Exfoliation of montmorillonite in protein solutions

[Display omitted] ► Sequential adsorption of proteins leads to exfoliation of montmorillonite stacks. ► At high protein-to-silicate ratio platelets form randomly structured secondary particles. ► Despite exfoliated, secondary gel-like aggregates retain submicron dimensions. ► Described method can be utilized to stabilize aqueous dispersions of clay particles. In the study we demonstrate a method to obtain stable, exfoliated montmorillonite–protein complexes by adsorption of the proteins extracted from hen-egg albumen. Analysis of the process by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) revealed that the complexes are formed by sequential adsorption of ovotransferrin, ovalbumins, ovomucoid and lysozyme on the surface of the silicate. Structural studies performed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the adsorption of ovotransferrin and albumins is accompanied by disintegration of clay stacks into discrete platelets. Further analysis by dynamic light scattering (DLS) revealed that at protein to silicate weight ratios exceeding 20, the synergistic adsorption of albumen components leads to reaggregation of silicate platelets into disordered, microgel-like particles. By means of DLS it was found that exfoliation predominantly leads to formation of particles with average hydrodynamic radii (Rh) of 0.19μm while their aggregation causes formation of particles having Rh in of approx. 0.5μm and larger.