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Abstract  

Three n-alkylammonium salts of varying alkyl chain length were ion exchanged with montmorillonites (MMT) of different cation exchange capacity (CEC). The intercalated MMTs were characterized by thermogravimetry (TG), XRD, FTIR to acquire an insight into the intergallery structural arrangement of the organic alkylammonium cations (AAC). The increment in the intergallery spacing from XRD pattern was correlated with chain length and interlayer arrangement of AAC. Multiple organic mass-loss stages in thermogravimetric analysis indicate two types of anchorage of AAC in intercalated clay. CEC of MMT was found to influence the intergallery confinement and excess adsorption of AAC.

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Abstract  

In this paper the cation exchange capacities (CEC) of zeolites A, X,Y, ZSM-5 and erionite were determined and the results obtained were comparedwith the retention of cadmium by zeolites A (determined in this work), X,Y and erionite as well as with the retention of cobalt by zeolites A, X, Y,ZSM-5 and erionite reported elsewhere.

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Abstract  

A method has been purposed to calculate some of the thermodynamic quantities for the thermal deformation of a smectite without using any basic thermodynamic data. The Hançılı (Keskin, Ankara, Turkey) bentonite containing a smectite of 88% by volume was taken as material. Thermogravimetric (TG) and differential thermal analysis (DTA) curves of the sample were obtained. Bentonite samples were heated at various temperatures between 25–900°C for the sufficient time (2 h) until to establish the thermal deformation equilibrium. Cation-exchange capacity (CEC) of heated samples was determined by using the methylene blue standard method. The CEC was used as a variable of the equilibrium. An arbitrary equilibrium constant (K a) was defined similar to chemical equilibrium constant and calculated for each temperature by using the corresponding CEC-value. The arbitrary changes in Gibbs energy (ΔG a 0) were calculated from K a-values. The real change in enthalpy (ΔH 0) and entropy (ΔS 0) was calculated from the slopes of the lnK vs. 1/T and ΔG vs. T plots, respectively. The real changes in Gibbs energy (ΔG 0) and real equilibrium constant (K) were calculated by using the ΔH 0 and ΔS 0 values. The results at the two different temperature intervals are summarized as below: ΔG 1 0H 1 0−ΔS 1 0 T=−RTlnK 1=47000−53t, (200–450°C), and ΔG 2 0H 2 0S 2 0T=−RTlnK 2=132000−164T, (500–800°C).

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Partially exchanged organophilic bentonites

Part I. characterization by thermal analysis on calcined mass basis

Journal of Thermal Analysis and Calorimetry
Authors: Jo Dweck, Emerson Paes Barreto, Sergio Meth, and Pedro Mauricio Büchler

organic cations present in the organophilic clay prepared using excess of quaternary ammonium salt. This new protocol allows an alternative procedure to estimate the cation exchange capacity (CEC) of the clay. Materials and methods

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Hungarian). MSZ-08-0214-1 . 1978 . Quantitative and Qualitative Determination of Cation Exchange Capacity in Soil . Hungarian Standards Association , Budapest (in Hungarian

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Agrokémia és Talajtan
Authors: Barbara Simon, E. Michéli, G. E. van Scoyoc, and et al.

The Typic Haplustalfs soils (Karád and Oltárc) and the Typic Ustochrepts (Gödöllő) are developed on loess, and on aeolian sand parent material, under forest vegetation, resp. The Dystric Ustochrepts (Velem) soil formed on metamorphic schist parent material and had forest vegetation, while the Typic Medisaprists (Zalavár) soil developed on peat parent material and had marsh vegetation.   Based on this study the spatial variability of surface pH samples indicate that the TIM sampling procedure should be improved. Ten to thirty samples must be collected at each site to be able to monitor changes of 0.2 pH units. If only one sample is taken at each site yearly, spatial difference in pH or other parameters are likely to obscure differences which may be occurring over time.  The colloidal composition (organic matter and clay minerals), influenced by parent material, vegetation, and precipitation, showed a close relationship with the acidity factors, such as pH, HAC 1 and EAC 1 values. The pH values were the lowest in the Velem and Oltárc soils where the annual precipitation was the highest (750-800 mm), and in the Karád soil, where the annual precipitation was 650-700 mm. The Gödöllő soil had the highest pH values, probably due to the lowest amount of rainfall (550-600 mm) and the disturbance. The Zalavár soil had fairly high pH throughout the profile probably due to a fluctuating water table.   The HAC 1 and EAC 1 values were the highest in the Velem soil when compared to the other mineral soils.  The pH values were the lowest at this site. The HAC 1 and EAC 1 values were lower in the other three forest soils, at the Karád, Oltárc, and Gödöllő sites. The Zalavár soil had fairly high HAC 1 values in the H3, H4 and H5 horizons, probably due to the very high OM content, which provided a lot of H + ions that can dissociate from the exchange sites.   The E4/E6 ratios were closely related to the decomposition or humification rate in the upper and the subsurface horizons with accumulation of low molecular weight soluble fraction in the deeper horizon.   The mineralogical analysis showed similar compositions for the soils developed on loess (Karád and Oltárc), or aeolian sand (Gödöllő), where the major minerals were vermiculite, mica, kaolinite, and chlorite. A different mineral composition (mica, vermiculite, clintonite, and kaolinite) was observed for the Velem site, where the parent material was metamorphic schist. The four mineral soils are forest soils, with a predominant downward water movement, thus with fairly intensive leaching process. However, there was a distinct difference among the soils formed on loess (Karád and Oltárc), or aeolian sand (Gödöllő), and the soil (Velem) developed on metamorphic schist parent material.  The soils at the Karád, Oltárc, and the Gödöllő sites were less acidified, with higher pH, and lower HAC 1 , and EAC 1 values as compared to the Velem soil, even if the precipitation was very high. The calcareous loess parent material probably compensated for the higher precipitation and the resulting leaching process at the Karád and the Oltárc sites. The Gödöllő soil received a very low amount of precipitation, which resulted in a low degree of weathering, with higher pH, and lower HAC 1 , and EAC 1 values. However, the metamorphic schist parent material probably contributed to a lower pH and lower buffering of the developing soil.   Based on the chemical and physical analyses, we concluded that among the soil forming factors, precipitation and parent material had the greatest influence on the acidity characteristics of the examined soils. The parent material influenced the mineralogy of the developing soil, which then influenced the pH, HAC 1 , EAC 1 , and CEC values of the soil. In order to substantiate these tendencies more samples from a wider array of geological regions are needed.   

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relatively low. On the contrary, Na/Li-montmorillonites used for cosmetics require high quality in terms of outstanding water absorption capability and good stability as well. Montmorillonites with excellent cation exchange capacity have been used as an

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Abstract  

The sorption properties of three titanosilicate materials, AM-4, ETS-4, and Na2Ti2O3SiO4 . 2H2O of different framework structure and cation exchange capacity were studied towards the uptake of uranium from aqueous systems. Selectivity factors were estimated by determining batch distribution coefficient (Kd) and uranium removal (mg) per gram of the exchanger as a function of contact time, uranium concentration and batch factor (solution volume to exchanger mass ratio). The difference in their ability to take up uranium was discussed by in terms of their framework structure and the determination of their cation exchange capacity. Comparisons to ETS-10 have been made.

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et al., 2018). In Europe, C REAMER et al. (2016) noted that soil respiration rate was greatly influenced by soil properties, such as pH, SOM, total nitrogen (TN), and cation exchange capacity (CEC). Temperature and water content were also found to be

Open access
Agrokémia és Talajtan
Authors: G. Gelybó, E. Tóth, C. Farkas, Á. Horel, I. Kása, and Z. Bakacsi

cation exchange capacity . In: Standard Soil Methods for Long-Term Ecological Research, Oxford University Press , New York . 106 – 111 . Rosenzweig

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