废水处理膜蒸馏用氟烷基化多孔碳微球-PVDF混合基质膜构建与微结构调控机制

Membrane distillation (MD) could realize wastewater reuse, the treatment of water resource fouled by hazarduous materials. The most important barrier for MD development, is the low flux and leaking of membrane owing to the hydrophobicity deficiency of the membrane. The development of high hydrophobic membranes for MD process may improve the developing of water treatment and environmental protection..In this application, a mixed matrix membrane will be constructed by mixing high hydrophobic carbon particles with poly(vinylidene fluoride) (PVDF). There are micro-channels running-through the particle, which could act as the mass transfer road for MD process. To improve the consistence of the particle and PVDF, hydrophobic fluoride alkyl chains will be grafted on the particles by chemical method..The effect of grafting fluoride chain structure on the surface property of the particles, the consistence of the particles and PVDF will be studied. The reciprocity between the modified particles and PVDF chains during the formation process of the membranes will be detected. The formation mechanism of the membranes will be constructed. The effect of the microstructure of the membranes on the hydrophobicity and performance will be studied. The effect of wastewater composition on the MD performance will be also detected to establish the microstructure control mechanisms for typical wastewater. At last, the mass and heat transfer strengthening mechanisms of the modified particles will be studied to construct MD mass and heat transfer model.

膜蒸馏是实现废水资源化、高危害水体净化、节水减排的重要技术。针对膜蒸馏特性研制高性能疏水膜，解决当前膜蒸馏用膜疏水性不足、通量低和亲水化等问题，是环保、水处理和膜科学发展的迫切需求。.本申请构建疏水多孔碳微球-聚偏氟乙烯混合基质膜，微球的贯通孔可作为传质通道，促进膜蒸馏传质。通过分子结构设计与表面接枝化学，在多孔碳微球表面接枝氟烷基链段，在保证微球强疏水性的同时提升其与膜材料的相容性。.研究接枝链结构对微球表面特性及与膜材料相容性的影响，建立接枝链结构调控方法。研究相分离成膜过程中，多孔碳微球及接枝链与聚偏氟乙烯、溶剂等的协同作用规律，探明膜微结构形成机制。研究膜的微结构对其疏水性、膜蒸馏性能的影响，探明水质特性与膜蒸馏性能的关系，建立疏水膜微结构调控方法、原则，获得适于典型废水处理的疏水膜。研究氟烷基化多孔碳微球在膜蒸馏传质传热过程中的促进传质效应及作用机制,探讨膜蒸馏机理。

膜蒸馏过程以疏水性微孔膜为分离介质，利用膜两侧的蒸汽压差使热流体中易挥发组分的蒸汽透过膜孔，从而实现待处理液的分离、纯化或浓缩。由于膜蒸馏技术在废水中易挥发组分的回收、溶液高度浓缩、含砷等高危害水体治理、节水减排等方面的巨大潜力，而成为膜分离与水处理领域的研究热点，应用前景广阔。当前的膜蒸馏技术研究与应用探索中，仍面临着膜材料疏水性不足、通量不理想及运行中的亲水化渗漏问题。探索膜材料疏水性提升方法，研制高通量、抗亲水的膜蒸馏用膜材料，是当前膜蒸馏技术及膜科学发展的迫切需求，对实现含砷等各类高危害污水处理、节水减排等具有重要意义.本项目构建疏水多孔碳微球-聚偏氟乙烯混合基质膜，微球本体的贯通孔可作为传质通道，促进膜蒸馏传质。通过分子结构设计与表面接枝化学，在多孔碳微球表面接枝氟烷基链段，在提升膜整体疏水性的同时增进微球相与膜本体相的相容性。.按项目研究计划，探索了炭微球表面活化、氟烷基化反应调控机理，系统研究了氟烷基链构型对其烷基化反应活性、微球表面接枝率及其物化特性的影响规律；探究了氟烷基化微球在聚合物溶液中、膜本体中的分散状态及相容性，为混合基质膜研制提供支撑；在此基础上，系统研究了非溶剂致相分离成膜过程中无机粒子、溶剂/添加剂分子、聚偏氟乙烯链间的协同作用规律，初步探明了混合基质膜微结构形成机制，建立了氟烷基化微粒/聚偏氟乙烯混合基质膜的可控制备及微结构调控方法；探明了硅粒子表面亲水基诱导聚偏氟乙烯链结晶及晶型转变原理，构建了原位诱导混合基质膜超疏水表面制备及调控机制。进而，研究了膜的微结构对其疏水性、膜蒸馏性能的影响，探明水质特性与膜蒸馏性能的关系，建立了疏水膜微结构调控方法、原则，获得适于典型废水处理的疏水膜。膜表面纯水接触角超过150°，脱盐率超过99.9%，初步验证该系列膜具备良好的抗润湿能力。