Fe3+增强氢氧化钙固硫效率:氧化、催化双重机制OA

Sulfur dioxide(SO2)is a major air pollutant that poses severe hazards to environment and human health.Currently,calcium hydroxide(Ca(OH)2)is widely used as a common desulfurizing agent due to its simple preparation process,low cost and relatively good desulfurization performance.However,how to further improve its sulfur fixation efficiency remains unknown.Here,a novel calcium-iron desulfurizing agent was prepared in a stepwise manner by incorporating ferric hydroxide during hydration process of calcium oxide(CaO),and then its desulfurization performance was investigated.The results demonstrated that sulfur fixation efficiency of the calcium-iron desulfurizing agent was significantly enhanced,increasing by 26.16%compared to the maximum sulfur fixation efficiency of pure Ca(OH)2.Addition of Fe3+modified the morphology of Ca(OH)2,rendering its surface much rougher with an increasing of pores and cracks.This morphological change provided more active sites for the desulfurization reaction.X-ray photoelectron spectroscopy analysis revealed that after desulfurization the proportion of hexavalent sulfur(S6+)in the sample increased from 9.71%(pure Ca(OH)2)to 33.33%(calcium-iron desulfurizing agent).Experiment study revealed that before desulfurization,all iron in the calcium-iron desulfurizing agent was in the form of Fe3+,but after desulfurization,Fe2+amazingly accounted for 68.42%while Fe3+only accounted for 31.58%of the total calcium-iron agent.Calculations based on these data indicated that 35.56%sulfur was oxidized while 64.44%was catalyzed.These calculation findings confirmed that oxidation and catalytic effects of the iron promoted the conversion of tetravalent sulfur(S4+)to S6+,thereby further improving the sulfur fixation efficiency.This study provides a promising approach to enhance the sulfur fixation efficiency of Ca(OH)2 and an effective material for removing sulfur dioxide from industrial flue gas.