Self-Dewatering Polyacrylic Acid-Alginate-Graphene Oxide Hydrogel as an Osmotic Drawing Agent in Groundwater Fertigation

A PAG hydrogel was fabricated by crosslinking of polyacrylic acid (PAA), sodium alginate (SA), and graphene oxide (GO). The PAG hydrogel was used for the first time in the fertigation experiments, where the PAG hydrogel was infiltrated with potassium chloride (KCl) and then used to treat real groundwater and to prepare the diluted fertilizer solution, where 26.5 ± 3.5 mL of water was drawn and corresponding to 2.3 L/m² h, respectively, and the product water as diluted fertilizer solution achieved a concentration equivalent to 0.14-M KCl deemed suitable for irrigation application. The PAG hydrogel showed a high swelling ratio of 25.8. The PAG hydrogel incorporated with GO nanosheets increased the water drawn by 73% compared with the PA only hydrogel, which was attributed to the introduced slit-like channels by GO nanosheets within the polymeric matrix facilitating water passage. This work also reported using a self-dewatering hydrogel system where the combined weight of the feed solution and testing cell compressed out the absorbed water from the swelled hydrogel continuously. The work's results demonstrated that PAG enhanced by GO nanosheets could be a novel and sustainable draw agent material for fertigation applications, ensuring the treatment of groundwater without requiring additional energy. Summary: PAG hydrogel with GO was fabricated and showed a high swelling ratio KCl-infiltrated PAG hydrogel was used to treat real groundwater in FO fertigation The diluted fertilizer solution was obtained and was suitable for irrigation GO in the hydrogel helped the water passage and increased the water drawn by 73% Hydrogel achieved self-dewatering due to weights of feed solution and testing cell.