Characterization of Ag-exchanged clinoptilolite treated with a plasma jet at atmospheric pressure

Abstract

AbstractThis study reports on the effects of dielectric barrier discharge-like (DBD-like) plasma jet treatment at atmospheric pressure on Ag cation-exchanged clinoptilolite. In the plasma treatment process, argon plasma was applied to the surface of pellet samples prepared with Ag-clinoptilolite. After DBD-like plasma jet treatment for 30 and 60 min, remarkable colour changes were observed in the pellet samples. These changes indicate that the DBD-like plasma jet application led to the successful reduction of Ag+ to its metallic forms, which was further confirmed by the results of ultraviolet–visible diffuse reflectance spectroscopy. The structural, composition and morphological properties of the DBD-like plasma jet-treated samples were characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive X-ray analyses, and they were compared to the untreated Ag-clinoptilolite. The DBD-like plasma jet treatment caused no detectable structural changes in clinoptilolite within the analytical limitations of the methods used. The FTIR spectra show that the plasma treatment causes discharge-induced functional changes in the hydroxyl stretching region. The peaks appearing in the XRD patterns confirmed the reduction of Ag+ to Ag0 after exposure to the plasma. The present study indicates that the reduction of Ag+ cations to their metallic forms can be performed successfully using the proposed method without collapsing the crystal structure of the Ag-clinoptilolite.