电场辅助制备分层多孔扩散渗析膜
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摘要
传统的扩散渗析膜厚度较大,传质阻力较大,使得氢离子较难透过,酸回收率不高.本文通过采用外加电场辅助致密膜成孔的方法,探讨了电场强度和作用时间对聚(QVBC-DVB)/PVDF离子交换膜形貌的影响,制备出"三明治"型分层多孔扩散渗析膜,将致密层厚度从80.0μm降低至46.8μm.扩散渗析测试表明,经100 mA/cm~2的电场作用72 h后,氢离子渗析系数和分离因子分别达到12.12×10~(-3) m/h和198,与致密基膜相比分别提高了121.7%和57.1%,为改善扩散渗析膜性能提供了新思路.
Diffusion dialysis process for acid recovery from industrial waste water suffers from high transport resistance of conventional anion exchange membranes, thus limiting the recovery efficiency. In this study, electric field induced sandwich-like hierarchical porous membranes have been prepared and characterized. Effects of current density and time on the thickness reduction of dense layer and the formation of sandwich-like structure have been investigated in details. The resulting membranes exhibit good mechanical and chemical stabilities. When being applied at a current density of 100 mA/cm~2 for 72 h, the thickness of dense layer is successfully decreased from 80.0 μm to 46.8 μm. The corresponding membrane has an excellent acid permeability efficiency of 12.12×10~(-3) m/h and a separation factor of 198, which are 121.7% and 57.1% higher than those of the pristine dense membrane, respectively. This new method finds new way for the formation of porous structure and further proves that thin dense structure is favorable to the improvement of diffusion dialysis process for acid recovery.
Diffusion dialysis process for acid recovery from industrial waste water suffers from high transport resistance of conventional anion exchange membranes, thus limiting the recovery efficiency. In this study, electric field induced sandwich-like hierarchical porous membranes have been prepared and characterized. Effects of current density and time on the thickness reduction of dense layer and the formation of sandwich-like structure have been investigated in details. The resulting membranes exhibit good mechanical and chemical stabilities. When being applied at a current density of 100 mA/cm~2 for 72 h, the thickness of dense layer is successfully decreased from 80.0 μm to 46.8 μm. The corresponding membrane has an excellent acid permeability efficiency of 12.12×10~(-3) m/h and a separation factor of 198, which are 121.7% and 57.1% higher than those of the pristine dense membrane, respectively. This new method finds new way for the formation of porous structure and further proves that thin dense structure is favorable to the improvement of diffusion dialysis process for acid recovery.
引文
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[2] German M,SenGupta A K,Greenleaf J.Hydrogen ion (H+) in waste acid as a driver for environmentally sustainable processes:Opportunities and challenges[J].Environ Sci Technol,2013,47(5):2145-2150.
[3] Ismael M,Carvalho J.Iron recovery from sulphate leach liquors in zinc hydrometallurgy[J].Miner Eng,2003,16(1):31-39.
[4] ?zdemir T,?ztin C,Klncal N S.Treatment of waste pickling liquors:Process synthesis and economic analysis[J].Chem Eng Commun,2006,193(5):548-563.
[5] Chen G.Electrochemical technologies in wastewater treatment[J].Sep Purif Technol,2004,38(1):11-41.
[6] Kul M,Oskay K O.Separation and recovery of valuable metals from real mix electroplating wastewater by solvent extraction[J].Hydrometallurgy,2015,155:153-160.
[7] Ran J,Wu L,He Y,et al.Ion exchange membranes:New developments and applications[J].J Membr Sci,2017,522:267-291.
[8] Luo J,Wu C,Xu T,et al.Diffusion dialysis-concept,principle and applications[J].J Membr Sci,2011,366(1/2):1-16.
[9] Wang L,Zhang F,Li Z,et al.Mixed-charge poly(2,6-dimethyl-phenylene oxide)anion exchange membrane for diffusion dialysis in acid recovery[J].J Membr Sci,2018,549:543-549.
[10] Cheng C,Yang Z,He Y,et al.Diffusion dialysis membranes with semi-interpenetrating network for acid recovery[J].J Membr Sci,2015,493:645-653.
[11] Luo J,Wu C,Wu Y,et al.Diffusion dialysis of hydrochloride acid at different temperatures using PPO - SiO2 hybrid anion exchange membranes[J].J Membr Sci,2010,347(1/2):240-249.
[12] Zhang Y,Liu R,Lang Q,et al.Composite anion exchange membrane made by layer-by-layer method for selective ion separation and water migration control[J].Sep Purif Technol,2018,192:278-286.
[13] Kim D H,Park J H,Seo S J,et al.Development of thin anion-exchange pore-filled membranes for high diffusion dialysis performance[J].J Membr Sci,2013,447:80-86.
[14] Wu D,Xu F,Sun B,et al.Design and preparation of porous polymers[J].Chem Rev,2012,112(7):3959-4015.
[15] Lin X,Shamsaei E,Kong B,et al.Asymmetrically porous anion exchange membranes with an ultrathin selective layer for rapid acid recovery[J].J Membr Sci,2016,510:437-446.
[16] Ran J,Wu L,Lin X,et al.Synthesis of soluble copolymers bearing ionic graft for alkaline anion exchange membrane[J].RSC Adv,2012,2(10):4250-4257.
[17] Wang J,Zhao Z,Gong F,et al.Synthesis of soluble poly(arylene ether sulfone) ionomers with pendant quaternary ammonium groups for anion exchange membranes[J].Macromolecules,2009,42(22):8711-8717.
[18] George S C,Thomas S.Transport phenomena through polymeric systems[J].Prog Polym Sci,2001,26(6):985-1017.
[19] Koros W,Fleming G,Jordan S,et al.Polymeric membrane materials for solution-diffusion based permeation separations[J].Prog Polym Sci,1988,13(4):339-401.