The Experiment And Mechanism Of The Macromolecular Chitosan To Remove Mercury In The Flue Gas Of Coal Combustion

Now, the high-speed development of electric power industry brings great convenience to people's life, but it does great harm to the environment. It causes the green house effect,acid rain and metal pollution. Trace metal pollution destroys peoples health,especially the mercury. It causes fatal damage to mental system. It's urgent to control the mercury emission of coal-fired power plants, which cause the main mercury polluting.Several technologies are considered for reducing mercury from coal combustion flue gases, such as carbon-based adsorption, zeolite adsorption and other novel sorbent adsorption,liquid scrubbing and trace metal amalgamation. Adsorption is the most promising technology for mercury removing from coal-fired boilers. But it cost so much that the power plants can't endure. Attention on cost reduction and high mercury removal efficiency should be paid on in the future research and development.The destination of this article is to find an abundant, cheap and high efficient adsorption to control the mercury emission. So the macromolecule chitosan is introduced for the first time to remove the mercury in flue gas.First, four kinds of chitosan sorbents—Cu2+ template spherical colophony chitosan, cross link chitosan sphere, chitosan sphere which loaded sulphur and ternary composite chitosan sorbent were made and were analyzed by specific surface and FTIR spectroscopy to disclose the mechanism of action with Hg.Next, a one-dimension furnace test bench experiment and simulation experiment were conducted to study the Chitosan sorbent's adsorption efficiency of mercury in coal-fired flue gas. In this work,the method of Ontario Hydro and Atomic Absorption Spectrometry was used to analysis the form distribution and content of the mercury in the flue gas of coal combustion. At the same time,three kinds of modified Chitosan sorbents were prepared to remove the mercury in the flue gas. The results show that the element mercury is more than bivalent mercury and the ratio is 3:2. The CS sorbents can adsorb Hg2+ and Hg0. The mercury adsorption efficiency is 96.34% at 80℃,and it can increase with the temperature rising. Especially, the CS can remove the SOx and NOx simultaneously,and the exist of SOx and NOx can promote the efficiency of mercury removing.At last, different sorbents'adsorption efficiency were compared and analyzed. Fresh and after adsorption of the same kind of sorbent were compared by infrared spectrum analysis. The results show that the mechanism of CS removing mercury is that 4 free aminoes(—NH2)chelated 1 mercury or 2 free amino and 2 hydroxyls(—OH)chelated 1 mercury to be a ring. The free amino is the main active group.In a word, the chitosan is an ecnomic, effective and reproducible adsorption in the field of mercury removing in flue gas.