The Crafts Study Of Supported Liquid Membrane Extraction To Treat Coal Gasification Wastewater Containing High Concentrations Phenol

Coal gasification wastewater is a kind of toxic and hazardous industrial wastewater, which contains high concentrations of phenolic compounds with high recovery value. Supported liquid membrane extraction technique is a new separation technology combined solvent extraction and membrane separation, with advantages of a small extractant use and low extractant loss, high extraction efficiency, low running costs,energy consumption and secondary pollution, showing broad research and application prospects.Hollow Fiber Supported liquid membrane (HFSLM) extraction was introduced to treat coal gasification wastewater to recover the phenolic compounds, with tributyl phosphate (TBP) as carrier, kerosene as the membrane solvent, sodium hydroxide solution as the stripping agent and PVDF as the membrane material. Many factors having strong impact on the extraction efficiency were studied in detail, including the mass transfer mode, two-phase flow rate, membrane filling factor, temperature and the optimal operating conditions were obtained. On this basis, the mass transfer process of HFSLM extraction of phenol was analyzed, the overall mass transfer coefficient model was stablished and the mass transfer coefficient of feed solution, membrane phase and stripping phase and the sub-total mass transfer coefficient were calculated. The experiments were gradually enlarged and the operating conditions were optimized for a certain degree.The optimum operating conditions of HFSLM extraction of coal gasification wastewater were: extraction system of 20% TBP-kerosene, membrane vertically, and mass transfer, stripping phase concentration of 0.1mol/L, feed solution flow rate of 5L/h, stripping phase flow rate of 5L/h, the membrane component filling factor of 19%, experiment temperature of 300K. Under the optimum operating conditions, the time required to reach equilibrium for the extraction is 50min, extraction rate of phenol is 86.2% and the phenol concentration of effluent is 98.64mg/L.The paper established the mass transfer coefficient model of HFSLM extraction of phenol and calculated the mass transfer coefficient of liquid material, membrane phase and stripping phase and the sub-total mass transfer coefficient: k_w=8.044×10^-6 m/s, k_m=5.333×10^-6m/s, k_s=1.404×10^-5m/s, K_w=4.942×10^-6m/s. It showed that the mass transfer resistance of feed solution and membrane phase share in total mass transfer resistanceThe pilot-scale experiments was carried out successfully and the optimum operating conditions of HFSLM extraction for 250L coal gasification wastewater were: stripping phase concentration of 0.1mol/L, phase ratio of 1:200, feed solution flow rate of 100L/h, stripping phase flow rate of 60L/h. Under the optimal operating conditions, the time required to reach extraction equilibrium is 240min, the extraction rate of phenol is 75.71% and the phenol concentration of effluent is 262.73mg/L.