Biomod/2013/NanoUANL/Reactor

What is a reactor?

Introduction

The CCMV capsid was considered as a continuous stirred-tank reactor with accumulation of the product. This is a common ideal reactor type in chemical engineering. This is an open system that operates on a steady-state assumption, where the conditions of the reactor do not change with time. It is a complete opposite of tubular plug-flow and stirred batch reactors, and can be very useful when studying the behavior of a gas, liquid or solid.

The reactor is modelled by that of a Continuous Ideally Stirre-Tank Reactor (CISTR), assuming perfect mixing in the container.

Enzymatic Reaction

The general reaction scheme is as follows:

[math]\displaystyle{ E + S \leftrightarrow ES \rightarrow E^0 + P }[/math]

With a reaction rate of:

[math]\displaystyle{ \frac{d[ES]}{dt}=k_1[E][S]-k_{-1}[ES]-k_2[ES] }[/math]

This equation is affected by the constants k₁ , k_-1 and k₂.

Considerations

We established the following considerations in our system:

• Uniform distribution throughout the reactor
• K_-1 >> K₁ and K₂
• One enzyme per reactor/VLP
• Tortuosity approaches zero during diffusion

Mass balance

Mass balance was presented as such:

INFLOW= OUTFLOW- DISAPPEARANCE BY REACTION + ACCUMULATION

where

Inflow= F₀

Outflow= F₀(1-X_S)

Disappearance = V(-r_S

Accumulation = [math]\displaystyle{ \tfrac{d[P]}{dt} }[/math]

F₀ = F₀(1-X_S) - V(-r_S) + [math]\displaystyle{ \tfrac{d[P]}{dt} }[/math]

The intake and outflow flux were determined by diffusion , considering a spherical container.

[[Image:CCMV2.jpg]thumb|right|Diagram of the container]]

For the simplification of the diffusion phenomenon we considered:

• Constant temperature
• Constant pressure
• Species B stays in a stationary state (it does not diffuse in A)
• The container (VLP) has a spherical shape

A mass balance, taking into account a spherical envelope leads to:

[math]\displaystyle{ \frac{d}{dr}(r^2N_{Ar})=0 }[/math]

where N_Ar represents molar flux. For N_Br we obtain:

[math]\displaystyle{ \frac{d}{dr}(r^2\frac{cD_{AB}}{1-x_A}\frac{dx_A}{dr})=0 }[/math]

At a constant temperature the product (cD_AB) is equally constant and x_A=1-x_B, the equation can be integrated into the following expression:

[math]\displaystyle{ F_A=4\pi r_1^2N_{Ar}|_{r=r1}= \frac{4\pi cD_{AB}}{1/r_1=1/r_2} \ln\frac{x_{B2}}{x_{B1}} }[/math]

where x are the fractions, c is the concentration and r are the respective radii.

This equation defines the nanoreactor inflow; a similar analysis yields the reactor outflow.

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The ionic silver diffusion coefficient in function to the solution is described by Nerst's equation (1888)¹:

[math]\displaystyle{ D_{AB}°= \frac{RT}{F^2} \frac{\lambda^o_+\lambda^o_-}{\lambda^o_++\lambda^o_-} \frac{|Z_-|+|Z_+|}{|Z_+Z_-|} }[/math]

where

• F = Faraday's constant
• D_AB°=Diffusion coefficient at infinite dilution
• λ₊°=Cationic conductivity at infinite dilution
• λ_-°=Anionic conductivity at infinite dilution
• Z⁺=Cation valence
• Z^-=Anionic valence
• T=Absolute temperature

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Via Joback's method, we obtain the normal boiling temperature:

[math]\displaystyle{ T_b=\mathbf{198} + \sum_{k} N_k(tbk) }[/math]

in which N_k is the number of times that the contribution occurs in the compound.

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Using a similar approach, also by Joback, we estimated the critical temperature:

[math]\displaystyle{ T_c=T_b\Bigg[ \mathbf{0.584}+\mathbf{0.965} \bigg\{\sum_{k} N_k(tck) \bigg\} - \bigg\{\sum_{k} N_k(tck) \bigg\}^2 \Bigg]^{-1} }[/math]

Joback Method Contributions (C1 Prausnitz)

[TABLA]

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Conductivity was determined by the Sastri method:

[math]\displaystyle{ \lambda_L=\lambda_ba^m }[/math]

where λ_L = thermic conductivity of the liquid [ W/(m·K)] λ_b = thermic conductivity at normal boiling point T_br= T/T_c = reduced temperature T_c = critical temperature, K

[math]\displaystyle{ m=1-\bigg(\frac{1-T_r}{1-T_{br}}\bigg)^n }[/math]

a=0.16 n=0.2

Contribución de Sastri (Tabla 10.5. Prausnitz 5a)

[TABLA]

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Silver density

{pendiente}