Activated Carbon: Production, Properties, and Multifunctional Applications

1. Introduction

Activated carbon (AC) is a highly porous carbonaceous material with exceptional adsorption capacity, derived from carbon-rich precursors such as coconut shells, wood, or coal through physical/chemical activation. Its unique pore structure (micro-, meso-, and macropores) and tunable surface chemistry make it indispensable in environmental remediation, energy storage, and medical applications. This paper reviews AC’s synthesis methods, characterization techniques, and modern applications.

2. Production Methods

2.1 Physical Activation

Involves carbonization (pyrolysis at 400–900°C under inert gas) followed by gasification (using steam/CO₂ at 800–1100°C) to create pores. Advantages include low chemical consumption but higher energy input.

2.2 Chemical Activation

Precursors are impregnated with agents (KOH, H₃PO₄, ZnCl₂) and heated (400–800°C). This method yields higher surface areas (up to 3,000 m²/g) but requires post-washing to remove residues.

3. Key Properties

Surface Area: 500–3,000 m²/g (BET analysis).

Pore Structure: Micropores (<2 nm) dominate adsorption; mesopores (2–50 nm) facilitate diffusion.

Surface Chemistry: Oxygen-containing groups (carboxyl, carbonyl) enhance polarity and metal adsorption.

4. Applications

4.1 Environmental Remediation

Water Treatment: Removes heavy metals (Pb²⁺, Hg²⁺), organic pollutants (dyes, pesticides), and pharmaceuticals via adsorption.

Air Purification: Captures volatile organic compounds (VOCs) and CO₂ in industrial emissions.

4.2 Energy Storage

Supercapacitors: AC’s high surface area enables electric double-layer capacitance (EDLC).

Battery Electrodes: Used in lithium-sulfur batteries to trap polysulfides.

4.3 Medical Uses

Drug Delivery: Porous AC carriers control drug release rates.

Toxin Removal: Oral AC tablets treat poisonings (e.g., acetaminophen overdose).

5. Challenges and Future Prospects

Cost-Effectiveness: Scalable production from waste biomass (e.g., agricultural residues) is being explored.

Functionalization: Grafting nanoparticles (e.g., TiO₂) can enhance photocatalytic activity.

6. Conclusion

Activated carbon’s versatility stems from its tunable porosity and surface chemistry. Future research should focus on sustainable production and hybrid materials for emerging applications like hydrogen storage and carbon capture.

References (Example)

Foo, K. Y., & Hameed, B. H. (2019). Advances in activated carbon modification for water treatment. Environmental Science and Technology.

Sevilla, M., & Mokaya, R. (2021). Energy storage applications of activated carbons. Chemical Reviews.