Microwave irradiation used for all steps of pre-pillaring Al-montmorillonite
- Autor: Yapar, S. / Torres-Sánchez, R.M. / Emroel, M. / Weidler, P.G. / Emmerich, K. (2009)
Clay Min. 44 (2009), 267-278
- Datum: 2009
Yapar, S. / Torres-Sánchez, R.M. / Emroel, M. / Weidler, P.G. / Emmerich, K. (2009): „Microwave irradiation used for all steps of pre-pillaring Al-montmorillonite“. In: Clay Min. 44 (2009), 267-278
In this study, a new procedure for the synthesis of pillared clays is proposed. Ageing processes and intercalation reactions were carried out using microwave irradiation in order to decrease the consumption of three industrially-important parameters; time, water consumption and energy. The effects of microwave irradiation, the amount of Al and the Al3+/clay ratio on the physicochemical properties of Al-pillared montmorillonites were investigated.
The structural changes, depending on the intercalation and microwave irradiation, were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM) analyses and by measuring the specific surface area and pore-size distribution. Additionally, simultaneous thermal analyses (STA) and zeta potential measurements were carried out to determine physicochemical properties.
According to the XRD measurements, the d001 value of microwave-irradiated samples is not affected by the amount of Al and the Al3+/clay ratio; microwave irradiation causes a 0.20 nm contraction in the d001 value in comparison to that of a conventionally pillared sample. The results of FTIR analyses reveal that the intensity of peaks assigned to Keggin-OH and Keggin-H2O stretches is diminished in the case of microwave-irradiated samples.
The STA analyses indicate that the amount of water released during dehydroxylation is decreased in the case of microwave-irradiated samples. By considering the contraction in d001 values and the decreases in Keggin-stretching bands and also in the amount of dehydroxylation water, it was concluded that microwave irradiation has a calcination effect.