Amine-functionalized Zr-MOF/CNTs nanocomposite as an efficient and reusable photocatalyst for removing organic contaminants

In the current study, a new water-stable nanocomposite and amine-functionalized zirconium-based metal-organic framework/carbon nanotube (UiO-66-NH2@CNT) was synthesized using the hydrothermal approach, displaying superior photodegradation of anionic and cationic dyes under visible-light irradiation. Methyl orange (MO) and Rhodamin B (RhB) were used as organic contaminant models. The prepared materials were fully characterized by FTIR, XRD, SEM, TEM, BET, TGA, UV–Vis absorption, and ICP analysis. The optimal nanocomposite, UiO-66-NH2@CNT(3 wt%) exhibited the highest degradation efficiency of RhB (100%) and MO (93%) in less than 30 min under optimum conditions in comparison with other prepared materials (F-CNT, UiO-66, Ui-66-NH2, and other UiO-66-NH2@CNT-X samples). Different effective parameters such as initial dye concentration, catalyst dosage, and solution pH have been also studied. The possible mechanism for photodegradation of dyes over UiO-66-NH2@CNT(3 wt%) showed that the increase in the photocatalytic activity can be attributed to the range of improved visible-light absorption (lower band gap), and the great specific surface area based on composite and water stability as well as the formation of an effective hetero-junction. Trapping studies also revealed that hydroxyl radicals (OH•) and photo-generated holes (h+) had the most influence on the photocatalytic degradation of both dyes. The kinetic study for the dye degradation process was fitted with a first-order kinetic model. Also, after six-reuse cycles, the optimum composite still showed high photodegradation ability (>90%). © 2021 Elsevier B.V

Highly catalytic oxidative desulfurization and denitrogenation of diesel using anchored-silica-gel vanadium-substituted Dawson-type polyoxometalate

[EN] 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 °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 min 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