Lanthanum-doped Zinc-iron Spinel/Ulva lactuca Linnaeus Biochar: Enhanced electron transfer for superior phosphorus-containing contaminants adsorption

Inefficient removal of phosphorus-containing contaminants can trigger water degradation and threaten human health. Herein, lanthanum (La) as efficient electron donors and adsorption sites were introduced in the Zinc-iron Spinel/ Ulva lactuca Linnaeus Biochar (La-Spinel/Biochar) to enhance the adsorption of phosphorus-containing contaminants. The La-Spinel/Biochar demonstrated remarkable adsorption capabilities, achieving adsorption capacities of 92.40 mg/g for phosphate, 134.90 mg/g for glyphosate (GLY), and 123.55 mg/g for tris (2-chloroethyl) phosphate (TCEP) at a dosage of 0.01 g/L. Meanwhile, the maximum removal efficiencies were achieved at 97.23 % for phosphate, 96.17 % for GLY, and 83.74 % for TCEP, respectively. The adsorption kinetics closely followed a pseudo-second-order model, while the adsorption of phosphate and TCEP was consistent with the Langmuir and Freundlich adsorption isotherm models, respectively. X-ray photoelectron spectroscopy (XPS) analysis, along with density functional theory (DFT), revealed that the introduction of La not only enhances the adsorption energy through the formation of bridging bonds (La-O-Fe) but also promotes the electron transfer of neighboring Fe sites, thereby increasing bonding strength. Additionally, La-Spinel/Biochar demonstrated positive selectivity in removing phosphorus-containing contaminants from real wastewater and perfect regenerative cycling ability, retaining over 82 % adsorption efficiency after five cycles. This study offers a novel perspective for designing biochar systems to adsorb contaminants containing specific elements, laying the groundwork for future targeted research and applications. • Phosphate and phosphorus-containing emerging contaminants were effectively adsorbed. • La-Spinel/Biochar has excellent practical application prospects and recyclability. • Adsorption kinetics revealed chemisorption with enhanced P-O bond strength. • La induces much electron transfer and facilitates the formation of bridging bonds. • This study offers a novel perspective for designing efficient adsorption systems.