Adsorption Processes for Phenolic Compound Removal

Phenolic compounds are priority pollutants in industrial and municipal effluents due to their toxicity, persistence and potential for bioaccumulation. Adsorption has emerged as a versatile and cost-effective treatment, capable of removing phenols at low concentrations with minimal secondary pollution. The principle relies on interactions—physical (van der Waals), chemical (π–π stacking, hydrogen bonding) and electrostatic forces—between phenolic molecules and a solid surface. Key process parameters include pH, which influences adsorbate speciation and surface charge; contact time, which determines approach to equilibrium; temperature, which affects sorption thermodynamics; and initial concentration, which governs driving force for mass transfer. Material selection is critical: carbonaceous adsorbents (activated carbons, biochars), clays, zeolites and emerging graphene-based composites each offer distinct pore structures and surface chemistries. Characterisation by specific surface area, pore size distribution and surface functional groups guides optimisation. Equilibrium data are commonly modelled via Langmuir and Freundlich isotherms, while kinetic profiles often follow pseudo-second-order models. Regeneration and reusability define real-world applicability, with chemical desorption, thermal treatment or solvent extraction used to restore capacity. Overall, adsorption processes contribute to sustainable water management by enabling modular designs, low energy footprints and integration with existing treatment schemes.

Research from Nature Portfolio

Recent studies have demonstrated the potential of waste-derived carbonaceous materials to achieve high phenol uptake. One investigation prepared activated carbons from oily sludge via KOH activation, yielding predominantly microporous structures with surface areas above 2 000 m² g−1 and maximum phenol capacities exceeding 400 mg g−1 under neutral conditions, with rapid equilibrium in 30 minutes and facile desorption across multiple cycles. Another work explored lignocellulosic agricultural residues activated by physical and chemical routes, reporting surface areas up to 2 490 m² g−1 and phenol uptake around 160 mg g−1, governed by pseudo-second-order kinetics and Langmuir adsorption. A third study developed ball-milled biochar from wood-apple shell waste, achieving phenol and chlorophenol removal capacities of over 100 mg g−1 and 200 mg g−1 respectively, with equilibrium reached within 45 minutes and consistent performance at pH 6.

Adsorption Processes for Phenolic Compound Removal publication trend

The graph below shows the total number of articles in adsorption processes for phenolic compound removal across all publications each year (not limited to Nature Index journals).

Technical terms

Adsorption: surface phenomenon whereby solute molecules accumulate on the external or internal surfaces of a solid phase.

Activated carbon: porous carbon material with high surface area, used for reversible adsorption of organic pollutants.

Biochar: carbon-rich solid produced by pyrolysis of biomass, serving as a low-cost adsorbent.

Adsorption isotherm: mathematical model describing equilibrium distribution of an adsorbate between liquid and solid phases (e.g. Langmuir, Freundlich).

Adsorption kinetics: rate models characterising the time-dependent uptake of solutes by adsorbents (e.g. pseudo-second-order).

Specific surface area: total surface area of a material per unit mass, typically measured by the Brunauer–Emmett–Teller (BET) method.

References

1. Towards sustainable physiochemical and biological techniques for the remediation of phenol from wastewater: A review on current applications and removal mechanisms. Journal of Cleaner Production (2023).
2. Investigating the potential of using solid waste generated from stone cutting factories for phenol removal from wastewater: A study of adsorption kinetics and isotherms. Results in Engineering (2023).
3. Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies. Scientific Reports (2019).
4. High adsorption capacity of phenol and methylene blue using activated carbon derived from lignocellulosic agriculture wastes. Scientific Reports (2022).
5. Removal of phenols and dyes from aqueous solutions using graphene and graphene composite adsorption: A review. Journal of Environmental Chemical Engineering (2021).
6. Engineered biochar from wood apple shell waste for high-efficient removal of toxic phenolic compounds in wastewater. Scientific Reports (2021).