Removal of Cu(II) ions using alginate-based composite wastes from dental impression materials

In this study, alginate-based composite materials commonly used in dental impression procedures were evaluated as low-cost and sustainable adsorbents for the removal of Cu(II) ions from aqueous solutions. The effects of pH, initial Cu(II) concentration, temperature, and contact time on adsorption performance were systematically examined. Comprehensive characterization of the composites revealed interactions between Cu(II) ions and surface functional groups, while imaging and elemental analyses confirmed the porous morphology of the materials and the accumulation of copper on their surfaces, suggesting that cation exchange also contributed to metal uptake. The surface charge and PZC were determined to elucidate the pH-dependent adsorption mechanism. The equilibrium data fitted best to the Langmuir isotherm model, indicating monolayer adsorption behavior, while the pseudo-second-order kinetic model accurately described the adsorption mechanism, suggesting chemisorption. Thermodynamic parameters confirmed that the process is spontaneous and endothermic. Among the tested materials, the maximum adsorption capacities were 25.38, 25.19, and 33.00 mg/g for Plastalgin, Cavex CA37, and Kromalgin, respectively. These findings highlight the novel potential of dental alginate composites as efficient, cost-effective, and environmentally sustainable adsorbents for heavy metal removal, supported by detailed chemical and morphological analyses. Moreover, the reuse of discarded dental impression materials provides an interesting strategy for waste valorization and circular sustainability.