Abstract

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 Al(3+)/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 d(001) value of microwave-irradiated samples is not affected by the amount of Al and the Al(3+)/clay ratio; microwave irradiation causes a 0.20 nm contraction in the d(001) 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-H(2)O 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 d(001) 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.