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Purpose <p>The study synthesized montmorillonite (Mont) -supported nano-zero valent iron (nZVI) composite materials using green tea (GT) GT-nZVI/Mont, and investigated its simultaneous removal efficiency to hexavalent chromium and dyes from simulated groundwater media during their cotransport. Thus, it provides a theoretical guide for achieving an effective nano-technique for the simultaneous removal of organic pollutants and metals.</p> Materials and methods <p>The GT-nZVI/Mont composite was successfully produced using tea polyphenols and montmorillonite support. The Cr(VI) and dye removal capability during cotransport with GT-nZVI/Mont in single and binary systems were tested in groundwater systems using batch and column experiments.</p> Results and discussion <p>This study demonstrated that the GT-nZVI/Mont composite exhibited superior simultaneous removal of Cr(VI) (94.39%) and dye (100%) in groundwater compared to GT-nZVI alone. This enhancement was primarily attributed to Fe⁰/Fe²⁺ driven reduction of Cr(VI) to Cr(III) and radical-based oxidation of dye (evidenced by S = O and N-oxide formation). Additionally, Mont facilitated adsorption via Si–O bonding and π–π interactions. These synergistic effects led to a significant increase in the pseudo-second-order rate constant, rising from 0.0107 to 0.0338&#xa0;g mg⁻¹ min⁻¹ and from 0.0058 to 0.0148&#xa0;g mg⁻¹ min⁻¹ for the simultaneous removal of Cr(VI) and dye, respectively. Low ion strength in water favored the sufficient transportability of GT-nZVI/Mont with an efficient reaction to Cr(VI) and dye during their cotransport. This was mainly because of the suppressed electrostatic repulsion of nanoparticles to avoid the aggregation of nanoparticles.</p> Conclusions <p>The study shows that the synthesis of nZVI supported by Mont via green tea ensured the effective simultaneous removal and cotransport of Cr(VI) and dye with GT-nZVI/Mont from groundwater. The results of this report provide a theoretical basis for the practical application of nZVI composites in the in-situ treatment of Cr(VI) and dye simultaneously contaminated groundwater via an environmentally benign technique.</p>

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Simultaneous removal of chromium and dye from groundwater using synthesized nano zero-valent iron supported by montmorillonite via tea polyphenols

  • 期刊论文

  • 发表日期：

    2025年10月23日

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  • Iradukunda Blaise,
  • Wenxin Jiang,
  • Tiwonge Chisi,
  • Xinyue Ma,
  • Nan Xu

摘要

Purpose

The study synthesized montmorillonite (Mont) -supported nano-zero valent iron (nZVI) composite materials using green tea (GT) GT-nZVI/Mont, and investigated its simultaneous removal efficiency to hexavalent chromium and dyes from simulated groundwater media during their cotransport. Thus, it provides a theoretical guide for achieving an effective nano-technique for the simultaneous removal of organic pollutants and metals.

Materials and methods

The GT-nZVI/Mont composite was successfully produced using tea polyphenols and montmorillonite support. The Cr(VI) and dye removal capability during cotransport with GT-nZVI/Mont in single and binary systems were tested in groundwater systems using batch and column experiments.

Results and discussion

This study demonstrated that the GT-nZVI/Mont composite exhibited superior simultaneous removal of Cr(VI) (94.39%) and dye (100%) in groundwater compared to GT-nZVI alone. This enhancement was primarily attributed to Fe⁰/Fe²⁺ driven reduction of Cr(VI) to Cr(III) and radical-based oxidation of dye (evidenced by S = O and N-oxide formation). Additionally, Mont facilitated adsorption via Si–O bonding and π–π interactions. These synergistic effects led to a significant increase in the pseudo-second-order rate constant, rising from 0.0107 to 0.0338 g mg⁻¹ min⁻¹ and from 0.0058 to 0.0148 g mg⁻¹ min⁻¹ for the simultaneous removal of Cr(VI) and dye, respectively. Low ion strength in water favored the sufficient transportability of GT-nZVI/Mont with an efficient reaction to Cr(VI) and dye during their cotransport. This was mainly because of the suppressed electrostatic repulsion of nanoparticles to avoid the aggregation of nanoparticles.

Conclusions

The study shows that the synthesis of nZVI supported by Mont via green tea ensured the effective simultaneous removal and cotransport of Cr(VI) and dye with GT-nZVI/Mont from groundwater. The results of this report provide a theoretical basis for the practical application of nZVI composites in the in-situ treatment of Cr(VI) and dye simultaneously contaminated groundwater via an environmentally benign technique.