Studies of membrane fouling mechanisms involved in the micellar-enhanced ultrafiltration using blocking models

Abstract

Micellar-enhanced ultrafiltration (MEUF) is a promising technology to remove organic contaminants from wastewater. A laboratory experiment was carried out to study the performance of four Gemini surfactant systems (CG₁₂, CG₁₆, CG₁₂ + Brij35, CG₁₆ + Brij35) for treating synthetic wastewater. The results show that CG₁₆–Brij35 possesses the lowest flux behavior and the best rejection efficiencies toward phenol and surfactants. Pore blocking models are utilized to estimate membrane fouling of surfactant systems. For CG₁₂ and CG₁₂ + Brij35 systems, internal pore blocking, intermediate pore blocking and cake formation models occur simultaneously. Internal pore blocking and cake formation are the main fouling mechanisms of CG₁₆ micelles. With respect to CG₁₆–Brij35, cake layer is the main type of fouling mechanism. The increased pore blocking degree follows the order of CG₁₂ < CG₁₆ < CG₁₂ + Brij35 < CG₁₆ + Brij35. Furthermore, SEM, ATR-FTIR and a mercury porosimeter are used to analyze membrane surface morphology, membrane material characteristics and membrane fouling layer, as well as examine and verify fouling mechanisms. Due to high flux behavior, excellent phenol rejection and low membrane fouling, CG₁₂ is a more desirable selection. Studies output helps to understand the fouling mechanism of MEUF in the presence of Gemini surfactants, and gave valuable evidence to optimize operation strategies.