Formation of highly porous electrochemically etched silicon carbide: A novel reusable adsorbent for air purification technology

Abstract

In this study, carbon-rich mesoporous silicon carbide (CRP-SiC: thickness of 1.3 mu m and surface area of 77.3 m(2)/g) was obtained by electrochemical etching of polycrystalline SiC using HF/acetonitrile (1:5.6 ratio) at an optimum current density of 30 mA/cm(2). The selective etching of Si from SiC was validated by Raman and X-ray diffraction analyses. High resolution-transmission electron microscope and atomic force microscope analysis showed the mesoporous structure (range: 10-100 nm) and a valley-and-peak form on the surface of CRP-SiC, respectively. The potential utility of CRP-SiC as an ideal adsorbent for commercial application was investigated against the low-molecular aliphatic volatile organic compounds (VOCs) like glutaraldehyde (GA) and formaldehyde (FA) as model target compounds. The maximum specific adsorption capacity of CRP-SiC, when measured for the GA and FA at the initial concentration 30 ppm, were 89.1 and 79.2 mg/g, respectively. The total adsorption capacity of this adsorbent was above 90%, when reused up to five times. The adsorption performance of CRP-SiC was also remarkably high in terms of partition coefficient relative to many other types of common sorbents (e.g., powder or granular activated carbon). The potential of carbon-rich surface on a stable and hard SiC semiconducting material is investigated in depth to help find the better alternative for the conventional or other well recognized adsorbent for treating VOCs. (C) 2019 Elsevier Ltd. All rights reserved.