A novel technique for studying the behavior of swelling clays is demonstrated. Using atomic force microscopy (AFM) with a fluid cell, samples of Na+ and K+ NAu-1 were exposed to various aqueous environments and the differences in swelling behavior were observed. The resistance of K+ saturated clays to osmotic swelling was examined by first imaging a quasi-crystal in ultra-pure H2O. A 0.05 M solution of NaCl was exchanged for the water to induce cation exchange and an increase in swelling occurred. KCl (0.05 M) was then exchanged for the NaCl solution to test whether speciation in the aqueous environment affects already swollen quasi-crystals. Effects of concentration of the aqueous solution on clay swelling were also investigated by imaging the same quasi-crystal in varying concentrations of NaCl and KCl. For many of the observed quasi-crystals, individual layers could be imaged, and the swelling behavior of individual interlayer spaces could be observed.

In situ observation of clay swelling at the quasi-crystal level during cation exchange using atomic force microscopy

245th National Meeting (2013)

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