A new kinetic model for heterogeneous photocatalysis with titanium dioxide: Case of non-specific adsorption considering back reaction

Valencia, Sergio; Cataño, Francisco A.; Ríos, Luis; Restrepo, Gloria; Marín, Juan

doi:10.1016/j.apcatb.2011.03.015

Cited by 59 publications

(20 citation statements)

References 23 publications

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“…However, at higher light intensity, the reaction rate increasingly shows diminishing returns. This behavior was often observed for other photocatalytic reactions as well and attributed to increased charge carrier recombination at higher light intensity (Upadhya and Ollis, 1998; Satuf et al, 2008; Valencia et al, 2011; Mills et al, 2015; Nosaka and Nosaka, 2018). Some kinetic models account for this by using a mixed linear and square root dependence for the light intensity (Ollis, 2005; Mills et al, 2006; Dillert et al, 2013; Montoya et al, 2014; Camera-Roda et al, 2015; Deng, 2018).…”

Section: Resultssupporting

confidence: 53%

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

2019

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The photocatalytic reduction of nitrobenzene to aniline in alcoholic solutions appears as an interesting alternative to the classical hydration. However, little is known about the influence of reaction parameters on the kinetics of the reaction which were therefore studied herein. The effects of light intensity, catalyst concentration, initial concentration, and temperature were systematically investigated under more than 50 different conditions and accurately described with an appropriate kinetic model. The results show that the efficiency of the reaction is extremely high and apparent quantum yields of up to 142 % were observed under optimized conditions. Particularly interesting is the fact high efficiencies were also obtained at high reaction rates of up to 74.3 mM h −1 . Overall these results demonstrate that heterogeneous photocatalytic reactions can be very efficient and productive at the same time and may therefore present a powerful tool in synthetic organic chemistry.

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Section: Resultssupporting

confidence: 53%

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

2019

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“…Mills et al ( 2015 ) have termed this pseudo steady state approach the “disrupted adsorption kinetic model” and analyzed it along with other pseudo-steady state models for photocatalyzed reactions, paying particular attention to the most promising, those of Gerischer ( 1995 ); Emeline et al ( 2000 ), Valencia et al ( 2011 ), and Montoya et al ( 2014 ). They concluded that “The best of those tested, in terms of overall fit, simplicity, usefulness, and versatility is the disrupted adsorption kinetic model proposed by Ollis.”…”

Section: Lesson 3: Photocatalysis Kinetics Require a Pseudo-steady Stmentioning

confidence: 99%

Kinetics of Photocatalyzed Reactions: Five Lessons Learned

Ollis

2018

Front. Chem.

100

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Elucidation of kinetics of photocatalyzed chemical mechanisms occurring at interfaces (gas-solid, liquid-solid) has been challenging. We summarize here five lessons learned over five decades.1. An assumed reaction network leads to a single kinetic model, but a common model, the Langmuir–Hinshelwood rate equation, r = kcat K C/ [1 +KC], arises from multiple mechanisms, hence models alone do not reveal unique mechanisms.2. The Langmuir–Hinshelwood model parameter kcat represents the slow step at a catalyst surface, and in thermal catalysis, depends upon the reactant structure. However, early photocatalysis work with light chlorinated hydrocarbons in aqueous solutions showed a single kcat value, independent of reactant structure.3. The dependence of the Langmuir-Hinshelwood parameters, kcat and K, upon intensity indicates that a pseudo-steady state approach is more fundamental than the presumed equilibrated adsorption of the LH model.4. Dyes and phenols are commonly studied, and claimed as first order reactions, despite often exhibiting rate constants which diminish with increasing contaminant concentration. We show that such studies are the result of intrinsic zero order data plotted on a semilog graph, and involve zero order rate limitation by reactant saturation, electron transfer to O2, oxygen mass transfer, or light supply.5. The apparent kinetics for contaminant removal from photocatalytic self-cleaning surfaces depends upon multiple circumstances, including the geometry of reactant deposit, catalyst porosity, and reactant light absorption. A single decision table suffices to indicate the apparent reaction order, n, to assume when fitting photocatalytic kinetic data from self-cleaning surfaces to a power law rate form, rate = k Cn.

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“…I n recent years, heterogeneous photocatalysis in the presence of TiO 2 has attracted a great deal of attention for the purification of water (Valencia et al, 2011). TiO 2 photocatalysis accelerates the photochemical transformation by the action of a catalyst, which is active, low in cost, nontoxic, and chemically stable over a wide pH range (Nieto-Suárez et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Removal of Carbamazepine from Water by a Novel TiO₂–Coconut Shell Powder/UV Process: Composite Preparation and Photocatalytic Activity

Khraisheh

Kim

Campos

et al. 2013

Environmental Engineering Science

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A novel TiO-coconut shell powder (TCNSP) composite, prepared by the controlled sol-gel method with a subsequent heat treatment, was investigated as an innovative photocatalytic absorbent for the removal of carbamazepine (CBZ). CBZ is used worldwide as an antiepileptic drug, which has recently been recognized as an important organic pollutant increasingly found in wastewaters from urban areas and other aquatic environments. The granulation process was performed by using a semiautomated mass production line to produce sufficient quantities of TCNSP composites, possessing sufficient crush strength for commercialization. Physical properties of the TCNSP composite such as crystallinity, morphology, crush strength, and the Brunauer-Emmett-Teller (BET)-specific surface area were controlled by the mass ratio of titanium dioxide sol and coconut shell powder (CNSP). Calcination at 700°C produced anatase phase TiO in the TCNSP composites with a BET high surface area of 454 m/g. Anatase crystallite size of the TCNSP composite increased from 2.37 to 15.11 nm with increasing calcination temperature from 500°C to 800°C. Calcinated TCNSP composites had higher CBZ removal efficiency (98%) than pure TiO (23%) and CNSP (34%) within a 40-min reaction time. Optimization of this innovative adsorption/photocatalytic process was obtained by a response surface methodology and a central composite design model, which indicated that this novel and sustainable technology was successful in removing CBZ from a solution.

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A new kinetic model for heterogeneous photocatalysis with titanium dioxide: Case of non-specific adsorption considering back reaction

Cited by 59 publications

References 23 publications

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

Kinetics of Photocatalyzed Reactions: Five Lessons Learned

Removal of Carbamazepine from Water by a Novel TiO₂–Coconut Shell Powder/UV Process: Composite Preparation and Photocatalytic Activity

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A new kinetic model for heterogeneous photocatalysis with titanium dioxide: Case of non-specific adsorption considering back reaction

Cited by 59 publications

References 23 publications

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

Kinetics of Photocatalyzed Reactions: Five Lessons Learned

Removal of Carbamazepine from Water by a Novel TiO2–Coconut Shell Powder/UV Process: Composite Preparation and Photocatalytic Activity

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Product

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Removal of Carbamazepine from Water by a Novel TiO₂–Coconut Shell Powder/UV Process: Composite Preparation and Photocatalytic Activity