The Dynamic Character of a Chloritized Vermiculitic Soil Clay

Abstract Interlayer removal experiments using a chloritized vermiculitic soil clay showed its dynamic character by rapid alteration to vermiculite. The Ca/Mg cation exchange capacity of one sample dispersed ultrasonically and treated with dilute NaOH at pH 10 increased from 33 to 169 meq/100 g while the K/NH 4 CEC remained in a range of 25 to 35. This particular sample contained all of the organic matter and the natural surface oxides. On standing for 12 days at lower pH, interlayer material was redeposited as indicated by Ca/Mg CEC reduction. Another sample of the same soil clay was pretreated in a conventional manner. The Ca/Mg CEC also increased from 24 to 113 and the K/NH 4 CEC increased from 20 to 31 meq/100 g when treated with NaOH in the same manner. A standard prochlorite showed small but equal upward increases of both kinds of CEC. Deuteration experiments using a chloritized vermiculitic soil clay, a vermiculitic soil clay, and a standard prochlorite showed the easy accessibility of interlayer OH groups to deuteration at moderate temperatures. The interlayer OH groups of chloritized vermiculite showed deuteration at 68C, while the OH groups in the 2:1 structure of the vermiculitic soil clay started deuteration at 150C and those of the prochlorite at 200C.