Novel Fe–Mg@Alginate–MXene composite beads for efficient phosphate removal and recovery: Mechanistic and performance insights

Novel FMAB-MX beads were developed for efficient phosphate removal and recovery. • The Langmuir maximum phosphate adsorption of 155 mg P g⁻¹ was achieved. • Pseudo-second-order kinetics confirmed a chemisorption process. • Phosphate binding via electrostatic attraction and Fe/Mg chemisorption. • FMAB-MX achieved ∼90% phosphate recovery with excellent reusability. The present study explores a novel Fe/Mg-functionalized alginate–MXene composite bead (FMAB-MX) as an efficient adsorbent for phosphate removal and recovery from water. The physicochemical properties and surface chemistry of FMAB-MX were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) to elucidate its structural characteristics and adsorption mechanisms. FMAB-MX achieved phosphate removal efficiency of up to 82% in batch tests, demonstrating approximately 64- and 20-fold higher removal efficiency than MXP and MXB, respectively. FMAB-MX exhibited a maximum adsorption capacity of 155.1 mg P g⁻¹ (475.3 mg PO₄ g⁻¹), whereas FMP-MX showed 64.2 mg P g⁻¹ (196.8 mg PO₄ g⁻¹). Isotherm and kinetic modeling showed that phosphate adsorption onto FMAB-MX was best described by the Langmuir isotherm and pseudo-second-order model, respectively, suggesting monolayer adsorption behavior. FMAB-MX also exhibited high resistance to interference from inorganic anions commonly found in natural water. Furthermore, approximately 89% of the adsorbed phosphate was recovered under mild alkaline conditions, demonstrating excellent reusability and stability over five successive cycles. These findings indicate that FMAB-MX beads represent a sustainable and efficient adsorbent for nutrient recovery and advanced water treatment applications while providing a novel contribution to the still-limited literature on alginate-crosslinked MXene composites for phosphate removal and recovery. Download: Download high-res image (256KB) Download: Download full-size image