Recent Advances, Applications, and Challenges in Superabsorbent Polymers to Support Water Sustainability

Superabsorbent polymers (SAPs) can absorb and retain water thousands fold their weight, so it is believed can overcome water depletion issues. However, the applications are dominantly found in daily consumer goods, while still limited especially in agricultural and environmental sectors. This review aims to provide insights into the preparation, synthesis, key properties, recent applications, and challenges of SAPs targeted to support water sustainability. The resources for SAPs synthesis are cellulose, chitin, chitosan (as natural-based), and polyacrylate (as synthetic-based). Likewise, semi-synthetic SAPs have also been explored by graft copolymerization and crosslinking between natural and synthetic resources. Several key properties in SAPs are absorption capacity, biodegradability, antibacterial capabilities, swelling properties, and grain size. It is found that cellulose-based SAPs have high water absorption capacity and biodegradability, chitosan-based SAPs are superior in biodegradability and antibacterial capabilities, and polyacrylate-based SAPs are eminent in water absorption capacity. As a further recommendation, cellulose-based SAPs from plants or seaweeds can be a solution to replace synthetic polymer materials that are not environmentally friendly while supporting sustainable agricultural needs. The properties of SAPs, including salt resistance, should also be rectified by physicochemical modifications to overcome dynamic agricultural conditions by means of soil moisture, soil salinity, and microclimate alterations.