Effects of hydrochloric acid treatment on structure characteristics and C2H4 adsorption capacities of Ünye bentonite from Turkey: a combined FT-IR, XRD, XRF, TG/DTA and MAS NMR study

In this study, a bentonite sample from Unye, Turkey was treated with various HCl solutions (0.1, 1.0 and 5.0 M) at 90 °C during 3 and 6 h. X-ray diffraction (XRD), X-ray fluorescence (XRF), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infrared (FT-IR), magic angle spinning nuclear magnetic resonance (29Si and 27Al MAS NMR) and surface area measurement methods were employed in order to investigate the structural and thermal changes occurring as a result of the acid activation. The data for the adsorption of C2H4 obtained at 273 K and pressures up to 100 kPa correlated with structural properties of the acid treated bentonite samples. With the increase of both concentration of acid solution and treatment time, the specific surface area values and the retentions of C2H4 gas of bentonite samples increased. Bentonite treated with 5.0 M HCl for 6 h adsorbed C2H4 most effectively.