Mathematical Model for Photocatalytic Destruction of Organic Contaminants in Air

Sanongraj, Wipada; Chen, Yongsheng; Crittenden, John C.; Destaillats, Hugo; Hand, David W.; Perram, David L.; Taylor, Roy

doi:10.3155/1047-3289.57.9.1112

Cited by 7 publications

(8 citation statements)

References 13 publications

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“…[ 72 ] Toluene is used as the reference component for TVOCs and the reaction rate of toluene decomposition on the catalyst surface ( r T ) is

r_{T} = - \frac{k K_{T} ([], T)}{1 + K_{T} ([], T)}

where k is the surface reaction rate constant, K T is the ratio of the adsorption rate constant to the desorption rate constant, and [ T ] is the toluene concentration in air. According to Sanongraj et al, [ 72 ] the surface reaction rate constant for toluene can be expressed as

k = \frac{K_{m} I}{A + I} ((), K_{3} + K_{4} ([], T_{0}) + K_{5} {[T_{0}]}^{2}) ((), K_{5} + K_{2} italicRH)

where K m , K 2 , K 3 , K 4 , K 5 and K 6 are fitting parameters, RH is the relative humidity of the air, I is the light intensity, and A is the constant for accounting the influence of the UV light intensity. As light attenuates when it penetrates the catalyst bed, the light intensity at different catalyst depth ( z ) can be described by the Beer's law.…”

Section: Example 2:air Purifiermentioning

confidence: 99%

“…As light attenuates when it penetrates the catalyst bed, the light intensity at different catalyst depth ( z ) can be described by the Beer's law. [ 72 ]

I = I_{0} e^{- italicεz ρ_{b}}

where I 0 is the light intensity at the catalyst surface, ε is the UV light adsorption coefficient of the catalyst, and ρ b is the bulk density of the catalyst. To ensure the regressed parameters are applicable, the minimum light intensity in the catalyst bed needs to be larger than 2000 mW/m 2 (ie, I ≥ 2000 mW/m 2 ).…”

Section: Example 2:air Purifiermentioning

confidence: 99%

“…From the engineering statement, V r equals 50 m 3 , [ T 0 ] and [ T f ] equal 150 and 0.6 mg/m 3 , respectively, and G equals 0.28 mg/min. Assuming the indoor air is at a RH of 80%, the reaction rate constant k ′ can be obtained using the regressed parameters summarized in Table S6 for toluene degradation conducted using Pt‐TiO 2 catalyst coated on an HEPA filter, [ 72 ] which has an ε = 1131.9 cm 2 /g and ρ b = 3.76 g/cm 3 . To ensure the target performance is achieved (ie, toluene concentration reaches 0.6 mg/m 3 in 8 hours), design parameters including the required I 0 , A f , and L need to be determined.…”

Section: Example 2:air Purifiermentioning

confidence: 99%

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Conceptual design of chemical devices

Fung

Wibowo

et al. 2020

J Adv Manuf & Process

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Chemical devices are chemical products that transform a feed stream into an outlet stream with the desired attributes by performing reaction, fluid flow, heating, cooling, and/or separations. They resemble small chemical plants and can be described by device flowsheets, similar to the process flowsheets of chemical plants. This article proposes a generic design framework for chemical devices. It shares some steps with Douglas' hierarchical design procedure for chemical processes but has its own distinguishing features such as capturing of consumer preferences, formulation of an engineering statement, and the use of unconventional processing techniques in device manufacturing. Two examples, domestic dehumidifier and air purifier, are discussed to illustrate the design framework. A new dehumidifier design was found using this framework.

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“…[ 72 ] Toluene is used as the reference component for TVOCs and the reaction rate of toluene decomposition on the catalyst surface ( r T ) is

r_{T} = - \frac{k K_{T} ([], T)}{1 + K_{T} ([], T)}

k = \frac{K_{m} I}{A + I} ((), K_{3} + K_{4} ([], T_{0}) + K_{5} {[T_{0}]}^{2}) ((), K_{5} + K_{2} italicRH)

Section: Example 2:air Purifiermentioning

confidence: 99%

“…As light attenuates when it penetrates the catalyst bed, the light intensity at different catalyst depth ( z ) can be described by the Beer's law. [ 72 ]

I = I_{0} e^{- italicεz ρ_{b}}

Section: Example 2:air Purifiermentioning

confidence: 99%

Section: Example 2:air Purifiermentioning

confidence: 99%

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Conceptual design of chemical devices

Fung

Wibowo

et al. 2020

J Adv Manuf & Process

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“…1 Among the wide variety of VOCs, the halogenated VOCs are considered the primary environmental pollutants and are harmful to human health. 2 In response to treat these halogenated VOCs, ultraviolet (UV) photochemical technology is often regarded as one of the effective methods. [3][4][5][6] A low-pressure mercury lamp with a main output at 254 nm and a small fraction of the total irradiation at 185 nm is a widely used UV light source.…”

Section: Introductionmentioning

confidence: 99%

Effects of Operation Conditions on Removal Rate Constant and Quantum Yield of Gaseous Chlorobenzene Degradation in a Photochemical Reactor

Wang

2009

Journal of the Air & Waste Management Association

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A photochemical reactor with a low-pressure mercury ultraviolet (UV) lamp was established to treat waste gas containing chlorobenzene. Operation conditions such as light intensity, gas humidity, and inlet chlorobenzene concentration were varied. Two significant parameters, the removal rate constant and the quantum yield (relating to removal kinetic and light energy utilization), were investigated under each set of conditions. The experimental results indicated that the removal of chlorobenzene by UV irradiation in the gas phase followed a first-order kinetic model at inlet chlorobenzene concentrations ranging from 200 to 2500 mg x m(-3). With increasing light intensity from 10 to 37 microW x cm(-2), the chlorobenzene removal rate constant rose from 0.004 to 0.011 sec(-1), whereas the quantum yield maintained the same value of 0.60. The effects of gas humidity on the parameters indicated that the highest humidity of 80% could achieve the highest removal rate constant (0.046, 0.029, and 0.015 sec(-1)) and the highest quantum yield (1.91, 1.19, and 0.60) among the tested gas humidities at the inlet concentrations of 400, 1000, and 2500 mg x m(-3), respectively. An increase in inlet chlorobenzene concentration from 200 to 2500 mg x m(-3) resulted in reduction in both removal rate constant (from 0.060 to 0.014 sec(-1)) and quantum yield (from 2.50 to 0.56) that may be attributable to competition between the intermediates and chlorobenzene. On the basis of the quantum yield, the total power expended per mass of chlorobenzene was calculated as 483 kWh x kg(-1) under the conditions of an inlet concentration of 200 mg x m(-3) and an empty-bed residence time of 27 sec.

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“…Indoor air quality can be affected by VOCs, tinny particulates, microbes, or various types of hazardous pollutants which present a health risk to people. Rigorous mathematical modeling of fluid dynamics leads to a system of partial differential equations describing chemical behavior (Sanongraj et al, 2007). To understand the fate and dynamics of a chemical pollutant entering an airconditioned environment, a conceptual box model is proposed, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Using Box Modeling to Determine Photodegradation Coefficients Describing the Removal of Gaseous Formaldehyde from Indoor Air

Lin

Jwo

et al. 2017

Aerosol Air Qual. Res.

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Human exposure to volatile organic compounds (VOCs) indoors is receiving increasing attention. Formaldehyde (HCHO) is the most common VOC emitted from household materials and is associated with many health risks, including sick building syndrome. In this study, a simple box model was developed and applied to help understand the fate and degradation mechanisms of HCHO in the indoor environment. The model was validated using observations from an air handling system under different conditions. A UV/TiO 2 filter reactor was installed in a closed box with the air conditioning unit. Three parameters, temperature, relative humidity, and circulation wind speed, were investigated for their effects on the performance of the air handling system. Our results show that the operation mode of the air handling system has a greater effect on the removal of HCHO than any of the air conditioning parameters. From a kinetic perspective, the removal of gaseous HCHO from a constant-volume box clearly represents a zero-order reaction. After UV irradiation with a TiO 2 filter for 2 hours, the removal efficiency of gaseous HCHO increases to approximately 90%. Contributions to the removal of gaseous HCHO from natural dissipation, photodegradation, and photocatalytic oxidation decomposition are 12%, 30%, and 58%, respectively. Our results have implications for reducing indoor air pollution and reducing stress on air conditioning systems. Meeting these goals is beneficial for human health and energy conservation in modern society.

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Mathematical Model for Photocatalytic Destruction of Organic Contaminants in Air

Cited by 7 publications

References 13 publications

Conceptual design of chemical devices

Conceptual design of chemical devices

Effects of Operation Conditions on Removal Rate Constant and Quantum Yield of Gaseous Chlorobenzene Degradation in a Photochemical Reactor

Using Box Modeling to Determine Photodegradation Coefficients Describing the Removal of Gaseous Formaldehyde from Indoor Air

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