Porphyrin-based Fe/La metal-organic frameworks as photocatalysts for dye photodegradation: Syntheses and mechanism investigation

Organic dyes are typical chemical reagents that find applications in printing, textile, leather, and other industries. However, their overuse and uncontrolled discharge in water bodies have a negative impact on the aquatic ecosystem and humans. Metal-organic frameworks are assorted multifunctional materials that find potential application as photocatalysts. In this work, the application of two porphyrin-based metal-organic frameworks (TCPP-La and Fe-TCPP-La) have been reported as photocatalytic materials to degrade dyes methyl orange (MO) and methylene blue (MB). The results suggest that TCPP-La can eliminate 16 % MO and 23.7 % MB in 125 min under UV irradiation of 385 nm. On the other hand, only 4.8 % MO and 16 % MB were removed by Fe-TCPP-La under the same condition. However, when hydrogen peroxide (2 % H2O2) was added to the reaction medium, the degradation activity of TCPP-La was improved upto 26 % for MO and 61 % for MB, while, Fe-TCPP-La exhibits more enhancement in photocatalytic degradation upto 55 % for MO and 93 % for MB. The result implied that introducing ferric ions using post-synthetic strategy to engender both lanthanum and iron centers into the framework could improve the photocatalytic performance of the MOF against dye photodegradation.