Lu Sheng-yong, Yan Jian-hua, Li Xiao-dong, Ni Ming-jiang, Cen Ke-fa, Dai Hui-fen
State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China.
J Environ Sci (China). 2007;19(6):756-61. doi: 10.1016/s1001-0742(07)60126-0.
Chlorine source is indispensable for polychlorinated dibenzo-p-dioxin and furan (PCDD/F) formation during municipal solid waste (MSW) incineration. Inorganic chlorine compounds were employed in this study to investigate their effects on PCDD/F formation through heterogeneous synthesis on fly ash surfaces. A fly ash sample obtained from a fluidized bed incinerator was sieved to different size fractions which served as the PCDD/F formation sources. The capability of different metal chlorides which facilitate the formation of PCDDs/Fs was found to follow the trends: Na < Mg < K < Al < Ca, when two particle fractions of >177 miocrom and 104-125 microm were used in the experiments. However, the capability of NaCl, MgCl2 and KCl did not seem much different from each other, whereas CaCl2 and AlCl3 were much more active in PCDD/F formation. NaCl and MgCl2 were relatively effective to produce more PCDDs, while KCl, AlCl3 and CaCl2 generated more PCDFs during heterogeneous reactions occurring on fly ash. 2,3,7,8-TCDF was the most significant contributor to the toxicity of the PCDDs/Fs formed from inorganic chlorine sources. Decreasing the sizes of fly ash particles led to more active formation of PCDDs/Fs when NaCl was used as inorganic chlorine in the experiment. The highest PCDDs/Fs produced from particles with size <37 microm, while the lowest PCDDs/Fs produced from particles with size >177 microm. The toxicity generally increased with decreasing size of the fly ash particles. The formation of PCDDs was mainly facilitated by the two size fractions, 104-125 microm and <37 microm, while the formation of PCDFs was favored by the two other size fractions, >177 microm and 53-104 microm.
氯源是城市固体废物（MSW）焚烧过程中多氯二苯并对二噁英和多氯二苯并呋喃（PCDD/F）形成所不可或缺的。本研究采用无机氯化合物，通过在飞灰表面的非均相合成来研究它们对PCDD/F形成的影响。从流化床焚烧炉获得的飞灰样品被筛分成不同的粒径级分，作为PCDD/F形成的来源。当在实验中使用大于177微米和104 - 125微米的两个颗粒级分时，发现不同金属氯化物促进PCDDs/Fs形成的能力遵循以下趋势：Na < Mg < K < Al < Ca。然而，NaCl、MgCl2和KCl的能力似乎彼此差异不大，而CaCl2和AlCl3在PCDD/F形成中活性更高。在飞灰上发生的非均相反应过程中，NaCl和MgCl2相对有效地产生了更多的PCDDs，而KCl、AlCl3和CaCl2产生了更多的PCDFs。2,3,7,8 - TCDF是由无机氯源形成的PCDDs/Fs毒性的最主要贡献者。当在实验中使用NaCl作为无机氯时，减小飞灰颗粒尺寸会导致PCDDs/Fs的形成更活跃。粒径小于37微米的颗粒产生的PCDDs/Fs最高，而粒径大于177微米的颗粒产生的PCDDs/Fs最低。毒性通常随着飞灰颗粒尺寸的减小而增加。PCDDs的形成主要由104 - 125微米和小于37微米这两个粒径级分促进，而PCDFs的形成则受另外两个粒径级分，大于177微米和53 - 104微米的青睐。
