The Performance and Mechanism of Solvothermal Synthesis of a Ca-Fe-La Composite for Enhanced Removal of Phosphate from Aqueous Solutions

• Published in: Water (Basel) 2024-10, Vol.16 (20), p.2932
• Main Authors: Xu, Xiaojun, Hu, Qili, Qu, Weiyi, Liu, Hengyuan, He, Zhihao
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Equilibrium; Experiments; Fertilizers; Fourier transforms; Fractals; Phosphates; Phosphorus; Spectrum analysis; Waste management; Water quality
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w16202932

Since it is a limiting nutrient element in rivers and lakes, the effective removal of phosphorus is key to alleviating eutrophication. In this study, the one-pot solvothermal method was adopted to prepare an environmentally friendly Ca-Fe-La composite. This is an amorphous material with a large specific surface area of 278.41 m2 g−1. The effects of coexisting anions and pH on the phosphate removal performance were explored. Phosphate adsorption mechanisms were revealed by various characterization techniques. The phosphate adsorption obeyed the fractal-like pseudo-second-order (PSO) kinetic model, implying that the overall adsorption system was highly heterogeneous. In this work, the maximum adsorption capacity predicted by the Langmuir model was 93.0 mg g−1 (as PO43−-P). The phosphate-loaded Ca-Fe-La composite could be used as a slow-release fertilizer, achieving waste management and resource utilization. The presence of SO42−, CO32− and HCO3− anions inhibited the phosphate adsorption significantly. It was unfavorable for phosphate removal at a high pH value. Inner-sphere complexation and electrostatic attraction were mainly responsible for phosphate adsorption onto the Ca-Fe-La composite.