[Objective] The low-temperature(–20~ –40 ℃) oxidation adsorption of multiple pollutants from coalfired flue gas onto activated carbons enables their integrated removal
which has promising application prospect and environmental benefits. [Methods] This article studied the adsorption processes of NO and SO2 by four activated carbons(graded-pore activated carbon
coal-based activated carbon
and two coconut shell-based activated carbons) in inert atmosphere and simulated flue gas under low temperature conditions of –20 ℃. [Results] The experimental results showed that in an inert atmosphere
the adsorption performance of the four activated carbons for NO was weak
with a saturated nitrogen capacity of less than 0.07 mg/g
and the saturated sulfur capacity for adsorbing SO2 was 31.70~57.07 mg/g. In simulated flue gas conditions
the presence of O2 increased the saturated nitrogen capacity of activated carbons by three orders of magnitude and the saturated sulfur capacity by 2~5 times. The optimal coconut shell activated carbon-2 had a saturated nitrogen capacity of 175.70 mg/g and a saturated sulfur capacity of 320.65 mg/g. Density functional theory(DFT) calculations show that the adsorption binding energies of NO
SO2
and their oxides on the zigzag edge carbon model follow the order of NO2> SO3> SO2> NO. After NO and SO2 are oxidized by O2 into NO2 and SO3
their adsorption on activated carbon surfaces is significantly enhanced. [Conclusion] The research results can provide an important theoretical basis for the integrated adsorption and removal of NO and SO2 in coal-fired flue gas under low temperature conditions.