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Interactions of pH‐Dependent and Permanent Charges of Clays: I. Use of Specific Ion Electrodes for Measuring Ca and Rb Activities in Bentonite and Illite Suspensions
Author(s) -
McLean E. O.,
Snyder G. H.
Publication year - 1969
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1969.03615995003300030017x
Subject(s) - bentonite , divalent , chemistry , illite , electrode , ion , ion selective electrode , ionic bonding , inorganic chemistry , ionic strength , clay minerals , analytical chemistry (journal) , mineralogy , environmental chemistry , geology , geotechnical engineering , organic chemistry , selectivity , catalysis , aqueous solution
Recent development of selective electrodes for many ions is revitalizing analytical potentiometry. Examination of recent evidence appeared to justify their use for measuring ionic activities in clay suspensions. Calcium and Rb ion activities in Fithian illite and Panther Creek bentonite were measured with the Orion divalent and the Beckman monovalent ion electrodes. The clays were saturated reciprocally with Ca‐Rb, Ca‐H, and Rb‐H. Electrode‐measured Ca and Rb activities were generally valid indexes of tracer‐measured root uptake and clay retention of cations, details of which are given in companion reports. Activities and fractions active of Ca and Rb reached minimal or near minimal values when sufficient H was added to equal the pH‐dependent CEC of each clay, a fact which suggested interaction of pH‐dependent and permanent charges.