Redlich-Peterson isotherm

Regarding submerged plants, sorption of Cu(II) by Myriophyllum spicatum L. (Eurasian water milfoil) has been shown to be fast and fits isotherm models such as Langmuir, Temkin, and Redlich-Peterson. The maximum sorption capacity (c/lll l j ) of copper onto M. spicatum L. was 10.80 mg/g, while the overall sorption process was best described by the pseudo-second-order equation.115 Likewise, Hydrilla verticillata has been described as an excellent biosorbent for Cd(II). In batch conditions, the qmsx calculated was 15.0 mg/g. Additionally, II. verticillata biomass was capable of decreasing Cd(II) concentration from 10 to a value below the detection limit of 0.02 mg/L in continuous flow studies (fixed-bed column). It was also found that the Zn ions affected Cd(II) biosorption.116... 

Langmuir photoadsorption equilibrium constant (M ) Redlich-Peterson isotherm constant (dm g )... 

The dual-mode isotherm is merely a combination of Hemy s law and the Langmuir isotherm. Other isotherms, such as the Redlich-Peterson, Langmuir-Ereundlich, Sips, and Toth [g, h, i, and j, respectively, in Table 14.3] versions extend the Langmuir isotherm by accounting for subtle... 

Consider the following adsorption isotherm data for water vapor on silica gel at 25°C. Fit the data to the Langmnir, Freundlich, Redlich-Peterson, and B.D.D.T. equations. 

The parameters in the adsorption isotherms were estimated from the experimental equilibrium data using MATLAB Curve Fitting Toolbox. The comparison of experimental and estimated data by Langmuir, Freundlich, Redlich-Peterson and combined Langmuir-Freundlich models for the investigated systems are presented in Figures 1 to 3 for six investigated systems. 

The equilibrium isothoms were measured for Acid Blue 80 (AB80) and Acid Yellow 117 (AYl 17) on Activated Carbon F400. The Redlich-Peterson isotherm (equation 14) is used to relate equilibrium concentrations between liquid phase and solid phase loading. The values of Kg, og and are 28.32dmVg, 103.6 (dmVmmole) 0.%5 for AB80 on activated carbon and SS.40dmVg, 200.2 (dmvmmole) , 0.910 for AYl 17 on activated carbon. Those isotherm parameters have been used in the multicomponent HSDM to correlate the concentration decay curve. 

At this stage in the analysis, in order to solve Eq. (15.2) for A/, it is necessary to use an isotherm equation to determine Three of the most common isotherm equations are Langmuir, Freundlich, and Redlich-Peterson, as shown in Eqs. (15.3), (15.4), and (15.5), respectively. 

Redlich-Peterson (1959) KrC, l + fl C It approaches the FrermcUich model at high concentrations and is in accord with the low concentration limit of the Langmuir equation. Furthermore, the R-P equation incorporates three parameters into an empirical isotherm and, therefore, can be applied in either homogeneous or heterogeneous systems due to its high versatility. 

P constant of Redlich-Peterson isotherm X wavelength T] effectiveness factor 0 mean residence time 0B batch reaction time pj density of solid particles Pb molal density of reactant E, fractional solids hold up of the bed E volume fraction of the dense phase... 

Although, this model describes enzyme adsorption, other studies have shown that the lipase distribution on the support surface can be presented by a Freundlich model (Knezevic et al., 1998 Mojovic et al., 1998) that describes nonidentical adsorption on the support surface, or by a Redlich-Peterson model (Al-Duri and Yong, 2000) that combines the Langmuir and Freundlich isotherms. The Langmuir model reflects irreversible adsorption and is based on the assumption that every adsorption site is identical and energetically equivalent. However, this is a condition that is rarely... 

The Redlich-Peterson equation only differs from the Langmuir-Freundlich equation by the absence of exponent on at the numerator part of the equation (Ng et al, 2002). Meanwhile, the Dubinin-Radushkevitch (D-R) isotherm describes the adsorption on a single type of uniform pores and can be applied to distinguish between physical and chemical adsorption. This isotherm does not assume a homogeneous surface or a constant adsorption potential (Unlu and Ersoz, 2006). 

Fig. 19.2 (a) The mechanism of the adsorption of Cu(II) on PVA/Si02 composite nanofibers, (b) Adsorption isotheim of Cu(II) on thiol-functionalized PS/Si02 membranes and its fitting curves by Langmuir, Freundlich, and Redlich-Peterson isotherms, (c) Langmuir, Freundlich, and Redlich-Peterson isotherms for the adsorption of different heavy metal ions ((a) Reprinted with permission from Ref. [74]. 2010 Elsevier, (b) Reprinted with permission from Ref. [75]. 2012 The Royal Society of Chemistry, (c) Reprinted with permission from Ref [77]. 2013 Elsevier)... 

Redlich O., Peterson D.L. A useful adsorption isotherm. J. Phys. Chem., 1959 63 1024 1026. Selvavathi V., Chidambaram V., Meenakshisundaram A., Sairam B., Sivasankar B. Adsorptive desulfurization of diesel on activated carbon and nickel supported systems. Catdl. Today, 2009 141 99-102. 

Redlich, O. Peterson, D.L. (1959) A useftil adsorption isotherm. The Journal of Physical Chemistry, 63, 1024-1026. 

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