guidelines Regenerated Water Grading”（GB/T 41018-2021）.It also meets the boiler make-up water standard in the“Urban Sewage Reuse Industrial Water Quality”（GB/T 19923-2005）and can be used as a source of industrial water.The combined process can flexibly adjust unit processes according to reuse requirements and exihibited satisfactory performance in actual wastewater reuse.The combined process showed more advantageous water resource reuse efficiency.In summary,the sequential-separation-catalysis-membrane-based combined process was designed through the development of new catalytic membrane materials and the rational combination of reuse technologies.The multiple pollutants in complex water matrix can be efficient removed at low pressure,and advanced treatment and wastewater reuse on actual wastewater was achievd.This research outcomes provide new strategies for the development of industrial wastewater reuse technology.