Preparation And Application Study Of Based On MIL-53(Fe) Hybrid Forward Osmosis Membrane

Forward osmosis（FO）membrane technology has attracted wide attention due to its low pollution and low energy consumption.However,ordinary cellulose acetate（CA）FO membranes have problems of permeability and selectivity.Therefore,modification of CA forward osmosis membranes is necessary to improve the performance of FO membranes.In this paper,we prepared MIL-53（Fe）and MIL-53（Fe）@γ-Al₂O₃,and then MIL-53（Fe）,γ-Al₂O₃ and MIL-53（Fe）@γ-Al₂O₃ were used as membrane additives to improve properties and structures of FO membranes.The specific research contents are as follows:MIL-53（Fe）was successfully prepared using solvent-thermal method.MIL-53（Fe）was characterized and analyzed by XRD,SEM,FTIR and N₂ adsorption-desorption curves.And then,MIL-53（Fe）was used as a membrane additive to fabricate CA/MIL-53（Fe）hybrid FO membranes.The effects of MIL-53（Fe）content,casting solution temperature,coagulation bath temperature,and annealing temperature on the properties of the membranes were systematically studied.The optimal parameters were established including 0.6 wt.%of MIL-53（Fe）content,casting solution temperature at 50°C,coagulation bath temperature at30°C,and annealing temperature at 60°C.The water flux and reverse salt flux of the CA/MIL-53（Fe）hybrid FO membranes were 34.9 L/（m²·h）and 2.02 g/（m²·h）,respectively.The properties and structure of the prepared CA/MIL-53（Fe）hybrid FO membranes were characterized.Compared to HTI and CA membranes,the properties and structure characterized of the CA/MIL-53（Fe）hybrid FO membranes showed that the addition of MIL-53（Fe）increased the membrane pore,hydrophilicity,and roughness of FO membranes and improved the performance of FO membranes.γ-Al₂O₃ was used as a membrane additive to prepared CA/γ-Al₂O₃ hybrid FO membranes.Firstly,γ-Al₂O₃ was characterized and analyzed using SEM,FTIR and N₂adsorption-desorption curves.The effects ofγ-Al₂O₃ content,casting solution temperature,coagulation bath temperature,and annealing on the properties of the membranes were systematically studied.The experiment drew the following conclusions:the optimum content ofγ-Al₂O₃ was 0.5 wt.%,the optimum casting solution temperature was 60°C,the optimum coagulation bath temperature was 30°C,and the optimum annealing temperature was 70°C.The water flux and reverse salt flux of CA/γ-Al₂O₃ hybrid FO membranes under these conditions reached 31.6 L/（m²·h）and 3.57 g/（m²·h）,respectively.The properties and structure of the prepared CA/γ-Al₂O₃ hybrid FO membranes were characterized.Compared to HTI and CA membranes,the addition ofγ-Al₂O₃ improved permeability of FO membranes.MIL-53（Fe）@γ-Al₂O₃ was successfully prepared using solvent-thermal method.MIL-53（Fe）@γ-Al₂O₃ was characterized and analyzed by XRD,SEM,FTIR and N₂adsorption-desorption curves.And then MIL-53（Fe）@γ-Al₂O₃ was used as a membrane additive to fabricate CA/MIL-53（Fe）hybrid FO membranes.The effects of MIL-53（Fe）@γ-Al₂O₃ content,casting solution temperature,coagulation bath temperature,and annealing on the properties of the membranes were systematically studied.The experiment drew the following conclusions:the optimum content of MIL-53（Fe）@γ-Al₂O₃was 0.5 wt.%,the optimum casting solution temperature was 60°C,the optimum coagulation bath temperature was 30°C,and the optimum annealing temperature was 60°C.The water flux and reverse salt flux of CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO membranes under these conditions were 37.1 L/（m²·h）and 1.78 g/（m²·h）,respectively.The properties and structure of the prepared CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO membranes were characterized.The experimental results showed that the structure of FO membranes was improved and the performance of FO membranes was enhenced.Finally,HTI membrane and self-made CA membranes,CA/MIL-53（Fe）,CA/γ-Al₂O₃,and CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO membranes were studied in seawater desalination.In the experiment,the changes of water flux and salt rejection of each FO membrane prepared were tested in 1 h under the conditions of 2 M glucose solution as the draw solution and seawater as the feed solution.In terms of water flux,the water flux of the CA/MIL-53（Fe）,CA/γ-Al₂O₃,and CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO membranes were better than one of HTI membrane.However,stability of the water flux of self-made FO membranes was worse than that of HTI membrane.As for the salt rejection,the salt rejection and stability of self-made FO membranes were worse than that of HTI membrane.But the salt rejection of CA/MIL-53（Fe）,CA/γ-Al₂O₃,and CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO membranes were significantly better than them of CA FO membranes.Moreover,the performance of CA/MIL-53（Fe）@γ-Al₂O₃ hybrid FO were better than that of the other two membranes.