Microwave irradiation used for all steps of pre-pillaring Al-montmorillonite

Abstract

AB ST R ACT : 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 microwaveirradiated 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.

Surface and interface properties of benzethonium chloride-montmorillonite

“…The ammonium ions or R-ammonium salts selectivity showed by montmorillonite generated the so called organo-montmorillonites, which traditional preparation method for different cationic (ammonium) surfactants used oven heating [24,[26][27][28]. Previous work using microwave in synthesis of silico-aluminate products [29][30][31] and also in obtaining organo-clays [32] showed that it allows a more direct and rapid heating, reducing the time to a fraction of that generally required using conventional conditions.…”

Pillaring of bentonite clay with Al and Co

“…Thus, the lamellar spacing and specific area increase, making these materials attractive catalysts for various reactions. Several methods of preparing pillared clays are outlined in the literature, and variations in the synthesis result in materials with different characteristics [11][12][13]. However, no general rules for the best synthesis conditions exist.…”

Influence of high-frequency microwave radiation on montmorillonite structure parameters

“…The third type of bounds, hydrogen bonds, which are the weakest bonds, are formed between water molecules of an ion-hydrate layer in the basal plane of montmorillonite particles. In [9], it was established that microwave radiation treatment leads to a reduction of the interplanar distance d 001 by 0.20 nm due to degradation.…”