Characterization and dehydration behavior of a natural, ammonium hydroxide, and thermally treated zeolitic tuff

Abstract

Aqueous NH4OH-treated and subsequently calcined forms of local natural zeolitic tuff were characterized by different techniques including scanning electron microscopy (SEM), X-ray powder diffraction, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), volumetric N2 adsorption at -196°C, thermogravimetry (TG), differential scanning calorimetry (DSC), and transmittance infrared spectroscopy. The dehydration behavior of the samples was investigated using an in situ temperature-programmed diffuse reflectance Fourier transform infrared spectroscopy (TP-DRIFTS) method under vacuum. The DRIFTS spectra recorded yielded information about the effect of the NH4OH treatment and subsequent calcination on the dehydration behavior of the natural zeolite.Changes in the infrared bands corresponding to vibrations of the O-H and N-H bonds upon in situ heating under vacuum were analyzed.