A vanadium-substituted Dawson-type polyoxometalate [cetronium] 11 P 2 W 13 V 5 O 62 was fabricated to use in the extractive−catalytic oxidative desulfurization (ECODS) of fuels using hydrogen peroxide and ionic liquids (ILs), ethylene glycol, and a deep eutectic solvent. Taguchi robust was utilized to investigate the effects of operation parameters including H 2 O 2 dosage, type of solvent, solvent-to-oil volume ratio, temperature, and contact time. The results demonstrated that the highest level of desulfurization could be achieved using a volume ratio of IL to oil = 1:6, O/(S + N) mole ratio = 4, and temperature = 70 °C after 45 min. The combination of the extraction and catalytic oxidation process showed that the step-by-step system (extraction in series with ECODS) was much better than the one-pot system (ECODS in one pot), which can remove 90% sulfur from 500 ppmw fuel and 87% sulfur from 1500 ppmw fuel under optimized conditions. The best system could also be reused 7 times in a 500 ppmw model fuel desulfurization and 4 times in a 1500 ppmw model fuel desulfurization.

In this study, we aimed at investigating the catalytic oxidative desulfurization (CODS) of the model diesel oil and real diesel oil using the vanadium-substituted Dawson-type emulsion catalyst ([cetrimonium]6+x P2W18–x V x O62 (x = 1, 3, 5)). Among all prepared samples, [cetrimonium]11P2W13V5O64 showed the best results in CODS of model diesel oil under determined conditions (10 g/L catalyst and O/S mole ratio = 4). The Taguchi method was then applied to optimize the catalyst dosage, hydrogen peroxide dosage, and the reaction temperature in CODS using the best emulsion catalyst. Then formic acid and acetic acid were used as a co-oxidant to improve the oxidation ability. Under optimum conditions, a mixture of H2O2/formic acid (1:1), in the presence of [cetrimonium]11P2W13V5O62 could remove 98% of dibenzothiophene and 82% of benzothiophene. Finally, under optimum conditions of CODS, 90% of total sulfur was removed from a real diesel sample. It is worth mentioning that we could recycle [cetrimonium]11P2W13V5O64, eight times without a significant decrease in catalyst activity.

The aim of this article is to study the extractive-catalytic oxidative desulfurization (ECODS) of the model oil containing several model S-containing compounds as well as N-containing compound using a heterogeneous vanadium substituted Dawson-type polyoxometalate catalyst under atmospheric pressure and temperature lower than 100 o C. The catalyst was prepared by ion exchange with alkyl ammonium derivatives covalently anchored to silica gel.The potential of this methodology was illustrated by oxidation of 100% quinoline and 80% of total sulfur in model oil containing 500 ppmw sulfur and 70% of total sulfur in model oil 1500 ppmw in less than 30 minutes of reaction, in the absence of solvent. However, when acetonitrile was employed as an extractive solvent, the desulfurization was increased considerably. Under the reaction conditions, activated catalyst and acetonitrile, solvent to oil ratio 1:6, could remove approximately 100% of quinoline, 95% of sulfur from 500-ppmw model oil, 87% of sulfur from 1500-ppmw model oil in less than 30 min. The catalyst is very active in ECODS and can be reused fifth times from 500-ppmw model oil and third times from 1500-ppmw model oil without an important decrease in activity. The ECODS could remove 83% of total sulfur from 1235-ppmw-S real diesel.

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Antibiotics are resistant to biodegradation, and their removal by biological processes is difficult. The purpose of this study was to investigate the removal of azithromycin from water using ultraviolet radiation (UV), Fe (VI) oxidation process and ZnO nanoparticles. The effect of different parameters such as pH, temperature, hydraulic retention time (HRT), the concentration of Fe (VI) and ZnO nanoparticles and UV intensity on the removal of azithromycin from water was investigated. The optimal conditions for the removal of azithromycin were a pH of 2, a temperature of 25 • C, a HRT of 15 min, and a ratio of ZnO nanoparticles to the initial concentration of azithromycin (A/P) of 0.00009 which was fitted by Langmuir isotherm. In addition, the optimal conditions for the removal of azithromycin using UV radiation were a pH of 7, a temperature of 65 • C, a HRT of 60 min, and UV radiation power of 163 mW/cm 2 . For the Fe (VI) oxidation process, the optimal conditions were a pH of 2, a temperature of 50 • C and a HRT of 20 min. Also, the optimal ratio of Fe (VI) to the initial concentration of antibiotic was between 0.011 and 0.012. The results of this study showed that the Fe (VI) oxidation process, UV radiation, and ZnO nanoparticles were efficient methods for the removal of azithromycin from water.

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