Superior efficacies adsorptions on hydrotalcite-like compound as dual-functional clay nanomaterial for heavy metals and anionic dyes

Abstract

Layered double hydroxide (LDH) calcined material, noted as flower-like Mg(Al)xOy clay nanostructures, with a Mg2+/Al3+ ratio of 2/1 has been involved as a potential low-cost adsorbent for the removal of cadmium ion and Congo red (CR) dye from wastewaters. The characterization was performed by FE-SEM, BET, TEM, XRD, FT-IR, and XPS analysis. A detailed study regarding the influence of pH, flower-like Mg(Al)xOy clay nanostructures dose, initial concentration, contact time, temperature, and desorption study was conducted for cadmium ion. Both Freundlich and Langmuir models fit the obtained data. Based on the thermodynamic results, the adsorption process for cadmium ion using the proposed adsorbent is spontaneous. The flower-like Mg(Al)xOy clay nanostructures material presents good recyclability after three cycles of adsorption/desorption. Also, this report includes a preliminary study (effect of initial concentration, temperature and contact time) regarding the capacity of flower-like Mg(Al)xOy clay nanostructures material to remove an anionic dye, i.e. CR. Kinetic data for the removal of both pollutants were best fitted by the pseudo second order kinetic model. Since the structure of the prepared material can allow cadmium ion and CR dye to be adsorbed in high amounts (up to 625 mg/g for cadmium ion and 1666.6 mg/g for CR dye), the water quality may considerably be improved.