Investigating VOCs Speciation Characteristics at the Fenceline of Synthetic Rubber Manufacturing Industries via Active and Passive Monitoring Techniques

Abstract

Volatile Organic Compounds (VOCs) are prevalent emissions from a plethora of industries, known for their role in the formation of atmospheric ozone, thus contributing to secondary pollution. Both the United States and the European Union have presented various regulatory measures to mitigate VOC emissions. Nevertheless, the diversity of VOCs, some exhibiting carcinogenic properties, pose substantial challenges in devising comprehensive mitigation strategies. In light of this, the current study focuses on the synthetic rubber manufacturing industry, specifically analyzing VOCs with high emission volumes and elevated Photochemical Ozone Creation Potentials (POCPs). A total of 88 compounds, including PM-57 and TO-14A, were examined in this study. The Active and Passive monitoring methods, two out of the six recommended by the Environmental Protection Agency (EPA) for Fenceline monitoring, were employed. For business entity ‘A’, the Active method revealed the highest emission rates of n-butane (13.5%) and n-Pentane (12.8%). In contrast, the Passive method indicated styrene (9.4%) and toluene (8.1%) as the most prominently emitted compounds. Benzene, though detected at all points ranging from 1~3 µg/m³, is not manipulated in this industry, suggesting potential influence from neighboring enterprises. Compounds such as benzene, toluene, ethylbenzene, xylene, and styrene demonstrated convertible concentrations using both Active and Passive methods, detected within the range of 0~3 µg/m³. Notably, the average concentrations determined by both methods exhibited remarkable similarity. For business entity ‘B’, the Active method detected significant levels of n-hexane (45.0%) and methylcyclopentane (14.4%), whereas the Passive method identified high concentrations of n-hexane (37.7%) and isopentane (8.8%). A general pattern emerged where high concentrations were exhibited at points 9, 10, and 11, located within the production area, while points 1, 2, and 3 displayed lower concentrations, likely due to the influence of eastward wind patterns. In terms of compounds with high POCPs, business entity ‘A’ demonstrated substantial emission of n-butane (38.80%) and n-hexane (27.15%) using the Active method, and toluene (28.62%) and n-hexane (25.23%) via the Passive method. For business entity ‘B’, n-hexane emerged dominantly, detected at 84.57% using the Active method and 68.85% via the Passive method. This suggests that in the synthetic rubber manufacturing industry, n-hexane should be prioritized in formulating effective emission reduction strategies.