Water treatment: Mn-TiO2 synthesized by ultrasound with increased aromatics adsorption

Abstract

Pharma-products are mostly single or multiple cyclic compounds. They pollute surface water and are persistent in the aquatic ecosystem. When irradiated by UV light, TiO catalysts cleave or degrade organic contaminants in water. Removal of organics by photocatalysis results from a synergistic effect of adsorption and photocatalysis. Synthesis of catalysts by ultrasound (US) produces high surface area and porous solids. Here, we synthesized Mn-doped TiO with a US-assisted sol-gel method. Compared to the classical synthesis, US increased the BET surface area from 83 m g to 90 m g in the Mn-TiO sample and from 9.0 m g to 53 m g in the control TiO. Accordingly, acetaminophen and amoxicillin adsorption increased from 44% to 52%, and from 34% to 94% for the Mn-TiO obtained in absence and presence of US, respectively. When in a mixture, the two drugs strongly compete for adsorption on TiO.

Ultrasound to improve both synthesis and pollutants degradation based on metal nanoparticles supported on TiO2

“…Both anatase and rutile (even to a minor extent) polymorphs of TiO2 have been identified based on the fringe patterns and electronic diffraction: this evidence well agrees with literature data as well [41].…”

The Sonophotocatalytic Degradation of Pharmaceuticals in Water by MnOx-TiO2 Systems with Tuned Band-Gaps

“…UV-Vis measured the absorbance wavelength of the samples of Mn-doped TiO 2 ( Table 2). The absorbance wavelength of bare TiO 2 has a sharp edge at 400 nm, which is related to the excitation of the electrons from the valence band to the conduction band of the semiconductor (Figure 3) [29]. Oxygen occupies the 2p and 4d orbitals of the valence band (VB) of TiO2.…”

“…However, its large band-gap (from 3.0 eV to 3.2 eV), low quantum yield, and fast recombination of electron-hole pairs limits its commercial application under visible light. Metal, metal oxide, and non-metal doping extends the absorption of TiO 2 to a longer wavelength [24][25][26][27][28][29][30]. The efforts of researchers in the field of photocatalysis aim mainly at extending the band-gap to the visible light region of the solar spectrum (λ > 400 nm).…”

“…The efforts of researchers in the field of photocatalysis aim mainly at extending the band-gap to the visible light region of the solar spectrum (λ > 400 nm). To cope with the lengthy catalyst preparation steps and to improve the mixing between active phase and dopant(s), spray drying and ultrasound is an approach that has been recently adopted by the authors of this paper [29][30][31][32][33][34]. The shape and size of catalysts vary with the operating parameters, including the ultrasound irradiation time, temperature, power density, the ultrasonic source (bath-type and horn-type), magnetic stirring, and reactor shape and size [24,[35][36][37].…”

“…Stucchi et al investigated the effect of ultrasonication on Ag-doped TiO 2 's photocatalytic degradation of acetone under UV and visible light [32]. Stucchi et al also report that doping TiO 2 with Mn shifts the absorption towards the visible light region of the electromagnetic spectrum [29]. Among all the 3d metals, only Mn absorbs radiation in the visible region and infrared solar light [39,40].…”