Activated Carbon from Tobacco Waste Shows Promise in Removing Heavy Metals from Water

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Researchers at Czestochowa University of Technology in Poland have developed a method to produce activated carbon from waste tobacco stems, which has shown great promise in removing heavy metals such as lead, zinc, and cadmium from water. The study, published in the journal Materials, used thermal conversion and chemical activation with potassium hydroxide (KOH) to create the activated carbon. The team's findings indicate that the activated carbon has a high specific surface area, pore volume, and negative surface charge, making it an efficient metal adsorbent.

Key Takeaways:

  • The researchers used waste tobacco stems from the tobacco industry to produce activated carbon through thermal conversion and chemical activation with KOH.
  • The study aimed to investigate the adsorption ability of the activated carbon towards Zn(II), Cd(II), and Pb(II) from aqueous solutions.
  • The obtained activated carbon was characterized by a high specific surface area, pore volume, and negative surface charge, which indicates its potential as an efficient metal adsorbent.
  • The team used Central Composite Design to determine the optimal adsorption conditions, and found that the adsorption rate is very high for Pb(II) and Cd(II), whereas it is noticeably lower for Zn(II).
  • The study concluded that the adsorption process of the tested metal ions is feasible and proceeds spontaneously, as indicated by the negative value of Gibbs free energy change (ΔG).
  • The thermodynamics of the adsorption process indicate that the adsorption of zinc and lead on the tested carbon is an exothermic process, and for cadmium, this process is endothermic.
  • The research was conducted by Pawel Jablonski, Beata Jablonska, and Jerzy Gega at Czestochowa University of Technology, and was supported by the university.

Statistics:

  • The central composite design used to determine the optimal adsorption conditions consisted of 35 experiments.
  • The adsorption rate was found to be very high for Pb(II) (97.5%) and Cd(II) (95.6%), whereas it was noticeably lower for Zn(II) (67.1%).
  • The negative value of Gibbs free energy change (ΔG) confirmed that the adsorption process of the tested metal ions is feasible and proceeds spontaneously.
  • The thermodynamics of the adsorption process show that the adsorption of zinc and lead on the tested carbon is an exothermic process, with a ΔH of -20.5 kJ/mol and a ΔS of -0.06 kJ/(mol*K) for zinc, and a ΔH of -24.1 kJ/mol and a ΔS of -0.08 kJ/(mol*K) for lead.
  • The adsorption of cadmium on the tested carbon is an endothermic process, with a ΔH of 13.5 kJ/mol and a ΔS of 0.03 kJ/(mol*K).

Sources:

  • Materials, 2025;18(10):2324
  • Mdpi, St Alban-Anlage 66, Ch-4052 Basel, Switzerland
  • Kinetics and Thermodynamics of Pb(II), Zn(II), and Cd(II) Adsorption from Aqueous Solutions onto Activated Biochar Obtained from Tobacco Waste (2025)