Fabrication of sodium alginate doped phosphoric acid composite hydrogel and its application of the adsorption of La (III) in wastewater.

Recycling rare earth ions from wastewater is an important task, as rare earth elements have a wide range of applications and can cause harm to the environment if discharged arbitrarily. In this work, a simple and inexpensive hydroxyethylidene diphosphate-based adsorbent (SA@HEDP) for adsorbing lanthanum was designed and fabricated. The adsorbent SA@HEDP with the surface rich in phosphate and hydroxyl functional groups provided active sites for adsorption of lanthanum. Research on adsorption performance was conducted by testing the amount of HEDP added, the amount of adsorbent used, the effect of initial pH of La (III), adsorption time, and temperature. The results showed that the adsorption capacity of the adsorbent was 158.0 mg/g. Adsorption of La (III) in real wastewater was tested, when the initial concentration of La (III) was 319.2 mg/L, it could be basically all recovered through three adsorption processes. SEM, EDS mapping, XPS, FTIR, and Zeta potential were used to characterize and analyze the mechanism, and mass transfer kinetics was used to analyze the adsorption process of the adsorbent for La (III).