蜈蚣草燃烧过程中As迁移转化规律  

Arsenic transformation behavior during combustion of P.vittata

作　　者：李小乐[1] 段伦博[1] 雷梅[2] 赵长遂[1] 

机构地区：[1]东南大学能源与环境学院能源热转换及其过程测控教育部重点实验室,江苏南京210096 [2]中国科学院地理科学与资源研究所环境修复中心,北京100101

出　　处：《化工学报》2017年第1期281-288,共8页CIESC Journal

基　　金：国家自然科学基金项目(51206023)~~

摘　　要：蜈蚣草是砷(As)的高富集植物,为研究蜈蚣草燃烧过程中As的迁移规律及形态演变,在管式炉中对蜈蚣草进行了燃烧实验,实验发现:蜈蚣草中As挥发率随温度的升高先增加后减小,在500℃达到最高。500℃之前挥发率升高是由于低温区无机As的挥发;温度高于500℃时挥发率下降,是由于As的快速氧化使挥发的As3+减少以及灰中元素对As的固定作用。蜈蚣草燃烧后底灰中的水溶As主要是As^(5+),其含量随着温度的升高先降低再增加,800℃到达峰值,占原样品As含量的81%。在400~500℃之间,水溶As^(5+)含量下降主要是由于As的挥发率增加;在500~700℃之间,As的固定主要为灰的物理吸附;当温度到800℃,As的固定主要为化学吸附。水溶As^(5+)的比例在900℃时有所下降,可能是因为温度过高使生物质灰烧结,As^(5+)无法充分溶解,使测量到的As^(5+)含量减少。综合考虑As的回收再利用工艺,推荐800℃为蜈蚣草的最佳燃烧温度。P. vittata is one of the hyperaccumulators of arsenic（As）, the combustion experiments were conducted in a horizontal tube furnace to investigate the transformation behavior of As during the combustion of P. vittata. Results show that the release of As in P.vittata increased first then decreased, reaching the highest at 500℃. With increasing temperature from 400℃ to 500℃, the higher release rate is due to the volatility of the inorganic As at lower temperature. With further increase the temperature from 500℃ to 900℃, As release decreased which may be attributed to the fast oxidation of As and the formation of some inorganic compounds. Moreover, the soluble As in the solid residue mainly presents as As5＋, and the content varies largely with the temperature with a peak value of 81% of total As at 800℃. The content of soluble As5＋decreases before 500℃ due to the volatility of the inorganic As. The physical adsorption of some compounds plays an important role for the As fixation at the temperature from 500℃ to 700℃, while the As fixation is mainly conducted by the chemical oxidation at 800℃. The content of soluble As5＋ decreases a little, possibly because of the sintering of the ash. Considering the As recycling process, 800℃ is recommended as the optimum combustion temperature for the P. vittata.

关 键 词：蜈蚣草 燃烧 AS 可溶As 形态 

分 类 号：X712[环境科学与工程—环境工程]