Steam-assisted-crystallization synthesis of mesoporous hectorite: A universal adsorbent for rapid capture of methylene blue and copper ions

Eliminating organic dyes and heavy metal ions remains challenging in environmental remediation. Hectorite shows promise for this application due to its layered structure and negative surface charge, but conventional energy-intensive hydrothermal synthesis hinders scalable production. Herein, we develop a novel steam-assisted crystallization (SAC) strategy to synthesize mesoporous hectorite from leached natural clay. This one-step approach significantly reduces solvent use and energy requirements. According to the Langmuir model, the material exhibits exceptional adsorption capacities for methylene blue (MB, 603.3 mg·g ⁻¹) and copper ions (Cu ²⁺, 68.72 mg·g ⁻¹), surpassing conventional adsorbents. Rapid equilibrium is achieved within 10 min (MB) and 5 min (Cu ²⁺), facilitated by the abundance of active sites and mesoporous structure. MB adsorption involves electrostatic interactions, hydrogen bonding, and ion exchange, while Cu ²⁺ uptake occurs primarily via complexation with secondary electrostatic contributions. This work enables the sustainable utilization of natural clay resources and the green, scalable production of high-performance mesoporous hectorite adsorbents.