Preparation of microfiber composite nitrogen doped carbon nanotube membranes and their degradation properties of phenol in the structured fixed bed

Abstract

Microfiber composite nitrogen doped carbon nanotube membranes (NCNT/PSSF) were prepared by chemical vapor deposition on paper-like sintered stainless steel fibers (PSSF) using both camphor and melamine as precursors. FE-SEM, TEM, Raman, TG and other characterization methods were employed to investigate the influence of synthesis temperature, carrier gas flow rate and the ratio of precursors on the performance of NCNT/PSSF, respectively. Besides, the metal composition encapsulated in the NCNT tube was analyzed by XRD, XPS and HR-TEM. The pretreatment of PSSF promoted the migration of Fe and Cr to the stainless steel surface and reduced the particle size of the catalyst. Fe, as the only catalyst form, drove the growth of NCNT and was transformed into Fe3C after the reaction. Subsequently, the performance of NCNT/PSSF as a metal free catalyst for activating PMS (peroxymonosulfonate) to degrade phenol was evaluated on a structured fixed bed. The results revealed that about 85 % and 50 % of the phenol was transformed and mineralized during the first few hours of the reaction. Non-mineralized organic aromatic compounds included catechol, hydroquinone and p-benzoquinone. The concentration difference between the intermediate and the remaining total organic carbon represented some refractory open-loop carboxylic acids. Finally, the satisfactory results of the removal of phenol by NCNT/PSSF in actual water highlight its advantages in continuous treatment. Nonmetallic nitrogen doping not only provided a creative strategy for the development of nanocarbon materials, but also afforded an excellent catalyst to assist advanced oxidation techniques for the continuous removal of phenols from wastewater.