Performance And Mechanisms Of Water Treatment Via A Superwetting Microalgae Biochar/PVDF Membrane

Frequent accidents involving industrial wastewater or sanitary sewage have significantly impacted the aquatic environment.These accidents also create potential ecological threats.Therefore,this highlights the importance of developing an efficient,simple,and environmentally friendly for treating wastewater in practice.Rencently,superwetting membrane materials have been shown a significantly advantange in efficient oil/water filtration.However,single superwetting membrane materials still have some disadvantages,such as multiphase emulsion separation and soluble organic contaminants（SCOD）removal.Therefore,the development of multifunctional superwetting membrane separation system has become an important direction of oil/water separation membrane research.In this paper,based on solid waste recycling witch the highly graphene-like microalgal residue biochar was loaded onto polyvinylidene fluoride（PVDF）film under vacuum to achieve the surface of micro-nano multistage bionic structure,and establish the common characteristics of the membrane in the preparation process.Through noticing the scientific problem of the efficient separation of oily pollutants coupled with the simultaneous removal of SCOD in the industrial wastewater,this project will focus on developing an enhanced microalgal residue-derived superwetting coupled with advanced oxidation membrane treatment system,exploring the degradation mechanisms of SCOD,revealing the environmental stability and biotoxicity of coupling system.The underwater superoleophobic/underoil superhydrophobic smart carbon membrane-design strategy used in this study is extremely simple and can be easily extended to other various smart materials,and thus,this strategy may open the door to new prospects in the design of novel materials for the continuous filtration of multiphase oil/water emulsions.The hierarchical surface topography of dually prewetted underwater superoleophobic and underoil superhydrophobic carbon black membrane（DCBM）was mainly formed from the micron PVDF roughness and hollow surface of the microspheres.The unique surface may contribute to the liquid storage capacity and improved wettability.Furthermore,the quasi-spherical shape of both underwater oil droplets and underoil water droplets was measured with CAs of 152°and 155°,respectively.Additionally,the DCBM displayed underwater superoleophobicity for a series of tested oils（chloroform,tetrachloromethane,and dichloroethane,all of which had CA values greater than 150°）.The underoil superhydrophobicity for a series of tested oils had values of water CAs that were greater than 150°.Thus,the DCBM has outstanding antifouling properties for both oil and water.Also,the filtrate droplet sizes of the various emulsions are observed to be only a few nanometers,for all of the systems,the content of the emulsion in the filtrate after separation was<45 ppm,the purity of each phase was above 99.5%,demonstrating the high separation efficiency of the DCBM.The fluxes for water-in-light oil and water-in-heavy oil emulsions are more than 5000 L/m²·h and 6000L/m²·h,the fluxes for oil-in-water emulsion are more than 2500 L/m²·h.The DCBM is able to achieve fast,continuous and corrosive stable separation of water-in-heavy oil,oil-in-water（containing 1 mol/L HCl,Na OH and Na Cl）and water-in-heavy oil multiphase emulsions mixtures.The stabilization of water droplets at the water/heavy oil interface is described by the augmented Young Laplace equation.Large amounts of inorganic salts（a natural pore-forming and graphitization agent）and protein（a natural N-doping agent）are present in industrial C-Phycocyanin-extracted microalgal residue.As such,for this study,we designed a novel hybrid underwater superoleophobic and underoil superhydrophobic microalgae-derived biochar membrane（DBCM）from C-Phycocyanin-extracted microalgal residue.When coupled with PDS,the DBCM efficiently processed multiphase emulsions wastewater containing SCOD,mitigating the limitations of conventional membrane filtration.The multiphase emulsion separation performance of DBCM/PDS system almost as well as DCBM,the fluxes for water-in-oil emulsions are more than 5000 L/m²·h,the fluxes for oil-in-water emulsions are more than 2000L/m²·h,the separation efficiency of each phase was above 99.5%.In addition to recovering the emulsions,DBCM also provided a breakthrough in lowering the use of the PDS/catalyst and enhancing the SCOD degradability（BPA,STZ,phenol,SMX,MB,MO,CR and RB）in AOPs.The study also included a comprehensive analysis of the corresponding mechanisms at the DBCM interface.Chemical quenching agents and EPR test indicated that both·OH and O2·-were the ROSs in the DBCM/PDS system,with a lower contribution asociated with non-radical pathways.Moreover,the stability test of the conventional stirring system and DBCM/PDS system show that DBCM/PDS system with satisfactory stability,which benefits long-term operation.The abundant N dopants in DBCM largely improved the AOPs catalytic activity.This study revealing the abundant N dopants in DBCM largely improved the AOPs catalytic activity by exploring the greater E_ads of six types of N functionalities,transition-state searching and HOMO and LUMO orbitals of excellent electronic activity of the zigzag edges,eventually exploring the pd Nz and pd Na species primarily facilitated the catalytic performance.To investigate the effect of complex environment on DBCM/PDS system and the effect of intermediates,catalysts and microplastics by DBCM/PDS system on environment.In this study,the DBCM/PDS system was applied to successive separation of multiphase emulsion mixtures and degradation of BPA.Moreover,the solution’s p H and presence of inorganic anions have only a minor inhibitory effect on BPA degradation.Thus,DBCM/PDS system is a promising method of purification for complex wastewater mixtures,since it is not susceptible to interferences from background substances.The toxicity estimates of the intermediates of BPA from DBCM/PDS system were verified using the ECOSAR tool.Treatment or degradation of DBCM/PDS system along with BPA significantly reduce BPA mediated toxictiy.Although the toxicities of BPA degradation from DBCM/PDS system had shown a downward trend,its residual cytotoxicity still can not be disregarded.Meanwhile,the ratios of live/dead cells in the six types of oil-in-water phase before and after multiphase emulsion separation.The live/dead cell ratio increased sharply from an initial ratio of 10%to 98%after filtering.Cell experiments were also carried out with osteoblastic viability in vitro bone after exposure to various concentrations of BPA and PDS.Moverover,the IC 50 of BPA degradation filtrate did not cause significant cell death and the degradation filtrate with initial IC 50 of PDS led to about 100%cell viability.Therefore,DBCM/PDS system not only shows excellent performs for the separation of three-phase emulsions but also for removal of BPA from water emulsions with low cell toxicity.The results demonstrated that the techonology by DBCM/PDS system was applicable for the complex wastewater and provided a biotoxicy evaluation system.