Adsorption of low-concentration organic pollutants from typical coal-fired power plants by activated carbon injection

Abstract

Activated carbon (AC) injection was applied to remove the organic pollutants from coal-fired power plants. The total hydrocarbon (THC) concentration in flue gases was 0.512–0.998 mg/m3, aromatic hydrocarbons and oxygenated volatile organic compounds (VOCs) were the major components. With the AC injection (150 mg/m3), the THC was removed by 36.52–46.49%. The mesopores could capture some larger organic molecules and facilitate the intrapore diffusion. Improving the AC injection amount promoted the organic pollutant adsorption, but lowered the AC adsorption capacity. Removal performance of organic pollutants was affected by their physicochemical properties. The removal efficiency for most VOCs was within the range of 15–50%, while that was 45–90% for semi-VOCs. Minor amounts of VOCs achieved high removal efficiency through specific interactions, especially oxygenated VOCs. However, the removal efficiency of the total oxygenated VOCs was lower due to competition adsorption with inorganic components. AC injection had no significant effect on the physicochemical properties of fly ash. This work and results provide a feasible method and reference for the reduction of organic pollutants in coal-fired power plants and other combustion exhaust gases.