Organic xerogels doped with Tris(2,2′-bipyridine) ruthenium(II) as hydroxyl radical promoters: Synthesis, characterization, and photoactivity

Xerogels based on resorcinol-formaldehyde (XRF) doped with different doses of Tris(2,2′-bipyridine) ruthenium(II) (RuBpy) were synthesized and characterized, and their photoactivity was determined in the presence of solar radiation. The addition of RuBpy did not modify the morphological and textural properties of the xerogels, which were all ultramicroporous, with a mean micropore surface of 240 m2 g−1; micropore volume of 0.10 cm3 g−1, and pore diameter of 0.64 nm. The addition of RuBpy reduced the band gap energy (Eg) values of the xerogels, which were 5.68 eV for XRF and 0.98 eV for XRF doped with 150 mg L−1 of RuBpy (X150RuB), due to the inclusion of RuBpy as charge center. The photocatalytic activity of the doped xerogels in pollutant degradation by solar radiation was analyzed in the photooxidation of chlortetracycline (CTC) as a model pollutant. The degradation percentages of CTC were 35.23%25 for XRF, 36.17%25 for X50RuB, 50.16%25 for X150RuB, and 31.33%25 for direct photolysis. The effect of radical scavengers (NO3− and tert-butanol) on the degradation and XPS analysis demonstrated that the hydrated electron (eaq−) generated by irradiation in the charge centers of the material migrates through the material and interacts with its functional groups, promoting the generation of OH radicals and the reduction and subsequent deactivation of the material. © 2016 Elsevier B.V.

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