Hybrid macroporous materials for heavy metal ion adsorption

Hybrid macroporous materials with thiol functional groups attached to titania and zirconia frameworks have been prepared via colloidal crystal templating techniques for use as heavy metal ion adsorbents. Synthesis procedures are described for the preparation of thiol-metal oxide materials containing either siloxane or sulfonate linkages. The hybrid macroporous materials were characterized by SEM, FT-IR, ²⁹Si MAS NMR, elemental analysis, and nitrogen adsorption. The materials contained high levels of chemically anchored thiol groups and had uniform porous structures. The hybrid macroporous materials were effective adsorbents for the removal of heavy metal ions from solution, with adsorption capacities ranging from 0.33 to 1.41 mmol g^-1 for mercury(II) ions and 0.27 to 1.24 mmol g^-1 for lead(II) ions. The hybrid materials remained effective for metal ion adsorption after regeneration by an acid wash, with metal ion loading capacities of the recycled materials being on average two-thirds that of the original capacities. The metal ion adsorption capacity and reusability of hybrid macroporous materials makes them promising adsorbents for wastewater cleanup.