Mercury oxidation and adsorption characteristics of potassium permanganate modified lignite semi-coke

The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke(SC)for gaseous Hg0 were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission.Brunauer-EmmettTeller(BET)measurements,X-ray powder diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)were used to analyze the surface physical and chemical properties of SC,Mn-SC and Mn-H-SC before and after mercury adsorption.The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke,such as the specific surface area,pore structure and surface chemical functional groups.The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature,but much higher at high temperature.Amorphous Mn7+,Mn6+ and Mn 4+ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0,which oxidized the elemental mercury into Hg2+ and captured it.Thermal treatment reduced the average oxidation degree of Mnx+ on the surface of Mn-SC from 3.80 to 3.46.However,due to the formation of amorphous MnOx,the surface oxidation active sites for gaseous Hg0 increased,which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.