Measurement of Volatile Organic Compounds (Vocs) in Ambient Air & Fugitive Emissions using Sorption Tube Active Sampling Followe

Abstract:

The volatile organic compounds (VOCs) constitute a wide range of carbon molecules i.e., aliphatic & aromatic hydrocarbons, ketones, aldehydes, chlorinated hydrocarbons .The industries like refineries, petrochemicals, pharmaceuticals, pesticides, dye and paints & varnish are the major sources, which are emitted VOCs in the atmosphere. As the industries are using different solvents in their processes they emits huge amount of VOCs to the environment. Some of these VOCs like benzene are known carcinogen and may lead to disease like leukemia through prolonged exposure. VOCs are significant in creating ozone in the lower atmosphere Ozone is also formed by the reaction of some VOCs with nitrogen oxides in air in the presence of sunlight. Although ozone is beneficial in the upper atmosphere but high concentration in lower atmosphere may cause respiratory problems & damage to the vegetation. These may prolong the life of methane in the environment thus enhancing the green house effect. Keeping the importance of measurement as above in view and increasing trend of VOCs in the atmosphere, Central Pollution Control Board has standardized method and undertaken a study on volatile organic compounds (VOCs) to asses, identify & quantify these organic compounds at the Refinery, Petrochemicals, and Pesticides, Pharmaceuticals, Paints & varnish during September, 2007. The aliphatic, aromatic and chlorinated hydrocarbons were the target volatile organic compounds. The sampling for volatile organic compounds was divided into ambient air and fugitive emissions. The sampling was conducted using calibrated SKC low flow sampler at low flow rates ranging between 50 ml/litre and 200ml/min using activated charcoal tube (Anasorb CSC) manufactured by SKC.The VOC adsorbed samples in the adsorbent charcoal tubes were transferred to lab desorbed ultra sonically in carbon di sulphide (CS2) & then analysed using capillary GC-MS to find out the VOC content in the sample. A correct methodology is necessary for successful measurement procedures and subsequent recommendations for their standards, reduction & control strategies formulation and implementation.

Keywords: VOCs, chemical industries, ozone precursors, GC-MS