Simple and Scalable Approach for Fabrication of a Durable Conjugated Polymer-Decorated Multichannel Tubular Ceramic Membrane with Superoleophobic (Underwater) and Superhydrophilic Surface for Treatment of Oily Wastewater

Treating oily wastewater/sewage coming from industry and domestic supplies is an enormous challenge, as well as an opportunity in disguise. An efficient treatment technology can not only treat but also generate high-quality product water, which can be reused for several applications. Given the extremely complex nature of oily wastewater/sewage, we have designed and fabricated a highly durable and recyclable semipilot scale ceramic/polymeric membrane by using a simple and scalable approach. In contrast to various lab-scale studies using dead-end and gravity-driven treatment of oily wastewater, a semipilot scale cross-flow filtration system was used in the current study. A zirconia/alumina multichannel tubular ceramic membrane was used as a microfiltration membrane and a polypyrrole active layer was grown onto the multichannel tubular ceramic membrane by simple iron chloride-catalyzed oxidative polymerization of an aqueous solution of a pyrrole monomer. The resultant membrane showed highly desirable features required for treating emulsified oily wastewater streams which include surface super hydrophilicity and underwater superoleophobicity determined by the underwater-oil contact angle of θ_O,W = 161.5°. These features allow the development of a strong hydration layer on the membrane surface, preferably allowing water to permeate while impeding the passage of oil through the membrane. Hence, the fabricated membrane demonstrated high separation efficiency in treating emulsified oily wastewater where >99% of the oil was retained by the membrane with a pure water permeance of 66.7 L m^-2 h^-1 bar^-1. Moreover, the stability tests and cleaning cycles also highlighted the remarkable performance of the membranes under cross-flow filtration conditions.