Green Synthesis of La(OH)3 @Fe3O4@PC Nanocomposite for Removal of Phosphate from Wastewater

Abstract

The removal of contaminants from wastewater is a major challenge in the area of water pollution. The removal of phosphorus (P) from wastewater is primarily to reduce the potential for eutrophication in receiving water, and common in many countries. Developing a highly efficient, environmentally friendly and selective adsorbent for phosphate removal is a major challenge these days. Lanthanum- based nanocomposites have attracted much attention for their efficiency and capacity in removing phosphate from water because La3+ ion has a strong affinity with oxygen-donor atoms from phosphate. In addition phosphate could easily desorb from Lanthanum- based nanocomposites due to the weak H-bonding interaction between phosphate and the H-bond acceptor groups on the surface of Lanthanum-based nanocomposites. This study developed La(OH)3@Fe3O4@PC nanocomposite by first preparing Fe3O4 NPs, La(OH)3 NPs and porous carbon separately by using algae extract as reducing agent, and then combining these nanoparticles in a fixed ratio to remove phosphate from wastewater. The synthesized nanomaterials were characterized by FTIR, XRD, BET, TGA, and SEM for surface, and physicochemical characteristics. Performance of the nanocomposite was evaluated in terms of adsorption kinetics, adsorption isotherms, different solution pH values, dose, contact hour and regenerative ability. Using the optimized parameters the result revealed that, the adsorption efficiency of the composite decreased by increasing the pH of the solution, increased by increasing the adsorbent dose and contact time, and reached maximum at pH 5, adsorbent dose of 0.2g, contact time of 30 min, initial phosphate concentration of 50 mg/L at room temperature. The La(OH)3@Fe3O4@PC nanocomposite showed a 98.42% phosphate removal efficiency, an excellent phosphate removal capacity of 40.16 mg/g, and excellent reusability for six cycles. It was found that, in 30 min, 0.2 g/L dosage of the nanocomposite was able to reduce the phosphate from Adama Science and Technology University Wastewater Treatment Plant effluent from 3.729 mg/L to 0.05877 mg/L.