钴掺杂的铁酸铋催化PMS氧化单质汞的实验研究

采用酒石酸溶胶凝胶法制备了一系列的钴掺杂的铁酸铋催化剂(BiFe_(1-x)Co_xO_3,x=5%-20%,x为Co/CoFe物质的量比),借助于X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积(BET)、磁强振动计(VSM)、X射线光电子能谱(XPS)等手段对催化剂进行表征。在自制鼓泡反应器内,利用钴掺杂铁酸铋活化过一硫酸氢钾(PMS),开展了模拟烟气中单质汞脱除实验,获得反应的最佳条件。当钴掺杂量为10%,催化剂用量为0.5 g/L,PMS浓度为3.9 mmol/L,溶液初始pH值为8,反应温度70℃时,反应100 min内Hg~0的平均脱除效率达89.36%。以乙醇和叔丁醇为淬灭剂,证明了·OH和SO~(·-)_4为Hg~0催化氧化的活性物种,且SO~(·-)_4起主要作用,并结合XPS分析结果推测了脱汞反应机理。

Removal of elemental mercury in flue gas with PMS solution catalyzed by Co doped BiFeO3

A aseries of Co-doped BiFeO₃ magnetic catalysts(BiFe_1-xCo_xO₃, x=5%-20%) were synthesized by the tartaric acid sol-gel method, and the prepared catalysts were characterized using X-ray powder diffraction (XRD), Brunauer Emmett Teller (BET) technique, vibration sample magnetometer (VSM) and X ray photoelectron spectroscopy(XPS). The catalytic activity of Co doped BiFeO₃ to activate Peroxymonosulfate (PMS) was evaluated at a self-designed bubbling reactor. The effects of Co ration in catalyst, dosage of the catalyst, PMS concentration, and solution pH and reaction temperature on the removal of elemental mercury were investigated systematically, and the optimum conditions were obtained. The result indicates that the average removal efficiency of elemental mercury reaches 89.36% within 100 min under the following condition:70℃, 10% doping Co, 3.9 mmol/L PMS concentration, 0.5 g/L catalyst dosage and pH 8. Moreover, it is testified that SO₄^·- and·OH are the active species when Hg⁰ is oxidized to Hg²⁺, where the tert-butyl alcohol and ethyl alcohol are used as quenchers. Finally, the mechanisms of mercury removal with PMS solution catalyzed by BiFe_0.9Co_0.1O₃ are speculated on the basis of XPS results.