Some Studies of the Autotransformation of H‐Bentonite to Al‐Bentonite

Duplicate samples of suspensions of H‐bentonite prepared by the method of Aldrich and Buchanan (1) were heated at 35°, 50°, 65°, 80° and 95°C. At appropriate time intervals, samples were removed, cooled to 25°C., and titrated electrometrically with NaOH solution. The titration curves were markedly differentiated functions of time and temperature of heating. Specimens heated for various periods at 95°C. were analyzed for the amount of replaceable Al and examined by X‐ray diffraction analysis. Replaceable Al increased progressively with time of heating. X‐ray diffraction analysis revealed that basal spacings and intensity of diffraction maxima increased with time of heating. The authors conclude that these changes are related to increase in the ratio of replaceable Al to H.