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石油石化和餐厨等含油废水的无害化处理与资源化利用是水环境安全和行业可持续发展的重要保障[1-2]。膜分离具有操作简单、污染小、分离效率高等优点[3],是油水分离的重要技术手段。然而,现有膜材料如常用的聚偏氟乙烯(Polyvinylidene fluoride, PVDF)和聚醚砜(Polyether sulfone, PES)等疏水高分子膜材料,在油水分离过程中膜表面容易出现油污黏附和结垢,导致膜孔堵塞,分离效率降低、能耗增加[4]。亟需开发具有优异油水分离效率及抗污特性的新型膜材料,实现高效、稳定的油水分离。
将导电聚合物和电化学技术相结合,研究人员提出了新型导电膜分离技术[5],该技术可利用电致润湿[6]、静电排斥[7]和氧化还原[8]等作用,在高效除油的同时,实现一定的抗污染及自清洁功能,得到了学界的广泛关注。其中,聚吡咯(polypyrrole, PPy)是一种典型的导电聚合物,PPy膜不仅具有良好的导电性,还能实现孔径、润湿性等关键油水分离特性的电化学在线调控[9],在油水分离领域具有较好的应用前景。已报道的PPy导电膜制备方法通常包括基膜制备与PPy表面改性2个步骤[10-12],流程较长、稳定性差,不利于膜材料的规模化制备。开发操作简单、经济高效的PPy导电膜制备方法和油水分离工艺具有重要的研究意义和应用价值。
本研究采用共混改性-原位化学氧化法,将聚偏氟乙烯、聚乙烯吡咯烷酮和单体吡咯混合形成铸膜液,一步制备得到PPy导电膜,考察了该导电膜的表面结构与电响应特性,进一步分析了电辅助PPy导电膜的油水分离性能与抗污染效果,此外,通过施加-1 V偏压,可以有效提升PPy导电膜亲水性、减小膜孔径,在实现高效除油的同时,可很好地缓解膜污染。
聚吡咯电响应膜的油水分离及抗污染性能
PPy electro-responsive membrane for oil/water separation and its anti-fouling performance
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摘要: 膜分离是重要的油水分离技术,但由于高分子膜材料的疏水性,在油水分离过程中易发生膜的油污黏附和堵塞,导致膜分离效果下降和膜工作寿命缩短。该研究采用共混改性-原位化学氧化一步法制备了聚吡咯(PPy)导电膜,发现PPy掺杂后膜表面具有更多微纳凸起结构,粗糙度增加;施加还原电位可调节膜孔径收缩并增加亲水性,提高油水分离性能和抗污染能力。持续施加-1 V电压时,PPy导电膜孔径收缩10.59%,水接触角由96 °降低至45 °;此时油水分离效率高达99.38%。经过5次乳化液污染循环实验后,PPy导电膜仍可保留77.11%的通量,相较未改性时膜通量提升5倍。制备的PPy导电膜兼具良好的油水分离效果与抗油污性能,在含油废水处理领域具有较好的应用前景。Abstract: Membrane separation is an important technique for oil-water separation. However, due to the hydrophobic nature of polymeric membrane materials, membranes are prone to oil fouling and clogging during oil-water separation, resulting in reduced separation efficiency and a shortened lifetime. Herein, a novel polypyrrole (PPy) conductive membrane was prepared by a one-step method of blending modification and in situ chemical oxidation. The PPy-doped membrane surface exhibited more micro-nano bulged structure and higher roughness than unmodified one. The application of reduction potential was found to shrink the pore size and increase the hydrophilicity of the PPy conductive membrane, which can improve the oil-water separation and anti-fouling performance. When a constant voltage of -1 V was applied, the pore size of the PPy conductive membrane shrank by 10.59% and the water contact angle decreased from 96° to 45°. At the same time, the oil-water separation efficiency reached up to 99.38%. After 5 cycles of emulsified liquid fouling experiments, the PPy conductive membrane still retained 77.11% of its original flux, which is a fivefold increase compared with the flux of the unmodified membrane. The prepared PPy conductive membrane exhibits an excellent oil-water separation performance and resistance to oil fouling, showing great application prospects in oily wastewater treatment.
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Key words:
- polypyrrole /
- conductive membrane /
- oil-water separation /
- antifouling
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