Treatment of organic pollutants in water using TiO2 powders: photocatalysis versus sonocatalysis

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

“…This phenomenon is referred to as acoustic cavitation. It is accompanied by a number of secondary effects, among them sonoluminescence, an emission of sonoluminescent light (mainly UV light) during the implosion of the cavitation bubbles suspended in a liquid [39, 40]. …”

“…Therefore, a specific “electron-hole” pair (e −  + h + ) is created [40–42]. This bound state, called exciton, lacks stability and exhibits redox properties.…”

“…Excited negative electrons (e − ) reduce molecular oxygen (O 2 ), forming superoxide radical anion ( • O 2 − ). Generated positive holes (h + ) oxidize water molecules (H 2 O) and hydroxide ions (OH − ), producing hydroxyl radicals ( • OH) and hydrogen peroxide molecules (H 2 O 2 ) [40–43] (Fig. 1).…”

“…The recombination of the electron-hole pair (e −  + h + ) is accompanied by the emission of a photon (radiative recombination). In this process, the excitation of ground state oxygen (O 2 ) by photon occurs and singlet oxygen ( 1 O 2 ) is formed [40, 43] (Fig. 1).…”

Novel one pot synthesis and spectroscopic characterization of a folate-Mn3O4 nanohybrid for potential photodynamic therapeutic application

“…Thus, exposure to the blue light facilitates the excitation followed by relocation of valence band electrons to conduction band of the metal, which in turn creates an electron-hole pair in the metal. [31][32][33] The excited state electrons may either migrate towards the dissolved oxygen present in the solution to reduce it to superoxide radical anion (cO 2 À ), or generate singlet oxygen ( 1 O 2 ) during their return to the ground state. [31][32][33] Similarly, the holes can oxidize hydroxyl ion or water molecules and generate hydrogen peroxide (H 2 O 2 ) or hydroxyl radical (HOc).…”