Modification of magnetite ore as heterogeneous nanocatalyst for degradation of three textile dyes: Simultaneous determination using MCR-ALS, process optimization and intermediate identification

Degradation of mixture of three textile dyes (C.I. Basic Blue 3 (BB3), C.I. Basic Red 46 (BR46) and Malachite Green (MG)) was investigated simultaneously through the heterogeneous Fenton process. The investigated catalyst was natural magnetite nanostructures (NMNs) prepared by modification of natural magnetite microparticles (NMMs) by a green glow discharge plasma (GDP) technology. A complete characterization such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses were executed to investigate various characteristics of the untreated and GDP treated-magnetite particles. The multivariate curve resolution with alternating least squares (MCR-ALS) modeling which is an important chemometrics technique was introduced and utilized as a novel method for multivariate calibration of the spectrophotometric data. The presence of four absorbing species were confirmed by MCR-ALS. In addition, by the use of this technique, the spectra and the concentration profiles of each dye were attained during the degradation process. A response surface methodology (RSM) was utilized to study, model and optimize the influence of several parameters on the dyes decolorization efficiencies. Also, the degradation by-products of the dyes generated during Fenton process were determined using gas chromatography coupled to mass spectrometry (GC-MS).