Аннотация
This study investigates the adsorption performance of bentonite from the Darbaza deposit (southern Kazakhstan) activated by three methods—acid, salt, and soda treatments—for the removal of heavy metals from real industrial wastewaters. Bentonite has been extensively studied worldwide, but no previous work has evaluated Darbaza bentonite using multiple activation approaches on real multi-metal effluents. Comprehensive characterization (SEM–EDS, FTIR, XRF, DTA, XRD) confirmed the preservation of the montmorillonitic structure after activation. Batch experiments were conducted using real wastewaters from Sozak, Kentau, and Kazphosphate facilities containing Zn²⁺, Pb²⁺, Cd²⁺, Cu²⁺, and Fe³⁺. NaCl- and Na₂CO₃-activated samples achieved Zn²⁺ removal up to 97.7% (q = 5.036 mg·g⁻¹), Pb²⁺ up to 65% (q = 0.074 mg·g⁻¹), and Cd²⁺ up to 81% (q = 0.182 mg·g⁻¹), compared to 30–40% for raw bentonite. Adsorption kinetics followed a pseudo-second-order model (R² > 0.99), indicating high sorption capacity and rapid adsorption kinetics driven by chemisorption. These results demonstrate that simple activation substantially enhances the performance of Darbaza bentonite, offering a cost-effective local material for industrial wastewater treatment in Central Asia. • Activated Darbaza bentonite was used for industrial wastewater treatment • Acid, soda, and salt activation improved bentonite sorption performance • Na₂CO₃ and NaCl activation achieved up to 98% Zn²⁺ removal efficiency • Kinetic studies revealed chemisorption as the dominant adsorption mechanism • First study on multi-activated Darbaza bentonite for real wastewater treatment