Mechanochemical synthesis of microscale zero-valent iron/N-doped graphene-like biochar composite for degradation of tetracycline via molecular O2 activation

Abstract

In this study, we prepared a micron zero-valent iron/N-doped graphene-like biochar (mZVI/NGB) composite using a mechanochemical method for tetracycline (TC) degradation through O₂ activation. The mZVI and NGB components formed a strong coupling catalytic system, with mZVI acting as an electron pool and NGB as a catalyst for H₂O₂ generation. Under circumneutral pH (5.0-6.8), the mZVI/NGB composite exhibited exceptional TC removal efficiency, reaching nearly 100 % under optimal conditions. It also showed good tolerance to co-existing anions, such as Cl^-, SO₄^2-, and humic acid. Further studies found that the TC degradation mechanism was mainly ascribed to the non-radical pathway (¹O₂ and electron transfer), and the Fe²⁺/Fe³⁺ redox cycle on the composite's surface also played a crucial role in maintaining catalytic activity. This research contributes to the development of advanced materials for sustainable and effective water treatment, addressing pharmaceutical pollutant contamination in water sources.

Keywords: Antibiotics; Fenton-like; Molecular oxygen activation; N-doped graphene-like biochar; mZVI.