A critical review on applications of microreactors for the treatment of polluted water with organic dyes

Abstract

The scale-down of reaction processes by microreactors enables significant benefits over the applications of conventional reactors due to the intensification of reaction which become an emerging prospect in the environmental engineering. In the last decades, there has been a rapid pollution increase connected with various industries, in particular due to the dye and textile industries, which generate huge amounts of wastewater containing organic dyes. The abatement of dyes in wastewater using microreactors therefore has great potential. This paper reviews a rapidly emerging area of microreactors applications in the removal of dyes from polluted water and describes a survey on recent advances in the development of microreactors in this area. With respect to the nature of the treatment technique, the scope of the literature was divided into several categories - Fenton reaction, ozonation, photocatalytic degradation, reductive degradation, biotreatment, and separative sequestration. This review focusses on summarizing different configurations of reaction conditions of the respective treatment techniques, their efficiency, and, mainly, the characteristics including design, construction materials, and fabrication of microreactors applied. The evaluation and evolution of treatment techniques have also been critically analyzed, and future perspectives are proposed in this work. From the present study, it can be concluded that several treatment methods can be applied for removal of organic dyes in a wide range of microreactor designs. Furthermore, this work showcases how microreactor technology may improve mass transfer as well as treatment efficiency. A novelty of the this review article lies in (i) data analysis with emphasis on reaction conditions as well as microreactor designs, and, based on this, in (ii) the proposition of decision-making algorithm which can facilitate a designing of the dyes removal in microreactors.