Activated carbon is widely used for vapor-phase adsorption of volatile organic compounds (VOCs). To evaluate carbon performance, manufacturers and engineers rely on several standard test parameters—most notably carbon tetrachloride (CCl₄) adsorption, benzene adsorption, and butane working capacity (BWC). While these tests all assess VOC adsorption capacity, they differ in methodology, indicative value, and suitability for specific applications.
What Each Metric Measures
CCl₄ Adsorption (%)
Measured according to ASTM D3467 or GB/T 7702.11, this test evaluates the weight percent of carbon tetrachloride vapor adsorbed under equilibrium conditions. It is a traditional benchmark for micropore volume and general VOC adsorption potential. The test is performed in dry conditions at 25 °C, making it suitable for internal quality control or baseline comparison.
Benzene Adsorption (%)
Benzene adsorption capacity is tested under dynamic vapor-phase conditions, reflecting how well the carbon captures aromatic VOCs in realistic airflow systems. It correlates more specifically with removal efficiency for workplace air, solvent vapors, or process emissions containing benzene-like compounds.
Butane Working Capacity (g/100 mL)
This test, often used in automotive and air filtration industries, measures the weight of butane adsorbed and desorbed in a controlled flow-through cycle. Standards such as ASTM D5228 and SAE J2556 define the process. It better reflects the real-world adsorption–desorption dynamics for low-molecular VOCs and cyclic regeneration behavior.
Key Differences Between the Three
| Parameter | Test Type | VOC Target | Realism | Typical Use |
|---|---|---|---|---|
| CCl₄ Adsorption | Static (Equilibrium) | General organics | Low | Factory QC, baseline comparison |
| Benzene Adsorption | Dynamic (Vapor phase) | Aromatic VOCs | Medium | Industrial air filtration, PPE |
| Butane Working Capacity | Dynamic (Flow-through) | Light hydrocarbons | High | Automotive canisters, HVAC filters |
Are the Metrics Interchangeable?
While they are all related to VOC adsorption, these tests are not directly interchangeable because of differences in molecular size, polarity, test conditions, and operational relevance. However, empirical correlations exist, especially for non-impregnated carbon types. For example:
- Benzene (%) ≈ 0.4 × CCl₄ (%)
- BWC (g/100 mL) ≈ 0.18 × CCl₄ (%)
These relationships vary depending on the carbon’s pore structure. Coconut shell carbons, with their microporous dominance, typically show high CCl₄ and benzene but moderate butane capacity. In contrast, coal-based carbons with broader mesopores may favor BWC.
Which Metric Should You Use?
- Use CCl₄ when comparing raw material lots or performing factory QC
- Use Benzene for designing industrial emission control or chemical respirators
- Use Butane for automotive, HVAC, or regenerative adsorption systems
Conclusion
Each of the three metrics offers valuable insight into an activated carbon’s adsorption performance, but they serve different purposes. Understanding their differences—and how they relate—allows engineers to select or specify the most appropriate test based on the application context.
How HANYAN Can Help
At HANYAN, we provide detailed adsorption profiles, including CCl₄, benzene, and butane values across our product lines in our lab. We help clients interpret these metrics based on real-world VOC targets and system conditions.
Contact us to receive technical data sheets or request lab testing support.
Article Keywords: CCl4 adsorption, benzene adsorption, butane working capacity, VOC adsorption performance, activated carbon testing methods, adsorption comparison, HANYAN carbon, gas phase filtration, activated carbon metrics, activated carbon specifications
