Effect of pH on the cation exchange capacity of some halloysite nanotubes

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Nia Gray ◽  
David G. Lumsdon ◽  
Stephen Hillier
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Halloysite Nanotubes ◽  
Exchange Capacity ◽  
Average Value ◽  
Two Samples ◽  
Wide Ph Range ◽  
Capacitance Model ◽  
Ph Dependent ◽  
Ph Range

AbstractThe cation exchange capacity (CEC) of seven well characterized halloysite nanotubes (HNTs) in the dehydrated 7 Å form has been measured using a method based on cobalt hexammine exchange. In addition to unbuffered measurements, which varied between 2.9 and 9.3 cmol(+)kg−1, CECs were also determined over a wide pH range and proton titration measurements were conducted on two samples. The data were fitted using a constant capacitance model based on the presence of two sites: permanently charged sites and pH-dependent variable charged sites. Normalization of CEC to the average specific surface area (BET) of the halloysite samples reduces considerably the variation of CEC values for the different samples particularly over the intermediate pH range (5–9) with the average value at pH 7 equal to 8.5 cmol(+)kg−1and a standard deviation of 1.17. Overall the CEC behaviour of the seven samples appears reasonably consistent throughout the set. Calculations based on proton titrations suggest a ratio of variable charge to basal sites for the dehydrated halloysite nanotubes of ∼3:1.

ETUDE SUR LA VALEUR DES CRITERES CHIMIQUES PROPOSES PAR LA COMMISSION PEDOLOGIQUE DU CANADA POUR LA CLASSIFICATION TAXONOMIQUE DES SOLS DU QUEBEC

1977 ◽  
Vol 57 (3) ◽  
pp. 233-247 ◽  
Author(s):  
ROGER W. BARIL ◽  
THI SEN TRAN
Keyword(s):  
Cation Exchange ◽  
Soil Ph ◽  
Classification System ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Taxonomic Classification ◽  
Single Test ◽  
Ph Dependent ◽  
Extractable Al

Correlations were made among chemical criteria used for taxonomic soil classificaton. The compared tests were: oxalate Δ (Fe + Al), pyrophosphate-extractable (Fe + Al), oxalate-extractable Al, pH-dependent cation exchange capacity (ΔCEC), ratios of pyrophosphate-extractable (Fe + Al) over clay or over dithionite-extractable (Fe + Al), and finally soil pH measured in 1 M NaF. Significant correlations were found among various measured parameters. However, no single test was found to be reliable as a single criterion when applied to the taxonomic classification of Quebec soils. The two chemical tests, pyrophosphate-extractable (Fe + Al) and its ratio over clay, combined with morphologic criteria appeared useful for classifying Quebec Podzols. A few soils, which presented discrepancies from chemical criteria were found difficult to classify, thus suggesting the possibility of establishing new sub-groups in the Canadain soil taxonomic classification system.

ESTIMATION OF THE INORGANIC AND ORGANIC pH-DEPENDENT CATION EXCHANGE CAPACITY OF THE B HORIZONS OF PODZOLIC AND BRUNISOLIC SOILS

1968 ◽  
Vol 48 (1) ◽  
pp. 53-63 ◽  
Author(s):  
J. S. Clark ◽  
W. E. Nichol
Keyword(s):  
Organic Matter ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Acid Soils ◽  
Exchange Capacity ◽  
Hydrous Oxides ◽  
Before And After ◽  
Ph Dependent ◽  
The Difference ◽  
Wyoming Bentonite

Heating in hydrogen peroxide, dilute oxalic acid, and dilute aluminum oxalate did not change the effective cation exchange capacity (CEC) or the pH-7 CEC of Wyoming bentonite and Alberni clay soil containing excess Al(OH)x. This indicated that treatment of soils with H2O2 to oxidize organic matter and the possible production of oxalates during oxidation did not change the CEC values of the inorganic fraction of soils even if some clay exchange sites were blocked by hydrous oxides of Al.With soils of pH less than approximately 5.4, oxidation of organic matter did not change the effective CECs although the pH-7 CEC values were decreased. Thus, organic matter in acid soils appeared to have little or no effective CEC. Because of this and the negligible effect of H2O2 oxidation on the CEC values of clays, the difference of the pH-7 CEC of soils before and after H2O2 oxidation provided a simple means of estimating the amount of organic pH-dependent CEC in acid soils.The amount of organically derived pH-dependent CEC was determined in a number of soils by means of peroxide oxidation. The technique provided a useful indication of the quantities of sesquioxide–organic matter complexes accumulated in medium- and fine-textured soils.

COMPONENTS OF pH DEPENDENT CATION EXCHANGE CAPACITY

Soil Science ◽  
1970 ◽  
Vol 109 (5) ◽  
pp. 272-278 ◽  
Author(s):  
B. L. SAWHNEY ◽  
C. R. FRINK ◽  
D. E. HILL
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Ph Dependent

Acid character of nontronite: permanent and pH-dependent charge components of cation exchange capacity

Clay Minerals ◽  
1972 ◽  
Vol 9 (4) ◽  
pp. 425-433
Author(s):  
B. S. Kapoor
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Dependent Component ◽  
Ph Dependent ◽  
The Difference ◽  
The Cost ◽  
Fe Ions ◽  
Acid Character

AbstractThe cation exchange capacity (C.E.C.) of nontronite was determined by titrating the acid clay, prepared by the action of H-resin on nontronite, in water and some nonaqueous solvents. The base-titratable acidities of the acid nontronite, freshly prepared as well as aged, were found to be greater than the acidities extractable with 1 N NaCl; the difference was attributed to the non-exchangeable pH-dependent component of C.E.C. In the freshly prepared sample, H+ and Fe3+ ions were the only exchangeable cations. Ageing produced basic Fe ions which were exchangeable and whose amount increased at the cost of H− and Fe3+ ions. Whatever the age, the total quantity of these exchangeable cations corresponding to the total isomorphous charge, remained constant. The amount of the pH-dependent acidity also remained unchanged. A likely mechanism to account for the observed pH-dependent component of the C.E.C, of nontronite is suggested.

Complex conductivity tensor of anisotropic hydrocarbon-bearing shales and mudrocks

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. D403-D418 ◽  
Author(s):  
A. Revil ◽  
W. F. Woodruff ◽  
C. Torres-Verdín ◽  
M. Prasad
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Solid Phase ◽  
Exchange Capacity ◽  
Electrical Anisotropy ◽  
Dielectric Tensor ◽  
Two Samples ◽  
Complex Electrical Conductivity

A model was recently introduced to describe the complex electrical conductivity and high-frequency dielectric constant of isotropic clayey porous materials. We generalized that approach to the case of anisotropic and tight hydrocarbon-bearing shales and mudrocks by introducing tensorial versions of formation factor and tortuosity. In-phase and quadrature conductivity tensors have common eigenvectors, but the eigenvectors of the dielectric tensor may be different due to influence of the solid phase at high frequencies. In-phase and quadrature contributions to complex electrical conductivity depend on saturation, salinity, porosity, temperature, and cation exchange capacity (alternatively, specific surface area) of the porous material. Kerogen is likely to have a negligible contribution to the cation exchange capacity of the material because all exchangeable sites in the functional groups of organic matter may have been polymerized during diagenesis. An anisotropic experiment is performed to validate some of the properties described by the proposed model, especially to verify that the electrical anisotropy factor is the same for in-phase and quadrature conductivities. We used two samples from the Bakken formation. Experimental data confirm the validity of the model. Also, the range of values for cation exchange capacity determined when implementing the new model with experimental data agree with the known range of cation exchange capacity for the Bakken shale. Measurements indicate that the bulk-space tortuosity in the direction normal to bedding plane can be higher than 100.

CONTRIBUTION OF EXCHANGEABLE ALUMINUM TO CATION EXCHANGE CAPACITY AT LOW pH

1987 ◽  
Vol 67 (1) ◽  
pp. 175-185 ◽  
Author(s):  
MARTIN DUQUETTE ◽  
WILLIAM H. HENDERSHOT
Keyword(s):  
Cation Exchange ◽  
Soil Ph ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Low Ph ◽  
Soil Samples ◽  
Maximum Amount ◽  
Exchangeable Al ◽  
Exchangeable Aluminum ◽  
Ph Dependent

The cation and anion exchange capacities (CEC and AEC) as functions of pH were measured for 12 soil samples from various parts of Quebec. In addition to the index cation Ca, Al was measured in the replacing solutions in order to evaluate the contribution of Al to pH-dependent CEC at low pH. Although all of the soils possessed some pH-dependent CEC, the soils with the steepest rise in CEC with pH were those with the largest accumulation of sesquioxides. The effective CEC, measured at the soil pH, ranged from 2.4 to 37.2 cmol(+) kg−1 while the CEC at pH 7 minus the CEC at pH3 varied from 4.4 to 39.9 cmol(+) kg−1. The maximum amount of exchangeable Al was found to correlate very highly with the amount of amorphous inorganic Al in the samples. The inclusion of exchangeable Al in the calculation did not significantly reduce the amount of pH-dependent CEC measured for the soils. Key words: Effective CEC, permanent charge, pH-dependent CEC

scholarly journals Sorption properties of granulometric fractions in Haplic Cambisol developed from boulder loam

2019 ◽  
Vol 70 (2) ◽  
pp. 147-157
Author(s):  
Zygmunt Brogowski ◽  
Józef Chojnicki
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Sorption Properties ◽  
Average Value ◽  
Leaching Process ◽  
Central Poland ◽  
Exchangeable Bases ◽  
Dispersing Agents ◽  
Grain Diameter

Abstract The aim of the paper was to investigate the sorption properties of granulometric fractions separated from the genetic horizons of arable Haplic Cambisol developed from boulder loams of the Middle-Polish (Riss) Glaciation, Wartanian Stadial (central Poland). Separation of granulometric fractions was made with application of the Atterberg method without the use of centrifuging and dispersing agents. The cation exchange capacity average value in cmol(+)kg−1 and % contribution in particular fractions reached: 1–0.1 mm – 2.1 (1.6%), 0.1–0.05 mm – 5.5 (4.0%), 0.05–0.02 mm – 8.5 (6.1%), 0.02–0.01 mm – 13.0 (10.1%), 0.01–0.005 mm – 16.1 (12.8%), 0.005–0.002 mm – 28.6 (20.5%) and fraction <0.002 mm – 48.7 (44.9%). Leaching of the total exchangeable bases was the largest in the 0.1–0.05 mm fraction and decreased successively with decreasing grain diameter. Sorption properties of the tested soil determine its high agricultural value and buffer properties. The cation exchange capacity of the recognised granulometric fractions successively increased with decrease of their diameter while leaching process intensity in individual fractions decreased gradually as their dimensions decreased. Calcium was the most leached cation, followed by magnesium and sodium, whereas potassium was not leached at all. Significant increase of the cation exchange capacity in fractions from carbonate horizons was mostly caused by the increased contribution of calcium, which could be released from carbonates during extraction of bases.

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