What does the pseudo first order kinetics model say about the adsorption process?
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The pseudo-first-order (PFO) kinetics model in adsorption studies describes the initial adsorption rate and rate constant estimation. It is crucial to select initial adsorbate concentrations based on adsorption isotherms to ensure accurate rate constant determination. The PFO model's differential equations resemble those of first-order kinetic reactions, with the adsorption rate constant (k1) calculated from two distinct regions on the qt vs. time plot. This model is commonly used alongside the pseudo-second-order (PSO) model, which is popular for its application in adsorption processes . The PSO model, often analyzed using nonlinear optimization methods, is effective in minimizing error functions during modeling . However, different linear types of the PSO model have been proposed to identify potential errors in experimental data, particularly during the initial periods of adsorption kinetics .
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09 Mar 2023 2 Citations | Not addressed in the paper. |
| The pseudo-first-order kinetics model did not identify errors in initial adsorption periods. It ranked lower than the pseudo-second-order model in fitting experimental data. | |
| The pseudo first order kinetics model describes adsorption as a rapid initial phase towards pseudo-equilibrium, transitioning to a slower phase reaching a second pseudo-equilibrium. | |
| The pseudo-first-order kinetics model in adsorption studies involves calculating the adsorption rate constant from kinetic and equilibrium regions to accurately determine the adsorption process. | |
| The pseudo first order kinetics model, or PNO equation, is analyzed probabilistically with random variables, providing insights into mean, variance, confidence intervals, and other key parameters of the adsorption process. |
Related Questions
What is pseudo-second-order adsorption kinetic assumption?5 answersThe pseudo-second-order (PSO) adsorption kinetic assumption is a widely used model in adsorption studies. It assumes that the rate-limiting step of the adsorption process is chemisorption involving valency forces through the sharing or exchange of electrons between the adsorbent and adsorbate. This model is favored for its ability to describe the adsorption mechanism accurately. However, there are debates regarding the physical justification of the PSO model, as adsorption kinetics are typically dominated by a diffusion process. Despite this, the PSO model is extensively applied due to its high fitting quality and effectiveness in describing adsorption kinetics. The PSO model's assumption of chemisorption as the rate-limiting step makes it a valuable tool in understanding and predicting adsorption processes.
What is assumption of pseudo first order kinetic model?5 answersThe assumption of the pseudo-first-order kinetic model is based on the linearization of the simple bimolecular ligand-receptor binding interaction, particularly when one species is present in excess. This assumption is often utilized to simplify the kinetics of binding interactions. On the other hand, in the context of sorption processes, the pseudo-second order equation is substantiated by transforming the Langmuir kinetic equation into a polynomial relation, providing a good approximation over a wide range of conditions without the need for specific kinetic mechanisms. Furthermore, in adsorption studies, the pseudo-second order rate law is commonly favored due to its ability to represent various adsorption systems, although there are concerns about potential modeling biases and the need for improved validation methods.
What's defining pseudo second order adsorption model beside chemisorption?5 answersThe pseudo-second order (PSO) adsorption model is defined by its ability to approximate the kinetics of sorption processes over a wide range of conditions, without relying on concepts of chemisorption or special equations of kinetics controlled via chemical reactions or diffusion. The PSO model has been widely applied in the field of adsorption and is popular due to its excellent fitting to experimental points. It is a polynomial relation that can be transformed from the Langmuir kinetic equation and is represented as a sum of difference terms of first- and second-order kinetic equations. The PSO model is applicable to various adsorption processes and can estimate the initial adsorption rate and rate constant. It has been shown to be effective in fitting experimental data and can be modeled using nonlinear optimization methods. The PSO model is not sensitive to parameters such as adsorbate and adsorbent concentrations, but a modified version of the PSO model has been developed to address this limitation.
How does the pseudo-first-order model type affect the absorption kinetics of hydrogel?4 answersThe pseudo-first-order model type has an impact on the absorption kinetics of hydrogel. Studies have shown that the pseudo-second-order model is considered to be the superior model for representing many adsorption systems, including the adsorption of hydrogen sulfide (H2S) by hydrogel biochar. However, there are concerns regarding the validity of the assumptions underlying the application of the pseudo-second-order model to adsorption kinetics. It has been suggested that adsorption behavior that fits the pseudo-second-order model well can often be explained by diffusion-based mechanisms. Additionally, a new validation method has been proposed to eliminate modeling biasness and re-examine previously published adsorption kinetic data. Therefore, while the pseudo-second-order model is commonly used, further research is needed to fully understand the impact of the pseudo-first-order model type on the absorption kinetics of hydrogel.
What are the mechanisms that lead to adsorption kinetics inertia?4 answersThe mechanisms that lead to adsorption kinetics inertia can be influenced by various factors such as the combination of dissociative adsorption and surface abstraction. Additionally, the diffusion of solutes and the surface coverage of solutes can also affect the solute concentration at the surface, leading to nonlinear integro-differential equations for the surface coverage. In the case of surfactant adsorption, factors such as diffusion through a subsurface layer and hindrance to the act of adsorption itself can contribute to the kinetics inertia. The adsorption process can be described by various models such as the Langmuir-Freunlich model and the pseudo second-order model. These models take into account factors such as uptake reduction rate, film diffusion pattern, and the importance of mass transfer and pore diffusion in determining the adsorption rates.
Do the nature and size of the adsorbed molecules or ions affect the kinetics?3 answersThe nature and size of the adsorbed molecules or ions can affect the kinetics of the adsorption process. For example, in the study by Ito et al., they found that the rate of dinitrogen adsorption on silver cluster cations increased exponentially with cluster size up to a certain point, after which it started to decrease. In another study by Du et al., they observed strong specific ion effects in the adsorption kinetics of Li+, Na+, and Cs+ ions on a negatively charged montmorillonite surface. They also established new kinetic theories that take into account these specific ion effects, showing that the strength of the specific ion effects can quantitatively characterize the adsorption kinetics. Additionally, Rudzinski and Plazinski showed that the empirical pseudo-second order kinetic equation can be used to correlate kinetic data in interfacial transport, but its applicability depends on the conditions close to equilibrium and the presence of surface heterogeneity. Therefore, the nature and size of the adsorbed molecules or ions can have a significant impact on the kinetics of the adsorption process.