Electrochemical synthesis and efficient photocatalytic degradation of azo dye alizarin yellow R by Cu/CuO nanorods under visible LED light irradiation using experimental design methodology

Synthesis of Cu and CuO nanoparticles from e-waste and evaluation of their antibacterial and photocatalytic properties

Waste printed circuit boards (WPCBs) contain a plethora of valuable metals, considered an attractive secondary resource. In the current research, a hydrometallurgical process combined ammonia/ammonium chloride leaching and reduction (using L-ascorbic acid) to recover copper and its oxide (CuO) as nanosized particles from WPCBs was investigated. The results of leaching indicated that 96.7% of copper could be recovered at a temperature of 35 °C for a leaching duration of 2 h with ammonium chloride and ammonia concentration of 2 mol/L at a solid:liquid ratio of 1:10 g/cm3. The synthesized particles exhibit spherical and distorted sphere morphology with average particle size of 460 nm and 50 nm for Cu and CuO NPs, respectively. The antibacterial activity of Cu, CuO, and a (1:1) blend of both (Cu/CuO) has been examined against five different bacterial and fungal strains. The highest zone of inhibition was measured as 21.2 mm for Cu NPs toward Escherichia coli and 16.7 mm for Cu/CuO blend toward Bacillus cereus bacteria. The highest zone of inhibition was measured as 13 mm and 13.8 mm for Cu/CuO blend toward Fusarium proliferatum and Penicillium verrucosum fungi. Cu/CuO blend showed notable photocatalytic activity towards Rhodamine B dye under visible light irradiation with 96% degradation rate within 120 min. Using the process developed in this study, copper and its oxide as nanoparticles can be produced from WPCBs and used for multifunctional applications.

Performance of a C-containing Cu-based photocatalyst for the degradation of tartrazine: Comparison of performance in a slurry and CPC photoreactor under artificial and natural solar light

A carbon-containing Cu-based material (Cu@C) was used as photocatalyst for the degradation of a commonly food-industry azo-dye (tartrazine, also called Y5), under solar light at laboratory and pilot scale photoreactors. Important performance parameters such as dark adsorption capacity, catalyst́s loading and initial concentration of the dye were first optimized in a slurry photoreactor at laboratory scale under artificial solar light following the kinetics of degradation of the dye. Afterwards, the photocatalytic activity was investigated at pilot scale in a compound parabolic collector (CPC) photoreactor operating for 10 h of irradiation. The degradation of tartrazine is among the highest values reported for alternative metal oxide semiconductors, in both photoreactor configurations. Catalytic data revealed a 3 times faster degradation kinetics of tartrazine in the CPC photoreactor under natural solar light than in the slurry reactor under artificial solar light. This behavior indicates that a moderate photon flux in the CPC is more adequate to operate with the prepared photocatalyst, as it minimizes the recombination of charge carriers in the catalyst. This is important, since most of the photocatalytic tests designed to evaluate the activity of novel materials are frequently carried out under simulated solar light and disregard the impact of photon flux in outdoor conditions.

Degradation of methyldiethanolamine and gas refinery effluent using a TiO2@WO3/ZnO photocatalyst: central composite design optimization

Synthesis of a composite with a low band gap for the degradation of MDEA under LED light and gas refinery effluent under sunlight.

Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

New insights in photocatalytic removal of Alizarin Yellow using reduced Ce3+/TiO2 catalyst

The present communication aims to obtain a novel Ce³⁺/TiO₂ thin film in a single step facile method using the in situ template process. The material was characterized by the XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), TEM (transmission electron microscope), and AFM (atomic force microscope) analyses. The thin film catalyst was intended to introduce in the degradation of one of potential dye Alizarin Yellow from aqueous solutions using the UV-A radiations. The mechanisms of degradation along with the physicochemical parametric studies were conducted extensively. The mineralization of pollutant and the replicate use of catalysts further enhance the applicability of present communication. Additionally, the real matrix treatment was conducted to simulate the treatment process.

Effective and viable photocatalytic degradation of rhodamine B dye in aqueous media using CuO/PVA nanocomposites

Graphical representation of CuO/PVA nanocomposite synthesis to degrade rhodamine B dye in aqueous medium

Magnetic Cu: CuO-GO nanocomposite for efficient dispersive micro-solid phase extraction of polycyclic aromatic hydrocarbons from vegetable, fruit, and environmental water samples by liquid chromatographic determination

In this research, we presented a magnetic dispersive micro-solid phase extraction (MD-μ-SPE) method coupled with high performance liquid chromatography (HPLC) based on the use of magnetic Cu: CuO-Graphene Oxide (GO) nanocomposite (Fe₃O₄/Cu: CuO/GO-NC) for the separation and preconcentration of polycyclic aromatic hydrocarbons (PAHs), i.e. naphthalene (Nap), phenanthrene (Phe), anthracene (Ant), and pyrene (Pyr), in vegetable (onion, tomato, carrot, herb, watermelon, lettuce, eggplant, and chili pepper), fruit (apple, watermelon, and grape), wastewater, and water samples. The MD-μ-SPE of PAHs in matrix samples was carried out, and the impacts of pH, ionic strength, extraction time, temperature, eluent volume, and sorbent mass on the recovery of PAHs were investigated by using Placket-Burman design (PBD). In addition, by using the central composite design (CCD), the best combination of each important variable was measured. Sorbent mass of 14 mg, eluent volume of 200 μL, and 12 min extraction time at the central level of other factors were optimal conditions of pretreatment for the highest extraction recovery (ER%) of trace PAHs. Under the optimal conditions, the method proposed herein provided high enrichment factors ranged from 116.51 to 133.05, good linearity in the range of 10-3800 ng mL^-1 for Pyr, 3.0-3500 ng mL^-1 for Phe, 5.0-3200 ng mL^-1 for Nap, and 5.0-3000 ng mL^-1 for Ant with coefficient of determination (R²) values between 0.9889 and 0.9963, low limits of detection (LOD) and quantification (LOQ) in the range of 0.015-0.061 and 0.485-2.034 ng mL^-1, respectively, and also satisfactory spiked recoveries (between 95.1% and 106.8%) with the relative standard deviations (RSDs) values in the range of 1.73%-5.62%. The Fe₃O₄/Cu: CuO/GO-NC-based MD-μ-SPE followed by HPLC-UV corroborated promising results for the convenient and effective determination of PAHs in the samples of vegetables, fruits, and environmental water. The results of this study revealed that our developed method is easy, feasible, precise, highly effective, and convenient to operate for the trace analysis of PAHs in different real samples. The extraction recovery was about 90% of the initial recovery after the sorbent usage for three times; therefore, the Fe₃O₄/Cu: CuO/GO-NC can readily be regenerated.

Sonophotocatalytic treatment of rhodamine B using visible-light-driven CeO2/Ag2CrO4 composite in a batch mode based on ribbon-like CeO2 nanofibers via electrospinning

CeO₂/Ag₂CrO₄ composite photocatalyst was successfully fabricated using electrospinning and calcination and chemical precipitation method based on CeO₂ ribbon-like fibers and characterized by field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS) and Fourier-transform infrared spectroscopy (FT-IR). The as-obtained CeO₂/Ag₂CrO₄ composite used photocatalytic performance in the sonophotodegradation of rhodamine B in aqueous solution under visible-light (LED) irradiation. DRS analysis illustrates that CeO₂/Ag₂CrO₄ composite exhibited enhanced absorption in the visible region-attributed CeO₂ nanofibers_. The effect of four effective parameters including initial concentration of rhodamine B (RhB), photocatalyst dosage, pH, and irradiation time was studied and optimized using central composite design. The kinetic studies confirmed ability of pseudo first-order reaction based on the Langmuir-Hinshelwood model for fitting empirical data, while its rate constant (k_obs), L-H rate constants (k_r), and L-H adsorption constants (K_A) were 0.0449 min^-1, 11.66 mg L^-1 min^-1 and 1.09E-3 mg L^-1, respectively. The enhanced photocatalytic activity could be ascribed to the ultrasound field and formation of a heterojunction system among CeO₂ and Ag₂CrO₄, which lead to a better mass transfer and higher efficiency of charge electron-hole separation, respectively.