Adsorption Investigations: Kinetic and Isotherm Models, Determination of Thermodynamic Parameters
To comprehend the mechanism of sorption onto the surface of any material, it is vital to validate and interpret the kinetic and isotherm models. The determined kinetic, isotherm, and thermodynamic parameters corroborate the nature of binding forces of flu
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Adsorption Investigations: Kinetic and Isotherm Models, Determination of Thermodynamic Parameters Solairajan Murugesh, T.A.M. Msagati, Venkataraman Sivasankar, and R. Hariharan
Abstract To comprehend the mechanism of sorption onto the surface of any material, it is vital to validate and interpret the kinetic and isotherm models. The determined kinetic, isotherm, and thermodynamic parameters corroborate the nature of binding forces of fluoride with the studied carbon adsorbents. In addition, the thermodynamic factors such as enthalpy change (ΔH), entropy change (ΔS), and free energy change (ΔG) predicted the nature of fluoride sorption process, disorderliness of the fluoride sorption system, and spontaneity of the fluoride sorption reaction, respectively. The compliance of each model has been validated for its fit with the present fluoride sorption dynamics at various concentrations and temperatures.
7.1 Introduction Kinetics of reactions is best understood from the rates of chemical reactions on particle surfaces. The fate and transport of contaminants in the subsurface environment of adsorbent particles are controlled in the time-dependent reactions and for which the knowledge of reaction kinetics is quite imperative. The predicted adsorption rate for a given system is probably the most important factor in adsorption system design, with adsorbate’s residence time and the reactor dimensions controlled by the system’s kinetics. A number of adsorption processes for pollutants have been studied in S. Murugesh Department of Chemistry, Thiagarajar College of Engineering (Autonomous), Madurai, Tamil Nadu 625 015, India T.A.M. Msagati University of South Africa, College of Science Engineering and Technology, UNISA Science Campus, 1709 Roodepoort, Johannesburg, South Africa V. Sivasankar (*) • R. Hariharan Post Graduate and Research Department of Chemistry, Pachaiyappa’s College, Chennai, Tamil Nadu 600 030, India e-mail: [email protected] © Springer International Publishing Switzerland 2016 V. Sivasankar (ed.), Surface Modified Carbons as Scavengers for Fluoride from Water, DOI 10.1007/978-3-319-40686-2_7
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an attempt to find a suitable explanation for the mechanisms and kinetics for sorting out fruitful solutions. The reaction rate and its influential factors are made explicated through chemical kinetics. The frequent and explicable ways of explaining the solid–liquid sorption process are executed successfully by reaction kinetic models such as pseudo-first-order and pseudo-second-order models (Ho and McKay 1998; Kumar et al. 2005; Fu and Viraraghavan 2000). First-order models often describe the reactions at the particle/solution interface. Early researchers did not approve the Lagergren pseudo-first order because the applicability was less significant based on experimental data for the entire sorption period and also the probable sorbate interactions were explored to be negligible. On the other hand, Ho’s pseudo-secondorder (Ho and McKay 1998) expression proved to be a better fit to
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