Heavy Metal Sorption by Natural Zeolite Modified with a Polysulfide Polymer

Contamination of aquatic environments with heavy metal ions represents an environmental problem and requires the development of effective sorbent materials based on available mineral resources. Therefore, this study aimed to obtain a sulfur-containing sorbent based on natural zeolite and evaluate its structural, morphological, and sorption properties. A sulfur-containing sorbent (PS–Z) was obtained by condensation of 1,2,3-trichloropropane with sulfur in a hydrazine hydrate–monoethanolamine system in the presence of natural zeolite with a particle size of 0.5–1.0 mm. The introduction of sulfur-containing groups was intended to provide additional interaction sites for heavy metal ions, potentially enhancing their sorption by the modified zeolite. The polysulfide-modified zeolite was characterized by FTIR spectroscopy and X-ray diffraction; surface morphology, elemental composition, and elemental distribution were investigated. BET analysis was used to determine the specific surface area, pore volume, and pore size distribution. The average sulfur content on the sorbent surface was 44.46 wt.%. Sorption studies demonstrated the ability of PS–Z to bind heavy metal ions at an initial concentration of 5000 mg/L: Pb2+ (377.2 ± 22.6 mg/g), Cd2+ (431.2 ± 5.0 mg/g), Hg2+ (427.0 ± 12.0 mg/g), Zn2+ (353.0 ± 26.5 mg/g), Cu2+ (179.4 ± 20.9 mg/g), and Co2+ (175.4 ± 13.4 mg/g). At 10 mg/L, the removal efficiency was 58.0–98.0%. These results indicate that PS–Z is a promising sorbent for the removal of heavy metals from aqueous solutions.