Investigating the effective carbon material for thermal chemical vapor deposition using aniline to enhance As(V) adsorption capacity of activated carbon

Abstract

To enhance the arsenic(V) adsorption capacity in the wide pH range, thermal chemical vapor deposition (tCVD) using aniline was conducted on various raw materials to prepare nitrogen-doped activated carbon samples. Phenol resin, polyacrylonitrile-based carbon fiber, cellulose-based activated carbon fiber, petroleum-derived beads-shaped activated carbon, and plant-based activated carbon powder were used as activated carbon precursors. We conducted the consecutive treatment (CVD) of steam activation as a pretreatment (8ST30), aniline tCVD (8ANL10), steam activation (8ST50), and heat treatment (9.5HT30). Steam activation was performed to improve tCVD efficiency and specific surface area. The annealing process at 950 °C was conducted to form quaternary nitrogen (N-Q) and reduce oxygen-containing acidic functional groups on the surface. The best result was obtained when we used cellulose-based activated carbon fiber as a precursor (KF-CVD). KF-CVD showed 0.172 mmol/g of the arsenic adsorption capacity, and it was at least 46% larger than that of all prepared samples. KF-CVD also indicated the highest adsorption capacity at any pH range. We assessed porous properties, elemental composition, nitrogen configuration by X-ray photoelectron spectroscopy, the number of surface functional groups by Boehm titration, and pHpzc of the prepared samples. Based on these surface characteristic studies; the increased specific surface area and the highest N-Q content of KF-CVD would enhance the arsenic adsorption in all pH ranges.