Pt Modified Heterogeneous Catalysts Combined with Ozonation for the Removal of Diclofenac from Aqueous Solutions and the Fate of by-Products

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.

Enhanced Removal and Toxicity Decline of Diclofenac by Combining UVA Treatment and Adsorption of Photoproducts to Polyvinylidene Difluoride

“…Both processes are accompanied by high operating expenses like pre-treatment and post-treatment [ 20 , 21 , 22 ]. Advanced oxidation processes (AOPs, like photocatalysis, photo-Fenton, ozonation or electrochemical oxidation) are highly discussed and investigated processes to eliminate micropollutants from water [ 23 , 24 , 25 , 26 ]. Reactive oxygen species (hydroxyl radicals, hydrogen peroxide, ozone, and superoxide anion radicals) are generated and completely mineralize micropollutants with a low selectivity to carbon dioxide, water, and inorganic ions or acids.…”

The Study of Designing Electro-Photo Catalytic Reactor with Photovoltaic Cells for Wastewater Treatment

“…Thus, it can be concluded that the electrochemical process is more effective under acidic conditions compared to alkaline conditions. These results suggest that the production rate of radicals for reducing organic pollutants in wastewater is higher in acidic solutions compared to alkaline solutions [35]. However, it is important to note that any increase in acidity should be carefully managed in consideration of the coating applied on the anode and cathode to prevent corrosion of these coatings [36].…”

Synthesis and Characterization of Metal Modified Catalysts for Decomposition of Ibuprofen from Aqueous Solutions

“…The catalyst activity was enhanced via metal loading; however, overloading the metal can block the pores and active sites of the catalysts, resulting in a dramatic decline of the catalytic activity. Consequently, the metal content was kept small for most of the synthesized catalysts [38]. The Cu, Ni, Pd, and Fe metal contents in the metal-modified catalysts were analyzed using energy-dispersive X-ray microanalyses (EDXA); the analysis was performed three times for each catalyst, and the average amount was calculated and presented in Table 2.…”