Construction of Fe3O4@β-CD/g-C3N4 nanocomposite catalyst for degradation of PCBs in wastewater through photodegradation and heterogeneous Fenton oxidation

Abstract

Herein, a multifunctional magnetic β-cyclodextrin/graphitic carbon nitride catalyst (Fe3O4@β-CD/g-C3N4) was fabricated for PCBs degradation in wastewater. The catalysts were investigated using various characterization methods including X-ray diffractometry, field emission scanning electron microscopy, vibrating sample magnetometry and UV–Vis diffuse reflectance spectroscopy et al. As-synthesized Fe3O4@β-CD/g-C3N4 displayed the superior catalytic activity, and the degradation efficiency of six PCBs was 77%–98% at 55 min, with pseudo-first order reaction rate constants were in the range of 0.027–0.065 min−1. The super synergy of photodegradation and heterogeneous Fenton oxidation was 2.1–4.6 times more efficient than that photodegradation or heterogeneous Fenton oxidation alone. Fe3O4@β-CD/g-C3N4 could be reused for at least 6 cycles without significant deterioration to its catalytic activity. Several reaction intermediates were identified using GC-MS/MS. The products of the last stage of the reaction were alkanes, aldehyde, ketone and ester, which were formed via ring opening, dechlorinating and isomerization reactions. For PCBs degradation, •OH played a major role, •O2− played a secondary role, 1O2, h± and e− played minor roles based on reactive species trapping experiments. The catalytic performance of the Fe3O4@β-CD/g-C3N4 − H2O2 − visible light system towards degradation of PCBs in river water and municipal wastewater was 89–100% and 69–92%, respectively, which means the Fe3O4@β-CD/g-C3N4 has great potential for environmental remediation.