不同气氛下蜈蚣草热处理过程中砷的迁移规律  

As transformation behavior in thermal treatment of P.vittata in different atmospheres

作　　者：李小乐[1] 段伦博[1] 赵长遂[1] LI Xiao-le;DUAN Lun-bo;ZHAO Chang-sui(Key Laboratory of Energy Thermal Conversion and Control, Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China)

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教育部重点实验室,江苏南京210096

出　　处：《中国环境科学》2017年第4期1418-1425,共8页China Environmental Science

基　　金：国家自然科学基金资助项目(51661125011)

摘　　要：蜈蚣草是砷(As)的高富集植物,为研究在不同气氛下蜈蚣草热处理过程中As的迁移规律,利用管式炉在不同气氛(空气、N_2、CO_2)下对蜈蚣草进行热处理,实验发现:当温度在400~800℃之间时,3种气氛下蜈蚣草热处理过程中As的挥发率均随温度的升高先增加后减小,空气气氛下在500℃达到最高,占总含量的43%,N_2、CO_2气氛下,在600℃达到最高,占总含量的60%.As挥发率先随温度升高而增加是甶于低温区无机As的挥发,之后下降可能是甶于蜈蚣草中碱金属和碱土金属元素对As的固定作用.当温度高于800℃时,空气气氛下As的挥发率继续下降,而N_2和CO_2气氛下As挥发率迅速升高到90%,可能是甶还原性气氛中As化合物的稳定性下降造成的.FactSage软件模拟结果表明,随着温度的升高,蜈蚣草中As在空气气氛下主要以Ca_3(AsO_4)_2的形式存在,而在CO_2和N_2气氛下,主要存在的形式分别为As单质和AsN.模拟As形态的转化趋势能很好的验证真实的实验结果.P.vittata is one of the hyperaccumulators of arsenic(As),a series of experiments were conducted in a horizontal tube furnace to study the transformation behavior of As during the thermal treatments of P.vittata in different atmospheres(air,N2,CO2).As release exhibited similar tend in different atmospheres during the temperature ranged from400℃to800℃.It increased firstly due to the volatility of inorganic As,and then dropped probably because of the self-retention of As by alkali and alkali earth metal enriched in this P.Vittata.The As release reached the peak value(43%)at500℃during combustion(in air),while the temperature was600℃when the peak value(60%)occurred both during pyrolysis(in N2)and gasification(in CO2).When the temperature exceeded800℃,the As release decreased continuously during combustion while it increased rapidly to90%during pyrolysis and gasification,which could be due to the falling of thermal stability of inorganic As compounds in reducing atmosphere.The results of simulation by FactSage showed that the main form of As in different atmospheres was different with increasing the temperature.The main form of As during combustion was Ca3(AsO4)2(s),while it was elemental As(g)and AsN(g)during pyrolysis and gasification,respectively.Moreover,the results of As transformation simulation were in accordance with the experimental results overall.

关 键 词：蜈蚣草 气氛 AS FactSage模拟 

分 类 号：X53[环境科学与工程—环境工程]