TiO2 photocatalytic degradation of 4-chlorobiphenyl as affected by solvents and surfactants

Abstract

Purpose TiO 2 photocatalytic degradation of 4-chlorobiphenyl (PCB3) in aqueous solution under UV irradiation was investigated as affected by different environmental factors, including initial PCB3 concentration, TiO 2 content, UV intensity, H 2 O 2 concentration, cosolvents, and surfactants. Materials and methods The solution of PCB3 with TiO 2 was irradiated by medium mercury lamp. The concentration of PCB3 and intermediates was analyzed by GC-μECD and GC-MS. The values of point charge and bond length were also calculated with ChemOffice 2004 (Mopac unit). Results and discussion Photocatalysis was very effective for PCB3 removal, and the degradation kinetics were fitted with a pseudo-first order reaction model. PCB3 was efficiently degraded in the presence of acetone and acetonitrile, but was completely inhibited with other examined cosolvents. HPCD and Tween80 also inhibited the degradation rate of PCB3, while Brij35 slightly decreased the degradation rate of PCB3 at first, and then increased. The reaction mechanism occurred principally by hydroxyl radicals involving the participation of holes and superoxide anion oxidation.A possible photocatalytic degradation pathway of PCB3 was proposed based on the identified reaction intermediates as well as computer simulation. Conclusions The photocatalytic approach could be successfully applied to degrade PCB3, and cosolvents and surfactants significantly influenced its degradation kinetics.

Hydrophobic TiO2‐SiO2 Aerogel Composites for Fast Removal of Organic Pollutants

“…From the above‐discussed hypotheses and optimization, it is clear that high surface area and porous SiO 2 adsorption site could contribute to the pollutant removal efficiency of the TiO 2 ‐SiO 2 aerogel if the composite is accessible by pollutant solution, which was confirmed by our previous study . As for non‐heat‐treated hydrophobic TiO 2 ‐SiO 2 aerogels, their photocatalytic ability was confirmed (Figure S1, SI), in order to improve their adsorption ability to pollutant solution, a lipophilic co‐solvent could be applied to modify the interface between TiO 2 ‐SiO 2 aerogel and solvent . In this study, the solvent water in methyl orange solution was replaced by ethanol in 1–50 vol.%, and the pollutant removal experiment was examined on the optimized TiO 2 ‐SiO 2 sample ( C si =6.5/ R =5:1) but without calcination.…”

“…[10] As for non-heat-treated hydrophobic TiO 2 -SiO 2 aerogels, their photo- catalytic ability was confirmed ( Figure S1, SI), in order to improve their adsorption ability to pollutant solution, a lipophilic co-solvent could be applied to modify the interface between TiO 2 -SiO 2 aerogel and solvent. [13] In this study, the solvent water in methyl orange solution was replaced by ethanol in 1-50 vol.%, and the pollutant removal experiment was examined on the optimized TiO 2 -SiO 2 sample (C si = 6.5/R = 5:1) but without calcination. The photolysis of methyl orange concentration, with 1 vol.% ethanol replacement, as a function of time presents a degradation of 40% of initial methyl orange concentration after 60 mins UV exposure, and the sample accomplished the degradation up to 99% of initial methyl orange concentration in 30 mins when 50 vol.% water was replaced by ethanol, shown in Figure 5.…”

Review of chemical and electrokinetic remediation of PCBs contaminated soils and sediments

“…For example, PCBs were completely photodegraded in acetone and acetonitrile solutions, but hardly degraded in tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, methanol, ethanol, propanol, and isopropanol solutions, due to the consumption of ROS (e.g., hydroxyl radical (cOH)) by these solvents. 28,42 It should be emphasized that these organic solvents not only inuence the degradation efficiency of PCBs, but also change the photodegradation pathway of PCBs, which resulted in different proles of PCB metabolites. For example, the hydroxylated chlorobiphenyl (OH-PCB) was the dominant intermediate of PCBs photodegradation via the hydroxylation reaction between cOH and PCBs in a TiO 2 /UV system in the presence of acetone.…”

Cu2O Cubes Decorated with Azine-Based Covalent Organic Framework Spheres and Pd Nanoparticles as Tandem Photocatalyst for Light-Driven Degradation of Chlorinated Biphenyls

“…Specifically, Wang et al 35 studied the photocatalytic degradation of 2chlorobiphenyl using TiO 2 and found that TiO 2 enhanced the catalytic degradation of 2-chlorobiphenyl with a rate constant of 0.029 min −1 . Zhu et al 36 also explored the use of TiO 2 in the photocatalytic degradation of 4-chlorobiphenyl and found that TiO 2 was capable of degrading 4-chlorobiphenyl with a rate constant of 0.009 min −1 . Paĺmai et al 37 reported that m-BiVO 4 /BiOBr and m-BiVO 4 /BiOBr/Pd were able to degrade 4-chlorobiphenyl with rate constants of 0.014 and 0.03 min −1 , respectively.…”