Copper nickel co-impregnation of Moroccan yellow clay as promising catalysts for the catalytic wet peroxide oxidation of caffeine.

Copper and nickel were incorporated into the prepared yellow clay (YC) using one of the most widely used methods, for the preparation of heterogeneous catalysts, which is the wet impregnation method (IPM) and its application as a heterogeneous catalyst for Caffeine (CAF). Several catalysts Cooper Nickel's Catalysts (Cu-Ni) were applied to the yellow clay with different weight ratio of Cu and Ni, in order to explore the role of both metals during the catalytic oxidation process CWPO. Furthermore, the CuNi-YC catalysts, were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Langmuir's surface area, Brunauer Emmett Teller (BET), scanning electron microscope (SEM) and inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), so as to get a better understanding concerning the catalytic activity's behavior of CuNi-YC catalysts. The optimization of the catalytic activity's effects on the different weight ratios of Cu and Ni, temperature and H2O2 were also examined, using Box-Behnken Response Surface Methodology RSM to enhance the CAF conversion. The analysis of variances (ANOVA) demonstrates that Box-Behnken model was valid and the CAF conversion reached 86.16%, when H2O2 dosage was equal to 0.15 mol.L-1, copper impregnated (10%) and temperature value attained 60 °C. In addition, the regeneration of catalyst's cycles under the optimum conditions, indicated the higher stability up to four cycles without a considerable reduction in its conversion performance.

Effective Catalytic Delignification and Fractionation of Lignocellulosic Biomass in Water over Zn3V2O8 Mixed Oxide.

The conversion of poplar wood biomass to highly value-added chemicals and molecular building blocks was achieved by using the dispersed mixed oxide Zn3V2O8 (ZVO) in water under 100 kPa of 10% O2/N2 at 160, 180, and 200 °C for 4 h. This nanostructured mixed oxide was prepared via the precipitation process and then characterized by several techniques. The results showed that this mixed oxide has interesting catalytic properties and is a versatile catalyst for biomass delignification and lignin and hemicellulose depolymerization. ZVO exhibited high activity on poplar biomass delignification and fractionation (degree of delignification > 97%) and lignin and holocellulose conversion with high yield into aromatic and furan compounds (80 mg/g initial wood at 200 °C), with high selectivities for 5-hydroxymethylfurfural (HMF) (25 mg/g of initial wood), vanillin, and syringaldehyde.

Role of Fe(III) in aqueous solution or deposited on ZnO surface in the photoassisted degradation of rhodamine B and caffeine.

Iron (III) was incorporated, to the surface of a synthesized ZnO, using two nominal molar percentages of Fe (III): 1% and 5% Fe relative to ZnO. Samples dried and calcined at 200 °C and 400 °C for 2 h, were characterized by XRD, XPS, XRF, N2-adsorption-BET and (UV-vis)-DRS. Photocatalytic activities of the catalysts were assessed based on the degradation of rhodamine B (RhB) and caffeine (CAF) in aqueous solution under two irradiation conditions: UV and visible light illumination. Prior to the photocatalytic tests, the interaction of each one of the substrates with either Fe(III) or Fe(II) was studied in homogeneous medium under UV-illumination and oxygenated environment. It was found that Fe (III) can play an important role in homogeneous media in the photoassisted degradation, both of rhodamine B and caffeine, while Fe (II) does not exert a relevant role in the photoassisted degradation of the referred substrates. Fe-ZnO samples display similar or poorer performance than pure ZnO in the presence of UV light for both studied substrates. The phenomenon can be attributed to the formation of either goethite or ZnFe2O4 at the ZnO surface where the coupled Fe3+/Fe2+ can act as recombination centers for the photogenerated charges. On the contrary, all Fe-ZnO samples showed enhanced photocatalytic activity under visible illumination which seems to be independent of the iron content. In this context, the mechanisms for photoassisted degradation of both the substrates in homogeneous medium and photocatalytic degradation are discussed, as well as the role of Fe in the photodegradation processes.

Characterization and Quantification of Heavy Metals in Oued Sebou Sediments.

The discharge of large quantities of industrial and domestic effluents into the estuaries, with or without treatment, has led to an increase in the amount of micropollutants present in the sediments. In this study, we have assessed the quality of sediments of Sebou river studying the physicochemical parameters, percentage of organic matter, mineralogy, and trace levels of metal elements trapped in the sample sediments of Sebou river. The sediments samples were collected from the upstream of Fez river, confluence between the Fez river and the Sebou river, Ain Nokbi river, and edge of Sebou river, where wastewaters from the city of Fez are discharged. The sediments samples were characterized by scanning electron microscopy, X-ray diffraction, and Fourier Transform Infrared Spectroscopy, while trace levels of metallic elements, Calcium, Zinc, Copper, Cadmium, Iron, and Nickel, were determined by the ICP-AES analysis. The obtained results show that there is a significant change in the values of the studied metals which is probably due to industrial effluents. Indeed, the metal content in the sediments reaches particularly high values exceeding the limit recommended by WHO. These results suggested that the pollution by metallic industrial effluents discharged without treatments poses potential threat to the receiving rivers and may represent a danger for humans which are exposed to pollutants due to the numerous uses of such river waters.