Jiaqi Li,Yidan Zhang,Pingyu Luo,Chun Li,Fanming Zeng,Tiantian Sun,Hanhui Lei,Xiaoteng Liu,Chunbo Liu
Persulphate-based advanced oxidation technology efficiently and cost-effectively removes organic dyes from water but designing stable photocatalytic systems and understanding their reaction mechanisms remain key challenges. Metal–organic frameworks (MOFs) have attracted considerable research attention for degrading organic pollutants owing to their high porosity, tunable structure, and ease of modification. In this study, a series of M-MOF-74 (M = Co, Fe, Ni) photocatalysts are synthesized by a hydrothermal method for methylene blue (MB) degradation. Among them, the Co-MOF-74 photocatalytic synergetic peroxymonosulfate system exhibits high catalytic activity after 30 min of visible light irradiation. MB degradation efficiency reaches 94.8%, and the reaction rate constant is 0.210 min−1, which is approximately 19.44 times higher than the reaction rate constant of the original Co-MOF-74. Compared with Fe-MOF-74 and Ni-MOF-74, Co-MOF-74 exhibits better photocatalytic performance due to the dynamic changes in the valence state of cobalt, which more effectively facilitate the activation of PMS. In addition, this study analyses the possible degradation pathways of MB in water and toxicological evaluations of intermediate products, providing new insights for the effective removal of dyes in water.
Xiaoyan Pei,Wangyue Song,Yunlei Shi,Yang Zhao,Zhiyong Li
Pickering emulsions with a stimulus response have been paid extensive concern due to their long-term stability and demulsification on-command. Metal-organic frameworks (MOFs) are expectable emulsifying agents to build Pickering emulsions based on their excellent properties such as high specific surface area, adjustable porosity and pore size. Herein, a novel kind of CO 2 -triggered Pickering emulsions formed by (3-aminopropyl)triethoxysilane (APTES)-functionalized M-MOF-74 (M-MOF-74-APTES, M = Zn, Cu or Mg) has been developed for the first time. It was found that even at the M-MOF-74-APTES amount of 0.5 wt%, the functionalized MOFs could still stabilize the n-hexane-water mixture to construct Pickering emulsions. The as-generated Pickering emulsions could be efficiently demulsified upon bubbling of CO 2 , resulting in complete separation of oil and water phases, but could be restored by subsequent N 2 bubbling under homogenization. Mechanism study indicated that the acid-base reaction of CO 2 with the amino group of M-MOF-74-APTES resulted in the creation of hydrophilic salts, which led to the lowering of particle wettability and broke the stability of the emulsion, causing demulsification of the Pickering emulsion. After removing CO 2 , the emulsion can be reconstructed by the reversible reaction. As an applied example, the Pickering emulsion has been availed as a micro-reaction system and M-MOF-74-APTES as a carrier of Pd(OAc) 2 catalyst to realize the efficient combination of Suzuki-Miyaura reaction, product isolation and reuse of catalysts via alternate bubbling or removing of CO 2 .
危险品化学品经营许可证（带存储）