Document Type

Article

Publication Date

Summer 5-6-2025

Abstract

This study explores the synthesis and characterization of a quaternary composite based on meta-kaolinite and metal oxides (MgO, Al2O3, and Fe2O3) for the formation of layered double hydroxides (LDHs), aimed to the efficient removal of synthetic dyes from wastewater. The composite was synthesized using a co-precipitation method (Mg:Al:Fe molar ratio = 3:1:1) and thermally activated at 400 ◦C to enhance porosity and active site availability. Instrumental characterization through XRD, FTIR, SEM-EDX, and BET analyses confirmed the effective combination of metal oxides into the meta-kaolinite matrix, with BET results revealing a surface area of 540 m2/g (vs. 190 m2/g for raw meta-kaolinite) and a pore volume increase from 0.12 cm3/g to 0.31 cm3/g. Batch adsorption experiments demonstrated remarkable adsorption capacities of 320 mg/g for methylene blue (MB), 280 mg/g for Congo red (CR), and 300 mg/g for malachite green (MG) at an optimal pH of 6–7 and equilibrium time of 90 min. Kinetic studies indicated pseudo-second-order adsorption (R2 > 0.98, rate constants: 0.002, 0.0018, and 0.0019 g/mg⋅min for MB, CR, and MG, respectively), while isotherm analysis aligned with the Langmuir model (R2 > 0.98, maximum capacities matching experimental values). The composite retained >85 % adsorption efficiency after five regeneration cycles, underscoring its reusability. Comparative analysis showed superior performance to activated carbon (320 mg/g MB) and magnetic Fe3O4 composites (34 mg/g MB). These results highlight the composite’s potential as a high-capacity, sustainable adsorbent for industrial wastewater treatment.

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