Influence of small amounts of water and ethanol on Na~+-montmorillonite solid-state modification by inorganic and organic intercalants

摘要

The possibility of solid-state solvent-free modification of Na+-montmorillonite by transition metal salts (NiCl2 center dot 6H(2)O, CoCl2, FeCl3 center dot 6H(2)O) and quaternary ammonium salts (cetyltrimethylammonium bromide, diocta-decyldimethylammonium chloride, alkylbenzyldimethylammonium chloride) was investigated in the presence of water or ethanol. The introduction of water or ethanol was necessary for the effective modification, small amounts (4-8 mmol per 2 g clay) were sufficient, as was the crystallohydrate water in the case of FeCl3 center dot 6H(2)O. Solid-state intercalation produces metal cation-and organo-modified montmorillonites (M-Mt and O-Mt), which were studied by wide-angle X-ray diffraction (WAXD), wavelength dispersive X-ray fluorescence analysis (WDXRF) and thermal analysis (TGA). On mechanochemical interaction during grinding Na+ and Ca2+ were exchanged for intercalant cations, the residual amount of initial cations in the rinsed modified montmorillonite did not exceed 0.1-0.2%, measured by WDXRF, and NaCl was produced as a distinct WAXD phase in quantities consistent with WDXRF, from 3.0% to a theoretical maximum of 5.6%. M-Mt were identical in structure and composition to ones obtained by solution modification. For O-Mt, the intercalation and modification proceeded to a larger extent compared to solution-modified and commercial equivalents, and with a substantially higher basal spacing (by 2-3 nm) and modifier content. The products were obtained as fine powders that did not require subsequent dispersion and fractional separation.