Treatment Of Phenolic Wastewater By Support Liquid Membrane Extraction System Using UV-induced Grafting Modified PVDF Membrane As A Support

The treatment of phenolic wastewater by support liquid membrane extraction system has the advantages of low energy consumption,simple operation,simultaneous extraction and stripping,but the disadvantages of the instability due to the easy loss of carrier.In order to improve the stability of the support liquid membrane extraction system,the support body was modified by UV-induced grafting method and applied it to the treatment of phenolic wastewater in this paper,and the main research content is as follows:First,the support body polyvinylidene fluoride membrane was hydrophobically modified by UV-induced grafting method,and styrene selected as graft monomer b comparative analysis.The effects of illumination time,temperature,concentration of initiator benzophenone and graft monomer on the grafting rate were investigated and the optimal experimental conditions for the production were determined: the concentration of benzophenone was 0.3 mol/L,the concentration of styrene was 4 wt.%,the pre-illumination time was 5 min,the reaction time of UV-induced grafting was 15 min,and the system temperature was 30 °C,under these experimental conditions,the grafting degree reached to 6.8 %.Fourier transform infrared spectrometer,scanning electron microscope and contact angle meter were used to analyze the functional groups,microcosmic morphology and contact angles of polyvinylidene fluoride membrane before and after modification,and the results show that after UV-induced grafting modification,the contact angle of polyvinylidene fluoride increased by 22.4° and the hydrophobicity of polyvinylidene fluoride membrane was significantly increased.In addition,the industrial phenolic wastewater were treated by support liquid membrane extraction system using UV-induced grafting modified membrane as a support,and hollow fiber membrane as the support by comparison with flat membrane.The effects of experimental conditions on the phenol removal rate were studied and the optimum operating conditions of the system were obtained:the liquid phase p H=4,the tributyl phosphate volume fraction is 20 %,the concentration of stripping agent Na OH is 0.2 mol/L,the feed phase passes the tube and the stripping phase flows through the shell of the membrane module,in pattern of countercurrent,the inlet pressure is 2.0 k Pa,the temperature at 20?.Under the operating conditions,an scale-up experiment was conducted to study the stability of the support liquid membrane extraction system,and the results show that after the modification of polyvinylidenefluoride membrane by UV-induced grafting method,the stability of the SLM extraction system could be significantly improved,after 180 h of continuous operations,the phenol removal rate remained stable by more than 75.6 % and the stable operating time was increased by 50 %.