关键词: 汞, 桑树枝焦, 蒸汽活化, 浸渍改性, 吸附性能

Abstract: Several mulberry twig (MT) chars were prepared by conventional pyrolysis, steam activation, and impregnation with H₂O₂, ZnCl₂ and NaCl.Adsorption performance of mercury in a simulated flue gas by MT chars were studied in a bench-scale fixed bed absorber, and the effects of steam activation, impregnation agent, adsorption temperature, and the composition of simulated flue gas, etc.on mercury adsorption performance were analyzed.The results indicated that steam activation could significantly increase surface areas of MT pyrolysis chars.Impregnation with H₂O₂ can further improve surface areas of steam activated MT chars and its pore structure. However, impregnation with ZnCl₂ and NaCl led to decrease of surface areas, D-R micro-pore and total pore volume of MT chars in some extent.The mercury adsorption capacities of MT chars impregnated with 10% and 30% H₂O₂ were 2.02 and 1.77 times of that for steam activated MT char, respectively, and that of MT char impregnated with ZnCl₂ was a little better than that impregnated with NaCl at the same impregnation concentration.The performance of mercury adsorption enhanced with increase of ZnCl₂ concentration for modified MT char.The mercury adsorption for MT600-A-ZnCl₂(5%) was 29.55 μg·g^-1, 3.37 times of that for steam activated MT char.At temperature of 60—120℃, the mercury adsorption efficiency and capacity of MT chars impregnated with H₂O₂ decreased with increase of adsorption temperature. However, the capacity of MT chars impregnated with ZnCl₂ showed an increase trend at first and then decrease, and its optimum adsorption temperature was 90℃.SO₂ and NO in the simulated flue gas showed adverse effect on mercury adsorption.Both mercury adsorption efficiency and capacity decreased slightly with increase of SO₂ and NO concentration.

Key words: mercury, mulberry twig char, steam activation, impregnated modification, adsorption characteristics