In the case of a batch adsorption process, many different equations are used to describe the kinetic data. Among them are the exponential and hyperbolic equations which are called in short PFO (pseudo first-order) and PSO (pseudo second-order). Maybe it is worth knowing where these terms came from and how well their use is justified.
In one of his paper Y.S. Ho wrote: “In order to distinguish kinetic equation based on sorption capacity of solid from concentration of solution , Lagergrenis first order rate equation has been called pseudo first-order, Ho and McKay 1998abcd.”
Well, the law of mass conservation shows that: mso - ms = m, where mso is an initial mass of adsorbate in solution, ms is a current mass od adsorbate in solution and m is a current adsorbed mass; and further: - dms/dt = dm/dt.
It follows that the only difference is limited to the sign. Thus, there is no justification of using the term “pseudo” in relation to the equations based on adsorbed mass and their parameters.
please refer to this paper
Mistakes and inconsistencies regarding adsorption of contaminants from aqueous solutions: A critical review
Hai Nguyen Tran, Sheng-Jie You, Ahmad Hosseini-Bandegharaeid, Huan-Ping Chao, Water Research 120 (2017) 88-116
http://dx.doi.org/10.1016/j.watres.2017.04.014
Dear Dr Ndifreke Etuk Williams,
I know this paper. In this work there is no reference to the term "pseudo" and the meaningfulness of its use in relation to exponential and hyperbolic equations.
Regards,
I came across this today
H. Moussout et al., Critical of linear and nonlinear equations of pseudo-first order and pseudo-second order kinetic models, Karbala International Journal of Modern Science (2018), https://doi.org/10.1016/j.kijoms.2018.04.001
Recently, several works have appeared where the so-called "pseudo models" in the explicit form with respect to qt (non-linear equations) and in the implicit form (also non-linear equations) are criticized. Suddenly after 20 years of continuing "pseudo" nonsense, something that is obvious is "discovered". Of course, it's obvious to people who can make numerical calculations properly. As for the above work, the title itself proves that the authors do not know what they write. Regards,
Dear Mirosław Grzesik,
For any reaction, there are two terms; Molecularity and Order of reaction.
When the molecularity is equal to the order of reaction, this implies that the reaction is first order or second order.. etc. While it is not, we should use the term "Pseudo".
i.e. the term pseudo is used when the molecularity is not equal to the order of reaction.
Regards.
Pseudo-order is absurd. The order of the chemical reaction/process depends on the form of the kinetic equation also called rate low. According to the definition, the reaction/process order is the sum of exponents in the kinetic equation in the form of a power monomial. Because frequently for a given reaction/process rate low has a different form than a monomial, such a reaction has no order. If we refer to the right side of the differential equation dq/dt = k1(qe-q), then it is a binomial, not a monomial. In turn, in the case of a differential equation dq/dt = k2 (qe-q)2 its right side is a trinomial. In both cases the order of the reaction/process is not applicable. Naming of two empirical functions by Ho and McKay: PFO and PSO, was a marketing trick on which, unfortunately, thousands have fallen for. Regards,
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