Abstract
The degradation of the pharmaceutical compound diclofenac in an aqueous solution was studied with an advanced oxidation method, catalytic ozonation. Diclofenac was destroyed in a few minutes by ozonation but several long-lasting degradation by-products were formed. For this reason, the combination of heterogeneous catalysts and ozonation was applied to eliminate them completely. The kinetics of the diclofenac degradation and the formation of by-products were thoroughly investigated. Loading of Pt on the catalysts resulted in an improvement of the activity. The Mesoporous Molecular Sieves (MCM) were one of the promising catalysts for the degradation of organic pollutants. In this study, six heterogeneous catalysts were screened, primarily MCM-22-100 catalysts with different Pt concentrations loaded via the evaporation-impregnation (EIM) method, and they were applied on the degradation of diclofenac. It was found that the presence of Pt improved the degradation of diclofenac and gave lower concentrations of by-products. The 2 wt % Pt-H-MCM-22-100-EIM demonstrated the highest degradation rate compared to the proton form, 1% or 5 wt % Pt concentration, i.e., an optimum was found in between. Pt-H-Y-12-IE and Pt-γ-Al2O3 (UOP)-IMP catalysts were applied and compared with the MCM-22 structure. Upon use of both of these catalysts, an improvement in the degradation of diclofenac and by-products was observed, and the 2 wt % Pt-H-MCM-22-100-EIM illustrated the maximum activity. All important characterization methods were applied to understand the behavior of the catalysts (X-ray powder diffraction, transmission electron microscopy, nitrogen physisorption, scanning electron microscopy, energy dispersive X-ray micro-analyses, pyridine adsorption-desorption with FTIR spectroscopy, X-ray photoelectron spectroscopy). Finally, leaching of Pt and Al were analyzed by inductively coupled optical emission spectrometry.
Highlights
The appearance of pharmaceutical compounds in the aquatic environment, in the surface waters, has become a global concern because various pharmaceuticals are frequently detected
MCM-structured catalysttowas applied in our Forcatalytic this reason, the MCM-structured catalyst wasthe applied in our experiments study the degradation experiments to study the degradation of by-products and the performance of the MCM catalyst was of by-products and the performance of the MCM catalyst was compared by other structures
The physico-chemical characterization of the catalytic materials was carried out using several techniques such as X-Ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), EDX, Transmissionelectron electron microscope microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and N2 -physisorption
Summary
The appearance of pharmaceutical compounds in the aquatic environment, in the surface waters, has become a global concern because various pharmaceuticals are frequently detected. The appearance of pharmaceutical compounds in the aquatic environment, in the waters, pharmaceuticals are sometimes observed at very high concentrations, even up to mg per liter surface waters, has become a global concern because various pharmaceuticals are frequently detected scales [1,2,3] This issurface mainlywaters due to as thewell residuals of veterinary and medical pharmaceuticals in wastewaters, as ground waters around the world. Advanced oxidation processes (AOPs) are one of the most promising technologies for the removal of organic macro-pollutants They could provide practical technologies to the degradation of non-biodegradable pharmaceuticals in contaminated wastewater as a replacement to the biological treatment [21,22,23]. The effect of the Pt loading on the catalysts, the catalyst concentration and catalyst structures in the transformation of DCF and its degradation by-products were studied, too
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