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Nano-sized ZnS functionalized with dioxa-dithio ligands for removal of Pb(II) from aqueous solution

Abstract In this paper, the adsorption of Pb(II) from aqueous solution was investigated on synthesized nano-sized ZnS functionalized with dioxa-dithio ligands (S2O2–ZnS). The thermal, structural and morphological properties of the S2O2–ZnS were determined by the SEM, TEM, XRD, FT-IR and DTA/TGA analyses. Furthermore, the efficiency of S2O2–ZnS to remove Pb(II) metal ions from aqueous solutions was surveyed. Metal ion adsorption was carried out in different initial concentration of Pb(II) (10–100 mgL−1) and various adsorbent dosage (1–10 mg), pH (2.5–11), and contact time (5–120 min). Results indicated that the removal efficiency was highly dependent on the pH, augmented by increasing the pH from 2.5 to 6. Moreover, the effect of the pH was significantly attributed to the interactions between the surface ligand of the S2O2–ZnS and Pb2+ ions, which presented in the water solution. It was also revealed that metal removal efficiency of the S2O2–ZnS was enhanced by 99.6% after 120 min agitation time. The maximum of Pb(II) ion removal was obtained while concentration of adsorbent and initial Pb(II) solution was 5.5 mg and 25 ppm, respectively. Regeneration studies also indicated that 97% recovery was achieved during the Pb(II) ion desorption using 0.1 M HCl. Therefore, S2O2–ZnS was proved as a good reusable adsorbent, being successfully used for elimination of Pb contamination in wastewater.