Kaolinite/TiO2/cobalt(II) Tetracarboxymetallophthalocyanine Nanocomposites as Heterogeneous Photocatalysts for Decomposition of Organic Pollutants Trimethoprim, Caffeine and Prometryn

Abstract

São Simão's Brazilian kaolinite has been treated with titanium(IV) isopropoxide and cobalt(II) tetracarboxymetallophthalocyanine under different conditions (acidic or basic), leading, after drying at 100 ºC, to new titania-doped cobalt(II)-metallophthalocyanine/kaolinite solids. These solids were characterized by chemical analysis, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermal analyses and nitrogen adsorption. No significant changes were observed by diffractometry, but the specific surface area depended of the synthetic route followed. The ability of these solids for photodegradation of trimethoprim, caffeine and prometryn was evaluated. The photodegradation was followed via mass spectrometry and UV-Vis absorption spectroscopy. The presence of photodegradation by-products was verified in all cases. All the photocatalysts showed high photodegradation rate against prometryn, trimethoprim and caffeine, the degradation efficiencies were 54, 30 and 90%, respectively, when using the heterogeneous photocatalysts. Comparison with commercial TiO 2 (Degusa ®) proved that the synthesized photocatalyst based on kaolinite present higher degradation rate than isolated titanium dioxide.

White and Red Brazilian São Simão’s Kaolinite–TiO2 Nanocomposites as Catalysts for Toluene Photodegradation from Aqueous Solutions

“…Values of S MB of ca. 60–80 m 2 /g were found, similar to values reported in the literature [15,30,37].…”

“…Other kaolinite reflections were maintained at 400 °C, but for solids calcined at 700 and 1000 °C kaolinite was dehydroxylated, and its structure collapsed. Reflections from TiO 2 anatase and rutile phases were close to those from kaolinite, making the identification difficult in the solid calcined at 400 °C, but for the solids calcined at 700 and 1000 °C the peaks from both titania polymorphs became evident [15,30].…”

“…Upon heating at 400 °C, bands from the organic groups strongly decreased in intensity, although not completely disappearing, while bands from kaolinite were not altered. Calcination at 700 and 1000 °C led to the transformation from kaolinite into metakaolinite, also observing the vibration from amorphous silica in the 1200–1050 cm −1 region [15,27,30,33]. No bands involving Ti atoms were detected.…”

Oxidative Degradation of Pharmaceuticals: The Role of Tetrapyrrole-Based Catalysts

“…These semiconductor-promoted oxidation mechanisms are complementary to the ROS formation pathways mentioned above for the TPM-based catalysts and thus potentiate drug degradation. [1,13] Thus, a significant portion of the work developed in this field has been focused on the development of hybrid catalysts comprising TPM immobilized in semiconductors [2,[14][15][16][17][18][19][20][21][22].…”

Electrolytic Cell Applied for the Breakdown of Endocrine Disrupting Drugs in Aqueous Tributaries

“…Trimethoprim in Mexico is one of the most used drugs for treating urinary tract infections, and it is commonly used in the foreign tourism for attending the traveler's diarrhea [4]. Trimethoprim is incompletely metabolized by humans during the therapeutic process and approximately 80% is excreted in the pharmacologically active form, which can promote the development of bacterial resistance to this compound's form promoting it as an emerging contaminant [5].…”