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

In this study, carbon-rich mesoporous silicon carbide (CRP-SiC: thickness of 1.3 μm 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.