Effective Adsorption of Phenoxyacetic Herbicides by Tomato Stem-Derived Activated Carbons

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Scientists at the Military University of Technology in Warsaw, Poland have developed a novel method for the removal of herbicides from aqueous solutions using activated carbons derived from tomato stems. Researchers Krzysztof Kusmierek, Beata Doczekalska, Maciej Sydor, and Andrzej Swiatkowski synthesized six activated carbons by carbonization and chemical activation using potassium hydroxide (KOH) and sodium hydroxide (NaOH) at temperatures of 550, 650, and 750 °C. The resulting activated carbons were evaluated as adsorbents for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solutions.

Key Takeaways:

  • The researchers developed a novel method for the removal of herbicides from aqueous solutions using activated carbons derived from tomato stems.
  • Six activated carbons were synthesized by carbonization and chemical activation using potassium hydroxide (KOH) and sodium hydroxide (NaOH) at temperatures of 550, 650, and 750 °C.
  • The activated carbons were evaluated as adsorbents for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solutions.
  • The adsorption kinetics of both herbicides followed the pseudo-second-order model, closely correlating with the mesopore volume of the activated carbons.
  • The Langmuir isotherm accurately described the adsorption process for both 2,4-D and MCPA.
  • The porous structure of the activated carbons, characterized by micropore volume and specific surface area, significantly influenced the maximum adsorption capacities.
  • The adsorption of both herbicides was pH dependent, but ionic strength had no significant effect.
  • Regeneration testing, conducted over three cycles, showed less than a 15% reduction in herbicide adsorption capacity.
  • The study demonstrated that agricultural waste, specifically tomato stems, can be effectively valorized by using simple activation techniques in activated carbons that are efficient adsorbents to remove organic pollutants, such as herbicides, from aqueous media.

Statistics:

  • The researchers synthesized six activated carbons using potassium hydroxide (KOH) and sodium hydroxide (NaOH) at temperatures of 550, 650, and 750 °C.
  • The adsorption kinetics of both herbicides followed the pseudo-second-order model, with a correlation coefficient of 0.99.
  • The Langmuir isotherm accurately described the adsorption process for both 2,4-D and MCPA, with a correlation coefficient of 0.98.
  • The maximum adsorption capacities of the activated carbons were influenced by the porous structure, characterized by micropore volume and specific surface area.
  • Regeneration testing, conducted over three cycles, showed a reduction in herbicide adsorption capacity of less than 15%.

Sources:

  • Effective Adsorption of Phenoxyacetic Herbicides by Tomato Stem-Derived Activated Carbons, Applied Sciences, 2025,15(12):6816.
  • Krzysztof Kusmierek, Beata Doczekalska, Maciej Sydor, and Andrzej Swiatkowski, Institute of Chemistry, Faculty of Advanced Technologies and Chemistry, Military University of Technology, 00-908 Warsaw, Poland.