Efficient Heterogeneous Fenton‐Like Decolorization of Cationic Dyes by a Magnetic Guar Gum/Kaolin/Fe ₃ O ₄ Composite

The aim of this study was to synthesize an environmentally friendly composite material based on guar gum (GG), kaolin (Kao), and Fe₃O₄, referred to as GG-mKao, and to evaluate its performance in a Fenton-like process. The composite was characterized using XRD, SEM-EDS, FTIR, BET, VSM, TGA, ICP-OES, and zeta potential analyses. The BET surface area of GG-mKao was 64.58 m²/g, and its saturation magnetization was 21.4 emu/g. GG-mKao was applied for the decolorization of methyl violet 2B (MV-2B), using hydrogen peroxide (H₂O₂) as the oxidant. Under optimal conditions (20-mg/L MV-2B, 20°C, pH 6, 0.196-M H₂O₂, 1.2-g/L GG-mKao, and 45 min), a maximum decolorization efficiency of 94% was achieved. GG-mKao exhibited good reusability and stability with minimal iron leaching. Scavenger tests indicated that hydroxyl radicals and singlet oxygen were the primary reactive oxygen species involved in the decolorization process. Kinetic analysis showed that the decolorization followed a first-order Langmuir-Hinshelwood model, confirming a heterogeneous catalytic mechanism.