Sonocatalytic degradation of norfloxacin in aqueous solution caused by a novel Z-scheme sonocatalyst, mMBIP-MWCNT-In2O3 composite

Abstract

In this study, a novel Z-scheme composite sonocatalyst, mMBIP-MWCNT-In2O3, is successfully fabricated by using hydrothermal and calcination methods. And then, the prepared sonocatalyst is characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV–vis diffuse reflectance spectra (DRS), fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS). The sonocatalytic activity of mMBIP-MWCNT-In2O3 composite is evaluated through the degradation of norfloxacin in aqueous solution under ultrasonic irradiation. Meanwhile, the impacts of ultrasonic irradiation time, used times and scavengers on the sonocatalytic degradation efficiency are researched by using UV–vis spectroscopy. The results indicate that the addition of MWCNT accelerates the electron (e−) transfer and restrains the recombination of electrons (e−) and holes (h+) in Z-scheme mMBIP-MWCNT-In2O3 sonocatalyst. In comparison, the formation of Z-scheme sonocatalytic system and the presence of and MWCNT make the mMBIP-In2O3 display much higher activity in the degradation of norfloxacin. The relatively high sonocatalytic degradation ratio of norfloxacin can be got when the 10.00 mg/L norfloxacin, 1.0 g/L mMBIP-MWCNT-In2O3, 150 min ultrasonic irradiation (40 kHz frequency and 300 W output power), 100 mL total volume and 25–28 °C temperature are used. Subsequently, several scavengers are used to confirm the formation of the hydroxyl radical (OH) and hole (h+) for elucidating the sonocatalytic degradation mechanism. It is concluded that most of the norfloxacin in aqueous solution can be degraded by using mMBIP-MWCNT-In2O3 as sonocatalyst under ultrasonic irradiation.