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<p>Among the numerous treatment technologies for Hg(II)-contaminated water, the coagulation-flocculation method has attracted extensive attention due to its excellent mercury capture ability, simple operation, convenient maintenance, and wide applicability in heavy metal treatment. Dithiocarboxyl hydroxymethyl-polyacrylamide (DTMPAM) as a polymer flocculant was synthesized by introducing dithiocarboxyl groups into hydroxymethyl-polyacrylamide (MPAM). Through a jar test, the Hg(II) removal performance of DTMPAM was evaluated, and the impacts of various influencing factors on the Hg(II) removal capacity were investigated, including DTMPAM dosage, hydrodynamic conditions, pH, Hg(II) concentration, coexisting inorganic ions, organic substance, and turbidity on the removal process. The results indicate that ideal flocculation hydraulic conditions were achieved by mixing at 160 r/min for 2&#xa0;min, followed by slower stirring at 30 r/min for 15&#xa0;min. DTMPAM demonstrates effective Hg(II) removal performance across a wide pH range. Specifically, at a pH value of 7, the addition of 50&#xa0;mg/L DTMPAM achieved the optimal removal efficiency for Hg(II) with an initial concentration of 25&#xa0;mg/L, and the Hg(II) removal efficiency reached as high as 99.9%. At low dosages of DTMPAM, the presence of turbidity, inorganic ions, and organic substance would hinder the removal of Hg(II). However, as the DTMPAM dosage increased, this inhibitory effect was diminished or eliminated. Furthermore, the fractal dimension for the flocs was found to be positively correlated with the removal efficiency of Hg(II). Fouriertransform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses confirm that Hg(II) forms insoluble chelates with the dithiocarboxylic and amine groups within the DTMPAM molecular chain, which results in the formation of flocs. The flocculation process primarily takes place via adsorption-bridging and net-sweeping mechanisms.</p>

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An efficient Flocculant Dithiocarboxyl Hydroxymethyl-polyacrylamide for Removing Hg(II) in Aqueous Solution: Chelation, Flocculation, and Precipitation

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Meng Duan,
  • Gang Wang,
  • Xiuyun Liu,
  • Yaping Yan,
  • Jinling Ma,
  • Bigui Wei

摘要

Among the numerous treatment technologies for Hg(II)-contaminated water, the coagulation-flocculation method has attracted extensive attention due to its excellent mercury capture ability, simple operation, convenient maintenance, and wide applicability in heavy metal treatment. Dithiocarboxyl hydroxymethyl-polyacrylamide (DTMPAM) as a polymer flocculant was synthesized by introducing dithiocarboxyl groups into hydroxymethyl-polyacrylamide (MPAM). Through a jar test, the Hg(II) removal performance of DTMPAM was evaluated, and the impacts of various influencing factors on the Hg(II) removal capacity were investigated, including DTMPAM dosage, hydrodynamic conditions, pH, Hg(II) concentration, coexisting inorganic ions, organic substance, and turbidity on the removal process. The results indicate that ideal flocculation hydraulic conditions were achieved by mixing at 160 r/min for 2 min, followed by slower stirring at 30 r/min for 15 min. DTMPAM demonstrates effective Hg(II) removal performance across a wide pH range. Specifically, at a pH value of 7, the addition of 50 mg/L DTMPAM achieved the optimal removal efficiency for Hg(II) with an initial concentration of 25 mg/L, and the Hg(II) removal efficiency reached as high as 99.9%. At low dosages of DTMPAM, the presence of turbidity, inorganic ions, and organic substance would hinder the removal of Hg(II). However, as the DTMPAM dosage increased, this inhibitory effect was diminished or eliminated. Furthermore, the fractal dimension for the flocs was found to be positively correlated with the removal efficiency of Hg(II). Fouriertransform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses confirm that Hg(II) forms insoluble chelates with the dithiocarboxylic and amine groups within the DTMPAM molecular chain, which results in the formation of flocs. The flocculation process primarily takes place via adsorption-bridging and net-sweeping mechanisms.