Preparation For A Novel PES Loose Nanofiltration Membrane And Study On Its Dye Desalination Performance

Dye industry is a dense labor industry with large energy consumption and energy consumption.A large amount of dye wastewater containing high salt concentration has been produced in the process.So in order to improve the separation efficiency of the dye/inorganic salt,based on the traditional nanofiltration membrane structure,we have develop durable new loose nanofiltration membranes to achieve dye purification and dye/salt wastewater recycling,which not only can greatly improve production efficiency,effectively reduce environmental pollution,but also be important for the recycling water resources and the ecological environment protection.Firstly,the polyethersulfone（PES）ultrafiltration supporting membrane was prepared by non-solvent induced phase inversion method.The PES/β-CD ultrafiltration substrate was prepared by blendingβ-cyclodextrin into the substrate casting solution to improve the hydrophilicity of the substrate.At the same time,hydroxyl groups in the outer surface ofβ-CD were used for subsequent surface modification.The influence of solvent type,pore agent type and concentration,and the concentration of hydrophilic additiveβ-cyclodextrin on the substrate structure,permeability and selectivity were also investigated.Then,titanium dioxide（Ti O₂）nanoparticles were modified with hexamethylene diisocyanate（HMDI）,and the functionalized Ti O₂ nanoparticles were chemically grafted onto the surface of PES/β-CD substrate by immersion method to prepare a novel loose nanofiltration membrane.The effects of soaking time soaking solution,concentration and HMDI ratio on membrane surface structure,separation performance and antifouling performance were investigated,determining the optimal modification process parameters.At the same time,a series of characterization and testing experiments for the optimized loose nanofiltration membrane to prove that functionalized Ti O₂ nanoparticles were successfully grafted onto substrate surface and the hydrophilicity and separation property of membrane were enhanced.Include SEM,XRD,XPS,ATR-FTIR etc.and pure water flux,retention tests for dyes and inorganic salts.Finally,the optimized loose nanofiltration membrane was applied in the dye/salt separation system to investigate the dye/salt separation efficiency and long-term stability of the membrane.The dye/salt separation test results showed that the membrane had high rejection rate for dyes and at the same time maintained the transmittance level of more than 90%for salts,namely a high dye/salt separation efficiency.The antifouling test results indicated that the membrane had good antifouling performance.The stability test results showed that the membrane kept stable permeate flux and separation property within 360 h in continuity experiment.The surface grafting method used in this study greatly shortened the preparation time,reduced the material costs,and the compatibility between inorganic nanoparticles and organic surface was obviously improved,and the hydrophilicity and fouling resistance of membrane surface were improved.This novel and facile loose nanofiltration membrane had high dye rejection,high dye/salt separation efficiency and great long-term stability.