Integration of Sn(IV)porphyrin on mesoporous alumina support and visible light catalytic photodegradation of methylene blue

Abstract

Two composite catalysts, designated as SnTTP/SA@Al2O3 and SnTTP@Al2O3, were synthesized by the reaction of Al2O3 and trans-dihydroxo-[5,10,15,20-tetrakis(p-tolyl)porphyrinato]tin(IV) (SnTTP) with and without succinic acid (SA) pretreatment, respectively. Chemically, SnTTP was more tightly incorporated onto the surface of Al2O3 through the anchoring group SA in SnTTP/SA@Al2O3 than that in SnTTP@Al2O3. The SA bridging anchoring groups hindered the dissociation of SnTTP from SnTTP@Al2O3 during photodegradation. Therefore, the strong association between Al2O3 and SnTTP via SA connections not only intensified the quantity of tin porphyrin on the surface of Al2O3 but also accelerated electron movement from the excited SnTTP molecules to the conduction band of Al2O3. The aforementioned mechanism demonstrates a significant improvement in the catalytic photodegradation of methylene blue (MB) dye for SnTTP/SA@Al2O3 compared to SnTTP, Al2O3, and SnTTP@Al2O3 under visible-light irradiation. Within 90 min of using SnTTP/SA@Al2O3 at a rate of 0.0406 min−1, the photodegradation capacity of MB was found to be 98 %. The synergistic effect between Al2O3 and SnTTP improved the catalytic efficiency of SnTTP/SA@Al2O3 compared to that of both SnTTP and Al2O3. This study provides a new direction for the construction of highly efficient porphyrin-based photocatalysts and has significant value for extending their applications in water treatment.