Problem 30-1E. The photocatalytic tubular reactor shown in Figure 30-1E is used to decompose organic contaminants in liquid waste water. The inter walls of the 1.5 cm inner diameter glass tube are lined with a thin, nonporous, transparent layer of nano-crystalline titanium dioxide (TiO₂), which catalyzes the oxidation of dissolved organic chemicals to carbon dioxide and water, using sunlight to drive this photocatalytic process. In the present process, waste water containing 10 g/m³ of benzene (solute A) dissolved in water enters the tube at 313 K, and it is necessary to have a Reynolds number (Re) of 5000 for flow through the tube. The steady state process temperature is 313 K. For purposes of analysis, assume the consumption of species A at the catalyst surface is so rapid that the effective concentration of species A at the catalyst surface is equal to zero (CALS~ 0). Potentially useful data at 313 K: molecular diffusion coefficient of benzene (CH6, species A) in liquid water, DAB = 1.45 x 105 cm²/sec, M₁ = 78 g/gmole, μB = 0.00658 g/cm-sec (0.658 CP), PB = 0.993 g/cm³. sunlight wastewater CALO 10 g A/m³ Re = 5000 313K D = 1.5 cm transparent TiO₂ catalyst layer lining inside of glass tube z = L = 25m CAL NA CAL,S 0 catalyst surface Figure 30-1E. Photocatalytic tubular reactor. (a) Identify the SOURCE and SINK for mass transfer of benzene. (b) Is the photocatalytic reaction is best represented as (1) A homogeneous reaction within the control volume for mass transfer or (2) A heterogeneous reaction at a boundary surface? Justify your response. (c) Estimate the convective mass transfer coefficient of benzene in water flowing through the tube, k₁.
Problem 30-1E. The photocatalytic tubular reactor shown in Figure 30-1E is used to decompose organic contaminants in liquid waste water. The inter walls of the 1.5 cm inner diameter glass tube are lined with a thin, nonporous, transparent layer of nano-crystalline titanium dioxide (TiO₂), which catalyzes the oxidation of dissolved organic chemicals to carbon dioxide and water, using sunlight to drive this photocatalytic process. In the present process, waste water containing 10 g/m³ of benzene (solute A) dissolved in water enters the tube at 313 K, and it is necessary to have a Reynolds number (Re) of 5000 for flow through the tube. The steady state process temperature is 313 K. For purposes of analysis, assume the consumption of species A at the catalyst surface is so rapid that the effective concentration of species A at the catalyst surface is equal to zero (CALS~ 0). Potentially useful data at 313 K: molecular diffusion coefficient of benzene (CH6, species A) in liquid water, DAB = 1.45 x 105 cm²/sec, M₁ = 78 g/gmole, μB = 0.00658 g/cm-sec (0.658 CP), PB = 0.993 g/cm³. sunlight wastewater CALO 10 g A/m³ Re = 5000 313K D = 1.5 cm transparent TiO₂ catalyst layer lining inside of glass tube z = L = 25m CAL NA CAL,S 0 catalyst surface Figure 30-1E. Photocatalytic tubular reactor. (a) Identify the SOURCE and SINK for mass transfer of benzene. (b) Is the photocatalytic reaction is best represented as (1) A homogeneous reaction within the control volume for mass transfer or (2) A heterogeneous reaction at a boundary surface? Justify your response. (c) Estimate the convective mass transfer coefficient of benzene in water flowing through the tube, k₁.
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Transcribed Image Text:### Problem 30-1E
The photocatalytic tubular reactor shown in Figure 30-1E is used to decompose organic contaminants in liquid waste water. The inner walls of the 1.5 cm inner diameter glass tube are lined with a thin, nonporous, transparent layer of nano-crystalline titanium dioxide (TiO₂), which catalyzes the oxidation of dissolved organic chemicals to carbon dioxide and water, using sunlight to drive this photocatalytic process. In the present process, waste water containing 10 g/m³ of benzene (solute A) dissolved in water enters the tube at 313 K, and it is necessary to have a Reynolds number (Re) of 5000 for flow through the tube. The steady state process temperature is 313 K. For purposes of analysis, assume the consumption of species A at the catalyst surface is so rapid that the effective concentration of species A at the catalyst surface is equal to zero (CAL,S ≈ 0).
Potentially useful data at 313 K:
molecular diffusion coefficient of benzene (C₆H₆, species A) in liquid water, D_AB = 1.45 x 10⁻⁵ cm²/sec,
M_A = 78 g/mole,
μ_B = 0.00658 g/cm-sec (0.658 cP),
ρ_B = 0.993 g/cm³.
**Figure 30-1E. Photocatalytic tubular reactor.**
**Graph/Diagram Description:**
The diagram illustrates a tubular reactor used in a photocatalytic process:
- Wastewater enters the tube containing benzene at a concentration \( C_{A,L0} = 10\, \text{g}/\text{m}^3 \), with a Reynolds number \( Re = 5000 \), and temperature 313 K.
- The inner diameter of the tube is \( D = 1.5\, \text{cm} \).
- A transparent TiO₂ catalyst layer lines the inside of the glass tube.
- Sunlight is used to drive the photocatalytic reaction.
- The process tube length is \( L = 25\, \text{m} \).
- At the catalyst surface, the concentration of species A (benzene) is approximately zero (\( C_{A,L,S} \approx 0 \)).
- The concentration of benzene at the end of the tube length
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