EFFECTIVE METHODS OF VERMICULITE MINERAL MODIFICATION: ACID, ALKALINE, AND THERMAL TREATMENTS
Keywords:
Vermiculite, acid activation, alkaline activationAbstract
Vermiculite is a layered magnesium aluminium silicate whose high cation exchange capacity, thermal expansibility and chemical inertness make it an attractive precursor for functional adsorbents, catalysts and thermal insulation fillers. The present study examines the physicochemical evolution of vermiculite subjected to three widely employed modification routes—acid leaching, alkaline activation and rapid thermal exfoliation—and compares their efficacy in generating surface area, porosity and functional surface groups. Samples of crude Tebinbuloq vermiculite were treated with 25 % H₂SO₄ at 95 °C for 6 h, with 1.5 M KOH at 60 °C for 24 h, and by flash heating to 850 °C for 5 min. X ray diffraction, FTIR spectroscopy, BET nitrogen adsorption and ICP OES were used to track structural and compositional changes, while Cu²⁺ uptake from aqueous solution provided an integral performance metric. Acid treatment produced a two fold rise in BET surface (61 → 128 m² g⁻¹) through dealumination and silica skeleton formation; alkaline attack enhanced microporosity and generated reactive –Si–O⁻ sites that boosted cation exchange capacity to 155 mmol kg⁻¹; thermal exfoliation yielded the largest pore volume (0.51 cm³ g⁻¹) and a six fold decrease in bulk density, facilitating rapid intraparticle diffusion.
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