Mechanisms of Mercury with typical organics in the incineration of sewage sludge: A computational investigation

Abstract In this work, using quantum chemistry methods the reactions of Hg and HgO with six organics including methane (CH4), benzene (C6H6), methanol (CH3OH), formaldehyde (HCHO), formic acid (HCOOH) and phenol (C6H5OH) in sludge incineration were investigated. The computational result indicates that Hg reacts with six organics via insertion mechanism to form CH3HgH, CH3OHgH, CH3HgOH, HHgCH2OH, HCOHgH, H2CHgO, HHgCOOH, HOCHHgO, HCOOHgH, HCOHgOH, C6H5HgH, C6H5OHgH, C6H5HgOH, and m-, o-, p-HHgC6H4OH. However, all barriers involved are extremely high and all products are rather unstable, therefore, Hg will be discharged as elements into fuel gas. With extra oxygen supplied Hg could be oxidized to HgO firstly; subsequently, CH3OHgOH, HCOHgOH, HOCOHgOH, C6H5HgOH and o-HOHgC6H4-OH were formed when HgO reacts with above above organics. The corresponding barriers are lower and all products are much more stable, indicating these Hg-contained organic compounds would be generated readily in incineration of sludge. Therefore it is presumed that in presence of oxygen Hg is more active to react with organics in sludge incineration.