Antibiotics Removal via Novel N-Doped Carbon Derived from Carbonization of Different Forms of Polyaniline

Abstract

N-doped carbon (CP) was synthesized through carbonization of a polyaniline (PANI) prepared using interfacial polymerization. Different forms of PANI, such as emeraldine salt (ES), emeraldine base (EB), and aniline oligomers, were carbonized at different temperatures (700°C–1,000°C) in the presence of the N2 atmosphere to form CPs (CP7–CP10). CP prepared under different conditions was applied as adsorbent for antibiotics. It was observed that ES-PANI carbonized at 1,000°C formed graphitic N-doped carbon (CP10) and showed better adsorption of metronidazole (MET) compared with other CPs. The adsorption results showed that CP10 derived from the ES-form of PANI (PA1) achieved ∼97% MET removal within 5 min following pseudo-second-order kinetics (k = 0.347 g mg−1 min−1). CP10 has a high specific surface area (Sa) of 800.65 m2 g−1 and high graphitic nitrogen content (52.26% of total N) responsible for the rapid adsorption of the antibiotics through π-π electron acceptor-donor interaction, hydrogen bonding, and electrostatic attraction. In addition, CP10 has an adsorption capacity of 200.8 mg g−1 for MET. The highest activity of CP10 was due to high graphitic nitrogen content and high Sa. However, CPs formed from EB-PANI and aniline oligomers did not perform efficiently due to low Sa and graphitic nitrogen content. Similarly, CP10 applied for the adsorption of the ciprofloxacin (CIP) and tetracycline (TET) achieved maximum adsorption capacity of 344.8 and 263.2 mg g−1, respectively. Therefore, CP10 is a promising adsorbent for removing emerging pollutants from an aqueous solution.