Impact of 2D lanthanum sheets and iron oxide dendrites composites on phosphate recovery from wastewater

Eutrophication and phosphorus depletion are the major concerns that have received increasing global attention. This study investigates the adsorption behaviour of phosphate onto α-Fe₂O₃ dendrites, composited with 2D lanthanum sheets adsorbents through comprehensive material characterization and kinetic experiments. The adsorbent was characterized using different analytical techniques to elucidate its structural, morphological, and surface properties. The impact of different lanthanum concentrations on phosphate sorption capacity was studied, and a sample with 0.6 g lanthanum nitrate (sample LF-6) showed exceptional phosphate adsorption performance and were utilized for additional evaluation. Kinetic and isotherm models were applied to describe the adsorption behaviour. The experimental data indicate Langmuir isotherm was most suitable for the adsorption process and the results indicated that pseudo-second-order model best described the adsorption process, suggesting chemisorption as a rate-limited step. The LF-6 demonstrated an outstanding phosphate sorption capacity of 229.66 mg P/g at pH 6.7 and 25 °C, which is roughly 4.1 times greater than that of the α-Fe₂O₃ dendrites (FO). Additionally, the LF-6 sorbent demonstrated exceptional adsorption when co-existing anions were present. After five consecutive cycles, the sorption capacity remained active, demonstrating the adsorbent's excellent regenerative performance. It is anticipated that these sorbents could be practically implicated in wastewater treatment.