Some physicochemical properties of methylammonium and ethylenediammonium smectites

The physicochemical properties of organosmectites prepared with methylammonium (MA+:CH3–NH3+)(MA+:CH3–NH3+) and ethylenediammonium (EDA2+:H3+N–(CH2)2–NH3+) cations were compared. The content of the MA+ and EDA2+ is taken just equivalent to the cation exchange capacity 1.08 eqv kg−1 of the sodium smectite used. The highly purified sodium smectite (NaS), methylammonium smectite (MAS) and ethylenediammonium smectite (EDAS) were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and low temperature N2 adsorption/desorption (N2-AD) techniques. The interlayer spacing of the NaS, MAS and EDAS were calculated from XRD data as 0.21, 0.26 and 0.31 nm, respectively. The specific surface area (S) and specific micro-mesopore volume (V) pairs for the NaS, MAS and EDAS extracted from (N2-AD) data are 61 m2 g−1 and 0.11 cm3 g−1; 54 m2 g−1 and 0.12 cm3 g−1 and 177 m2 g−1 and 0.19 cm3 g−1, respectively. The S and V values do not change considerable by MA+ intercalation whereas they are tripled and doubled, respectively, by EDA2+ intercalation. This shows that with EDA2+ which is large enough to hold the 2:1 layers permanently apart without filling all the interlayer space, a notable number of size-selective micropores were opened, but it is not the case for the MA+.