Synthesis and characterization of novel molybdovanadophosphoric acid supported kaolin hybrid catalyst for Chromotrope 2R dye degradation in water

The present study provides a complete perspective of recyclable molybdovanadophosphoric acid immobilized on kaolin (MVPA/Kaolin), a hybrid material for catalytic degradation of the dye, Chromotrope 2R in water under mild reaction conditions. Novel MVPA/Kaolin was synthesized with an advanced impregnation method. The material was characterized with PXRD, FTIR, ICP-OES, SEM–EDX, TEM, TGA, surface area, porosity, and ³¹P NMR measurements. The material that can be classified as a Keggin type catalyst, could be used for hydrogen peroxide oxidation of aromatic azo (–N=N–) dyes with –OH and –SO₃H functional groups. The degradation showed excellent conversion of 99.1% under optimum conditions of normal pressure and 60 °C temperature. Products like malonic acid and oxalic acid have been identified as the final products with GC–MS analysis. The present work has demonstrated the application of a simple and effective catalyst for degradation of azo dyes and the catalyst had the reusability capacity of up to six cycles without loss in performance.