Aluminum in Interlayers of Vermiculite

Abstract Aluminum sorbed from N AlCl 3 in the interlayer space of a 2 to 0.2µ fraction of vermiculite was not entirely removed by extensive washing with neutral salt solutions. The amount fixed was increased by heating the Al‐saturated clay with an AlCl 3 solution or with water. Treatment with a hydroxy‐Al solution for 4 days reduced the cation‐exchange capacity from 134 to 75 me. per 100 g. and treatment for 8 days reduced it to 1 me. Titration of Al‐vermiculite in N NaCl with NaOH to approximately pH 10 removed most of the Al from the interlayer space. Al‐vermiculite added to N NaCl formed two phases, one saturated with Na and the other with Na and Al. The extent and place of Al hydrolysis depended on the temperature, pH, and salt concentration of the system. X‐ray diffraction analysis of the sample which had an apparent cation‐exchange capacity of 1 me. showed that the 7Å./14Å. intensity ratio was about equal to that of a Ca‐saturated sample but was much less than that of chlorite. Ammonium fixation was reduced greatly by a small amount of interlayer Al. The stability of the vermiculite to heat treatment also was increased and its ability to expand when glycol solvated was decreased.