Competitive adsorption mechanism of ball clay in water contaminated by multi-component heavy metal

This study investigated the competitive adsorption of key heavy metals (Cr⁶⁺, Zn²⁺, Cd²⁺, Cu²⁺) onto ball clay. Batch and fixed-bed column experiments demonstrated a clear affinity order: Cr⁶⁺ > Zn²⁺ > Cd²⁺ > Cu²⁺, with maximum static adsorption capacities of 271.0, 202.7, 134.2, and 123.9 mg/g, respectively. The equilibrium process followed the Langmuir model, indicating monolayer adsorption. Dynamic adsorption capacity was notably higher than static capacity, decreasing with higher flow rates but increasing with greater bed height. The Thomas model effectively described the dynamic adsorption behavior. Furthermore, thermal treatment at 950 °C successfully solidified the adsorbed heavy metals within the clay matrix, reducing their leachability to meet landfill standards. In summary, ball clay shows great promise for remediating multi-metal contaminated water, offering high adsorption capacity and a feasible stabilization method for safe disposal. • Ball clay shows highest Cr⁶+ adsorption (271.0 mg/g) in multi-metal systems. • Langmuir model validates monolayer adsorption mechanism for heavy metals. • Dynamic adsorption surpasses static (>30%) with lower flow rate and higher bed. • Thomas model effectively predicts fixed-bed breakthrough dynamics. • 950°C thermal treatment stabilizes metals for safe landfill disposal.