An experimental study on the effect of the acid and heavy metal treatments on the adsorption of CH4 by sepiolite

Akbelen M., Durmus M.

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, vol.27, no.12, pp.13194-13204, 2020 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 27 Issue: 12
  • Publication Date: 2020
  • Doi Number: 10.1007/s11356-020-07936-9
  • Page Numbers: pp.13194-13204


This study investigated methane (CH4) adsorption by natural sepiolite-obtained from Eskisehir in Turkey-and its Ag-, Cu-, Fe-, and H-exchanged forms by using a volumetric gas adsorption method. Sepiolite was modified with 1 M AgNO3, 1 M Cu(NO3)(2)center dot 3H(2)O, 1 M Fe(NO3)(3)center dot 9H(2)O, and 1 M HCl solutions at 80 degrees C for 6 h, respectively. The natural and modified sepiolite samples were characterized by using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTG), differential thermal analysis (DTA), and the nitrogen adsorption method. Quantitative XRD analysis showed that the sample consisted primarily of sepiolite clay mineral and dolomite as an impurity in small amounts. It was found that acid and heavy metal treatments caused apparent changes in the structure and microporosity of the sepiolite samples. CH4 adsorption isotherms of clay samples were examined at temperatures of 0 degrees C and 25 degrees C and pressures up to 100 kPa. It was determined that the CH4 adsorption capacities of sepiolite samples increased at both temperatures according to the following sequence: CuS < AgS < HS < S < FeS. CH4 adsorption values of sepiolite samples varied between 0.084 mmol/g and 0.299 mmol/g. It was observed that the CH4 adsorption capacities of heavy metal cation-exchange clay samples were related to the surface area.