Comparative Study of Poly Vinyl Alcohol/Alginate Hydrogel Beads Crosslinked with Metal Ions for Removal of Phosphorus in Wastewater

Polyvinyl alcohol (PVA) hydrogel beads crosslinked with metal ions (Ca, Fe, and Al) were prepared using a chemical cross-linking method. The morphological analysis was performed by FE-SEM. The hydrogel beads effectively adsorbed phosphorus onto the surface of beads. Interestingly, the hydrogel beads simultaneously adsorbed both phosphorus and nitrogen. The FTIR analysis was also conducted for measuring the adsorption effectiveness of the hydrogel beads before and after phosphorus adsorption. In order to evaluate the mechanisms of adsorption reaction, the kinetic models as pseudo-first-order and second-order were applied and found that the adsorption of hydrogel beads well fit with the pseudo-second-order kinetic model. Furthermore, the adsorption isotherm for PVA-SA-Al was better described with the Langmuir Isotherm. The maximum phosphorus adsorption capacity of the hydrogel reached 10.58 mg-P/L. Therefore, the crosslinked hydrogel beads show significant potential for phosphorus removal and recovery.