Lanthanum-Doped Mesoporous Magnetic Carbon Microspheres Derived from Camellia Oleifera Shell Biomass for Phosphate Removal from Industrial Wastewater

Abstract

Abstract: Lanthanum-based adsorbents have garnered considerable attention due to their superior phosphate removal property and environmental harmlessness. This study introduces a facile hydrothermal technique for the fabrication of two lanthanum-doped mesoporous magnetic carbon microspheres variants, named MCMSs-LaEX and MCMSs-LaIN, derived from Camellia oleifera shells. These microspheres were synthesized by modifying carbon microspheres (CMSs) with La(OH)3 and Fe3O4 to enhance their phosphate adsorption efficiency in wastewater treatment. The adsorption kinetics and isotherms were fitted well to the pseudo-second-order model and Freundlich model, respectively, indicating a multilayer chemisorption mechanism. The materials exhibited excellent adsorption capacity across a wide pH range of 2-7 and notable selectivity for phosphate ions amidst the presence of high concentrations of common competitive anions in water. Moreover, the MCMSs-LaIN preserved an adsorption efficiency of 90% even after undergoing four cycles of adsorption and desorption with diluted NaOH solution, attesting to its durability and potential for reuse. In-depth XRD, FT-IR and XPS characterization results revealed that the adsorption process is primarily driven by ligand exchange between phosphates and La(OH)3. Importantly, both MCMSs-LaEX and MCMSs-LaIN displayed exceptional effectiveness in removing phosphate from complex industrial wastewaters, such as those generated in phosphating and electrophoresis operations, underscoring their practical applicability in environmental remediation.

Keywords: Keywords: Camellia oleifera shell, magnetic carbon microspheres (MCMSs), Lanthanum, phosphate adsorption, actual wastewater