Visible-Light Photocatalytic Degradation of Aniline Blue by Stainless-Steel Foam Coated with TiO2 Grafted with Anthocyanins from a Maqui-Blackberry System

Abstract

Anthocyanins from maqui (Aristotelia chilensis) and blackberry (Rubus glaucus) were used as light harvesters to improve the photocatalytic activity of titanium dioxide in visible light. Anthocyanins from both species were obtained using high-frequency ultrasound-assisted liquid-liquid extraction with methanol. Mixtures of anthocyanins were developed to study their effectiveness in the visible light/TiO2 reaction for the oxidation of aniline blue. For this purpose, stainless-steel foams were covered with TiO2 and anthocyanin and characterized by SEM. Different samples were fabricated by varying the ratio of the two anthocyanins in the mixture (100, 75, 50, 25 and 0 vol% of maqui-anthocyanin (delphinidin)). The mixtures of 25 vol% anthocyanin from maqui and 75 vol% anthocyanin from blackberry had higher total anthocyanin content and better photocatalytic activity in visible light: degradation of aniline blue was 40% at pH 7, 56% at pH 3 and 95% at pH 3 with the injection of oxygen for 2 h in comparison with TiO2-foam/UV light, which yielded values of 13% at pH 7 and 73% at pH 3 with and without the addition of oxygen. Natural dyes that are low-cost and environmentally friendly substances are shown to be capable of improving the visible-light photocatalytic activity of TiO2.

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

“… The cavitation bubbles created in the solvent penetrate the cells and accelerate the diffusion process. [175] Anthocyanins Grape pomace UAE ES: hydro alcoholic solution 10 g grape sample in 400 mL solvent, sonicated (USB) 40 kHz, 160 W, 65 °C for 30 min. Increased mobility of the solvent and samples improving the efficiency Extraction variation is due to the combination of the cavitation and thermal effects [176] Anthraquinones Stems and leaves of Heterophyllae pustulata Hook UAE ES: hexane, benzene and ethyl acetate Sonicated (USB) 80 W, 40 kHz frequency.…”

Editorial Catalysts: Special Issue on Recent Advances in TiO2 Photocatalysts

“…AOPs are highly effective due to the formation of reactive oxygen species, especially hydroxyl radicals, which act as oxidizing agents. Among AOPs, semiconductor photocatalysis, especially with titanium dioxide (TiO 2 ), has a great potential for the decontamination of water and wastewater, exhaust gases, and disinfection [1][2][3][4][5][6][7][8]. This inexpensive, stable, and non-toxic catalyst provides very good removal efficiency.…”

“…However, due to the large energy band gap, its activity in the range of natural solar light is quite limited. For this reason, the development of new TiO 2 -based photocatalysts active in the visible range has become a new research trend [1,3,6,13,[15][16][17][18][19]. The effectivity can also be improved by modifying TiO 2 with noble metals [2,13,15] or by Ti 3+ -self-doped TiO 2 modification [11].…”

“…Methylene blue degradation was investigated in the presence of polyaniline-wrapped, manganese-doped titanium oxide (PANi/Mn-TiO 2 ) [16] as well as Au-Ag co-decorated TiO 2 (Au x Ag (1−x) /TiO 2 ) [15] under visible light. Surprisingly, the presence of inexpensive and environmentally friendly natural dyes (anthocyanin pigments) improved the visible light photocatalytic activity of TiO 2 [1]. Stainless-steel foam coated with TiO 2 grafted with anthocyanins originating from a Maqui-Blackberry system was successfully applied for Aniline blue removal [1].…”

“…Surprisingly, the presence of inexpensive and environmentally friendly natural dyes (anthocyanin pigments) improved the visible light photocatalytic activity of TiO 2 [1]. Stainless-steel foam coated with TiO 2 grafted with anthocyanins originating from a Maqui-Blackberry system was successfully applied for Aniline blue removal [1]. However, despite the efficient degradation of dye solutions in the presence of TiO 2 -catalysts, the application of TiO 2 catalysts for industrial textile wastewater treatment was not satisfactory, even when it was enhanced by the presence of ozone [23].…”