Review on Methylene Blue: Its Properties, Uses, Toxicity and Photodegradation

Abstract

The unavailability of clean drinking water is one of the significant health issues in modern times. Industrial dyes are one of the dominant chemicals that make water unfit for drinking. Among these dyes, methylene blue (MB) is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to human health and environmental safety. It is usually released in natural water sources, which becomes a health threat to human beings and living organisms. Hence, there is a need to develop an environmentally friendly, efficient technology for removing MB from wastewater. Photodegradation is an advanced oxidation process widely used for MB removal. It has the advantages of complete mineralization of dye into simple and nontoxic species with the potential to decrease the processing cost. This review provides a tutorial basis for the readers working in the dye degradation research area. We not only covered the basic principles of the process but also provided a wide range of previously published work on advanced photocatalytic systems (single-component and multi-component photocatalysts). Our study has focused on critical parameters that can affect the photodegradation rate of MB, such as photocatalyst type and loading, irradiation reaction time, pH of reaction media, initial concentration of dye, radical scavengers and oxidising agents. The photodegradation mechanism, reaction pathways, intermediate products, and final products of MB are also summarized. An overview of the future perspectives to utilize MB at an industrial scale is also provided. This paper identifies strategies for the development of effective MB photodegradation systems.

Efficient Removal of Methylene Blue and Ciprofloxacin from Aqueous Solution Using Flower-like, Nanostructured ZnO Coating under UV Irradiation

“…Ciprofloxacin (Cipro), one of the most prescribed Qs used to prevent and treat infectious diseases, often appears in surface water, drinking water, ground water and waste water, ranging from ng/L to mg/L [3][4][5][6][7]. Similarly, methylene blue (MB), a blue cationic thiazine hazardous dye, is detected in the environment after being released in water bodies via effluents from textile, plastic, cosmetic, paper and pharmaceutical industries [8]. Exact data on the MB amount discharged in the environment are not available, but it is assumed that 10-15% of dyes are lost in the effluents during different stages of manufacture [9].…”

Magnetic Core-Shell Iron Oxides-Based Nanophotocatalysts and Nanoadsorbents for Multifunctional Thin Films

“…Under light exposure, the TMO photocatalyst is activated by absorbing photons with higher energy than its bandgap, generating an electron-hole (é-h + ) pair. These charge-carrier particles, in suitable conditions to avoid their recombination, interact with the molecules or ions in the reaction medium, generating a series of highly reactive oxidative radicals and/or molecules (ROS species) [ 67 ]: O 2 + 2H + + 2é → ∙H 2 O 2 h + + H 2 O → ∙∙HO 0 + H + …”

“…Modification and functionalization of the photocatalyst surface, including core-shell nanostructuring, is an important approach to tuning photocatalytic properties. Thus, the high enhancement in photocatalytic activity of SiO 2 functionalized IONPs is explained by the effect of the silica shell on reducing the bandgap energy and the electron-hole recombination [ 67 ].…”

Zero-Valent Copper-Mediated Peroxymonosulfate Activation for Efficient Degradation of Azo Dye Orange G

“…Since the catalyst is recognized as providing active sites for a catalytic reaction, its dosage variation can generally affect the reaction rate to a large extent [4,26]. As presented in Figure 7, the OG removal efficiency raised from 92.4% to 100.0% with ZVC dosage switching from 0.1 g/L to 0.3 g/L.…”