TiO2 Modified with Organic Acids for the Decomposition of Chlorfenvinphos under the Influence of Visible Light: Activity, Performance, Adsorption, and Kinetics

Abstract

Photocatalytic decomposition of chlorfenvinphos (CFVP) in the presence of titanium dioxide (TiO2) modified with organic acids: pyruvic (PA) and succinic (SA) under the visible light radiation has been studied. The following tests were examined: dose of photocatalysts, adsorption time, pH of the model solution, deactivation of catalysts, the role of oxygen, identification of free radicals for the CFVP decomposition, Langmuir-Hinshelwood kinetics. The synthesized materials were characterized by Scanning Electron Microscopy (SEM) and UV-Vis. At 10 wt.% of acid (90:10) decomposition of chlorfenvinphos was the most effective in the following conditions: dose of catalyst 50.0 mg/L, time of adsorption = 20 min, pH of model solution = 3.0. Under these conditions the order of photocatalyst efficiency has been proposed: TiO2/PA/90:10 > TiO2/SA/90:10 > TiO2 with the removal degree of 85, 72 and 48%. The mathematically calculated half-life at this conditions was 27.0 min and 39.0 min for TiO2/PA/90:10 and TiO2/SA/90:10 respectively, compared to 98 min for pure TiO2. It has been determined that the O2•− radicals and holes (h+) are the main reactive species involved in the photodegradation of chlorfenvinphos. The results of this study showed that method may be an interesting alternative for the treatment of chlorfenvinphos contaminated wastewater.

Visible Light–Driven Advanced Oxidation Processes to Remove Emerging Contaminants from Water and Wastewater: a Review

“…CFVP removal processes during visible light–driven photocatalysis have not been carried out by many studies. The use of modified titanium(IV) oxide to degrade CFVP has been studied by Zawadzki ( 2020 ). Approximately 85% degradation of CFVP (initial concentration C 0[CFVP] = 1 mg/l) in the presence of TiO 2 modified with pyruvic acid in a 90:10 ratio (TiO 2 :pyruvic acid (PA), 90:10) was achieved.…”

“…The presence of these injected electrons will then interact with the dye to start its degradation Acosta-Esparza et al ( 2020 ) Chlorfenvinphos Photocatalysis in the presence of pyruvic acid (PA)-doped TiO 2 (TiO 2 /PA) The photodegradation is mainly due to radicals, then h + and least OH − . In the model solution at pH = 3, due to the change in hydrophobic properties of TiO 2 modified with organic acids, the mechanism involves the adsorption of CVFP on the catalyst surface, followed by cleavage of the aromatic ring by oxidizing radicals, mainly Zawadzki ( 2020 ) Chlorfenvinphos Visible light–driven photoelectrochemical degradation in the presence of WO 3 nanorods Degradation in the presence of WO 3 nanotubes occurs by cleavage of the aromatic ring (π-π*). The time evolution of the UV absorption spectra of CFVP took values greater than 0, which means that the degradation of CFVP probably takes place by opening the aromatic ring and then generating intermediate compounds Degradation by hydroxyl radicals or directly with photodegenerated holes on the WO 3 surface in semiconductor/electrolyte solution Further analytical work is needed to propose the full mechanism of chlorfenvinphos degradation in the presence of WO 3 nanotubes Fernández-Domene et al ( 2019 ) Roselló-Márquez et al ( 2019 ) Chlorfenvinphos Photodegradation by using WO 3 nanostructures • OH radicals are used as the main oxidizing agent for the degradation of CFVP.…”

“…Over the last years, authors of many works have attempted to produce photocatalysts active in visible light or develop methods and/or materials for semiconductor modification. This issue has been extensively discussed in the works of Parnicka et al (2017), Liao et al (2018), D'Amato et al (2018, Farhadian et al (2019), Qi et al (2019), andZawadzki (2020). In brief, various types of metal or non-metal dopants (e.g., carbon, silver, gold, neodymium), activated carbon (granular or powdered), graphene oxide or carbon nanotubes or biopolymers (e.g., chitosan), and organic acids (e.g., ascorbic acid, succinic acid, pyruvic acid) are used to modify semiconductors.…”

“…1 ). In recent years, researchers have focused on modifications of advanced oxidation processes (Cheng et al, 2019 ; Zawadzki et al, 2020 ; Zawadzki, 2020 ; Nguyen et al, 2020 ). Modifications simplify the way catalysts are activated, and increase the degree of pollutant removal efficiency with variable wastewater quality.…”