Lanthanum-doped chitosan-based polyacrylamide double network hydrogels for adsorption of phosphorus from wastewater

Excessive phosphorus in aqueous solutions can cause eutrophication, which can harm aquatic organisms and pose a risk to the safety of drinking water for humans. The Chitosan/Polyacrylamide/Lanthanum (CS/PAM/La) hydrogel was designed to get rid of phosphate from aqueous solutions. La (III) was used to enhance the capacity of adsorption of CS. Polyacrylamide was used to enhance the mechanical properties of CS. The results showed that the adsorption capacity of CS/PAM/La hydrogel for phosphate was increased compared with that of CS. When pH of 5.0, the adsorption capacity was 80.07 mg-P/g. In addition, after five adsorption and desorption cycles, the adsorption efficiency remained above 90%. The mechanism of phosphate adsorption on CS/PAM/La material was analyzed using a mass transfer factor model (MTF) and the possible structure of CS/PAM/La hydrogel was calculated by density functional theory calculation (DFT). The application of CS/PAM/La composite hydrogel for removal of phosphate from actual wastewater was investigated, and the results met the requirement of national standard.