REMOVAL OF ELEMENTAL MERCURY USING MAGNETIC ADSORBENT PREPARED FROM SLUDGE FLOCCULATED WITH FERROUS SULFATE BY Mn ACTIVATION
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摘要: 采用Mn(NO3)2活化铁盐絮凝污泥制备磁性吸附剂用于烟气中Hg0的脱除。结果表明:1)Mn(NO3)2热分解产生的O2促进了污泥一次热解过程中产生的FeC<em>x分解,并有利于Mn4+与Fe3+等高价态金属氧化物的生成;Mn(NO3)2分解产生的气体有扩孔作用,在其掺杂量为10%时,吸附剂比表面积达到最大(88.5 m2/g),但Mn(NO3)2的掺杂量过高时会产生较多的晶相物质,并导致吸附剂的比表面积降低。2)当Mn掺杂量为10%(记为Mn10-SFS),反应温度为150℃时,吸附剂脱汞效率最高(92.7%)。3)烟气中的O2可对吸附剂中的活性氧进行有效补充,促进Hg0的脱除;NO以及低浓度的SO2对Hg0脱除有一定的促进作用,而H2O与高浓度的SO2则由于竞争吸附对Hg0脱除抑制作用明显。吸附再生试验表明:Mn10-SFS吸附剂具有良好的可再生循环利用性能及稳定性,5次Hg0的吸附脱附循环试验后,其脱汞性能无明显降低。
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关键词:
- 污泥 /
- 吸附剂 /
- 燃煤烟气 /
- 汞的脱除REMOVAL
Abstract: In this work, ferrous sulfate-flocculated sewage sludge (SFS) was activated by Mn(NO3)2 and then pyrolyzed to obtain magnetic adsorbent, which was adopted to remove elemental mercury (Hg0) from flue gas. Results showed that 1) O2 produced by the thermal decomposition of Mn(NO3)2 promoted the decomposition of FeC<em>x during primary pyrolysis of sludge, and that was conducive to the formation of high-valent metal oxides such as Mn4+and Fe3+. The gas produced by the decomposition of Mn(NO3)2 also showed the effect of pore expansion. With the addition of 10% Mn(NO3)2, the specific surface area of the adsorbent reached the maximum (88.5 m2/g), but when the Mn(NO3)2 amount continued to rise, it would produce many crystalline substances and then decreased the specific surface area of the adsorbent. 2) Mn10-SFS showed a maximum mercury removal efficiency of 92.7% at the reaction temperature of 150 ℃. 3) O2 could effectively supplement the active oxygen in the adsorbent, promoting the removal of Hg0, and presence of NO and a low SO2 concentration enhanced Hg0 removal, while H2O vapor and a high concentration of SO2 inhibited it. The Hg0 adsorption and desorption experiment showed that the adsorbent of Mn10-SFS exhibited good renewable recycling performance and stability. After Hg0 capture and regeneration for 5 cycles, the removal efficiency of the adsorbent was not notably degraded.-
Key words:
- sludge /
- adsorbent /
- coal-fired flue gas /
- mercury removal
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