Phosphorus recovery from water by lanthanum hydroxide embedded interpenetrating network poly (vinyl alcohol)/sodium alginate hydrogel beads

Sorption is recognized as an effective method for phosphorus removal or recovery in the aqueous environment. In this study, novel poly(vinyl alcohol)/sodium alginate/lanthanum hydroxide (PVA-SA-LH) hydrogel beads with an interpenetrating network (IPN) structure were synthesized, characterized and tested for phosphorus removal/recovery in wastewater. The hydrogel beads were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive spectrometry (SEM & EDS) and X-ray photoelectron spectroscopy (XPS) before and after sorption. Results indicated the hydrogel beads had an increased phosphorus removal efficiency with an increased hydrogel beads' dosage, reached their maximum sorption capacity for phosphorus at pH = 4, and exhibited favorable selective sorption towards phosphorus in the present of other anions. The pseudo-second-order kinetic model and Freundlich model fit the sorption process well. After five sorption-desorption runs, the sorbents' sorption capacity for phosphorus remained above 75% of the first run. The column test indicated a possibility for practical application. Hence, the developed PVA-SA-LH hydrogel beads may be a new kind of sorbent for phosphorus removal and recovery in the future.