Fe/Ti-MIL-NH2吸附-光催化降解NDPhA

通过水热法成功制备Fe/Ti-MIL-NH₂吸附-光催化复合材料,考察了该材料对亚硝基二苯胺(NDPhA)的降解效能与机制.结果表明,Fe/Ti摩尔比为3:1时,Fe/Ti-MIL-NH₂能在不同水质条件下稳定去除84.4%以上的NDPhA,10mmol/L HCO₃^-的加入可使去除率达95.1%.与Fe-MIL-NH₂相比,Fe/Ti-MIL-NH₂(3:1)优异的吸附-光催化性能归因于其原位异质结构的形成,使其比表面积增加(310.2m²/g),加速光生空穴对分离并抑制其复合.通过动力学、吸附等温线拟合,明确了Fe/Ti-MIL-NH₂对NDPhA的吸附机制为表面吸附和分配作用.自由基捕获与探针实验结果表明,Fe/Ti-MIL-NH₂光催化过程通过自由基(^·O₂^-, ^·OH)与非自由基(Fe[IV]=O, h⁺)的共同作用降解NDPhA,提出了Fe/Ti-MIL-NH₂去除NDPhA的吸附光催化机制.通过分析光催化氧化中间产物,提出了NDPhA可能的降解路径.此外,Fe/Ti-MIL-NH₂(3:1)可完全去除天然水体基质中浓度<0.1mg/L的NDPhA,且重复使用5次后仍能去除83%的NDPhA,表明该材料稳定性较高.

Adsorption-Photocatalysis for the Removal of NDPhA by Fe/Ti-Mil-NH2

A composite adsorption-photocatalyst, Fe/Ti-MIL-NH₂, was synthesized via the hydrothermal method and utilized to degrade NDPhA. The Fe/Ti-MIL-NH₂ with Fe-Ti molar ratio of 3:1 could degrade more than 84.4% of NDPhA under various conditions, and 95.1% under adding 10 mmol/L HCO₃^-. Compared to Fe-MIL-NH₂, the excellent performance of Fe/Ti-MIL-NH₂ (3:1) was attributed to the in situ formation of intimate heterojunctions, which increased the specific surface area (310.2m²/g), accelerated the separation of photogenerated cavity pairs, and inhibited their complexation. Both surface adsorption and distribution existed during the adsorption of NDPhA on Fe/Ti-MIL-NH₂ as observed from kinetic and adsorption isotherm fitting. The combination of radicals (^·O₂^-, ^·OH) and non-radical (h⁺, Fe[IV]=O) in the Fe/Ti-MIL-NH₂ photolytic system was responsible for NDPhA degradation. Diphenylamine and 2-Nitrodiphenylamine and/or 4-nitrodiphenylamine were identified as the main intermediates during NDPhA degradation, and the pathways were speculated based on these intermediates. In addition, Fe/Ti-MIL-NH₂(3:1) could completely remove NDPhA at concentrations <0.1mg/L in source water of water treatment plant and maintain an NDPhA removal efficiency of 83% after 5times of use, indicating the high stability of this material.