Novel water purification technique using kaolinite clay: adsorption followed by thermolysis for complete degradation of methyl orange, reusability, and sustainability

This work introduces a novel water purification method that integrates adsorption with thermolysis for regeneration of the adsorbent. ZnCl₂-modified kaolinite was demonstrated to effectively adsorb methyl orange (MO) from contaminated water with maximum removal under acidic conditions (pH < pHpzc). Thermolysis at 600 °C led to total decomposition of MO, as supported by TGA and FT-IR, indicating the loss of MO-specific functional groups. Kaolinite was structurally stable, allowing reuse for five cycles with stable removal efficiencies (82–85%). Kinetic studies revealed fast adsorption, and thermolysis provided complete mineralization of MO. In contrast to traditional regeneration procedures, this method maintains the efficiency of the adsorbent, rendering it a viable, cost-effective, and environmentally friendly solution for water treatment at a large scale. The coupling of adsorption and thermolysis ensures the complete degradation of pollutants while maintaining the reusability of the adsorbent, offering a green and new technology for wastewater remediation and pollution elimination.