Recent advances in forward osmosis (FO) membrane: Chemical modifications on membranes for FO processes

Forward osmosis (FO) has been developing rapidly in recent years and demonstrated its advantages in various applications. However, challenges from reverse solute diffusion, concentration polarization and membrane fouling are still extensively present in FO processes. To alleviate these problems, considerable efforts have been made in exploring appropriate FO membranes. Chemical modification on ready-made membranes has become an important method in novel FO membrane exploration in recent years. This paper focuses on the progress of FO membranes obtained specially from chemical modifications. First of all, an overview of FO membrane related to membrane materials and chemical modification approaches is provided. The strengths and weaknesses of the chemical modification methods are assessed. Then, typical FO applications promoted by the chemically modified FO membranes are exemplified. Finally, challenges and future directions of chemical modification approaches in exploring novel FO membranes are highlighted. This review may provide new insights into the future advancement of both FO membrane and FO technology.