Application of New Carbon Molecular Sieve in Determination of Volatile Organic Compounds from Industrial Sources

A new carbon molecular sieve Scalpha 1500 was prepared, and Scalpha 1500 was applied to replace the imported molecular sieve Carboxen 1000 to form a new adsorption tube (CB1500). The apparent morphology, elemental composition, pore structure and crystal phase composition of two carbon molecular sieves were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy(EDS), N₂ adsorption-desorption isotherms and X-ray diffraction (XRD). The testing performance of CB1500 adsorption tube and HJ 734—2014 recommended combination triple adsorption tube (Carbon 300 adsorption tube) in volatile organic compounds (VOCs) determination was compared by thermal desorption-gas chromatography-mass spectrometry(TD-GC-MS). The optimal desorption parameters for the adsorption tubes were desorption temperature of 300 ^oC, desorption time of 6 min, and desorption flow rate of 50 mL·min⁻¹. Under these conditions, the two types of adsorption tubes had similar background values, desorption performance, and penetration performance. As shown by the results, linear relationships between values of the corresponding peak area and mass of 24 VOCs in CB1500 and Carbon 300 adsorption tubes were found in the range of 5-100 ng, with detection limits（3S/N）in the range of 0.4-4.8 μg·m⁻³ and 0.4-4.6 μg·m⁻³, respectively. Test for recovery was made by the standard addition method, giving results in the range of 93.0%-107% for CB1500 adsorption tube and 92.0%-113% for Carbon 300 adsorption tube, with RSDs of the determined values (n=7) of 23 VOCs except for ethyl lactate less than 5.0%. Two types of adsorption tubes were used to sample and analyze the exhaust gas from stationary pollution source of an industrial park in Guangzhou. 24 VOCs were detected in CB1500 and Carbon 300 adsorption tubes, with detection amounts of 2.3-21.1 μg·m⁻³ and 2.4-21.3 μg·m⁻³, respectively. It was shown by the above results that the new carbon molecular sieve Scalpha 1500 could replace the imported carbon molecular sieve Carbon 1 000 to form a new adsorption tube for the collection of VOCs, which could greatly reduce the sampling cost.