What is zeroth order first order and second order dye degradation?
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In order to quantify photocatalytic activity of heterogeneous photocatalysts, Langmuir-Hinshelwood model is generally used:
Rate = -d[Pollutant]/dt = kK[Pollutant]/(1+K[Pollutant]) (1)
In which, K and k are thermodynamic adsorption constant and degradation rate constant of the pollutant over the photocatalysts, respectively. In low initial concentration of the pollutant, we have (K[Pollutant]+1) ~ 1. Hence, Eq. (1) is converted to a pseudo first-order reaction kinetics:
Rate = -d[Pollutant]/dt = kK[Pollutant] = kobs[Pollutant] (2)
By integration from Eq. (2), we have:
ln[Pollutant]/[Pollutant]o= - kobst (3)
Where [Pollutant]0 and [Pollutant] are “Pollutant” concentrations at times t = 0 and t = t, respectively, and kobs is the pseudo-first-order rate constant. In higher concentrations, we have K[Pollutant] + 1 ~ K[Pollutant]. Hence, Eq. (1) is converted to a zero-order reaction model:
Rate = -d[Pollutant]/dt = kK = kobst (4)
Rate = -d[Pollutant]/dt = kK[Pollutant]/(1+K[Pollutant]) (1)
In which, K and k are thermodynamic adsorption constant and degradation rate constant of the pollutant over the photocatalysts, respectively. In low initial concentration of the pollutant, we have (K[Pollutant]+1) ~ 1. Hence, Eq. (1) is converted to a pseudo first-order reaction kinetics:
Rate = -d[Pollutant]/dt = kK[Pollutant] = kobs[Pollutant] (2)
By integration from Eq. (2), we have:
ln[Pollutant]/[Pollutant]o= - kobst (3)
Where [Pollutant]0 and [Pollutant] are “Pollutant” concentrations at times t = 0 and t = t, respectively, and kobs is the pseudo-first-order rate constant. In higher concentrations, we have K[Pollutant] + 1 ~ K[Pollutant]. Hence, Eq. (1) is converted to a zero-order reaction model:
Rate = -d[Pollutant]/dt = kK = kobst (4)
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This property differs from both first-order reactions and second-order reactions. Origin of Zero Order Kinetics. Zero- order ...
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