Understanding the structural and photocatalytic effects of incorporation of hexagonal boron nitride whiskers into ferrite type perovskites (BiFeO3, MnFeO3) for effective removal of pharmaceuticals from real wastewater

Abstract

In this work, metal-free hexagonal boron nitride (h-BN) was incorporated into BiFeO3 and MnFeO3 type perovskites by facile impregnation method for the first time and the catalysts presented excellent photocatalytic activity towards various antibiotics and dyes. The characterization tests were carried out by SEM-EDS, TEM, XPS, FTIR, XRD, BET, PL and DRS techniques. The narrower band gap of Type-II heterojunction improved the photodegradation of tetracycline which the reaction rates were calculated as 2.5 times higher than raw perovskites. The outstanding photocatalytic performance of heterojunctions was explained by extended excitation wavelength and hindered recombination rate of charge-carriers. In lake and sea water media, 86% and 72% degradation degrees were achieved over BiFeO3/h-BN and MnFeO3/h-BN, respectively, suggesting their practical utilization. BiFeO3/h-BN and MnFeO3/h-BN catalysts also exhibited superior catalytic performances for the elimination other contaminants namely, ciprofloxacin, Orange II and Indigo carmine yielding approximately 75% removal at the end of photo-Fenton catalysed reaction. The heterojunctions effectively removed nearly ~50% and ~70% of ibuprofen from the real pharmaceutical wastewater. The incorporation of hexagonal boron nitride offers an innovative and ideal way to enhance the photocatalytic activity of perovskite catalysts for the elimination of organic pollutants.