Studies on the possible role of cation exchange capacity in the soil preference of mosses

1983 ◽  
Vol 70 (1) ◽  
pp. 77-93 ◽  
Author(s):  
N. Koedam ◽  
P. Büscher
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity

Lanthanide-Clay Nanocomposites: Europium(III) Complexes Intercalated in Bentonite

2007 ◽  
Vol 121-123 ◽  
pp. 1245-1248 ◽  
Author(s):  
Eglantina Benavente ◽  
Yuri Echeverría ◽  
Vladimir Lavayen ◽  
Clivia M. Sotomayor Torres ◽  
G. Gonzáles
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Optical Materials ◽  
Molecular Size ◽  
Exchange Capacity ◽  
Clay Nanocomposites ◽  
Emission Properties ◽  
The Matrix ◽  
Host Cation

The intercalation of [Eu(2,2 bipyridine)2 ]3+ and [Eu(1,10 phenantroline)2]3+ into bentonite results in new nanocomposites which preserve the emission properties of the lanthanide. The exchange of sodium by lanthanide in the bentonite correlates with the host cation exchange capacity as well as with the guest molecular size and the interlaminar volume available in the clay. The intercalated complexes exhibit luminescence indicating an efficient protecting role of the matrix. This in turn points to lanthanide-clay nanocomposite as novel optical materials.

Role of a Labile Terpene Compound in the Assessment of the Age of a Fossil Wood from Siena (Tuscany, Italy)

Holzforschung ◽  
2000 ◽  
Vol 54 (6) ◽  
pp. 591-596 ◽  
Author(s):  
G. Staccioli ◽  
A. Meli ◽  
G. Menchi ◽  
U. Matteoli ◽  
G. Ricottini
Keyword(s):  
Pinus Sylvestris ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Partial Loss ◽  
Wood Component ◽  
First Time ◽  
Geological Formations ◽  
Hydrolysis Of

Summary Fossil samples of Pinus sylvestris found near Siena (Tuscany, Italy) in geological formations 2–3 million years old were chemically examined in order to solve the problem of the contrast between the age of geological formations and their good degree of preservation. Comparison with a living Pinus sylvestris was carried out on standard wood component analyses, cation exchange capacity and residual terpene content. The analyses of wood components were close to those of the reference pine, whilst the cation exchange capacity values showed remarkable changes. The increase of salt carboxyls suggested the hydrolysis of ester carboxyls originally present, whilst the reduction of total carboxyls revealed a partial loss of hemicelluloses. Both changes were attributed to the percolation of salt-bearing water through the wood, thus causing ester hydrolysis, carboxyl salification and hemicellulose solubilisation. Residual terpene analysis showed, for the first time in a terrestrial fossil, tetrahydroabietic acid which forms by disproportion of the abietic acid. The 14C dating assigned the fossil to an age of about 18,000 years and suggested a landslide of Wurmian interglacial age occurred inside the geological formations of 2–3 million years old. Transient terpene compounds, formed in incipient diagenesis, are proposed as tracers for the assessment of particular ranges of fossil age, as previously suggested by the analyses of both a Larix decidua 14,500 years old and a Picea abies 100,000 years

Reply by author to discussion by Hubert Guyod.

Geophysics ◽  
1973 ◽  
Vol 38 (6) ◽  
pp. 1181-1181
Author(s):  
A. E. Worthington
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Accurate Method ◽  
Exchange Capacity ◽  
Oil Field ◽  
Additional Information

The purpose of this paper is to make available a practical, rapid, relatively inexpensive, and reasonably accurate method of measuring cation exchange capacity (CEC) of oil‐field rocks. There is no dearth of sound, detailed descriptions of how this information should be used by explorationists to enhance their ability to interpret resistivity and SP logs in shaly sands (see references in Introduction). Waxman and Thomas (1972) have subsequently published additional information on the application to oil‐saturated shaley sands. Smits (1969) has confirmed the role of CEC in shales, a matter not considered in this paper.

scholarly journals Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

2013 ◽  
Vol 12 (3) ◽  
pp. 248-255
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Metal Uptake ◽  
Exchange Capacity ◽  
Point Of Zero Charge ◽  
Heavy Metal Uptake ◽  
Smectite Clays ◽  
Analysis Scheme ◽  
High Cation Exchange Capacity

A High Cation Exchange Capacity (HCM) montmorillonite clay has been prepared by acetate treatment of Zenith clay. The HCM has been evaluated for metal-uptake from aqueous solutions. The present data show that the cation exchange sites can play a significant role in the adsorption of metals in smectite clays. A theoretical analysis scheme has been developed which shows that permanent-charge sites can become dominant in metal-uptake by clays. In addition, it was shown that the permanent charge can influence the ionic-strength sensitivity of the Point of Zero Charge of the clay.

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