Quantitative methylene blue decolourisation assays as rapid screening tools for assessing the efficiency of catalytic reactions

• Published in: Chemosphere (Oxford) Vol. 175; pp. 247 - 252
• Main Authors: Kruid, Jan, Fogel, Ronen, Limson, Janice Leigh
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2017
• Subjects: Benzhydryl Compounds - chemistry; bisphenol A; Catalysis; Catalyst screening; catalysts; catalytic activity; Color; copper sulfate; Copper Sulfate - chemistry; decolorization; Ferrous Compounds - chemistry; high performance liquid chromatography; hydrogen peroxide; Hydrogen Peroxide - chemistry; Indoles - chemistry; manganese; Manganese - chemistry; Metallophthalocyanine; Methylene blue; Methylene Blue - chemistry; monitoring; oxidation; Oxidation reaction; Oxidation-Reduction; Phenols - chemistry; pollutants; rapid methods; research support; screening; Water Pollutants, Chemical - chemistry; Water Purification - methods; Catalyst screening; Oxidation reaction; Metallophthalocyanine; Methylene blue
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2017.02.051

Identifying the most efficient oxidation process to achieve maximum removal of a target pollutant compound forms the subject of much research. There exists a need to develop rapid screening tools to support research in this area. In this work we report on the development of a quantitative assay as a means for identifying catalysts capable of decolourising methylene blue through the generation of oxidising species from hydrogen peroxide. Here, a previously described methylene blue test strip method was repurposed as a quantitative, aqueous-based spectrophotometric assay. From amongst a selection of metal salts and metallophthalocyanine complexes, monitoring of the decolourisation of the cationic dye methylene blue (via Fenton-like and non-Fenton oxidation reactions) by the assay identified the following to be suitable oxidation catalysts: CuSO4 (a Fenton-like catalyst), iron(II)phthalocyanine (a non-Fenton oxidation catalyst), as well as manganese(II) phthalocyanine. The applicability of the method was examined for the removal of bisphenol A (BPA), as measured by HPLC, during parallel oxidation experiments. The order of catalytic activity was identified as FePc > MnPc > CuSO4 for both BPA and MB. The quantitative MB decolourisation assay may offer a rapid method for screening a wide range of potential catalysts for oxidation processes. [Display omitted] •MB decolourisation assay can screen possible catalysts for oxidative processes.•MB reacts broadly to oxidative processes, beyond hydroxyl radical production.•Catalysts performed similarly for both MB decolourisation and bisphenol A removal.