A review of membrane wettability for the treatment of saline water deploying membrane distillation

Membrane distillation (MD) is an alternative membrane technology that offers the capacity to treat highly saline water including industrial wastewater, seawater, brine water from other processes, and oil-gas field produced water. However, conventional hydrophobic membranes suffer fast wetting and severe fouling especially when low surface tension chemicals exist in saline water, which compromises the performance of MD. Recent advances in material science and nanomaterials research have led to the incorporation of special wetting properties on membrane surfaces. Membranes with special wettability can achieve high resistance against membrane fouling and wetting, as well as overcome the trade-off between membrane permeability and selectivity. This review summarizes the progress and recent development of studies on MD membranes with special wettability. Firstly, the fundamental concepts pertaining to membrane surface wettability including insights of their benefits and potential issues are highlighted in this review. Secondly, fabrication methods and applications of membranes utilizing various special wettability are discussed in detail, along with their challenges. Finally, this review concludes the advantages of membranes with special wettability and demonstrates potential solutions to the above-mentioned challenges for future research in high saline wastewater treatment.