PTFE导电微孔膜EVMD过程研究及其电催化应用

发布时间：2018-02-27 19:41

本文关键词： PTFE 导电膜 MWCNTs 石墨烯 EVMD 电催化　出处：《天津工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：电化学膜分离耦合技术在水处理领域扮演着日益重要的角色,但传统导电膜柔性不足的缺点,使其发展受到制约。碳纳米管与石墨烯作为先进导电材料被广泛研究。本文以聚四氟乙烯(PTFE)双向拉伸膜为导电膜基膜,以多壁碳纳米管(MWCNTs)与石墨烯混合物为导电基质,抽滤使导电基质负载于PTFE膜表面并制得PTFE导电微孔膜。将其应用于电场辅助减压膜蒸馏(EVMD)实验以及电催化降解染料废水中。首先,以MWCNTs为导电基质,制备PTFE/MWCNTs导电微孔膜,研究导电基质单位面积负载量(PUALM)对膜性能的影响。结果表明,随着PUALM增加,膜导电性逐渐增加、N2通量逐渐下降。当PUALM为10g/m2时,其导电性为0.12±0.01(Ω/sq)-1、N2通量为59.24±5.0m3/m2h,兼具良好的导电性能与分离性能。将石墨烯掺杂入导电基质时,导电膜疏水性得到明显改善,当石墨烯与MWCNTs比例为2:1时,其水接触角可达134.3±0.76°。其次,将导电膜应用于EVMD过程以缓解膜污染,以腐植酸(HA)为有机污染物,并以导电膜为阴极、不锈钢网为阳极。结果表明,由于电场排斥力及电化学作用,EVMD能对膜污染进行有效抑制。当电场强度为1.0v/cm时能取得较好的抗污染效果,MD通量从4.97L/m2h提升为8.89L/m2h。当用电化学方法对膜进行清洗时,其MD通量能得到有效恢复,且通量恢复效果会随着电场强度、清洗时间的增加而增加,当电场强度为1.Ov/cm、清洗时间为8h时,其初始通量可由8.5L/m2h 恢复至 11.75 L/m2h。最后,当将导电膜用于电催化降解染料时,导电膜作阳极、不锈钢网作阴极。结果表明,染料降解效率会随着PUALM的增加、催化时间增加、电场强度增加以及电催化剂的添加而增加,而随染料浓度的增加而下降。当PUALM为20g/m2时,染料脱色率接近100%。此外,导电膜展现了良好的催化稳定性,循环使用6次后,染料脱色率仍达90.05%。
[Abstract]:Electrochemical membrane separation coupling technology plays an increasingly important role in the field of water treatment, but the traditional conductive membrane is not flexible enough. Carbon nanotubes (CNTs) and graphene are widely studied as advanced conductive materials. In this paper, the composite of MWCNTsand graphene is used as the conductive matrix, and the biaxial stretching film of PTFEs is used as the conductive film base film, and the composite of MWCNTsand graphene is used as the conductive matrix. The conductive PTFE microporous membrane was prepared by filtering the conductive matrix onto the surface of the PTFE membrane. It was applied to the electric field assisted vacuum distillation membrane (EVMD) experiment and electrocatalytic degradation of dye wastewater. Firstly, the PTFE/MWCNTs conductive microporous membrane was prepared by using MWCNTs as the conductive substrate. The effect of conductive substrate loading per unit area on membrane properties was studied. The results showed that with the increase of PUALM, the conductivity of the membrane gradually increased and the N _ 2 flux decreased. When PUALM was 10 g / m ~ 2, the flux of N _ 2 decreased gradually. The conductivity of the film is 0.12 卤0.01 (惟 / sq-1N _ 2 flux 59.24 卤5.0 m ~ 3 / m ~ 2 h). When graphene is doped into the conductive matrix, the hydrophobicity of the conductive membrane is obviously improved. When the ratio of graphene to MWCNTs is 2: 1, the water contact angle is 134.3 卤0.76 掳. The conductive film was applied to the EVMD process to mitigate the membrane fouling, with humic acid (HA) as the organic pollutant, the conductive film as the cathode, and the stainless steel mesh as the anode. The results showed that, Due to the repulsive force of electric field and electrochemical action, EVMD can effectively inhibit the membrane fouling. A better antifouling effect can be obtained when the electric field intensity is 1.0 v / cm. The MD flux is increased from 4.97 L / m ~ 2 h to 8.89 L / m ~ 2 h. When the membrane is cleaned by electrochemical method, The MD flux can be recovered effectively, and the flux recovery effect will increase with the increase of electric field intensity and cleaning time. When the electric field intensity is 1.Ov / cm and the cleaning time is 8h, the initial flux can be recovered from 8.5 L / m ~ 2 h to 11.75 L / m ~ 2 h. When the conductive film was used for electrocatalytic degradation of dyes, the conductive film was used as anode and stainless steel mesh as cathode. The results showed that the degradation efficiency of dyes increased with the increase of PUALM, catalytic time, electric field intensity and the addition of electrocatalyst. When PUALM is 20 g / m ~ 2, the decolorization rate of the dye is close to 100. In addition, the conductive film exhibits good catalytic stability. After six cycles, the decolorization rate of the dye is still 90.05%.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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