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Breakthrough indicator for aromatic VOCs using needle trap samplers for activated carbon adsorbent
Wen-Hsi Cheng1, Jia-Rong Jiang, Yi-Ning Huang
1Department of Occupational Safety and Hygiene, Fooyin University, Kaohsiung City, Taiwan. pl031@mail.fy.edu.tw
Journal of the Air & Waste Management Association (1995)
|August 25, 2012
Summary
Granular activated carbon (GAC) effectively adsorbs toluene and o-xylene in lab cabinets. Needle trap sampling (NTS) accurately predicts GAC replacement time, preventing volatile organic compound (VOC) breakthrough.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
Background:
- Internal circulation cabinets with granular activated carbon (GAC) are crucial for storing organic solvents in Taiwanese laboratories.
- Effective management of volatile organic compounds (VOCs) is essential to prevent adsorbent breakthrough and ensure laboratory safety.
Purpose of the Study:
- To evaluate the VOC adsorption capacities of GAC for toluene and o-xylene mixtures.
- To assess needle trap sampling (NTS) technology for indicating GAC replacement time.
- To develop models for simulating GAC adsorption equilibrium.
Main Methods:
- GAC adsorption experiments with gas stream mixtures of toluene and o-xylene at various adsorption times.
- Utilizing needle trap sampling (NTS) with divinylbenzene (DVB) particles for VOC monitoring.
- Comparing NTS extraction efficiency with Carboxen/polydimethylsiloxane-solid-phase microextraction (Carboxen/PDMS-SPME) for time-weighted average (TWA) sampling.
Main Results:
- Adsorption capacities of GAC for toluene and o-xylene were linearly correlated with the natural logarithm of adsorption time (ln(t)).
- Proposed models accurately simulated equilibrium adsorption capacities (Qe).
- Packed DVB-NTS demonstrated higher toluene extraction rates compared to Carboxen/PDMS-SPME.
- NTS accurately indicated GAC breakthrough times for toluene and o-xylene between 4700-5000 minutes.
Conclusions:
- GAC is effective for adsorbing toluene and o-xylene in laboratory settings.
- NTS is a reliable method for determining GAC replacement intervals, preventing VOC breakthrough.
- Operational instructions for GAC-NTS are provided for practical laboratory application.
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