Eco-friendly synthesis of zeotype from reused diatomaceous earth: characterization and adsorptive potential evaluation

Adsorption is a common method for effluent treatment and involves the use of porous solids. Conventional adsorbents are expensive compared to materials synthesized from agro-industrial waste, which may have similar chemical and physical properties. However, synthesizing adsorbents through an alternative route requires the development of strategies that add value to waste and produce micro and mesoporous materials with adsorptive characteristics. Here, sodium (NaZT) and acidic (HZT) forms were synthesized <i>via</i> a hydrothermal route using silica-rich Diatomaceous Earth (DE) waste from the brewing industry and applied for the removal of methylene blue (MB) dye. Characterization of the proposed zeotypes revealed high levels of muscovite (87.85% and 75.06%) and lower levels of cristobalite (12.15% and 24.04%) in NaZT and HZT, respectively. Textural analysis indicated an increase in specific surface area compared to DE. The adsorption kinetics reached equilibrium in 5 min, with removals of 85.46%, 60.92%, and 36.32% of MB at 110 mg.L⁻¹ using NaZT, HZT, and DE, respectively. The pseudo-first-order kinetic model provided the best fit to the experimental data. These results demonstrate that effluents contaminated with textile dyes can be efficiently treated using environmentally sustainable materials. Rapid synthesis of mesoporous zeotypes for adsorption of long-chain dyes.The zeotypes presented a larger surface area (44.9 and 53.5 m².g⁻¹ to NaZT-48h and HZT-48h, respectively) compared to the Diatomaceous Earth residue (3.1 m².g⁻¹).The adsorption of methylene blue reached equilibrium rapidly within 5 min.NaZT-48h obtained 85.46% removal, surpassing HZT-48h and the Diatomaceous Earth residue.The pseudo-first-order kinetic model described the experimental data well. Rapid synthesis of mesoporous zeotypes for adsorption of long-chain dyes. The zeotypes presented a larger surface area (44.9 and 53.5 m².g⁻¹ to NaZT-48h and HZT-48h, respectively) compared to the Diatomaceous Earth residue (3.1 m².g⁻¹). The adsorption of methylene blue reached equilibrium rapidly within 5 min. NaZT-48h obtained 85.46% removal, surpassing HZT-48h and the Diatomaceous Earth residue. The pseudo-first-order kinetic model described the experimental data well.