Degradation of binary mixtures of dyes by step-scheme quaternary photocatalyst in continuous flow-loop ultrasound assisted micro-photoreactor

Abstract

The development and design of micro-scale photocatalytic systems to achieve the degradation of organic pollutants such as dyes to improve environmental conditions is very desirable. In the current study, a microfluidic-based ultrasound-assisted photocatalytic microreactor was used for degradation of a mixture of cationic dyes including RhB and MB in binary mode by quaternary CeO2/Co3O4/Ag/Ag3PO4 step-scheme (S- scheme) photocatalyst under visible LED light. Various characterizations were performed to determine the morphology and structure of the photocatalyst. The ultrasound-assisted photocatalytic micro-photoreactor shows a much higher degradation performance than the simple micro-photoreactor for the degradation of cationic dyes. Besides, the batch process shows higher photocatalytic activity compared to the micro-photoreactor under ultrasound-assisted process. In addition, the reaction constant of CeO2/Co3O4/Ag/Ag3PO4 composite in ultrasound assisted micro-photoreactor are about 0.0087 1/s and 0.0081 1/s (RhB and MB) which are almost 2.3 and 1.7 times higher than micro-photoreactor due to free radicals, ultrasonic waves and Dean vortices. The observation of findings illustrated the photocatalytic degradation of dyes by the as-prepared composite in various processes were in the order of batch mode > ultrasound assisted micro-photoreactor > micro-photoreactor. The strategy of micro-photoreactor with ultrasonic waves using photocatalytic composite to improve dye degradation performance can lead to the development of advanced micro-photoreactor based on photocatalytic composites with high performance for wastewater treatment applications.