Highly efficient and selective Hg(II) adsorbent: ZnS grown on the surface of 4A zeolite and supported on starch aerogels.

ABSTRACT

In this study, ZnS nanoparticles were loaded on the surface of zeolite NaA and embedded in a carbon aerogel to prepare C@zeolite-ZnS, where zeolite NaA was used in order to adsorb Zn2+ ions released during ion exchange, and the carbon aerogel had good dispersion as a carrier for ZnS to solve the ZnS agglomeration problem. The morphology and structure of C@zeolite-ZnS were characterized by FT-IR, XRD, SEM, BET, and XPS. C@zeolite-ZnS showed excellent selectivity and high removal rate for Hg(II) ions with a maximum adsorption capacity of 795.83 mg/g. When the pH, adsorption time, and Hg(II) ion concentration were 6, 30 min, and 25 mg/L at 298 K, the corresponding adsorption and removal rates reached 99.90% and 124.88 mg/g, respectively. Thermodynamic studies have shown that the adsorption process is a spontaneous heat absorption process. Furthermore, after up to 10 cycles of adsorption, the adsorbent still exhibited outstanding stability and high adsorption capacity with removal rates exceeding 99%. In conclusion, C@zeolite-ZnS, which is stable and reusable and has the ability to meet industrial emission standards after adsorption of Hg(II) ions, is very promising for industrial applications.