Preparation And Properties Of Organic/Inorganic Hybrid Positive Permeation Films Based On Hydrotalcite

The osmotic pressure difference between the raw material liquid and the drawi ng fluid on both sides of the membrane was the positive osmosis technology of the driving force,and has the advantages of high retention rate,low energy consumpti on,low pollution and the like,and was more and more widely concerned in the a spects of seawater desalination and sewage treatment.In order to solve the problem of serious internal concentration polarization and reverse osmosis in positive infiltr ation system.Hydrotalcite-doped polysulfone membrane was prepared by blending m ethod with hydrotalcite-lamella?EHT?as additive.Inter-phenylenediamine?MPD?an d trimesoyl chloride?TMC?as water and oil phase monomers,the PA/PSF-EHT hy brid membrane was constructed by interfacial polymerization.The effects of the ne w PA/PSF-EHT Hybrid Membrane Preparation Conditions?Volatilization Time,Gel Bath Temperature,Basement Film Thickness,MPD Concentration,TMC Concentrati on,EHT Addition?,Operating Conditions?pH Value,Raw Material Concentration a nd Flow Rate,Orientation?on the membrane performance,the main research conten ts were as follows:?1?The optimum preparation conditions of PA/PSF-EHT hybrid positive osmosis membrane were as follows:PSF 18 wt.%,Volatilization time 50s,support membrane thickness 100um,gel bath temperature 35?,MPD 3.4 wt.%,EHT 0.06 wt.%,Post-treatment temperature 50?.At this time,the flux Jw of the PA/PSF-EHT hybrid positive osmosis membrane was 55.3 L/m²?h?raw material solution was deionized water,the draw solution was 0.5 mol/l NaCl?.Therefore,for commercial HTI positive osmotic membrane of CTA increased 4-fold and the anti-diffusion flux Js was 0.1 g/m²?h,which was much lower than that of HTI's CTA membrane?10.2-11.5 g/m²?h?.As the volatilization time increased,the water flux Jw increased from 10 L/m²?h to 55.3 L/m²?h and the anti-diffusion flux Js increased from 0.1 g/m²?h to 0.4 g/m²?h,the water flux Jw increased from 0.9 L/m²?h to 7.0 L/m²?h as the temperature of the gel bath increased.The anti-diffusion flux Js decreased from 0.4 g/m²?h to 0.05 g/m²?h.When the concentration of TMC was constant,the water flux Jw increased from 0.3 L/m²?h to 6.8 L/m²?h,and the anti-diffusion flux Js decreased from 0.42 g/m²?h to 0.04 g/m²?h.The water flux Jw increased from 2 L/m²?h to 16 L/m²?h with the change of the concentration and type of extract?Na2SO4,MgCl2,MgSO4,NaCl?,and the counter diffusion flux Js was 0.36g/m²?h to 0.04 g/m²?h.Scanning of the positively charged membrane material by doping the hydrotalcite-Electron microscopy?SEM?and hydrophilic contact angle characterization analysis showed that the active layer of PA/PSF-EHT hybrid positive osmosis membrane was smooth and compact with a hydrophilic contact angle of 35o,which was significantly higher than that of HTI's CTA membrane with a hydrophilic contact angle of 76oImprove membrane hydrophilicity.?2?Cr???,Pb²⁺,Cd²⁺performance test of PA/PSF-EHT hybrid membrane.The effects of pH value,concentration and flow rate of raw material solution,draw solution concentration and flow rate,film orientation on Cr???,Pb²⁺and Cd²⁺removal were investigated.The results showed that when the pH of Cr???=5,feed concentration was 20mg/L,the concentration of the extract was 1.0 mol/L NaCl solution,the flow rate of feed solution was 189.15 mL/min and the flow rate of draw solution was 359.27 mL/min,the flux Jw of the permeating membrane PA/PSF-EHT to remove Cr???reaches 43.5 L/m²?h,the rejection R was more than 80%and the highest was nearly 99%.When the pH of Pb²⁺=2,feed concentration was 20 mg/L,the concentration of the extract was 1.0 mol/L NaCl solution,the flow rate of the feed solution was 189.15 mL/min and the flow rate of the draw solution was 359.27 mL/min,the flux Jw of the permeating membrane PA/PSF-EHT to remove Pb²⁺reaches 77.5 L/m²?h,the rejection R was more than 95%and the highest was close to 98%.When the pH of Cd²⁺=3,feed concentration was 20 mg/L,the concentration of the extract was 1.0 mol/L NaCl solution,the flow rate of the feed solution was 189.15 m L/min and the flow rate of the draw solution was 359.27 mL/min,the flux Jw of the permeating membrane PA/PSF-EHT to remove Cd²⁺reaches 56.4 L/m²?h,the rejection R was more than 93%and the highest was 97%.