Degradation of Phenol Using Sea Urchin‐Like Nanostructured γ‐MnO 2 : Process Optimization by CCD‐RSM

ABSTRACT Sea urchin‐like γ‐MnO 2 nanostructures were synthesized via a simple hydrothermal route using MnSO 4 ·H 2 O and Na 2 S 2 O 8 without any template or surfactant. X‐ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analyses confirmed a highly crystalline γ‐MnO 2 phase with uniform urchin‐like morphology (2–3.4 µm in diameter, nanorod width 8–40 nm) and a specific surface area of 39.39 m 2 /g. Phenol degradation was investigated through the direct interaction of γ‐MnO 2 with phenol in aqueous suspension at room temperature. UV–vis analysis demonstrated significant catalytic activity, achieving 98.17% phenol degradation following pseudo‐first‐order kinetics. Using a central composite design (CCD) and response surface methodology (RSM), the optimal conditions were determined as 70 mg/L of MnO 2 , pH 2, and an initial phenol concentration of 20 mg/L, yielding a predicted efficiency of 93.42% ( R 2 = 0.990). The integration of intermediates identified by high‐performance liquid chromatography (HPLC), and chemical oxygen demand (COD) measurements allowed the development of a phenol degradation pathway, highlighting the effectiveness of urchin‐like γ‐MnO 2 under optimized conditions.