UV-Absorption—The Primary Process in Photocatalysis and Some Practical Consequences

Egerton, Terry A.

doi:10.3390/molecules191118192

Cited by 65 publications

(45 citation statements)

References 52 publications

(65 reference statements)

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“…UV absorbance is an important parameter affecting photocatalysis [10,35]. The maximum output wavelength of the UV lamp in our study was 365 nm, and the RO concentrate had an absorbance of 0.049 cm −1 at 365 nm (Table 1).…”

Section: Photocatalytic Degradation Of Crotamiton By the F9/p25 Compomentioning

confidence: 69%

Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

et al. 2017

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Abstract:Reverse osmosis (RO) concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO 2 ) and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO 2 /zeolite composite sheet. The RO concentrate was obtained from a pilot-scale municipal secondary effluent reclamation plant. Effective immobilization of the two powders in the sheet made it easy to handle and to separate the photocatalyst and adsorbent from purified water. The TiO 2 /zeolite composite sheet showed excellent performance for crotamiton adsorption without obvious inhibition by other components in the RO concentrate. With ultraviolet irradiation, crotamiton was simultaneously removed through adsorption and photocatalysis. The photocatalytic decomposition of crotamiton in the RO concentrate was significantly inhibited by the water matrix at high initial crotamiton concentrations, whereas rapid decomposition was achieved at low initial crotamiton concentrations. The major degradation intermediates were also adsorbed by the composite sheet. This result provides a promising method of mitigating secondary pollution caused by the harmful intermediates produced during advanced oxidation processes. The cyclic use of the HSZ-385/P25 composite sheet indicated the feasibility of continuously removing crotamiton from RO concentrate.

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Section: Photocatalytic Degradation Of Crotamiton By the F9/p25 Compomentioning

confidence: 69%

Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

et al. 2017

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“…In other words, the optical change arising from aggregation and agglomeration can reverse the photocatalytic effect expected from finer actual particles for other causes. This has been elegantly shown and discussed by Egerton [8]. The net effect obviously depends on the incident radiant flux.…”

Section: Absorption Of Photonsmentioning

confidence: 88%

Fundamentals of TiO2 Photocatalysis. Consequences for Some Environmental Applications

Pichat

2015

Green Chemistry and Sustainable Technology

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This chapter considers the fundamental phenomena occurring when TiO 2 is excited by photons. The focus is first on the formation and fate of the charges generated by the excitation. Then, the roles in photocatalytic reactions of water and oxygen which are almost always present are presented and discussed; the effects of adding ozone or hydrogen peroxide are also briefly indicated. Regarding the photocatalytic degradation of organic compounds -which is involved in potential applications such as self-cleaning materials and air or water purification -the following issues are examined: the hole-induced and hydroxyl radical-induced pathways and the predictability of the nature of the intermediate products. Some of the material aspects of photocatalysis are dealt with through (1) the influence of the structural and textural characteristics of pristine TiO 2 , (2) the effects of modifying TiO 2 by metal deposits or ion doping, and (3) the basic outcomes of combining TiO 2 with either another oxide (insulating or semiconducting) or a supplementary adsorbent of high surface area. Conclusions are drawn from these fundamental topics about the applicability of TiO 2 photocatalysis.

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“…In the case of oil paint, the binder is broken down into volatile components until the pigment is left unbound at the paint surface (chalking). UV absorption is the first step in photocatalytic degradation [9,10]. The penetration of light into a paint film is dependent on absorption and scattering of light by the binding medium and particles within it [11], which in turn are dependent on their intrinsic properties (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…The penetration of light into a paint film is dependent on absorption and scattering of light by the binding medium and particles within it [11], which in turn are dependent on their intrinsic properties (e.g. refractive index and photocatalytic properties), composition and particle size, as well as on the quality of dispersion [9]. The combination of short penetration depths of short wavelengths and the presence of UV-absorbing pigments will confine the degradation to the top surface of the paint [12,13].…”

Section: Introductionmentioning

confidence: 99%

Investigating the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints

et al. 2018

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This study reports on the effect of artists' paint formulation on degradation rates of TiO 2 -based oil paints. Titanium white oil paint exists in a multitude of different recipes, and the effect of the formulation on photocatalytic binder degradation kinetics is unknown. These formulations contain, among others, one or both titanium dioxide polymorphs, zinc oxide, the extenders barium sulfate or calcium carbonate and various additives. Most research performed on the photocatalytic degradation process focusses on pure titanium white-binder mixtures and thus does not take into account the complete paint system. Since photocatalytic oil degradation is a process initiated by the absorption of UV light, any ingredient or combination of ingredients influencing the light scattering and absorption properties of the paint films may affect the degradation rate. In this study three sets of experiments are conducted, designed using the design of experiments (DoE) approach, to screen for the most important formulation factors influencing the degradation rate. The benefits of using DoE, compared to a more traditional 'one factor at a time approach' are robustness, sample efficiency, the ability of evaluate mixtures of multiple components as well as the ability to evaluate factor interactions. The three sets of experiments investigate (1) the influence of the TiO 2 type, (2) the impact of different mixtures of two types of TiO 2 , ZnO and the additive aluminum stearate and (3) the influence of common extenders in combination with photocatalytic TiO 2 , on the photocatalytic degradation of the oil binder. The impact of the formulation on the degradation rate became apparent, indicating the shortcoming of oversimplified studies. The protective effect of photostable TiO 2 pigments, even in a mixture with photocatalytic TiO 2 pigments, as well as the negative effect of extenders was demonstrated. Furthermore, the ambiguous role of ZnO (photocatalytic or not) and aluminum stearate is highlighted. Neither can be ignored in a study of degradation behavior of modern oil paints and require further investigation.

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UV-Absorption—The Primary Process in Photocatalysis and Some Practical Consequences

Cited by 65 publications

References 52 publications

Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

Fundamentals of TiO2 Photocatalysis. Consequences for Some Environmental Applications

Investigating the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints

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