Synthesis of PZ-DTC and Its Application in the Removal of Mercury Ions from Wastewater

Yifan Hu; Bingru Zhang

doi:10.62051/

Authors

Yifan Hu
Bingru Zhang

DOI:

https://doi.org/10.62051/

Keywords:

Heavy Metal Chelating Agent; Mercury Ions; Dithiocarbamate.

Abstract

In this study, a heavy metal chelating agent, PZ-DTC, containing two dithiocarbamate (DTC) groups, was synthesized using piperazine and carbon disulfide as raw materials for the removal of mercury ions from wastewater. The performance of PZ-DTC in removing Hg²⁺ was systematically investigated under various conditions, including pH, dosage, addition of flocculants (ferric chloride and polyaluminum chloride), and different filtration methods. The mercury removal efficiency of PZ-DTC was compared with that of the conventional chelating agent sodium dimethyldithiocarbamate (SDDC). The results indicate that PZ-DTC exhibits excellent Hg²⁺ removal performance under alkaline conditions (pH ≥ 11). At pH = 13 and a PZ-DTC: Hg²⁺ molar ratio of 3:1, the residual mercury ion concentration after filtration through a 0.22 μm membrane was 0.007 mg·L⁻¹, corresponding to a removal efficiency of 99.86%, which meets the wastewater discharge standard established by the World Health Organization (0.01 mg·L⁻¹). Compared with SDDC, which contains a single DTC group, PZ-DTC demonstrated higher removal efficiency and lower residual mercury concentrations under identical conditions. Particle size distribution analysis of the chelates revealed that the precipitates formed between PZ-DTC and Hg²⁺ were mainly distributed in the size range of 0.22–0.45 μm, and particle size increased with increasing dosage, facilitating solid–liquid separation. Upon the addition of polyaluminum chloride (PAC), the chelate particles significantly increased in size (>0.8 μm), the precipitation rate accelerated, and the mercury concentration in the supernatant was reduced to nearly zero. In summary, PZ-DTC exhibits superior Hg²⁺ removal performance under alkaline conditions, forming stable chelates with good precipitation characteristics, indicating its strong potential for engineering applications in mercury-containing wastewater treatment.

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