The Separation Performance Of Tubular Composite Membrane And Its Application In Dye Wastewater Treatment

Nanofiltration membrane,as a kind of water treatment technology with high efficiency,energy conservation and environmental protection,is an important means to solve water pollution and water resource shortage.Compared with other kinds of membrane components,tubular membrane has the advantages of high mechanical strength,wide flow channel and fast flow rate.In this paper,PVDF/PA tubular composite membranes with different retention properties were prepared by interfacial polymerization with PVDF tubular ultrafiltration membrane as basement membrane,piperazine?PIP?as water phase monomer and TMC as organic phase monomer.The separation performance of the tubular composite membrane was studied.The effects of different preparation conditions and test conditions on the separation performance of the membrane were investigated.The cutting molecular weight and pore size distribution of the composite membrane with different properties were calculated.The retention of different inorganic salts and sugars by the composite membrane with different properties and the effects of acid-base treatment and chlorine treatment on the performance of the membrane were also studied.Scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FTIR?and X-ray photoelectron spectroscopy?XPS?were used to analyze the membrane samples.The results showed that the optimum ratio of water phase and organic phase was PIP 0.2wt.%?0.4wt.%,TMC0.05wt.%?0.1wt.%;the ratio of loose composite membrane was PIP 0.05wt.%?0.08wt.%,TMC 0.05wt.%?0.7wt.%;the optimum blowing time was 10s;the surface of the composite membrane with different properties is negatively charged under the condition of p H 4?11;the dynamic contact angle experiment results show that,the hydrophilicity of the composite membrane is better than that of the compact composite membrane;the corresponding cutting molecular weight of different composite membranes with Mg SO₄ retention from 97%to 5%was 300 to 45000 da;the order of retention effect for four inorganic salts is Na₂SO₄,Mg SO₄,Na Cl and Mg Cl₂;the retention rate of sucrose was higher than that of Mg SO₄,and the retention rate of glucose was lower than that of Mg SO₄;the tubular nanofiltration membrane shows good stability during a long time operation;the acid-base environment of stable operation is p H=3?11;the composite nanofiltration membrane with piperazine amide has good chlorine resistance.The application of tubular composite nanofiltration membrane in dye wastewater treatment was also studied.The concentration and pressure of dye have little effect on the retention rate of dye;the retention rate of composite nanofiltration membrane for anionic dye erichrome black T,Congo red,acid fuchsin and direct red 80 is more than99.7%;the retention rate for anionic dye methyl orange at 0.8MPa is as low as 95%;the retention rate for cationic dye rhodamine B is higher than 98.5%.The retention rate of nanofiltration membrane for five kinds of dye and salt mixtures is more than 99.4%,and the salt penetration rate is more than 80%,which enables the separation of dye and salt effectively,and realizes the desalination and recovery of dye.