Chemical Activation and Characterization of Activated Carbons

Chemical activation of carbonaceous precursors involves impregnating biomass or waste materials with activating agents such as phosphoric acid, zinc chloride or potassium hydroxide, followed by controlled thermal treatment. This process promotes dehydration, cross-linking and pore development, yielding highly porous structures with tailored surface chemistries. The choice of agent and impregnation ratio governs the balance between micropores and mesopores, which in turn determines adsorption capacity, kinetics and selectivity for target molecules. Characterization techniques—low-temperature nitrogen sorption, scanning electron microscopy, Fourier-transform infrared spectroscopy and X-ray diffraction—quantify surface area, pore size distribution and functional groups. Such analyses underpin applications in water treatment, gas separation, energy storage and catalysis. Recent advances emphasise sustainable precursors, greener activation protocols and multiscale modelling to predict performance, reinforcing the global significance of activated carbons in environmental remediation and resource recovery.

Research from Nature Portfolio

Recent studies have demonstrated composite chemical activation of woody twigs using phosphoric acid and zinc chloride in a single step at elevated temperature. The resulting carbons exhibited a Brunauer–Emmett–Teller surface area exceeding 1 400 m²/g, with a bimodal pore distribution optimised for both dye and organic pollutant uptake. Batch experiments on methylene blue and congo red revealed maximum adsorption capacities of 438 mg/g and 217 mg/g respectively, fitting Langmuir isotherms and pseudo-second-order kinetics. Thermodynamic analysis confirmed that adsorption is spontaneous and endothermic, while spectroscopy indicated the emergence of oxygen- and phosphorus-containing surface groups. This work highlights the tunability of pore architecture and surface chemistry via composite activation for effective wastewater treatment.

Chemical Activation and Characterization of Activated Carbons publication trend

The graph below shows the total number of articles in chemical activation and characterization of activated carbons across all publications each year (not limited to Nature Index journals).

Technical terms

Chemical activation: A process in which a carbon precursor is impregnated with a chemical agent and then heat-treated to develop porosity and functional surface groups.

Impregnation ratio: The mass ratio of activating agent to precursor material, influencing the extent of pore formation and surface chemistry.

Micropores: Pores with diameters below 2 nm that dominate adsorption capacity for small molecules.

Mesopores: Pores with diameters between 2 nm and 50 nm that facilitate rapid mass transfer and adsorption of larger species.

BET surface area: The specific surface area determined by nitrogen adsorption data using the Brunauer–Emmett–Teller theory, reflecting total available adsorption sites.

Adsorption isotherm: A mathematical model, such as Langmuir or Freundlich, describing the equilibrium relationship between solute concentration and adsorbed amount at constant temperature.

References

1. Evaluation of acetanilide and antipyrine adsorption on lignin-derived activated carbons. Environmental Research (2024).
2. Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal. Scientific Reports (2020).
3. Activated carbon from hydrolysis lignin: Effect of activation method on carbon properties. Biomass and Bioenergy (2022).