The degradation of organic pollutants using photocatalysis is a more environmentally friendly method because it uses solar energy. Covalent organic frameworks (COFs) are photocatalysts that are composed of covalent bonds of light elements and do not contain harmful metals. COFs have been studied in various fields, but their use in removing organic pollutants has not been fully investigated. In this study, the photocatalyst TpPa-COF-Cl2 was made into a membrane and its activity against dyes was examined. TpPa-COF-Cl2 slightly decolorized methyl orange.
-Synthesis of catalyst
①Mesitylene (4.5 mL), 1,4-dioxane (4.5 mL), acetic acid (3M, 1.5 mL), 1,3,5-triformylphloroglucinol (Tp), and 2,5-dichloro-p-phenylenediamine (Pa) (molar ratio Tp:Pa=1:1.5) were added, heated, and stirred to obtain TpPa-COF-Cl2 powder.
②A mixture of 20 mg of TpPa-COF-Cl2 powder, sodium alginate, and 1.7 mL of water was heated and stirred, spread on a glass plate, and immersed in a CaCl2 solution (3 wt%) for 24 hours to synthesize 5 to 6 TpPa-COF-Cl2 films.
-Dye degradation
One membrane was placed in 5 ppm methyl orange (MO) and left in the dark for 30 minutes to reach adsorption equilibrium, after which it was irradiated with a 450 nm LED lamp for 60 minutes and its absorbance was measured every 10 minutes.
-Result, Conclusion
SEM and TEM revealed that the powdered TpPa-COF-Cl2 had a layered structure. In addition, an absorption edge at 600 nm was confirmed by DRS.
The TpPa-COF-Cl2 membrane formed by the cross-linking reaction of alginic acid and calcium ions maintained its structure even after the photocatalytic reaction. The TpPa-COF-Cl2 membrane decolorized approximately 5% of MO. Although the decolorization efficiency was inferior to that of the powder form, it was easier to remove the catalyst.
