Adsorption Characteristics of Carbon-Based Materials

Carbon-based adsorbents encompass a broad class of materials—from conventional activated carbons and biochars to emerging porous carbons derived from biomass and novel nanostructured forms such as Starbons®. Their performance hinges on a synergistic interplay between textural properties (specific surface area, pore size distribution) and surface chemistry (functional groups, dopants). Micropores (<2 nm) furnish high adsorption capacities by providing abundant binding sites, whereas mesopores (2–50 nm) accelerate mass transport, governing uptake kinetics. Surface oxygen or nitrogen functionalities modulate hydrophilicity, electrostatic interactions and π–π stacking, tailoring selectivity for dyes, organic vapours or gases such as CO₂. Equilibrium behaviour is commonly described by Langmuir and Freundlich models, while Redlich–Peterson or Temkin equations capture intermediate regimes. Kinetic profiles often follow pseudo-second-order rate laws, signalling chemisorption or strong physisorption mechanisms. Thermodynamic parameters (ΔG°, ΔH°, ΔS°) reveal spontaneity and the exothermic or endothermic nature of adsorption. This rich landscape of carbonaceous adsorbents has found global uptake in water treatment, gas separation, pollutant remediation and energy applications, driven by sustainability, low cost and tunable performance.

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Adsorption Characteristics of Carbon-Based Materials publication trend

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Technical terms

Specific surface area: Total accessible surface per unit mass of adsorbent, typically measured by the BET method.

Pore size distribution: The range and volume fraction of pore diameters within an adsorbent, classified as micropores, mesopores or macropores.

Langmuir isotherm: Model describing monolayer adsorption on a homogeneous surface with a finite number of identical sites.

Freundlich isotherm: Empirical model accounting for adsorption on heterogeneous surfaces with non-uniform site energies.

Pseudo-second-order kinetics: Rate expression assuming that the adsorption rate is proportional to the square of the number of unoccupied sites, often indicative of chemisorption.

ΔG°, ΔH°, ΔS°: Standard Gibbs free energy, enthalpy and entropy changes associated with adsorption, revealing spontaneity and heat effects.

References

1. Rapid and efficient adsorption of methylene blue dye from aqueous solution by hierarchically porous, activated starbons®: Mechanism and porosity dependence. Journal of Hazardous Materials (2022).
2. The Use of High Surface Area Mesoporous-Activated Carbon from Longan Seed Biomass for Increasing Capacity and Kinetics of Methylene Blue Adsorption from Aqueous Solution. Molecules (2021).