†State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China.
‡Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal 4700, Kingdom of Saudi Arabia.
Environ Sci Technol. 2015 Apr 7;49(7):4235-44. doi: 10.1021/es505572y. Epub 2015 Mar 11.
Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater.
由表面活性剂稳定的油/水（O/W）乳液是最难处理的含油废水部分。陶瓷膜超滤目前是处理 O/W 乳液的理想工艺。然而，对于 O/W 乳液处理过程中陶瓷膜的污染机制知之甚少。本文研究了 O/W 乳液的稳定表面活性剂如何影响陶瓷膜在超滤过程中的不可逆污染。观察到一个意外的现象是，当 O/W 乳液的稳定表面活性剂的电荷与膜相反时，不可逆污染要少得多。在这种情况下，陶瓷膜污染较少的原因被认为是协同的空间位阻效应和破乳效应，防止了油滴渗透到膜孔中，并导致较少的孔堵塞。扫描电子显微镜拍摄的污染和原始陶瓷膜的横截面图像、经典污染模型的回归结果以及膜截留的有机成分分析支持了这一机制，此外，空间位阻效应和破乳效应的存在也验证了这一机制。我们的发现表明，在 O/W 乳液的超滤中，应使用与稳定表面活性剂带相反电荷的陶瓷膜来减轻不可逆的膜污染。这可能是含油废水陶瓷膜超滤的有用规则。
