Non-fluoroalkyl functionalized hydrophobic surface modifications used in membrane distillation for cheaper and more environmentally friendly applications: A mini-review

Because of certain limitations in the use of conventional hydrophobic membranes in membrane distillation (MD), many studies have attempted to find alternatives to these membranes. There are many criteria for replacement membranes but the main criteria such as stability, cost, and environmental friendliness are the most important properties. When these criteria are met, one property that must be guaranteed in MD is the hydrophobicity of the membrane surface. Therefore, many studies have modified the surface of less hydrophobic or hydrophilic membranes into super-hydrophobic membranes. However, the use of agents derived from fluoroalkyl silane, although providing high performance, is expensive and not environmentally friendly. This study mainly reviews hydrophobic membrane surface modifications using non-fluoroalkyl agents applied in MD processes. In addition, other contents such as basic membrane requirements for use in MD, limitations of conventional hydrophobic membranes, some traditional fluoroalkyl functionalized hydrophobic surface modifications, and challenges and prospects were also discussed.