Abstract
Internal circulation cabinets equipped with granular activated carbon (GAC) to adsorb volatile organic compounds (VOCs) are extensively utilized to store bottles containing organic solvents in Taiwanese university, college, and hospital laboratories. This work evaluates the VOC adsorption capacity of GAC with various adsorption periods for 102-2652 ppm average inlet toluene concentrations at 27℃ and relative humidity (RH) 72±3%. Additionally, solid-phase micro-extraction (SPME) technology was employed for indicating the renew moment of GAC, and avoiding a breakthrough of toluene from adsorbents. Experimental results demonstrate that toluene adsorption capacity is linearly expressed as the natural logarithm of adsorption time (ln(t)) at a constant temperature, and the equilibrium adsorption capacity (Q(subscript e), g toluene/g GAC) for average 102-2652 ppm gaseous toluene was accurately simulated using the proposed models. The SPME fiber installed in the outlet air stream for adsorbing toluene exhausted through GAC effectively indicated the breakthrough of VOCs. The GAC-SPME operational instructions to indicate the replace time of adsorbent in the internal circulation cabinets are concluded in this study.
Highlights
Many organic solvents are used in laboratories in Taiwanese universities colleges, and hospitals
According to findings obtained by Scahill et al, the volatile organic compounds (VOCs) adsorption capacity (Q) by an adsorbent is proportional to the natural logarithmic value of adsorption time (t)
A series of adsorption experiments were performed for granular activated carbon (GAC), which was used as the adsorbent in an internal circulation cabinet for storing organic solvents in the laboratories of universities, colleges and hospitals in Taiwan
Summary
Many organic solvents are used in laboratories in Taiwanese universities colleges, and hospitals. Replace time and indication of VOCs breakthroughs the adsorbents have not been exactly described by storage cabinet manufacturers. This work, based on a study by Cheng and Tsai (2007), evaluated VOC adsorption capacity (Q) of GAC for average toluene concentrations of 102–2652 ppm at 27°C. Of the University of Waterloo, Canada, developed SPME in 1990 for sampling VOCs at concentrations in air, liquid, or soil phase. (Pawliszyn, 1997) Organic compounds are directly adsorbed and concentrated on the SPME fiber, coated with silicone compounds. (Gorlo et al, 1999; Koziel and Pawliszyn, 2001; Waidyanatha et al, 2001) the operation procedures and parameters of GCFID-SPME (e.g., the sampling period for adsorbing VOCs, and desorption temperature and time for GC-FID) must be modified by users. The standardized procedures of diffusion adsorption sampling with SPME fiber were described
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