Experimental investigation and numerical simulation of simultaneous desulfurization and denitrification by H2O2 solution assisted with microwave and additive

The integrated process for the simultaneous desulfurization and denitrification using H2O2 solution assisted with additive as well as microwave was presented, and researched by chemical dynamics simulations and experiments. The NOx removal process occurred in an atmosphere containing H2O2, center dot OH and HO2 center dot, where the NO was gradually oxidized into HNO3. However, the removal reactions of SO2 in flue gas had some strong competitive relevance with those reactions of NOx. But if with the microwave irradiation, it could tremendously decrease the activation energies of H2O2 decompositions and NOx oxidations with additive. Moreover, the O radical derived from the microwave irradiation could easily enhance the NO decomposition into the N radical, which would also react with the NO to regenerate another O radical, consequently the NO could be reduced into N-2 during the conversions among free radicals. By experiments it was found that the denitration efficiency increased first and then decreased with the variations of some factors, such as the temperature, the pH value, the reaction time, the liquid-gas ratio, and the gas volume fractions of O-2, NO as well as SO2. Additionally, the NO removal efficiencies presented a monotonous rise law with the increasing concentration of no matter H2O2 or additive. In detail, without the microwave irradiation, more than 99% desulfurization efficiency and 73.4% denitrification efficiency could be achieved at the optimal operating condition. Furthermore, for determining the microwave effects, the removal experiments with microwave stimulation were all performed at pH value of 7, at which the denitration efficiency was the lowest when without microwave irradiation, but now the desulfurization efficiency stabilized above 99.5%, and the denitration efficiency could raise greatly and reach 87.74%.