Adsorption Capacity and Thermal Desorption Efficiency of Selected Adsorbents

Vahdat, Nader; Swearengen, P.M.; Johnson, James S.; Priante, Steve; Mathews, Keith; Neidhardt, Amalia

doi:10.1202/0002-8894(1995)056<0032:acatde>2.0.co;2

Cited by 8 publications

(16 citation statements)

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“…As expected, physico-chemical properties of the sorbent (Tenax) and sorbate determine the extracted amounts of the analytes, and adsorption of the analytes increases with the heavier molecular weights, higher boiling points, and more similar structures of adsorbent materials. 37,38 Thus, at the same flow rate (e.g. 3.5 ml min 21 ), a-pinene, the compound with lowest molecular weight and the lowest boiling point among the three analytes, had the shortest breakthrough time (36 min).…”

Section: Breakthrough Of the Analytesmentioning

confidence: 99%

On-site monitoring of biogenic emissions from Eucalyptus dunnii leaves using membrane extraction with sorbent interface combined with a portable gas chromatograph system

Liu

Pawliszyn

Wang

et al. 2004

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Membrane extraction with sorbent interface, combined with a portable gas chromatograph system (MESI-Portable GC) for continuous on-line monitoring of biogenic volatile organic compounds (BVOCs) emissions (from leaves of Eucalytus dunnii in a greenhouse), is presented herein. A sampling chamber was designed to facilitate the extraction and identification of the BVOCs emitted by the Eucalytus dunnii leaves. Preliminary experiments, including; enrichment times, microtrap temperatures, stripping gas flow rates, and desorption temperatures were investigated to optimize experimental parameters. The main components of BVOCs released by the Eucalytus dunnii leaves were identified by comparing the retention times of peaks with those of authentic standard solutions. They were then confirmed with solid phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC-MS). BVOC emission profiles of [small alpha]-pinene, eucalyptol, and [gamma]-terpinene emitted by intact and damaged Eucalytus dunnii leaves were obtained. The findings suggest that the MESI-Portable GC system is a simple and useful tool for field monitoring changes in plant emissions as a function of time.

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Section: Breakthrough Of the Analytesmentioning

confidence: 99%

On-site monitoring of biogenic emissions from Eucalyptus dunnii leaves using membrane extraction with sorbent interface combined with a portable gas chromatograph system

Liu

Pawliszyn

Wang

et al. 2004

Analyst

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“…DPPO). The W e data of Tenax TA and GR from this experiment are in agreement with the reported values in literatures[43]. Since Tenax TA has a relatively higher surface area compared with Tenax GR, the Tenax TA exhibits relatively larger adsorption capacities toward the tested vapors.…”

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confidence: 90%

“…The time-dependent concentration of the vapor at the outlet from the bed is shown in Figure 1 However, it has also been employed to characterize adsorbent samplers and preconcentrator systems similar to that described here [45]. The expression for modified Wheeler equation is expressed as follows [43].…”

Section: Mip Adsorption Capacity Testsmentioning

confidence: 99%

“…The breakthrough time can be associated with the adsorption capacity by the modified Wheeler model. The modified Wheeler model relates several important design and performance parameters to the vapor adsorption capacity of a granular adsorbent bed under a continuous vapor flow[43]. It is derived from a mass balance between vapor entering, retained within, and exiting the bed, the sum of the gas adsorbed by the bed and the gas passing through the bed.…”

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Synthesis and characterization of molecularly imprinted polymers and their application in preconcentrators for gas phase sensors

Fu¹

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“…Tenax GR has a bulk density = 0.55 g mL À1 and an adsorption capacity (W e ) = 0.3 mg g À1 . 35 Our tube configuration was 0.4 cm in diameter, with a 1.0 cm long open path and 0.6 cm section of glass wool, y 2 = 0.92, t 2 = 0.79; y 3 = 0.4, t 3 = 0.7 for saturated adsorbent, and a typical D T = 0.067 cm 2 s À1 . 36 The effective uptake rate was solved numerically.…”

Section: Underestimation Of Passive Measurementsmentioning

confidence: 99%

Continuous, intermittent and passive sampling of airborne VOCs

2007

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Long sampling periods are often advantageous or required for measuring air quality and characterizing exposures. However, sampling periods exceeding 8 to 24 h using thermally desorbable adsorbent tube (TDT) samplers for the measurement of airborne volatile organic compounds (VOCs) face several challenges, including maintaining stable and low flow rates, and avoiding breakthrough of the adsorbent. These problems may be avoided using intermittent sampling; however, the literature contains few if any reports that have evaluated this technique in environmental, occupational or other applications. The purpose of this study is to evaluate continuous, intermittent and passive sampling methods using both laboratory and real-world tests. Laboratory tests compared continuous and intermittent (active) samplers in a controlled dynamic test gas generation system. Field tests used side-by-side active and passive samplers in an office, home workshop and four smokers' homes. All samples were analyzed for a wide range of VOCs by GC-MS. In most instances, intermittent sampling yielded better reproducibility (duplicate precision of 10 +/- 6%) than continuous low-flow sampling (18 +/- 5%), in part due to difficulty maintaining low flows. Concentrations obtained using intermittent sampling agreed with those for continuous sampling, with downward biases resulting primarily from errors in flow rate measurements. In the field, more VOC species were detected using active rather than passive sampling. Passive measurements were 12% lower than continuous measurements, a difference attributed to declining uptake rates at higher concentrations over the 3 to 4 d sampling period. Overall, most measurements obtained using the three sampling methods agreed within 20% for a wide range of concentrations (0.1 to 230 microg m(-3)). Both passive and intermittent sampling approaches are suitable for long sampling periods, but intermittent sampling provides greater flexibility with respect to sampling period, and permits the use of multi-bed adsorbents that can capture a wider range of VOCs.

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Adsorption Capacity and Thermal Desorption Efficiency of Selected Adsorbents

Cited by 8 publications

References 0 publications

On-site monitoring of biogenic emissions from Eucalyptus dunnii leaves using membrane extraction with sorbent interface combined with a portable gas chromatograph system

On-site monitoring of biogenic emissions from Eucalyptus dunnii leaves using membrane extraction with sorbent interface combined with a portable gas chromatograph system

Synthesis and characterization of molecularly imprinted polymers and their application in preconcentrators for gas phase sensors

Continuous, intermittent and passive sampling of airborne VOCs

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