Membrane Surface Modification by Electrospinning, Coating, and Plasma for Membrane Distillation Applications: A State‐of‐the‐Art Review

Abstract

Membrane distillation (MD) is a thermally driven separation process where a hydrophobic and microporous membrane separates nonvolatile compounds. Because of its advantages, this process appears as an efficient way to recover water from industrial effluents. However, the commercial membranes used in the MD process still have operational troubles with complex industrial wastewater and against harsh operational conditions. Fouling, wetting, and low time of operation compromise the membrane function and make the total consolidation of MD technology difficult beyond the traditional application (desalination). Membrane modification can be key to mitigating these operational problems, allowing MD's expansion to complex separations. In this context, herein the main technologies to modify the membranes for MD applications of the last five years are comprehensively summarized. Three kinds of postfabrication modifications are focused on: electrospinning, coating, and plasma, including polymeric and ceramic membranes. A critical analysis of each technique is developed, discussing their potentialities and the properties achieved through them. This review enables the understanding of the operational problems of MD technology and leads to finding feasible alternatives to their mitigation. It also clarifies the evolution in membrane modification, discusses the development directions, and points out the future challenges of modifications.