The denitrification characteristics of novel functional biocarriers immobilised by non-dissolved redox mediators

• PET–CAs were first synthesized with non-dissolved redox mediators.
• PET–CAs acted novel functional biocarriers applied in biotransformation processes.
• The denitrification efficiency was enhanced by PET–CAs.
• PET–CAs concentration was relatively related to the denitrification rate.

This study investigated the denitrification characteristics and practical applications of PET–CAs (chloroanthraquinones immobilised on polyethylene terephthalate), which are novel functional biocarriers. The PET–CAs were characterized using Fourier transform infrared spectroscopy (FT-IR) and energy dispersive spectrometry (EDS). Among the PET–CAs, PET-1,8-DCA (PET modified by 1,8-dichloroanthraquinone) was the best functional biocarrier for accelerating the denitrification process with approximately 0.14 mmol anthraquinone. The denitrification process was pseudo-zero order, with CNO3− = 175.64–19.28 t and R2 = 0.9715. The pH of the PET-1,8-DCA system increased and ultimately reached 9.7. The stabilized ORP value with PET-1,8-DCA was approximately 70 mV lower than that of the control with PET. This study explored a novel design concept for the immobilization of quinone.