Mn活化铁盐絮凝污泥制备磁性吸附剂脱除烟气中Hg0

REMOVAL OF ELEMENTAL MERCURY USING MAGNETIC ADSORBENT PREPARED FROM SLUDGE FLOCCULATED WITH FERROUS SULFATE BY Mn ACTIVATION

采用Mn(NO_(3))_(2)活化铁盐絮凝污泥制备磁性吸附剂用于烟气中Hg^(0)的脱除。结果表明:1)Mn(NO_(3))_(2)热分解产生的O_(2)促进了污泥一次热解过程中产生的FeCx分解,并有利于Mn^(4+)与Fe^(3+)等高价态金属氧化物的生成;Mn(NO_(3))_(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 m^(2)/g),但Mn(NO_(3))_(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O_(2)可对吸附剂中的活性氧进行有效补充,促进Hg^(0)的脱除;NO以及低浓度的SO_(2)对Hg^(0)脱除有一定的促进作用,而H_(2)O与高浓度的SO_(2)则由于竞争吸附对Hg^(0)脱除抑制作用明显。吸附再生试验表明:Mn_(10)-SFS吸附剂具有良好的可再生循环利用性能及稳定性,5次Hg^(0)的吸附脱附循环试验后,其脱汞性能无明显降低。

In this work,ferrous sulfate-flocculated sewage sludge(SFS)was activated by Mn(NO_(3))_(2)and then pyrolyzed to obtain magnetic adsorbent,which was adopted to remove elemental mercury(Hg0)from flue gas.Results showed that 1)O_(2) produced by the thermal decomposition of Mn(NO_(3))_(2)promoted the decomposition of FeCx during primary pyrolysis of sludge,and that was conducive to the formation of high-valent metal oxides such as Mn^(4+)and Fe^(3+).The gas produced by the decomposition of Mn(NO_(3))_(2)also showed the effect of pore expansion.With the addition of 10%Mn(NO_(3))_(2),the specific surface area of the adsorbent reached the maximum(88.5 m^(2)/g),but when the Mn(NO_(3))_(2)amount continued to rise,it would produce many crystalline substances and then decreased the specific surface area of the adsorbent.2)Mn_(10)-SFS showed a maximum mercury removal efficiency of 92.7%at the reaction temperature of 150℃.3)O_(2) could effectively supplement the active oxygen in the adsorbent,promoting the removal of Hg0,and presence of NO and a low SO_(2)concentration enhanced Hg^(0) removal,while H_(2)O vapor and a high concentration of SO_(2)inhibited it.The Hg^(0) adsorption and desorption experiment showed that the adsorbent of Mn_(10)-SFS exhibited good renewable recycling performance and stability.After Hg^(0) capture and regeneration for 5 cycles,the removal efficiency of the adsorbent was not notably degraded.