Removal of highly volatile organic compounds from effluents

In the production of toluylene diisocyanates, acidic effluents having an average o- and p-dichlorobenzene content (in the ratio 49:1) of 20-30 mg/liter are formed, whereas the maximum permitted concentration is 0.002 mg/liter. The most effective method of purification for such relatively low concentrations of organic impurities is adsorption. In this investigation the effective and total dynamic capacity of a number of carbons for the removal of o- and p-dichlorobenzenes from a gas stream has been achieved, and the conditions studied for the adsorption of impurities on carbons (rate of filtration of gas stream, height of working layer) and the effect of certain factors on the activity of the carbons, viz., the pressure in the system and the preliminary activation conditions of the carbons.