Allophane Determination in Ando Soils By Cation‐Exchange Capacity Delta Value

Abstract

One sample of H2O2‐treated, iron oxide‐extracted soil is treated with 2% Na2CO3 solution for 60 minutes and another with NaOAc of pH 3.5 for 15 minutes, at boiling. Both samples are washed with neutral NaOAc and the cation‐exchange capacity is determined with Ca replaced with NaOAc. The difference obtained between the two samples is referred to as the “cation‐exchange capacity delta value,” and averaged 100 me. per 100 g. for allophane from Ando soils of Japan developed on rapidly weathered volcanic ash and in some allophanes of Ross and Kerr. For example, the allophane content of fine clay of an Ando soil containing predominantly halloysite determined by delta value was 23.8% compared to 21.4% by water contents of constituent minerals.

Hydrothermal Origin of the Clays from the Upper Slopes of Mauna Kea, Hawaii

“…Aomine and Jackson (1959) introduced the concept of cation exchange capacity delta value for disclosing and estimating amorphous material in soil. The values reported in Table I show that the noncrystalline clay of Profile 3 displays a pH-dependent CEC with an intermediate delta value consistent with the SIO2/A1203 molar ratio (Hendricks, Whittig and Jackson, 1967;Jackson, 1969).…”

Geological Survey research 1965, Chapter B

“…Soil studies reported in the literature· also suggest a correlation between climate and amorphous materiaL Aomine and Jackson (1959) reported that soils developed on volcanic ash in Japan contained allophane. In a study of Hawaiian soils, Tamura and others ( 1953) found that soils in areas of highest rainfall contained considerable amounts of allophane.…”

Surface charge density dependency on Al2O3 content in imogolite

“…The cation exchange capacity of amorphic alumino-silicates is highly dependent upon pH, salt concentration, cations and anions used, volume of alcohol wash, and the water content of the alcohol wash used for removal of excess salts (Birrell and Fieldes, 1952;Harada, 1955;Birrell and Gradwell, 1956;Aomine and Jackson, 1959). The scatter of Besoain's data on the surface charge density-mole % AI.~O, piot may be due to the effect of different pH values and ionic strength during formation as well as to crystalline mineral impurities and possible errors in surface area measurement.…”