Synergetic Oxidation and Adsorption of Arsenite by Core-Shell β-FeOOH@MnO₂ Nanocomposite for Enhanced Removal of...

Arsenic contamination in water, particularly from highly toxic arsenite (As(III)), continues to pose a significant global public health challenge due to its high mobility and resistance to conventional treatment methods. This study presents an innovative core-shell β-FeOOH@MnO₂ nanocomposite, which synergistically integrates MnO₂ nanosheets to oxidize As(III) into adsorptive arsenate (As(V)) and β-FeOOH to facilitate the efficient uptake of As(V). This approach addresses common limitations such as particle aggregation and suboptimal adsorption observed in pure MnO₂ systems. The nanocomposite, synthesized by hydrothermal methods, exhibits a doubled surface area of 172.95 m²/g, offering numerous active sites and mesopores conducive to rapid mass transfer. Under optimized conditions (pH 3.0, 0.4-g/L dosage), the nanocomposite achieved 98.39% removal of As(III) and a maximum adsorption capacity of 50.26 mg/g at 25°C, following pseudo-second-order kinetics and endothermic chemisorption. Characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), confirmed the synergistic mechanism, wherein MnO₂ oxidizes As(III) through the reduction of Mn⁴⁺ to Mn³⁺, and the resulting As(V) is adsorbed by β-FeOOH. This advancement offers a cost-effective and efficient solution for improved arsenic remediation in water treatment applications.