Synthesis and Characterization of Hybrid Polymer Based on Functionalized Silica as Efficient Adsorbent for Heavy Metal Ions from Aqueous Solution

An organic-inorganic hybrid material based on a silica matrix and functionalized with imidazole group was successfully synthesized by the sol-gel process. The characterization techniques enabled the confirmation of the proposed structure as well as the effectiveness of the imidazole ring functionality in the structure of the material. It is insoluble in water and showed an anion exchange capacity of 2.944 mmol g-1, an excellent capacity for the adsorption of metal ions according to the literature. Thus, the metal halides CuCl2, CdCl2 and NiCl2 were adsorbed by the modified silsesquioxane from aqueous solutions. The adsorption isotherms results showed the availability of 3-n-propylimidazolium silsesquioxane chloride (SiImi+Cl-) as an efficient adsorbent material in the adsorption of metal ions, exhibiting a higher affinity for the Cu2+ ions at pH 4, with a maximum adsorption capacity of 2.80 mmol g-1. The Langmuir, Freundlich and Sips models were applied to the adsorption isotherms, both the pH and the nature of the ion were observed to be factors that influence the adjustment of the isotherms to the proposed models.