Preparation of superabsorbent polymer with slow-release phosphate fertilizer

A superabsorbent polymer with slow-release phosphate fertilizer was prepared by esterification of polyvinyl alcohol (PVA) and phosphoric acid (H3PO4), which was a slow-release fertilizer at the same time. The product's water absorbency (WA) was about 480 times its own weight if it was allowed to swell in distilled water at room temperature for 24 h. WA under various conditions, such as varying the reaction time, the amount of sodium carbonate ((NaCO3)-C-2), the reaction temperature, and the concentration of phosphoric acid ([H3PO4]), were investigated and optimized. The optimal sample of the product was characterized by FTIR and elemental analysis. The results showed that phosphoric groups had grafted on PVA molecule chains, and the content of P2O1 in the product was 31.2%. The water retention property and phosphate slow-release mechanism of the product were studied as well. (C) 2004 Wiley Periodicals, Inc.