One-pot synthesis of novel flower-like LaCO3OH adsorbents for efficient scavenging of phosphate from wastewater

Phosphorus removal from wastewater has been considered as an effective method to control eutrophication and mitigate phosphorus deficiency. Phosphate adsorption using lanthanum-based materials has awakened much attention and triggered extensive research. In this study, novel flower-like LaCO3OH materials were synthesized via a one-step hydrothermal method and evaluated for phosphate removal from wastewater. The adsorbent with flower-like structures prepared at the hydrothermal reaction time of 4.5 h (BLC-4.5) exhibited the optimum adsorption performance. BLC-4.5 had a rapid removal rate with more than 80% of the saturated adsorbed phosphate removed within 20 min. Furthermore, the maximum phosphate adsorption capacity of BLC-4.5 was as high as 228.5 mg/g. Notably, the La leaching amount of BLC-4.5 was negligible in the pH range of 3.0-11.0. BLC-4.5 outperformed most of the reported La-based adsorbents in terms of removal rate, adsorption capacity, and La leaching amount. Moreover, BLC-4.5 had broad pH adaptability (3.0-11.0) and high selectivity for phosphate. BLC-4.5 also displayed excellent phosphate removal efficiency in actual wastewater and great recyclability. The potential adsorption mechanisms of phosphate on BLC-4.5 were precipitation, electrostatic attraction, and inner-sphere complexation via ligand exchange. This study demonstrates that the newly developed flower-like BLC-4.5 reported here is a promising adsorbent for the effective treatment of phosphate in wastewater.