Zinc Oxide Catalyst Research Articles

3D flower-like ceria silver co-doped zinc oxide catalyst assembled by nanorod for electrochemical sensing of zearalenone in food samples.

To ensure food safety and quality, the development of rapid detection of mycotoxins using sensitive and accurate methods is essential. Zearalenone is one of the mycotoxins found in cereals, and its toxicity poses a serious risk to humans. For this concern, a simple ceria silver co doped zinc oxide (Ce-Ag/ZnO) catalyst was prepared by coprecipitation approach. The physical properties of the catalyst were characterized by XRD, FTIR, XPS, FESEM, and TEM. The Ce-Ag/ZnO catalyst was used as an electrode material for the detection of ZEN in food samples due to its synergistic effect and high catalytic activity. The sensor exhibits good catalytic performance with a detection limit of 0.26µg/mL. Moreover, the efficiency of the prepared sensor was confirmed by selectivity in interference studies and real-time analysis in food samples. Our research is an essential technique for using trimetallic heterostructures to study the construction of sensors.

Pyrolysis of Waste Plastic to Fuel Conversion for Utilization in Internal Combustion Engine

In the present study different plastic waste materials with various types of plastics such as low-density polyethylene and polypropylene with zinc oxide catalyst have been pyrolyzed in batch tubular reactor. Waste plastics were characterized by using TGA and DTG analysis and FTIR spectroscopy. The pyrolyzed products are analyzed by standard methods to determine various parameters.

THE CATALYTIC EFFECT OF ZINC-OXIDE (ZNO) ON THE KINETICS OF COMBUSTION REACTIONS OF SOLID WASTE MATERIALS

This study aims to determine the catalytic effect of ZnO on the kinetics of the decomposition reaction of burning solid waste. ZnO catalyst was chosen because it has high mobility and reactivity. samples were prepared and randomly selected consisting of 12 types of inorganic waste and 10 types of organic waste. The research instrument uses (DTA) Differential Thermal Analysis proximate testing. From this test the data in the form of a mass decrease graph will be analyzed descriptively. The description of the data is displayed through the TG-DTG curve and the calculation of the activation energy (Ea) using the fitting model. the DTG curve identifies three peaks indicating the decomposition stages of the three components have different characteristics. The decomposed components are 1. lignocellulosic organic and low stability organic components, 2. Volatile substances from plastic components, 3. hydrocarbon residues and ash reformation. The combustion temperature increases in samples with high catalyst concentrations, but the burnout temperature decreases in samples with high catalyst concentrations. The DTA curve shows the increased reactivity of samples with high catalyst concentrations. Oxidative reactions which are exothermic/external heating increase in samples with high catalyst concentrations. The catalytic effect on the addition of zinc-oxide (ZnO) catalyst concentration to the components showed a decrease in the hydrocarbon component and an increase in the short chain hydrocarbon component. Increasing the concentration of zinc-oxide (ZnO) catalyst in the sample increases the activation energy. However, overall the addition of catalyst concentration in the combustion of organic-inorganic solid waste samples was able to reduce the activation energy at the end of the combustion reaction

Synthesis of Multi Wall Carbon Nanotubes based Electronic Sensors for Internet of Things (IoT)

The Internet of Things (IoT) refers to advance devices other than computers that are connected to the Internet and can send and receive information. IoT is a new paradigm that has transformed traditional lifestyles into high-tech ones. It is the notion of a ubiquitous computer environment in which custom-sized electronics are effortlessly implanted into common things. Electronic sensors at the heart of the IoT detect physical/environmental occurrences, translate these measurements into electrical signals, and wirelessly transfer the data for remote computation. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. CNTs have demonstrated potential applications in electronics, biosensing, artificial intelligence and the Internet of ThingsIn present study, we report the synthesis of Multi Wall Carbon Nanotubes (MWCNTs) by Chemical Vapour Deposition (CVD) at 600C on Zinc Oxide (ZnO) catalyst coated silicon substrate by thermal evaporation technique. As-grown MWCNTs are characterized by Scanning Electron Microscope (SEM). High density growth of MWCNTs have been confirmed by SEM image. Catalyst nanoparticles play very important roles in the decomposition of the hydrocarbon source and to provide nucleation site for growth of MWCNTs. High MWCNT density is required for IoT-based sensors with high performance, sensitivity, selectivity, and distant sensing. Because IoT not only provides services but also creates massive amounts of data. Hence, this study would be helpful for the next generation 5G communication and cloud computing stimulate to enhance living style.

Impact on the Photocatalytic Dye Degradation of Morphology and Annealing-Induced Defects in Zinc Oxide Nanostructures.

In this study, three different morphologies, nanoflower (NF), nano sponge (NS), and nano urchin (NU), of zinc oxide (ZnO) nanostructures were synthesized successfully via a mild hydrothermal method. After synthesis, the samples were annealed in the atmosphere at 300, 600, and 800 °C. Although annealing provides different degradation kinetics for different morphologies, ZnO NS performed significantly better than other morphologies for all annealing temperatures we used in the study. When the photoluminescence, electron paramagnetic resonance spectroscopy, BET surface, and X-ray diffraction analysis results are examined, it is revealed that the defect structure, pore diameter, and crystallinity cumulatively affect the photocatalytic activity of ZnO nanocatalysts. As a result, to obtain high photocatalytic activity in rhodamine B (RhB) degradation, it is necessary to develop a ZnO catalyst with fewer core defects, more oxygen vacancies, near band emission, large crystallite size, and large pore diameter. The ZnO NS-800 °C nanocatalyst studied here had a 35.6 × 10-3 min-1 rate constant and excellent stability after a 5-cycle photocatalytic degradation of RhB.

Photodegradation of Ciprofloxacin and Levofloxacin by Au@ZnONPs-MoS2-rGO Nanocomposites

This study aimed to investigate the photocatalytic performance of diverse zinc oxide catalysts containing gold nanoparticles (AuNPs), molybdenum disulfide (MoS2), and reduced graphene oxide (rGO) toward the degradation of the antibiotics levofloxacin (LFX) and ciprofloxacin (CFX) in aqueous solutions. The obtained results demonstrate that LFX is more resistant to degradation when compared with CFX and that the principal route of degradation under visible light is the formation of hydroxyl radicals. Photoluminescence (PL) measurements were employed to verify the inhibitory effect of electron–hole recombination when AuNPs, MoS2, and rGO are integrated into a semiconductor. The catalyst that achieved the highest percentage of CFX degradation was 1%Au@ZnONPs-3%MoS2-1%rGO, exhibiting a degradation efficiency of 96%, while the catalyst that exhibited the highest percentage of LFX degradation was 5%Au@ZnONPs-3%MoS2-1%rGO, displaying a degradation efficiency of 99.8%. A gas chromatography–mass spectrometry (GC-MS) analysis enabled the identification of reaction intermediates, facilitating the determination of a potential degradation pathway for both antibiotics. Additionally, recyclability assessments showed that the synthesized catalysts maintained stable photocatalytic efficiencies after 15 cycles, indicating that the heterostructures have the potential for further usage and may be tested with other organic contaminants as well.

Density functional study on electrochemical reduction of carbon dioxide to C1 products using zinc oxide catalyst

Density functional study on electrochemical reduction of carbon dioxide to C1 products using zinc oxide catalyst

Phase evolution, speciation and solubility limit of aluminium doping in zinc oxide catalyst supports synthesized via co-precipitated hydrozincite precursors.

The preparation of Al-doped ZnO via thermal decomposition of crystalline precursors, with a particular emphasis on kinetic effects on the solubility limits, was studied. The promoting effect of Al3+ on the catalyst system is discussed for methanol synthesis where ZnO:Al is employed as a support material for copper nanoparticles. The synthesis of the Al-doped zinc oxides in this study was inspired by the industrial synthesis of the methanol synthesis catalyst via a co-precipitated crystalline precursor, here: hydrozincite Zn5(OH)6(CO3)2. To determine the aluminium speciation and the solubility limit of the aluminium cation on zinc positions, a series of zinc oxides with varying aluminium contents was synthesized by calcination of the precursors. Short precipitate ageing time, low ageing temperature and aluminium contents below 3 mol% metal were advantageous to suppress crystalline side-phases in the precursor, which caused an aluminium segregation and non-uniform aluminium distribution in the solid. Even if zinc oxide was the only crystalline phase, TEM revealed such segregation in samples calcined at 320 °C. Only at very low aluminium contents, the dopant was found preferably on the zinc sites of the zinc oxide structure based on the signal dominating the 27Al NMR spectra. The solubility limit regarding this species was determined to be approximately xAl = 0.013 or 1.3% of all metal cations. Annealing experiments showed that aluminium was kinetically trapped on the site and segregated into ZnAl2O4 upon further heating. This shows that lower calcination temperatures such as applied in catalyst synthesis conserve a higher aluminium doping concentration on that specific site than is expected thermodynamically.

Investigation of the effects of purge gas recycling for increasing methanol production and carbon dioxide reduction on the environment using dynamic simulation

Nowadays, not only development but also survival requires energy. In today’s world, this energy is supplied through various carriers such as oil, gas, electricity, and renewable energy. Due to the increasing expansion of urban communities and the expansion of industry and industrial life, the issue of environmental pollution and excessive increase in greenhouse gases has become one of the major problems of communities. Half of all carbon dioxide emissions are generated by fossil fuel and power plants. Synthesis gas, which includes carbon dioxide, carbon monoxide, hydrogen, methane, and nitrogen, is obtained by reforming natural gas. This gas is used to produce valuable products such as methanol. In general, methanol is produced from the hydrogenation of carbon dioxide and carbon monoxide separately in the presence of zinc oxide and copper catalysts by a complex mechanism. In this study, to increase methanol production in the unit, the effect of recycling different gas components in the industrial unit has been investigated using dynamic simulation. Also, the amount of carbon dioxide reduction and its effects on the environment are examined. These studies showed that by considering these changes, the rate of methanol production current can be increased by about two percent.

Facile bio-fabrication of ZnO@AC nanoparticles from chitosan: Characterization, hydrogen generation, and photocatalytic properties

In this work, activated carbon-supported zinc oxide nanoparticles (ZnO@AC NPs) were studied using the thermal synthesis method. The activated carbon-supported zinc oxide catalyst was characterized by UV–Vis spectrometry techniques, Fourier Transform Infrared Spectrophotometer (FTIR), Transmissive electron microscopy (TEM), and X-ray diffraction (XRD) methods. XRD characterization measurements showed that the average size of the crystal NPs was 6.89 nm. According to the TEM analysis results, the nanoparticles' average size was 11.411 nm, and the particles had a spherical structure. The catalytic properties of the synthesized material were determined using the sodium borohydride methanolysis reaction. A kinetic study was performed regarding the effects of temperature, catalyst, and substrate concentration on the methanolysis reaction. Reusability experiments showed that the catalyst had excellent catalytic activity (85%), stability, and selectivity. As a result of the kinetic study, activation energy, enthalpy (ΔH), entropy (ΔS), and hydrogen production rate activation parameters were found to be 42.52 kJ/mol, 39.98 kJ/mol, −181.42 J/mol.K, 1257.69 mL/min. g, respectively. Also, the photocatalytic activity of ZnO@AC NPs was analyzed against Rhodamine B (RhB) dye, and the maximum degradation percentage was observed to be 76% at 120 min. This study aimed to develop the ZnO@AC NPs into an efficient photocatalyst to prevent industrial wastewater pollution and as a catalyst for hydrogen synthesis as an alternative energy source.

Enhanced Photocatalytic Activity and Charge Carrier Separation of a Nickel Impregnated Zinc Oxide Catalyst for the Visible Photodegradation of Remazol Brilliant Violet-5R and Methyl Orange

ZnO was impregnated with Ni in order to increase its photocatalytic performance in the visible region. The Ni-impregnated ZnO catalyst was synthesized by wet impregnation. The synthesis of Ni/ZnO catalyst, its morphological analysis and elemental analysis was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy which confirmed that 4.66% Ni was impregnated at the surface of ZnO. The synthesized catalyst was applied for the photocatalytic degradation of Remazol Brilliant Violet-5R (RBV-5R) and methyl orange (MO) in aqueous solution. The catalyst dosage, pH, dye concentration, and effect of scavengers were optimized. 98.92% degradation of RBV-5R was observed at pH 10 using 0.1 g of catalyst, 5 mmol H2O2 in 20 min, whereas 83.77% MO was degraded using 0.2 g of the catalyst at pH 4 in 30 min. The order of reaction was also determined by applying kinetic models and the degradation followed pseudo first-order kinetics for both dyes.

Sonocatalytic removal of naphthalene from an aqueous solution using ZnO nanoparticles

Abstract This research presents the sonocatalytic degradation of naphthalene from an aqueous medium using a zinc oxide (ZnO) catalyst synthesised by the thermal decomposition method. The present paper also aims to apply the response surface methodology for the evaluation of the effect of different parameters on the degradation rate. The optimum parameters were found to be 50 min of reaction time, 2.2 g/l of the ZnO catalyst mass, 30 °C, 280 V, and 80 mg/l of initial concentration under a constant ultrasonic treatment at 20 kHz and 260 W of power intensity. The elemental composition of the catalyst was as follows: Zn 25.18%, O 37.03%, Mg 3.20%, K 0.83%, Ca 4.05%, N 5.07%, Na 4.13%, Cl 3.43%, and Fe 0.32%. Fourier Transform Infra-Red (FTIR) confirmed the Zn–O bond stretching at 510 cm−1. The degradation efficiency of naphthalene was almost double when the ZnO catalyst was used. The naphthalene degradation rate was a first-order reaction. Analysis of variance (ANOVA) results show that the quadratic model is suitable for the obtained data (P-value = 0.0001) and in an optimal process, performance conditions were set equal to 100%. Regression analysis with a high correlation coefficient (R2 = 0.989) and the model F-value of 6.94 indicated the adequacy of the model. The reusability study revealed that ZnO as a catalyst sustained the catalytic activity over five cycles.

Decoration of alumina hollow fibers with zinc oxide: improvement of the photocatalytic system for methylene blue degradation.

The photocatalytic degradation of methylene blue (MB) in aqueous solutions and under visible light was investigated with dispersed and supported zinc oxide (ZnO) as catalysts. The ZnO catalyst was successfully impregnated in asymmetric alumina hollow fibers by the simple vacuum-assisted dip-coating method. According to energy-dispersive analyses, the photocatalyst was homogenously distributed in the substrate. A strong correlation was observed between the initial dye concentration and the efficiency of the supported photocatalyst. For the initial MB concentration of 5mgL-1 and catalyst dosage of 1gL-1, the photocatalytic system with both dispersed and supported catalysts reached almost 100% of MB degradation. The photocatalytic process followed the pseudo-first-order kinetic model, and, for the initial MB concentration of 5mgL-1, the apparent constants were 0.05415 and 0.00642min-1 for suspended and supported catalysts, respectively. The treated MB solutions presented low phytotoxicity to the germination Lactuca sativa seeds with germination indexes greater than 80% after irrigation with the treated MB solutions. The produced supported ZnO catalyst showed suitable photocatalytic stability even after several reuse cycles.

Graphene-substrate fabricated oxides and zinc oxide catalysts for the degradation of the methylene blue in the industrial wastewater

Abstract The release of unsafe color dyes into various industrial effluents can harm the environment and human health and therefore needs remediation. The current research assesses the environmental friendly photo-less catalytic performance of zinc oxide/reduced graphene oxide (ZnO/RGO) nanocomposites, prepared via green synthetic route, for the degradation, and decontamination of methylene blue (MB) dye from industrial aqueous effluents and compared with that of zinc oxide (ZnO), hydrogen peroxide (H2O2), and reduced graphene oxide (RGO). The materials were characterized for surface morphology, functional groups, and crystallinity by using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analysis, respectively, showing that ZnO nanoparticles (NPs) were well-formed on the RGO surface and were having uniform pore sizes and large surface area. The degradation pattern of MB from its 40, 60, 80, and 100 ppm solutions by employing the degradation materials were examined using UV–Visible spectral analysis. The pH before and after the degradation of the MB in all the sample solutions was noted and found to change slightly after the degradation of MB. The results demonstrate that the ZnO/RGO nanocomposites display a better catalytic degradation efficiency (99.57%) as compared to the other degradation materials with the order of efficiency as ZnO/RGO > RGO > H2O2 > ZnO which shows that the degradation efficiency of ZnO (∼14%) can be significantly improved while fabricating its nanocomposite with RGO (99.57%). These findings can be utilized on a large-scale decontamination of dyes from industrial wastes without the involvement of light i.e., photo-less degradation.

Quantum-Chemical Study of Reactions between Dimethyl Carbonate and Methylamine Proceeding through an Addition–Elimination Mechanism on Zinc Oxide Catalysts

Quantum-Chemical Study of Reactions between Dimethyl Carbonate and Methylamine Proceeding through an Addition–Elimination Mechanism on Zinc Oxide Catalysts

Functionalization of Multiwall Carbon Nano-Tube Supported Zinc Oxide Solid Acid Catalyst Using Sulfonate Compound for Transesterification of Schleichera Oleosa L Oil

Biodiesel is an alternative energy obtained through the trasesterification of vegetable oil in the presence of a catalyst. The catalyst plays a very important role in the success of the transesterification process. One way to increase the activity of the catalyst is through chemical modification called functionalization, which generally using SO3 group as a sulfonating agent is known as the sulfonation process. However, the disadvantage of this process is that it uses strong acids which are corrosive, require high temperatures and are not environmentally friendly. This study aims to increase the activity of zinc oxide catalyst supported by multi-wall carbon nano tube (Z/MWCNTs) sulfonated using (NH4)2SO4 as sulfonating agent. The synthesis route includes co-precipitation, sulfonation and precipitation time. The effect of concentration of ammonium sulfate, co-precipitation time, and sulfonating time on yield of biodiesels of kesambi (Schleichera oleosa L) oil (OSOBD) was investigated. The result showed that the activity functionalized Z/MWCNTS catalyst (Z/s-MWCCNTs) could enhance significantly. The results of the catalyst activity test on transesterification of OSO into biodiesel showed that Z/s-MWCNTs gave a high yield of 91% for the functionalized catalyst using ammonium sulfate with a concentration of 35%, co-precipitation time 12 hours and sulfonation time 4 hours. The functionalization of MWCNTS with the sulfonation process using ammonium sulfate has the potential to increase catalyst activity and can increase the efficiency of the transesterification process for non-edible oils, especially kesambi oil.

Effect of magnetic fields on the efficiency of the photocatalytic degradation of methylene blue in a dynamic fluid system

Methylene blue dye can induce negative effects to aquatic life and the environmental system. So, it is important to remove it from water. Although, the photocatalytic degradation of dye solution during magnetic treatment (or static water process) can increase the dye degradation, but it cannot apply for a large wastewater. Therefore, the dynamic fluid system is required. This paper investigated the effect of magnetic fields (MFs) through dynamic fluid magnetization system on the degradation of dye solution. Ultraviolet (UV) irradiation experiments were carried out in the presence of zinc oxide (ZnO) catalyst. The experiment was divided into two parts. First, the dye solution was exposed to MFs multiple times. In the second part, the dye solution was exposed to MFs continuously using a dynamic fluid system. The results indicated that the dye solution degraded faster when the exposure time to MFs under dynamic fluid system was long. At least 60% of the dye solution degraded within 3 min when the MF of strength 600 mT was applied. On the other hand, the dye solution degraded by only 24% in the absence of MFs. The degradation mechanism was observed to fit the pseudo-first-order kinetic reaction. The rate constant of the reaction was higher in the presence of MFs than that in the absence of MFs. This resulted in better degradation performance. Therefore, it can be concluded that the photocatalytic degradation of the dye solution was enhanced when external MFs were applied to magnetize dye solution using dynamic fluid system.

High-Performance Piezo-Electrocatalytic Sensing of Ascorbic Acid with Nanostructured Wurtzite Zinc Oxide.

Nanostructured piezoelectric semiconductors offer unprecedented opportunities for high-performance sensing in numerous catalytic processes of biomedical, pharmaceutical, and agricultural interests, leveraging piezocatalysis that enhances the catalytic efficiency with the strain-induced piezoelectric field. Here, a cost-efficient, high-performance piezo-electrocatalytic sensor for detecting l-ascorbic acid (AA), a critical chemical for many organisms, metabolic processes, and medical treatments, is designed and demonstrated. Zinc oxide (ZnO) nanorods and nanosheets are prepared to characterize and compare their efficacy for the piezo-electrocatalysis of AA. The electrocatalytic efficacy of AA is significantly boosted by the piezoelectric polarization induced in the nanostructured semiconducting ZnO catalysts. The charge transfer between the strained ZnO nanostructures and AA is elucidated to reveal the mechanism for the related piezo-electrocatalytic process. The low-temperature synthesis of high-quality ZnO nanostructures allows low-cost, scalable production, and integration directly into wearable electrocatalytic sensors whose performance can be boosted by otherwise wasted mechanical energy from the working environment, for example, human-generated mechanical signals.

Improving the ZnO-photocatalytic degradation of humic acid using powdered residuals from water purification plant

Abstract Alum residuals were collected from a water treatment plant and used for improving the photocatalytic degradation of humic acid (HA) by combinations of zinc oxide (ZnO) and powdered residuals from a water purification plant (PRWPP). The influence of operating conditions such as initial humic acid concentration, pH, irradiation time, PRWPP to ZnO ratio, catalyst dose, and light illuminance have been investigated. The optimum PRWPP to ZnO ratio was 10:90. Using the prepared composites instead of bare ZnO raised the HA removal efficiency from 85.5% to 97.8%, and from 38% to 48.1% at catalyst doses of 1.2 g/l and 0.4 g/l, respectively. Moreover, it reduced energy consumption from 210.4 to 166.2 Wh per mg of HA. An artificial neural network model (ANN) was developed to predict the removal efficiency under different operating conditions. The optimum ANN structure yielded a coefficient of determination (R2 = 0.993). A modified Langmuir-Hinshelwood pseudo-first-order model was used for describing the degradation kinetics at different initial concentrations of HA.

Nanostructure Shape-Effects in ZnO heterogeneous photocatalysis

Selective oxidation of alcohols is an essential reaction for fine chemical production. Here, the photocatalytic oxidation of benzyl alcohol by zinc oxide (ZnO) nanocrystals was investigated to clarify the mechanism of selective oxidation with this process. Reactivity when in contact with three distinct ZnO nanocrystal shapes: nanocones, nanorods and nanoplates, was studied in order to compare crystal facet-specific effects in the reaction system. The same non-hydrothermal and non-hydrolytic aminolysis method was used to synthesise all three nanocrystal shapes. The ZnO catalysts were characterized using by a range of techniques to establish the key properties of the prominent ZnO crystal facets exposed to the reaction medium. The ZnO nanocrystals photocatalysed the benzyl alcohol oxidation reaction when irradiated by a 370 – 375 nm LED output and each ZnO crystal morphology exhibited different reaction kinetics for the oxidation reaction. ZnO nanocones displayed the highest benzyl alcohol conversion rate while nanorods gave the lowest. This established a facet-dependent kinetic activity for the benzyl alcohol reaction of (101¯1) > (0001) > (101¯0). Experimental and density functional theory computation results confirm that the {101¯1} facet is a surface that exposes undercoordinated O atoms to the reaction medium, which explains why the reactant benzyl alcohol adsorption on this facet is the highest. Light irradiation can excite valence band electrons to the conduction band, which are then captured by O2 molecules to yield superoxide (O2•–). In a non-aqueous solvent, the photogenerated holes oxidise benzyl alcohol to form a radical species, which reacts with O2•– to yield benzaldehyde. This results in 100% product selectivity for benzaldehyde, rather than the carboxylic acid derivative.