HYDROLYSIS AND SALT-RETENTION ERRORS IN CONVENTIONAL CATION-EXCHANGE-CAPACITY PROCEDURES

Abstract

Net charge is the reference datum for judging reliability of cation-exchange-capacity values determined by a conventional procedure with a washing step to remove excess saturating salt. Salt retention is a more common error source than is sample dispersion and loss, or index cation hydrolysis. Isopropanol is less efficient than methanol or ethanol for the removal of NH4OAC and NaOAc. Isopropanol induces aggregation of some samples sufficiently to slow salt removal. Water is more efficient than any of the alcohols, but high-speed centrifuging is required. Samples containing volcanic glass shards, with many pores and tubules, are freed of entrained salt only by water washing.[long dash]Authors.