CuO ZnO Research Articles

ANSYS simulation study of a low volume fraction CuO–ZnO/water hybrid nanofluid in a shell and tube heat exchanger

For the first time, the heat transfer performance of a CuO–ZnO (80:20)/water hybrid has been studied experimentally and numerically in a shell and tube heat exchanger under turbulent flow conditions nanofluid (STHE). All experiments are carried out with 0.01 ​vol% CuO–ZnO (80:20)/water hybrid nanofluid at Reynolds numbers (NRe) ranging from 1900 to 17,500. The stabilized hybrid nanofluids (30 ​°C-Tube side) are then used as a coolant to reduce the hot fluid (60 ​°C-shell side) temperature using a STHE, with the results for the convective heat transfer coefficient, Nusselt number, friction factor, and pressure drop reported. The primary goal of this paper is to investigate the impact of hybrid nanoparticle mixing ratio optimization on STHE heat transfer efficiency under various operating conditions. According to the findings, the CuO–ZnO (80:20)/water hybrid nanofluid improved the heat transfer performance of the STHE at all Reynolds numbers. When using nanofluid over water, the Nusselt number and pressure drop were improved by approximately 33% and 13%, respectively. The hybrid nanofluid's maximum thermal performance factor and thermal efficiency enhancement were 1.45 and 7%, respectively, at NRe ​= ​17,500. According to the study, the thermal conductivity of nanofluid varies by only 5% after ten trials. Furthermore, the ANSYS Fluent program was used to predict the behavior of the hybrid nanofluid in STHE, and the simulation results fit the experimental values very well.

Coherent CuO-ZnO nanobullets maneuvered for photocatalytic hydrogen generation and degradation of a persistent water pollutant under visible-light illumination

CuO–ZnO nanocomposite photocatalysts synthesized via a facile co-crystallization process followed by high pressure annealing demonstrated excellent photocatalysis of H2 gas generation via water splitting as well as methylene blue (MB) dye degradation. Morphological analyses revealed that CuO nanoparticles readily combined with ZnO crystals to give rise to unique hierarchical bullet-shaped composite particles referred to as nanobullets. Elemental analyses confirmed the uniform distribution of CuO nanoparticles in the ZnO nanobullets. X-ray photoelectron spectroscopic analysis showed peak shifts associated with changes in the electronic states of the Cu and Zn species, confirming the formation of a heterojunction. Successful heterojunction formation was further supported by several imaging and spectroscopic techniques. The composite samples demonstrated enhanced photocatalytic activity compared with both uncombined ZnO and uncombined CuO. Among the as-synthesized nanocomposites, the sample annealed for 30 min (abbreviated as CZ-30) displayed the highest activity, generating 4.094 millimoles of H2 within 3 h and 98.6% photodegradation of MB within 80 min under exposure to visible light. Such an enhancement in photocatalytic performance was ascribed to the synergistic migration of charge carriers across the heterojunction of the composites. A mechanism of synergistic photocatalysis was proposed on the basis of the results.

ZnO nanowires based e-nose for the detection of H2S and NO2 toxic gases

In this work, a novel ZnO NWs based e-nose has been developed and demonstrated successfully for its ability to discriminate H2S and NO2 test gases. For this, a MS was fabricated by modifying the surface of the ZnO NWs with suitable sensitizers (∼<10 nm) namely Ni, Au, Cu, and MgO. A post deposition annealing in oxygen environment results in the formation of ZnO–CuO, ZnO–Au, ZnO–NiO and ZnO–MgO heterojunctions. The data repository was formed by measuring the response curves for different set of gas, concentration and operating temperature. The gas sensing results were subsequently interpreted employing both graphical analysis (3D bar chart) and multivariate data analysis (principal component analysis) techniques. For better understanding, the steps involved in the PCA have been explained and discussed elaborately. Our result indicate that the e-nose is capable for producing the qualitative as well as quantitative discrimination of two test gases namely H2S and NO2.

Interactions of high temperature H2S and HCl cleaning sorbents with biosyngas main components and testing in a pilot integrated biomass gasifier SOFC system

High temperature biosyngas cleaning is more efficient when the end user operates at elevated temperature, as in biomass gasifier solid oxide fuel cell systems. However, there is not much experience with this technology and low temperature gas cleaning is usually adopted. This paper advances current knowledge by presenting the results from the investigation of side reactions catalysed by commercially available sorbents involving biosyngas main components, and the results obtained with the pilot plant developed within the Horizon2020 project “Flexifuel-SOFC”. K2CO3, used for HCl removal, appeared catalytically active towards the water gas shift reaction. Under conditions representative of a real system, the residence time was not sufficient for the gas composition to reach thermodynamic equilibrium. ZnO–CuO, used for H2S removal, showed a catalytic activity significantly higher. Both sorbents seemed not active towards the methanation reaction. The pilot plant tests confirmed the occurrence of the WGS reaction in the HCl removal reactor. The sorbents decreased H2S and HCl below the target value of 1 ppmv for H2S and 5 ppmv for HCl. The catalytic activity of sorbents and the heat released by these reactions should be carefully considered in the design phase of high temperature gas cleaning units.

Effect of Different Chelating Agents on the Physicochemical Properties of Cu/ZnO Catalysts for Low-temperature Methanol Synthesis from Syngas Containing CO&lt;sub&gt;2&lt;/sub&gt;

Nanostructured Cu/ZnO catalysts were prepared by a simple solid-state method, using cheap metal nitrates as raw materials. Special attention was paid to the influence of different chelating agents such as citric acid, formic acid and oxalic acid on the physicochemical properties of Cu/ZnO catalysts, which were characterized by detailed investigations. CuO crystallite size, oxygen vacancies and surface compositions were clearly affected by chelating agent types, leading to different CuO–ZnO interactions in the calcined catalysts as well as distinct reducibility. Different chelating agents also had significant effects on specific surface area, metallic Cu0 surface area, and Cu crystallite size, as well as ZnO (002) plane to ZnO (100) plane ratio (I(002)/I(100)) calculated based on the peak intensity of XRD patterns of the reduced samples, so influencing the catalytic activity for low-temperature methanol synthesis from syngas containing CO2. The structure-activity correlations, particularly the relationships between space time yield (STY) of methanol with Cu0 surface area and I(002)/I(100) ratio, were evaluated. Cu/ZnO catalyst prepared with oxalic acid showed the highest STY value, which was 2.3 and 5.3 times higher that of the catalysts obtained with citric acid and formic acid, respectively. The excellent catalytic performance was due to its greater Cu0 surface area, higher specific surface area and smaller Cu crystallite size. Stronger interactions between Cu and ZnO in the reduced samples were also favorable for enhancing catalytic activity for low-temperature methanol synthesis.

Validation of thermal models to predict the productivity and heat transfer coefficients for passive solar still with different nanoparticles

ABSTRACT The study aims to predict the internal heat transfer coefficient (HTC) and distillate output of single slope solar still with and without nanoparticles for 41° tilt angle of glass cover with 4 cm water depth using various existing thermal models. The experiment is conducted in the winter season at the Solar Lab of MITS, Gwalior campus, M.P., India. After experiment on SSs at three different tilt angles (11°, 26°, and 41°) and three different water depths (4 cm, 5 cm, and 10 cm) it is observed that for winter season, the optimum tilt angle of glass cover is 41° and optimum water depth is 4 cm. Therefore, in this paper, six different thermal models have been validated at optimal parameters. The yield predicted using different thermal models is validated with the experimental yield. Statistical tool correlation coefficient (r) and root mean square percentage deviation (e) are calculated to show the error between experimental and predicted values. It is noticed that the value of correlation coefficient (r) is almost 0.99 for all models and for all cases. Kumar and Tiwari model shows the better agreement with the experimental value, with the lowest yield percentage deviation of 8.41%, 9.52%, and 9.89% for solar still with ZnO nanofluids, CuO nanofluids, and without nanoparticles, respectively. The distillate obtained through the CuO nanofluids and ZnO nanofluids is about 41.11% and 9.75% higher than the water without nanoparticles for 41° tilt angle of glass cover and 4 cm of water depth.

Effects of Zinc and Aluminum on the CuO Crystalline Size for Direct Dimethyl Ether Synthesis from Syngas

AbstractThe effects of zinc and aluminum on the CuO crystalline size for direct dimethyl ether (DME) synthesis from syngas were investigated. Metal oxide catalysts were synthesized with various molar ratios of CuO by the precipitation method, and by the co‐precipitation method with CuO/ZnO (CZ), CuO/ZnO/Al2O3 (CZA), and CZA at ratios of 1:1, 2:2:1, and 6:3:1, respectively. The acid catalysts (γ‐Al2O3, HZSM‐5) were added to the metal oxide catalysts by physical mixing. The catalysts were characterized morphologically and their acidities were determined. Loading of zinc and aluminum at different ratios showed that CZA (2:2:1) gave the smallest CuO crystalline size, appropriate for the methanol synthesis reaction. γ‐Al2O3 has a weak to moderate acidity range, suitable for DME synthesis. Moreover, the bifunctional catalyst, CZA (2:2:1)/γ‐Al2O3, had the highest surface area as well as the highest %CO conversion and %DME selectivity.

Dye-sensitized solar cell performance and photocatalytic activity enhancement using binary zinc oxide-copper oxide nanocomposites prepared via co-precipitation route

Zinc oxide nanoparticles (ZnO NPs) and binary ZnO–CuO nanocomposites (ZnO–CuO NCs) were prepared through a simple chemical co-precipitation route. The influence of copper (Cu2+) ions concentration (0.03, 0.06, 0.09, and 0.12 M) on optical, morphological, structural, and elemental characteristics of the ZnO–CuO NCs was examined by appropriate characterization techniques. The visible light reactive CuO created absorption shift to red region that minimized band gap of the ZnO–CuO NCs. The concentration of Cu2+ ions produced appreciable impact on size of the ZnO–CuO NCs. The dye-sensitized solar cell (DSSC) constructed using ZnO–CuO NC photoanode with Cu2+ ions concentration of 0.06 M generated a conclusive solar to electrical energy transformation efficiency of 2.56%, which was a 2.2-times greater over the DSSC encompassed pristine photoanode of ZnO NPs. The electrochemical impedance spectroscopy analysis revealed the longer lifetime of the photogenerated electrons and reduction in the charge recombination rate in the ZnO(0.44)–Cu(0.06) NC photoanode based DSSC. Furthermore, the ZnO(0.44)–Cu(0.06) NC disclosed substantial photocatalytic activity towards methylene blue dye degradation that could be chiefly credited to its particles size induced visible light absorption property.

Photocatalytic performance of coupled semiconductor ZnO–CuO nanocomposite coating prepared by a facile brass anodization process

Coupled semiconductor metallic oxides have been largely taken into consideration due to the photocatalytic application. In this work, ZnO–CuO coating nanocomposite was fabricated by simple anodic oxidation of alpha brass at different anodizing times. The crystalline structure of hexagonal ZnO and monoclinic CuO phases were demonstrated by X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) observation indicated the heterostructure formation of ZnO flower-like and CuO patches-like after 30 min anodizing. Brunauer-Emmett-Teller (BET) method was conducted for specific surface area measurement of the samples. Cyclic voltammetry (CV) and Pourbiax diagram indicated that the brass oxidation process starts with the formation of ZnO followed by CuO formation. Diffuse reflectance spectroscopy (DRS) demonstrated that the band gap energy of the ZnO–CuO nanocomposite narrowed by raising anodizing time owing to the formation of the Cu(3d) energy state near the Zn (3d) valence band. Photoluminescence (PL) spectra revealed that the lifetime of the photo-excited electron-hole increased by the effective combination between CuO and ZnO in anodized brass after 30 min. The photocatalytic performance of ZnO–CuO nanocomposites with different anodization times was estimated by the degradation of 2 mg/L methylene blue (MB) and colorless phenol solution under visible light irradiation. After 30 min, the anodized brass with an estimated 3 eV band gap energy exhibited 54 and 49% degradation of MB and phenol, respectively, after 300 min, which was the highest efficiency among all the samples. Also, the highest photo-degradation was obtained at 8 mm2/mL of surface area to volume of dye solution. Recyclability results showed only a 5% drop-in photocatalytic activity after three cycles. Finally, the photo-degradation mechanism was proposed based on the role of holes and hydroxyl radicals, using various scavengers.

Roles of interaction between components in CZZA/HZSM‐5 catalyst for dimethyl ether synthesis via CO2 hydrogenation

AbstractThe roles of interaction between two catalyst components in CuO–ZnO–ZrO2–Al2O3 (CZZA)/HZSM‐5 bifunctional catalyst for dimethyl ether (DME) synthesis via carbon dioxide hydrogenation were investigated. It was found that CZZA catalyst showed excellent stability during methanol (MeOH) synthesis for 100 h, while there was a severe loss of catalytic activity in the bifunctional catalyst for DME synthesis. Hence, the effects of different degrees of intimacy of two catalyst components were studied for DME synthesis, including mixed and separated modes. For the mixed mode, the particle size of catalysts and the amount of reaction intermediates were proven to influence the catalyst deactivation. For the separated mode, the catalysts showed rapid deactivation within a short time. Various characterizations indicated that the remarkable deactivation of separated mode was mainly caused by the decrease of copper active centers (e.g., sintering and oxidation) and blockage of acid sites via increased coke deposition on HZSM‐5.

Role of preparation parameters of Cu–Zn mixed oxide catalyst in solvent free glycerol carbonylation with urea

Solvent-free carbonylation of glycerol with urea to glycerol carbonate (GC) was achieved over heterogeneous Cu–Zn mixed oxide catalyst. Cu–Zn catalysts with different ratios of Cu:Zn were prepared using co-precipitation (CP) and oxalate gel (OG) methods. As compared to CuO–ZnO(2:1) catalyst prepared by oxalate gel (OG) method, much higher conversion of glycerol and highest selectivity towards glycerol carbonate (GC) was achieved with CuO–ZnO_CP(2:1) catalyst. Physicochemical properties of prepared catalysts were investigated by using XRD, FT-IR, BET, TPD of CO2 and NH3 and TEM techniques. The effect of stoichiometric ratio of Cu/Zn, calcination temperature of CuO–ZnO catalysts and effect of reaction parameters such as molar ratio of substrates, time and temperature on glycerol conversion to GC were critically studied. Cu/Zn of 2:1 ratio, glycerol–urea 1:1 molar ratio, 145 ​°C reaction temperatures were found to be optimized reaction conditions to achieve highest glycerol conversion of 86% and complete selectivity towards GC. The continuous expel of NH3 from reaction the mixture avoided formation of ammonia complex with CuO–ZnO catalyst. As a result of this, CuO–ZnO catalyst could be recycled up to three times without losing its initial activity.

In Silico and Electrochemical Studies for a ZnO-CuO-Based Immunosensor for Sensitive and Selective Detection of E. coli.

Escherichia coli is a harmful Gram-negative bacterium commonly found in the gut of warm-blooded organisms and affects millions of people annually worldwide. In this study, we have synthesized a ZnO–CuO nanocomposite (NC) by a co-precipitation method and characterized the as-synthesized NC using FTIR spectroscopy, XRD, Raman spectroscopy, and FESEM techniques. To fabricate the immunosensor, the ZnO–CuO NC composite was screen-printed on gold-plated electrodes followed by physisorption of the anti-LPS E. coli antibody. The biosensor was optimized for higher specificity and sensitivity. The immunosensor exhibited a high sensitivity (11.04 μA CFU mL–1) with a low detection limit of 2 CFU mL–1 with a redox couple. The improved performance of the immunosensor is attributed to the synergistic effect of the NC and the antilipopolysaccharide antibody against E. coli. The selectivity studies were also carried out with Staphylococcus aureus to assess the specificity of the immunosensor. Testing in milk samples was done by spiking the milk samples with different concentrations of E. coli to check the potential of this immunosensor. We further checked the affinity between ZnO–CuO NC with E. coli LPS and the anti-LPS antibody using molecular docking studies. Atomic charge computation and interaction analyses were performed to support our hypothesis. Our results discern that there is a strong correlation between molecular docking studies and electrochemical characterization. The interaction analysis further displays the strong affinity between the antibody–LPS complex when immobilized with a nanoparticle composite (ZnO–CuO).

Hierarchical Sphere-Like ZnO–CuO Grown in a Controlled Boundary Layer for High-Performance H2S Sensing

Hierarchical Sphere-Like ZnO–CuO Grown in a Controlled Boundary Layer for High-Performance H2S Sensing

The enhanced photocatalytic activity of ZnO nanorods/CuO nanourchins composite prepared by chemical bath precipitation

In this work, ZnO nanorods (NRs)/CuO nanourchins (NUs) were composed together to achieve the highest efficiency in methylene blue (MB) degradation. The nanocomposites were fabricated via a one-step, facile, and solution-based method named chemical bath precipitation. Crystal structures of hexagonal ZnO NRs and monoclinic CuO NUs phases were detected by X-ray diffraction (XRD) analysis, while field emission scanning electron microscopy (FESEM) confirmed the formation of ZnO NRs and CuO NUs with favorable interconnectivity. The chemical bonding stage of the Cu2+, Zn2+, and O2− were investigated with high-resolution X-ray photoelectron spectroscopy (HRXPS). Brunauer-Emmett-Teller (BET) method depicted a relatively wide pore size distribution for all the samples. Diffuse reflectance spectroscopy (DRS) demonstrated that band gap energy of ZnO NRs further narrowed by raising CuO concentration owing to the formation of the Cu(3d) energy state near the Zn(3d) valance band. Photoluminescence (PL) spectra revealed that the combination of ZnO NRs with CuO NUs significantly increased the lifetime of the photo-excited charge carriers. The ZnO/(10 mol%)CuO nanocomposite with the band gap energy of 2.9 eV and pore volume of 0.0180 cm3/g exhibited the highest efficiency and complete degradation of MB in less than 240 min. The photo-degradation kinetics of the as-prepared nanocatalyst followed a pseudo-first-order reaction model and exhibited about 12 times faster than ZnO. Finally, the photo-degradation mechanisms are proposed based on the role of reactive oxygen species and photo-generated charge carriers.

Influences and mechanisms of nanoparticles on pentachloronitrobenzene accumulation by earthworms

Pesticides and nanoparticles may coexist in soil; however, influences of nanoparticles on accumulation of pesticides in terrestrial organisms are still unclear. This study aims to investigate the influences and mechanisms of metal oxide nanoparticles (nano ZnO and nano CuO) on accumulation of pentachloronitrobenzene (PCNB) in earthworms and their combined toxicity. The earthworms were cultivated in the soil spiked with nanoparticles (10, 50, 250 mg/kg) and PCNB (100 μg/kg) for 21 days. The concentrations of PCNB in earthworms in binary exposure treatments (PCNB + ZnO and PCNB + CuO) reached 2.47 and 3.13 times of that in individual PCNB exposure treatment, indicating that nanoparticles facilitated the accumulation of PCNB in earthworms. The contents of reactive oxygen species (ROS) in earthworms in treatments PCNB + ZnO 250 and PCNB + CuO 250 reached 379 and 316 fluorescence intensity/mg Protein, respectively, which were significantly higher than that in control group (183 fluorescence intensity/mg protein), indicating that nanoparticles would cause oxidative stress to earthworms. Earthworm coelomocytes were extracted from healthy earthworms and cultivated in culture media in cytotoxicity tests. Changes of intracellular ROS contents and cell viability suggested that PCNB and nanoparticles caused serious oxidative damage to earthworm coelomocytes, thus leading to the damage of cell membrane and cell death. In in vivo tests, changes of biomarkers (ROS and malondialdehyde) demonstrated that these pollutants injured the earthworms. Increased accumulation of PCNB in binary exposure treatments was due to the damage of body cavity caused by nanoparticles. This study provides a novel hypothesis for nanoparticles facilitating organic pollutants entering terrestrial organisms and determines whether nanoparticles would bring about greater environmental risks of other pollutants.

Interface study of hybrid CuO nanoparticles embedded ZnO nanowires heterojunction synthesized by controlled vapor deposition approach for optoelectronic devices

Fabrication of p-CuO/n-ZnO heterojunction through a vapor deposition growth of hybrid CuO nanoparticles embedded ZnO nanowires for enhance optoelectronic device properties has been investigated. The controlled growth of ZnO NWs with reasonably uniform size having an average length of 1.5 μm and an average diameter of 40 nm was achieved using smart thermal CVD without employing any catalyst. Embedding CuO NPs with sputtering and thermal oxidation approach, a good hybridization of CuO over 1D ZnO NWs was achieved. The hybrid structure involved uniform CuO NPs deposition with a size less than 10 nm in diameter on the surface of the ZnO NWs. The performance analysis reveals significantly improved photoluminescence (PL) emission properties with good crystallinity and lesser intrinsic defect properties compared to the pristine ZnO NWs. This was evidently due to good interface interaction between ZnO NWs and CuO NPs to construct p-CuO/n-ZnO heterojunction. The I–V characteristics of the fabricated single hybrid nanowire heterojunction at CuO/ZnO interface, measured in dark by conductive nanoprobe AFM (C-AFM) at ultra-high vacuum, shows a good rectifying behavior with a less significant hysteresis. A remarkably good p-n junction showing a lesser number of charges were trapped at the surface of CuO nanoparticles/ZnO nanowires heterojunction was determined. The fabricated heterojunction at the CuO/ZnO interface indicates comparably small turn-on voltage ~0.7 eV and excellent ideality factor ~1.58 under dark. The band offset of the heterojunction was determined by XPS and was found to be type II band structure. The superior tuning in the optical band gap without any intrinsic defects illustrated its better crystallinity and the formation of p-n heterojunctions at the CuO/ZnO interface can attributed to the good alignment, high aspect ratio, and better crystallinity of hybrid NWs. These results have shown that hybrid CuO Nanoparticles/ZnO Nanowires heterojunction synthesized by vapor deposition has the potential to be used in optoelectronic device and other energy applications.

Green synthesis of zinc oxide and copper oxide nanoparticles using Achillea Nobilis extract and evaluating their antioxidant and antibacterial properties

Recently nanotechnology, as an important area of scientific research, has a considerable growth in numerous fields. Biosynthesis of nanoparticles by using plants and microorganisms has received significant attention due to the growing need to develop environmental technologies in nanoparticle synthesis. The green synthesis of nanoparticles is safe for humans and the environment due to lack of pollution. Plants can act as both stabilizing and reducing agents for the synthesis of metal oxide nanoparticles (MO NPs). The research aim is an illustration of a novel method for the synthesis of zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs) using Achillea Nobilis extract. The crystalline structure and morphology of nanoparticles were studied using characterization techniques such as Fourier transform infrared analysis, ultraviolet–visible spectroscopy studies, X-ray diffraction, field emission scanning electron microscope, and transmission electron microscope methods. The antioxidant activities of ZnO NPs and CuO NPs were evaluated using DPPH assays. Antibacterial activities of nanoparticles were tested against Gram-negative and Gram-positive bacteria using the microdilution method. The results of this study showed that there was a significant relationship between MO NPs resistance and against bacteria.

Hydrogen Production from Supercritical Water Gasification of Lignin and Cellulose with Coprecipitated CuO–ZnO and Fe2O3–Cr2O3

In this study, CuO–ZnO and Fe2O3–Cr2O3 were prepared by coprecipitation and their catalytic activity in supercritical water gasification (SCWG) was evaluated at 500 and 600 °C. Both catalysts impro...

Novel green strategy for CuO–ZnO–C nanocomposites fabrication using marigold (Tagetes spp.) flower petals extract with and without CTAB treatment for adsorption of Cr(VI) and Congo red dye

The CuO–ZnO-Carbon (CZC) nanocomposites (NCs) were synthesized via a green method at 300 and 400 °C calcinated temperatures, using waste marigold (Tagetes spp.) flower petal extract as a reducing agent and carbon source. A novel green strategy for the synthesis of highly effective CZC NCs was developed which showed better adsorption of toxic Cr(VI) and Congo red (CR) dye compared to unsupported carbon NCs. In this strategy, fine powder of petals as carbon source were passed with the flower liquid extract during the filtration process, which supported the metal oxides nanorods(NRs)/nanoparticles(NPs) on the surface. Furthermore, the surface of the synthesized NCs was modified by Cetyl Trimethyl Ammonium Bromide (CTAB) cationic surfactant to increase surface functionality, surface area, and positive charge density of NCs. Additionally, the adsorption performance of Cr(VI) and CR dye improved from acidic pH to neutral pH after surfactant modification of NCs compared to unmodified NCs. The characterization techniques such as Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, Point of zero charge (pHpzc), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were performed to examine physio-chemical properties of NCs and CTAB modified NCs. The FTIR and BET analysis confirmed that CTAB modified NCs showed excellent functionality and more than 49% and ~67% greater surface area than CZC-300 and CZC-400, respectively, which prepared at 300 and 400 °C temperature. XRD analysis confirmed that NCs were highly crystalline and no phase change after surfactant modification. The FE-SEM and TEM analysis confirmed the pentagonal NRs and spherical NPs of ZnO and CuO, respectively, were formed on the carbon surface. After CTAB modification, no change in the surface morphology of NCs was observed. Thus, comparative study of NCs and CTAB modified NCs was done for Cr(VI) and CR dye adsorption by varying batch conditions, such as initial pH, contact time, temperature, and initial concentration of Cr(VI)/CR dye. The equilibrium time and concentration data were fitted with non-linear forms of kinetic and isotherm models, respectively. CTAB modified CZC-300 NCs showed excellent adsorption capacity for both pollutants up to pH 6 compared to CZC-300 and CZC-400 NCs. Additionally, the maximum adsorption capacity of CTAB modified NCs for Cr(VI) and CR dye were 201.56 and 331.36 mg/g, respectively, at pH 2 and 30 °C and increased with increasing temperature. The effect of co-existing anions on adsorption capacity of both NCs for Cr(VI) and CR dye adsorption was investigated. The regeneration and reusability experiments of both NCs were also performed.

Electrochemical synthesis of CuO–ZnO for enhanced the degradation of Brilliant Blue (FCF) by sono-photocatalysis and sonocatalysis: kinetic and optimization study

The purpose of this study was to improve the synthesis condition of the CuO–ZnO nanocomposite using a two-step protocol. Initially, an electrodeposition method was used to synthesize CuO nanoparticles (Nps) at different current densities (25–40–53A/dm2) then assembled with ZnO Nps via a milling process to obtain different catalysts. The performance of this new composite was evaluated by characterizing the nanocomposite with XRD, FE-SEM, FTIR, BET, BJH, pHzpc, UV-DRS and then comparing it with the sonocatalysis and sonophotocatalysis degradations of dye Brilliant Blue FCF (BBF). The preliminary results of the kinetic study and a structural characterization of the nanocomposite showed that the CuO–ZnO synthesis at low current density was an efficient catalyst to degrade BBF with a bigger surface area of 50.63 m2 g−1 and a pH zpc of 8.2. Furthermore, the optimization of operational parameters such as the synthesis temperature (300–500 °C), the mass ratio of CuO:ZnO (2–10%) and the catalyst dose (0.5–2 g L−1) was studied by a central composite design (CCD) using the NEMROOD Software. The adjustment of the model demonstrates an agreement between the experimental and predicted data as shown by the high values of the correlation coefficient (R2photosono = 0.999, R2sono = 0.998).