ZnO改性凹凸棒石陶瓷膜的制备及其油水乳液分离性能

Fabrication of ZnO−modified Attapulgite Ceramic Membranes for Oil−in−Water Emulsion Separation

  • 摘要: 凹凸棒石(ATP)因其一维结构特征,可堆积形成具有连通孔道的陶瓷分离膜,实现含油废水的有效处理,但废水中油滴黏附导致严重的膜污染问题限制了其推广应用。以氧化锌改性凹凸棒石(ZnO@ATP)纳米复合材料为主要原料,制备具有超浸润和抗污染功能的凹凸棒石基陶瓷膜,考察了制膜液分散体系组成和成膜工艺参数对膜表面性质和分离性能的影响。当ZnO@ATP固含量为1%、甲基纤维素溶液浓度为5%、pH值为10.5、聚苯乙烯磺酸钠作为分散剂时,可获得粒径均匀分布在500 nm左右的制膜液。采用浸渍提拉法在陶瓷载体上均匀浸涂制备好的制膜液,浸涂时间为60 s,并经过650 ℃烧结后,可制备得到ZnO@ATP陶瓷膜,其表面展现出超亲水和水下超疏油的特点,可以抑制油滴对膜的黏附。在含油乳化液处理过程中,对乳化液中油滴的截留率为100%,展现出了良好的分离精度。此外,该陶瓷膜在使用过后易于清洁,通过简单的水力清洗即可恢复69.2%的通量,展现出了优良的再生性能与运行稳定性。该研究大幅提升了凹凸棒石陶瓷膜的水处理性能,为凹凸棒石基矿物材料在膜分离领域高效应用及新型抗污染膜的设计提供了依据。

     

    Abstract: Attapulgite (ATP) is a naturally abundant and low−cost clay mineral featuring a unique one−dimensional nanorod structure, which serves as an ideal foundational building block for fabricating ceramic membranes with mutually interconnected porous channels for wastewater separation. Nevertheless, the large−scale practical application of pure ATP ceramic membranes in oily wastewater treatment is greatly restricted by serious membrane fouling issues, mainly triggered by irreversible oil droplet adhesion on the membrane surface and internal pore blockage during filtration. To solve this bottleneck problem, a high−performance ZnO−modified attapulgite (ZnO@ATP) nanocomposite was successfully fabricated in this work to construct a distinctive micro/nanostructured membrane separation layer, aiming to tailor the membrane interfacial wettability and significantly strengthen its antifouling comprehensive performance. The ZnO@ATP nanocomposites were prepared through a facile and controllable chemical coprecipitation method. The casting suspension for membrane preparation was systematically optimized by adjusting pH value, dispersant type, solid content and additive dosage to acquire stable colloidal dispersion and precise particle assembly. The target composite membrane was fabricated on porous alumina substrates via dip−coating process and subsequent sintering treatment at 650 ℃. Multiple advanced characterization tests including TEM, XRD, FT−IR, XPS, particle size, zeta potential and contact angle measurements were conducted to analyze membrane structural and surface properties. The optimized suspension presented a narrow particle size distribution of approximately 500 nm and excellent colloidal stability, forming a uniform and defect−free membrane separation layer. The prepared membrane exhibited prominent superhydrophilicity and underwater superoleophobicity derived from the synergistic effect of material inherent hydrophilicity and hierarchical surface roughness. This special wettability constructs a stable interfacial hydration layer, effectively isolating oil from membrane surface and alleviating fouling. In cross−flow filtration of 500 ppm surfactant−stabilized oil−in−water emulsions, the membrane achieved 100% oil rejection rate, and its flux recovery ratio exceeded 69% after simple hydraulic cleaning with reversible weak fouling. This work reveals the antifouling mechanism of hydration layer engineering and provides a low−cost strategy for developing mineral−based antifouling membranes for practical oily wastewater treatment.

     

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