Mn-Fe改性碳基磁性吸附剂去除Hg^(0)性能及机制  

The performance and mechanism of Hg^(0) removal by Mn-Fe modified magnetic carbon sorbent

作　　者：张敬东 杨娇羽 揭翠 李鸿鹄 彭喜燕 安淼 ZHANG Jing-dong;YANG Jiao-yu;JIE Cui;LI Hong-hu;PENG Xi-yan;AN Miao(Research Center for Environment and Health,School of Information Engineering,Zhongnan University of Economics and Law,Wuhan 430073,China)

机构地区：[1]中南财经政法大学,环境与健康研究中心,中南财经政法大学信息工程学院,湖北武汉430073

出　　处：《中国环境科学》2024年第12期6628-6640,共13页China Environmental Science

基　　金：国家自然科学基金青年项目(52100134);中南财经政法大学中央高校基本科研业务费专项资金资助项目(2722024EJ024,2722023BY020);中国博士后科学基金面上项目(2022M721284)。

摘　　要：采用溶胶凝胶法制备了一系列Mn-Fe改性碳基磁性吸附剂(Mn_(x)Fe_(y)/C),并评价了其对气态单质汞(Hg^(0))的脱除性能及抗SO_(2)中毒性能.采用SEM、TEM、BET、XRD、H_(2)-TPR、Raman、XPS等方法对吸附剂理化结构进行了分析,以此探讨了不同Mn_(x)Fe_(y)/C吸附剂性能差异的内在原因.结果表明,在反应温度150℃,Hg^(0)浓度250μg/m^(3)条件下,Mn_(2)Fe_(1)/C的Hg^(0)脱除性能最好,达到99.99%.适当含量Fe的加入会引起Mn-Fe间强相互作用,发生Mn^(3+)+Fe^(3+)Mn^(4+)+Fe^(2+)的氧化还原循环,促进Mn^(4+)的生成,同时降低Mn-O-Mn的化学键强度,增加氧空位(O_(v))、活性氧物种(O_(α))浓度,从而增强Hg^(0)的吸附脱除性能.此外,Mn_(2)Fe_(1)/C具有良好的抗SO_(2)性能,在2000×10^(-6)SO_(2)浓度下其Hg^(0)脱除率依然保持在80%以上.XPS表明Fe能保护大部分Mn活性位点免受SO_(2)中毒,同时抑制了吸附剂表面硫酸盐的形成与沉积.Mn_(2)Fe_(1)/C可以通过磁分离从粉煤灰中分离出来,其经4次吸附再生循环后仍有95.69%的Hg^(0)脱除效率,具备优越的再生能力,是一种具有应用前景的燃煤烟气汞吸附剂.In this study,a series of Mn-Fe modified carbon-based magnetic sorbents (Mn_xFe_y/C) were prepared by the sol-gel method and further evaluated for gaseous elemental mercury (Hg~0) removal and anti-SO_(2) poisoning.SEM,TEM,BET,XRD,H_(2)-TPR,Raman and XPS were employed to analyze the physicochemical structure of sorbents.According to the characterization results,the inherent reasons for the performance differences of Mn_xFe_y/C sorbents were clarified.The results indicated that Mn_(2)Fe_1/C achieved best Hg~0 removal performance (99.99%) under 150℃and 250μg/m^(3) Hg~0.The addition of an appropriate amount of Fe could cause strong interaction between Mn and Fe.It led to an oxidation-reduction cycle of Mn^(3+)+Fe^(3+)Mn^(4+)+Fe^(2+),thus promoting the generation of Mn^(4+)and weakening the chemical bond strength of Mn-O-Mn.Resultantly,the concentration of oxygen vacancies (O_v) and reactive oxygen species(O_α) was increased,which facilitated Hg~0 removal over Mn_(2)Fe_1/C.In addition,Mn_(2)Fe_1/C showed good resistance to SO_(2).Its Hg~0removal efficiency remained above 80%at a concentration of 2000×10^(-6) SO_(2).XPS showed that Fe could protect most of the Mn active sites from SO_(2) poisoning,thus inhibiting the formation and deposition of sulfate on the sorbent surface.Mn_(2)Fe_1/C could be separated from fly ash through magnetic separation.After four cycles of adsorption and regeneration,Mn_(2)Fe_1/C still exhibited a Hg~0removal efficiency of 95.69%.It showed superior regeneration ability and might be a promising mercury sorbent for coal-fired flue gas.

关 键 词：氧空位 过渡金属 吸附剂 气态单质汞 SO_(2)抗性 

分 类 号：X701.7[环境科学与工程—环境工程]