Use of general purpose adsorption isotherms for heavy metal clay mineral interactions

Altin, O
Özbelge, Hilmi Önder
Dogu, T
General purpose adsorption isotherm equations were fitted to the sorption data of lead and cadmium on both unmodified and Ca-saturated kaolinite and montmorillonite. Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, competitive Langmuir, and some modified forms of these isotherms were fitted to experimental data, and their goodnesses of fit are compared. The adjustable parameters of the Langmuir-and Freundlich-based isotherms were estimated by nonlinear least-squares analysis. The application of these two isotherms which allow for the effect of surface heterogeneity for both multiple and single desorbing ions during the sorption process was also studied. It was concluded that Redlich-Petersen, Toth, and original and modified forms of Dubinin-Radushkevich isotherms perform superior to the others both in high and lour concentration regions for both unmodified and Ca-saturated clays. Competitive Langmuir adsorption isotherm for Ca-saturated clays fitted web for Pb adsorption, while a change of slope was observed for Cd adsorption. (C) 1998 Academic Press.


Thermal characterization of glycidyl azide polymer (GAP) and GAP-based binders for composite propellants
Selim, K; Özkar, Saim; Yılmaz, Levent (Wiley, 2000-07-18)
Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to investigate the thermal behavior of glycidyl azide polymer (GAP) and GAP-based binders, which are of potential interest for the development of high-performance energetic propellants. The glass transition temperature (T-g) and decomposition temperature (T-d) of pure GAP were found to be -45 and 242 degrees C, respectively. The energy released during decomposition (Delta H-d) was measured as 485 cal/g. The effect of th...
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Guler, T; Hicyilmaz, C; Gokagac, G; Ekmekci, Z (Elsevier BV, 2004-11-01)
The mechanism of dithiophosphinate (DTPI) adsorption on chalcopyrite was investigated by diffuse reflectance Fourier transformation (DRIFT) spectroscopy and by cyclic voltammetry (CV) at various pHs. CV experiments showed that the redox reactions occurred at a certain degree of irreversibility on the chalcopyrite surface in the absence of a collector due to preferential dissolution of iron ions in slightly acid solution and irreversible surface coverage by iron oxyhydroxides in neutral and alkaline solution...
Electrochemical Behavior of Hydrazine Borane in Methanol Solution
Ozhava, Derya; Önal, Ahmet Muhtar; Özkar, Saim (The Electrochemical Society, 2014-01-01)
Electrochemical behavior of hydrazine borane (HB) was investigated on gold electrode in 0.5 M LiClO4 solution in methanol using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry. Two irreversible peaks at 164 and 530 mV are attributed to direct electro-oxidation of HB on gold electrode in methanol. Both EIS results and CV data at different scan rates indicate a diffusion controlled electron transfer reaction. Furthermore, the Tafel slope (b = 0.191 V) and charge transfer...
Effect of pH in an aqueous medium on the surface area, pore size distribution, density, and porosity of montmorillonite
Altin, O; Özbelge, Hilmi Önder; Dogu, T (Elsevier BV, 1999-09-01)
Surface area, pore volume distribution, and porosity of montmorillonite are determined after being exposed to aqueous solutions with various pH values. For measurement, after each pH treatment the clay samples were freeze-dried in order to keep the structure of the clay same as that in the aqueous solution. Surface area and pore size distribution measurements were performed on an unmodified and four pH (2.5, 4.0, 5.5, 9.0)-adjusted clay samples using N-2 and CO2 as adsorbates. The surface area measurements ...
Magnetically separable rhodium nanoparticles as catalysts for releasing hydrogen from the hydrolysis of ammonia borane
Tonbul, Yalcin; Akbayrak, Serdar; Özkar, Saim (Elsevier BV, 2019-10-01)
Magnetically separable catalysts attract considerable attention in catalysis due to their facile separation from the reaction medium. This propensity is crucial for efficient multiple use of precious noble metal nanoparticles in catalysis. In fact, the isolation of catalysts from the reaction medium by filtration and washing results usually in the loss of huge amount of activity in the subsequent run of catalysis. Although many transition metal nanoparticle catalysts have been reported for the H-2 generatio...
Citation Formats
O. Altin, H. Ö. Özbelge, and T. Dogu, “Use of general purpose adsorption isotherms for heavy metal clay mineral interactions,” JOURNAL OF COLLOID AND INTERFACE SCIENCE, pp. 130–140, 1998, Accessed: 00, 2020. [Online]. Available: