Mechanism Of Elemental Mercury Adsorption By Non-thermaT Plasma Modified Biochar

Mercury emission from coal combustion is one of the largest sources of mercury pollution,and taking measures to control mercury emissions from coal-fired power plants is imperative.Biochar,pyrolysed from agricultural waste in oxygen-free environment,has be attractive as sorbent due to its low cost,renewable property and simple preparation process.Non-thermal plasma oxidation of mercury technology with its adaptability,time-saving and efficient features caused widespread concern.In this paper,the use of dielectric barrier discharge(DBD)as the method of generating plasma,the different bio-carbon samples into the DBD reactor modified,studied the plasma modified biochar to explore possible Hg0 adsorption properties and mechanism.The main contents are as follow:Biochar,known as a byproduct of biomass pyrolysis,prepared from corn straw(C6),millet straw(M6),wheat straw(W6)and black bean straw(B6),rice straw(R6)and tobacco straw(T6)in high purity nitrogen at 600 ?.Chlorine(Cl)non-thermal plasma was used to improve Cl active sites on biochar to enhance the mercury removal efficiency in the flue gas.The biochar sample was placed in a DBD reactor and modified for 5 minutes.The discharge frequency was 23 W.The reaction atmosphere was 1%Cl2(equilibrium gas was nitrogen).The surface properties of biochars were characterised by proximate analysis,ultimate analysis,BET,SEM,TG,FTIR,and XPS to explore possible Hg6 adsorption properties and mechanism..The results indicated that the Hg0 removal efficiency was less than 10.0%with raw biochars and which increased to more than 80.0%with biochars modified by Cl2 plasma,the average Hg,removal efficiency of T6Cl was almost 10-28 times higher than that of T6 within 90 minutes.During plasma treatment,the biochar surface became porous because of plasma etching effects.The relative intensity of the oxygen functional groups(C-O,C=0 and C(O)-O-C)were enhanced,while the content of oxygen(O)decreased.The main reason for the improved mercury removal efficiency by modified biochars was attributed to the increased number of C-Cl groups on the surface of the biochars induced by Cl2 plasma.The C-Cl groups functioned as activated sites and promoted the Hg6 removal efficiency.