Improvement of activated carbon for air sampling

In order to improve the charcoal tube method, activated carbon was treated with benzyl chloride (5 and 20%) in methylene chloride and heated (300 degrees C). The carbons were evaluated with regards to water uptake, adsorption of toluene and carbon tetrachloride, desorption characteristics for polar compounds and storage stability of ketones. Carbons treated with benzyl chloride picked up less moisture, showed higher desorption efficiencies for polar compounds and lower catalytic activity compared with untreated carbons and those heat-treated with helium at 800 degrees C. The best results were obtained with 20% benzyl chloride.