Copper Nitrate Solution Research Articles

Synthesis and adsorption performance of Cu-BTC microspheres for Methylene Blue Dye

The MOFs, copper–1,3,5- benzenetricarboxylate (Cu-BTC) samples were synthesized by immersing self-assembled films in solutions of copper nitrate and trimesic acid through a biomimetic mineralization method. During the synthesis, self-assembled monolayers with different end groups acted as templates, facilitating the nucleation and growth of Cu-BTC crystals. The resulting products were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The influence of the synthesized materials on the adsorption performance of methylene blue (MB) dye was systematically investigated. The results show that the Cu-BTC compound microspheres, induced by sulfonic acid groups, have a uniform morphology and exhibit effective adsorption of MB dye. The theoretical maximum adsorption capacity of these microspheres for MB dye is 75.6 mg·g–1. The adsorption data from this process are consistent with both the pseudo-first-order kinetic model and the Langmuir isotherm model. After four adsorption-regeneration cycles, the microspheres retained a high adsorption efficiency for MB dye.

Carbon-doped CuO nanoparticle-constructed single tube adsorbent for high efficient adsorption of Pb2+ at near room temperature

How to prepare adsorbents using economical, environmentally friendly and simple methods has become the focus of research. In this paper, silk cotton (SC) was used as a biomass template impregnated with copper nitrate solution and then calcined to prepare CuO-based adsorbent. Carbon-doped CuO (C/CuO-400) adsorbent was obtained under 400 °C air calcination calcination. It completely replicates the morphology of kapok and consists of uniformly smaller nanoparticles. The effects of different calcination temperatures, adsorption temperatures, adsorption times, adsorbent dosages and different concentrations on the adsorption of lead ions were investigated. The results showed that C/CuO-400 had a good adsorption effect on Pb2+, which was suitable for Pseudo second-order and Langmuir, and the maximum adsorption amount of Pb2+ was 588.24 mg/g with good Reusability. This environmentally friendly, economical and simple to operate biomass template prepared adsorbent of single tube C/CuO has good adsorption effect on lead ions, which is very meaningful and easy to promote the preparation of adsorbent.

Effect of copper nanoparticles green-synthesized using Ocimum basilicum against Pseudomonas aeruginosa in mice lung infection model

Abstract The frequency of lung infection induced by multi-drug resistant strains of Pseudomonas aeruginosa has significantly risen, primarily due to the inadequate effectiveness of powerful chemotherapeutic methods. This study demonstrates that the Ocimum basilicum aqueous extract and copper nanoparticles (CuNPs) exhibited significant antioxidant and anti-infectious properties under in vivo conditions. To analyze the characteristics of the CuNPs synthesized from the reaction between copper nitrate solution and the aqueous O. basilicum extract, various techniques such as energy dispersive X-ray analysis, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and transmission electron microscopy were employed. The in vivo study encompasses the assessment of P. aeruginosa lethal dose in mice and the disease manifestation analysis, which comprises reduction in body weight, hypothermia, bacteremia, and other parameters, over a 48 h infection period. The infected mice exhibited a notable decrease in body temperature, measuring at 25°C after 48 h, compared to the initial temperature of 39°C. Additionally, a 30% reduction in weight was seen at the conclusion of the study. To assess the effectiveness of CuNPs on lung infection caused by the calculated lethal dose and bacteremia, histopathology analysis was employed. The bacterial load in the CuNPs group was determined to be 0.5 Log10CFU/mL on Day 8, indicating a notable decrease from the initial measurement of 1.5 Log10CFU/mL on Day 1. The histopathological findings revealed a widespread and sporadic buildup of alveolar space inflammatory cells, with infiltrates observed throughout all lung sections in infected mice. Enhanced lung histology was observed in the group of animal treated with reduced exudates noted at 200 µg/kg. CuNPs demonstrated inhibitory effects on the growth of P. aeruginosa at 8 µg/mL, while at 16 µg/mL, they effectively eradicated P. aeruginosa. The research unequivocally demonstrates the efficacy of CuNPs extract in combating lung infections induced by P. aeruginosa at 200 µg/kg. The recent survey aims to further explore the biomedical characteristics of these CuNPs in order to develop a powerful treatment against this dangerous pathogen.

In-situ evidence for the existence of surface films in electrochemical machining of copper in nitrate electrolytes

This contribution analyzes the electrochemical etching of copper in a sodium nitrate electrolyte using in-situ Raman spectroscopy. Experiments were conducted in a specially designed process chamber at voltages below, at, and above the limiting current plateau. Below the plateau, a Raman peak at 1050 cm–1 is detected, which is attributed to the symmetrical nitrate ion. However, the line shape changes at and above the plateau. Detailed line shape analysis indicates the presence of a copper nitrate surface film by ex-situ comparison with copper nitrate solutions. In addition, the conductivity and pH of copper nitrate solutions were determined. A 5 M copper nitrate solution exhibits a low conductivity of 55 mS cm–1 and a pH close to 0. A significant influence, especially of the low pH, on the surface structure and therefore on the etching mechanism is assumed.

Quench-induced Cu-ZnO catalyst for hydrogen production from methanol steam reforming

Methanol steam reforming (MSR) is considered as a promising approach to provide hydrogen for proton-exchange membrane fuel cells. However, it is challenging to develop effective and durable Cu-based catalysts. Herein, Cu-ZnO catalysts are prepared by facile quenching of ZnO in copper nitrate solution followed by reduction to obtain the desired metal loading and induce the doping of surface metal heteroatoms for producing more vacancies. Catalysts enriched with oxygen vacancies can efficiently activate H2O and rapidly transform C-containing intermediates, resulting in higher methanol conversion and lower CO selectivity. As a result, the quenched optimal catalyst achieves 100 % methanol conversion and 0.05 % CO selectivity at 280 ℃, exhibiting the excellent catalytic performance in MSR reaction. In practical applications, structured catalysts are more attractive for large-scale catalytic reactions owing to the low pressure drop and high utilization efficiency. Therefore, ZnO-Cu3 catalyst is coated on cordierite honeycomb ceramics with 100 % methanol conversion and 0.04 % CO selectivity at 280 ℃. After 100 h of the reaction, the structured catalyst remains ∼ 92.3 % with CO selectivity varying from 0.02 to 0.06 %, demonstrating the good catalytic stability in the long-term experiment. In addition, the evolution of reactants and intermediates on the catalyst surface are briefly described by FTIR spectra. This study offers a novel and efficient approach to obtain highly active and durable catalysts with great potential for industrial-scale preparation and application.

PRODUCTION OF BIOLUBRICANT BLEND FROM JATROPHA CURCAS OIL

Biolubricants derived from vegetable oils are environmentally compatible products due to their low toxicity and good biodegradability. Synthetic esters based on polyols and fatty acids possess suitable properties for lubricant applications, even at extreme temperatures. The current work investigates the oligomerization of fatty acid esters into biolubricant. The jatropha oil was esterified using recinoloeic acid and isobutyric acid over activated carbon from kaolin as a catalyst to produce biolubricant. Also, the carbon was prepared from kaolin through impregnation and activated with copper nitrate solution. The generated activated carbon was characterized using FTIR and XRF. The biolubricant (triesters) were produced via oligomeric fatty acid esters with recinoloeic acid under reflux at different reaction conditions and characterized using FTIR and GC-MS. Optimization of process parameters for oligomerization of jatropha oil with response surface based on Box-Beinkhen design. The process variables gave 90 min, 60oC and 1%, values corresponding to reaction time, reaction temperature and catalyst concentration as the optimal condition. A validation experiment was conducted to compare the optimal predicted value (93.07%) and experimental validated value (81.19%). The physicochemical properties of the jatropha oil and biolubricant produced were analyzed using ASTM methods. The quality parameters like kinematic viscosity, pour point, flash point viscosity index and blends of oil with that of commercial mineral oil were all in conformity with ASTM standard for biolubricant. The formulated oils also show the ability to significantly improve the kinematic viscosity, cold flow properties and possible potential as the replacement for the mineral-based lubricating oil

Study on the hydrogen production promotion effect and immobilization mechanisms of copper during the pyrolysis process of waste cotton textiles

Landfilling waste textiles causes a waste of resources. Copper is the main metal in waste textiles, and it is one of the widely used pyrolysis catalysts. This research investigated the role of copper during the pyrolysis process of waste cotton textiles, including the promoting effect on hydrogen generation and its immobilization in biochar. The pyrolysis experiment was conducted on waste pure cotton textiles impregnated with different concentrations of copper nitrate solutions. The experimental results showed that the addition of copper increased the hydrogen concentration by 121%, while the pyrolysis process reduced the copper leaching rate by 57.5%. Hydrogen concentration increased by 123% as the temperature increased, but the high temperature would affect the immobilization of copper. Hydrogen production and copper immobilization could be improved simultaneously around 700 ℃. The gas evolution was monitored by TG-MS and the biochar was characterized by XRD, FTIR, and XPS. The results indicated that the complexation of oxygen−containing functional groups and the generation of metallic copper decreased the leaching of copper, the heterostructure of copper on the surface of biochar catalyzed the secondary cleavage of organic fraction, increasing the production of hydrogen. The mechanism of hydrogen generation involved the decomposition of cellulose, the cleavage of organic macromolecules, and the secondary reaction of small molecule gases.

Selective recovery of silver ions from copper-contaminated effluents using electrodialysis

With the growing demand for silver, the recycling of this precious metal from secondary sources has become imperative. However, the presence of copper impurities poses a significant challenge. This study aims to explore electrodialysis for selectively recovering silver ions from copper-contaminated effluents, elucidating the effect of low pH on the process performance. Electrodialysis of 10 mM equimolar solutions of silver nitrate and copper nitrate was performed at various pH levels, using nitric acid for pH adjustment. Adjusting the operational current to the limiting current resulted in similar silver fluxes and copper leakages at pH 1, 2, and 4.5. The energy requirement was governed by proton abundance, competing with silver ions for charge transport in the electrodialysis cell. The specific energy consumption for silver removal decreased from 751 kJ/mol at pH 1 to 36 kJ/mol at pH 4.5, with the energy efficiency rising from 2 % at pH 1 to 37 % at pH 4.5. Copper leakage was approximately 20 % in all cases, yielding silver‑copper separation efficiencies of 55 % at pH 1 and 80 % at pH 2 and 4.5. This study highlights electrodialysis as a promising technique for purifying hydrometallurgical effluents, emphasizing the need for case-specific assessment depending on feed water properties. Notably, the limitations associated with low pH suggest potential advantages of adjusting the pH of the solution.

Biotemplate-assisted synthesis of CuO hierarchical tubes for highly chemiresistive detection of dimethylamine at room temperature

The fabrication of low-temperature metal oxide-based sensors with highly sensitive to carcinogenic organic-amines remains challenging. Herein, a biomorphic CuO-5 material was synthesized by simply immersing mulberry twig slices in copper nitrate solution and calcining the precursors in air at 500 ℃. Its multistage tubes are assembled from well-crystallized nanoparticles, and possess uniform mesopores and abundant oxygen vacancies. These microstructural factors facilitate the rapid diffusion of gas molecules to sensing layer, and improve the conductivity of CuO material, as well as the content of active sites and surface adsorbed oxygen species. In particular, under the synergy of adsorption and catalysis of the suspended bonds for surface Cu2+ ions, this material achieves the high sensing and selective detection of trace dimethylamine (DMA) at room temperature for the first time. At 25 °C, CuO-5 sensor reaches a response value of 35.9–50 ppm DMA, which is 8.3 times larger than that of template-free CuO-0 sample. Meanwhile, the sensor also has good response-recovery reproducibility, low detection limit, and satisfactory moisture resistance and stability. In addition, the mechanism for enhanced sensing of DMA at room temperature is discussed in detail.

Ultrasound pulse generation through continuous-wave laser excited thermo-cavitation for all-optical ultrasound imaging

The optical generation of pulsed ultrasound is attractive to nondestructive testing and biological imaging, especially for those involving narrow operation space or strong electro-magnetic interference. However, conventional techniques based on the photoacoustic effect inevitably required an expensive high-energy short pulsed laser and dedicated preparation of the optically absorptive composite film. Here, a fiber-optic ultrasound pulse transmitter based on continuous-wave (CW) laser triggered thermo-cavitation was demonstrated. The fiber-delivered CW laser light heated the highly-absorptive copper nitrate solution and generated explosive bubbles , which emitted strong ultrasound waves. Omnidirectional ultrasound pulses with an amplitude up to 0.3 MPa and a repetition rate of 5 kHz in the frequency range of 5–12 MHz were obtained by using a 50 mW optical heating power at a wavelength of 980 nm. The fiber-tip ultrasound transmitter was integrated with a polymer-cavity-based fiber ultrasound detector to construct an all-fiber ultrasound endoscopic imaging probe. Without the need for a wavelength-tunable laser, the ultrasound detector was interrogated by CW laser light with a fixed wavelength, coupled with feedback-controlled heating of the cavity to stabilize its spectral fringe. The CW laser-driven fiber ultrasound transmitter, in combination with the photothermally stabilized fiber ultrasound detector, opens new routes for a number of ultrasound-related industrial and biomedical applications.

Green synthesis of copper oxide nanoparticles using the outer layer of Allium cepa L. and evaluation of its antimicrobial properties

The recent antimicrobial resistant to the present antibacterial agents has been the biggest problem in the treatment of antimicrobial infection. Over the years, various strategies has been implemented to overcome the resistance the resistance to the available antibiotic agents. In regards to this, phytochemical found in plants like Allium cepa, which has exhibited potent antimicrobial activity has been used by researchers as natural products to fight against bacterial resistance. Allium cepa also known commonly as onion, is an herbaceous biennial plant in the amaryllis family (Amaryllidaceae) grown for its edible bulb. Copper oxide nanoparticles are one of the most vital nanomaterials used in biomedical application. The phytochemicals in the plant extract were used as reducing and capping agent. The aim of the study is to determine the antimicrobial activity of synthesized copper oxide nanoparticles using Allium cepa (onion) aqueous extracts. The dried outer layer of the Allium cepa was collected and boiled. 150 ml of the plant extract was mixed with 250 ml of the copper nitrate solution, for the purpose of green synthesis. After the reaction was completed, the synthesized nanoparticles was centrifuged, decanted and dried. The dried copper oxide nanoparticles were characterized and accessed for antimicrobial activity. The results of UV-Vis Spectroscopy, FTIR, DLS particles size analysis, TEM and XRD, were obtained and evaluated.

Antibacterial Electrodeposited Copper-Doped Calcium Phosphate Coatings for Dental Implants.

Dental implants provide a good solution for the replacement of tooth roots. However, the full restoration of tooth functions relies on the bone-healing period before positioning the abutment and the crown on the implant, with the associated risk of post-operative infection. This study aimed at developing a homogeneous and adherent thin calcium phosphate antibacterial coating on titanium dental implants by electrodeposition to favor both implant osseointegration and to limit peri-implantitis. By combining global (XRD, FTIR-ATR, elemental titration) and local (SEM, Raman spectroscopy on the coating surface and thickness) characterization techniques, we determined the effect of electrodeposition time on the characteristics and phases content of the coating and the associated mechanism of its formation. The 1-min-electrodeposited CaP coating (thickness: 2 ± 1 μm) was mainly composed of nano-needles of octacalcium phosphate. We demonstrated its mechanical stability after screwing and unscrewing the dental implant in an artificial jawbone. Then, we showed that we can reach a high copper incorporation rate (up to a 27% Cu/(Cu+Ca) molar ratio) in this CaP coating by using an ionic exchange post-treatment with copper nitrate solution at different concentrations. The biological properties (antibiofilm activity and cytotoxicity) were tested in vitro using a model of mixed bacteria biofilm mimicking peri-implantitis and the EN 10993-5 standard (direct contact), respectively. An efficient copper-doping dose was determined, providing an antibiofilm property to the coating without cytotoxic side effects. By combining the electrodeposition and copper ionic exchange processes, we can develop an antibiofilm calcium phosphate coating on dental implants with a tunable thickness and phases content.

The influence of zeolite X ion-exchangeable forms and impregnation with copper nitrate on the adsorption of phosphate ions from aqueous solutions

Removal of phosphate ions from aqueous environment has become a global concern. Adsorption is one of the most efficient methods for removal of various pollutants. In this study, zeolite NaX derived from fly ash was modified by simple ion exchange with ammonium nitrate solution to obtain ammonium form (NH4X) and calcinated to proton form (HX) of zeolite X. The obtained materials were investigated as potential adsorbents of phosphate ions from aqueous solutions to find out the effect of zeolite form on adsorption capacity. Furthermore, zeolites NaX and NH4X were impregnated with copper nitrate solution and calcinated at 550 °C to obtain materials with Cu content of 3 wt% to simulate the potential utility of spent catalysts. The obtained results indicated that parent zeolite NaX has rather weak affinity towards phosphate ions — 4.38 mg (PO43−) g−1, only. The ammonium and proton forms of zeolite X showed significantly improved adsorption capacities of 12.09 and 35.33 mg (PO43−) g−1, respectively, implying the positive effect of ion exchange on removal of phosphate ions from aqueous solutions. Impregnated zeolites exhibited sufficient adsorption capacities of 11.86 and 26.53 mg (PO43−) g−1 for 3%Cu@NaX and 3%Cu@HX, respectively. However, no synergic effect of impregnation and zeolite form was observed due to partial pore blockage after preparation of zeolite 3%Cu@HX. To gain a deeper knowledge about the adsorption mechanisms, selected samples were subjected to kinetic adsorption studies and XPS measurements.

Catalytic conversion of glucose to methyl levulinate over metal-modified Beta zeolites

Methyl levulinate was selectively formed from glucose and methanol over a copper modified Beta zeolite bifunctional catalyst at 180 °C under argon atmosphere. The selectivity to methyl levulinate substantially exceeded previously reported in the open literature results. The copper modification was done through an ion-exchange method using a solution of copper nitrate, followed by drying and calcination of the catalyst. Copper modification changed the distribution of acid sites namely, less Brønsted and more Lewis sites were observed with FTIR using pyridine adsorption. Application of the proton form H-Beta-25 gave the methyl levulinate yield of ca. 89%, which could be elevated with the addition of copper, as the apparent selectivity exceeds 99%, assuming that methyl glucosides are eventually transformed to methyl levulinate. The non-acidic Cu/SiO2 catalyst was completely inactive in methyl levulinate formation. Metal modification of Beta zeolite with Sn and Zn did not perform as well as Cu in the formation of methyl levulinate during glucose transformation.

High resolution optical investigation of laser intensity and solution temperature effects on thermocavitation

This paper studies cavitation induced by focusing a continuous wave laser in a highly absorbing aqueous copper nitrate solution. The Spatial Transmittance Modulation method was used to detect the cavitation bubbles and verified by high-speed shadowgraphy. The influence of intensity, solution temperature, and absorption coefficient on the cavitation dynamics was investigated by observing the bubble diameters, bubble lifetimes, cavitation times, and cavitation frequencies. The intensity was varied by changing the optical power between 1.2 W and 4.7 W and shifting the laser focal point from 4.5 mm outside to 3.5 mm inside of the cavitating solution by 1 mm increments. Additionally, six solution temperatures between 22 °C to 74 °C were tested, and three concentrations of copper nitrate (10.7, 6.35 and 3.49 g copper nitrate per 10 mL of water) were used to change the solution’s absorption coefficient. The results reveal that on average, larger intensities result in shorter cavitation times, higher frequencies, and higher percentages of small bubbles. Increasing the copper nitrate concentration has a similar effect on the cavitation events. With higher solution temperature, the time to initiate cavitation decreases, and higher percentage of larger bubbles appear due to a decrease of surface tension. However, the solution temperature does not change the cavitation randomness significantly. The findings of this investigation may allow for effective control of thermocavitation dynamics where current laser cavitation applications require managed outcomes.

Surface and structural characterization of Cu-exchanged hydroxyapatites and their application in H2O2 electrocatalytic reduction

We report on the preparation of hydroxyapatite (HA) nanoparticles with high specific surface area, terminated with calcium-rich {010} facets, and their subsequent surface functionalization with copper by cationic exchange with copper nitrate solutions at different concentrations. Elemental analysis highlighted a progressive increase of the amount of copper incorporated into the HA, reaching a maximum of ∼ 7 wt%. A combined X-ray diffraction and solid-state NMR investigation showed no significant structural differences after the Cu functionalization, confirming that the copper exchange occurs mainly at the surface until saturation and, for the higher Cu concentrations, also in the sub-surface/bulk layers of the material, without altering the HA crystal structure. The gradual substitution of surface Ca2+ by Cu2+ was studied also by IR spectroscopy using carbon monoxide as probe molecule. Finally, we assessed the catalytic activity of the materials testing the electrochemical reduction of H2O2 by cyclic voltammetry. We observed a progressive increase in catalytic activity correlated with the amount of Cu, suggesting the possible application of copper-exchanged HA as electrochemical H2O2 sensors.

Structural, morphological and optical characterization of chemically deposited Cu2O/PbS thin films

Cu2O/PbS core-shell thin films were synthesized by a chemical bath deposition technique using a reactive mixture containing copper nitrate, lead nitrate, ethylenediaminetetraacetic acid, tetraethyl amine and ammonia solution. Their structural and optical properties are reported in this work. For the elemental composition estimation, Rutherford backscattering spectroscopy (RBS) was performed. From the proton induced scan on the substrate containing the films, all the elements that make up the films were extracted as Cu (34.86%), Pb (1.69%), S (42.31%) and O (65.15%). This is an indication that Cu2O-PbS quaternary thin films were actually deposited on the substrate. The X-ray diffraction analysis showed the formation of multiple peaks indicating that the films possess polycrystalline structure. The scanning electron micrographs of the films depicted particles of different sizes scattered across the film surface. The absorbance, transmittance, absorption coefficient, band gap and extinction coefficient were modified by thermal annealing. Absorbance varies from 1.175 to 1.35 for as-grown, 1.475 to 1.50 for annealed at 150 oC and 1.65 to 2.00 for annealed at 200 oC. The percentage transmittance of 6.75 % was obtained for as-grown sample while those of the annealed samples are 6.0 % and 5.0 % at 150 oC and 200 oC respectively. Maximum absorption coefficient values are 3.48 x 106 m -1 , 3.68 x 106 m -1 and 4.60 x 106 m -1 for As-grown, annealed at 150 oC and 200 oC respectively. The band gap energy value is found to increase from 3.50 eV to 4.00 eV as a result of the increase in annealing temperature from 150 oC – 200 oC. Extinction coefficient values generally varies from 0.75 to 2.70 for as-grown, 0.80 to 2.85 for annealed at 150oC and 0.85 to 3.00 for annealed at 200oC. Based on the wide band gap exhibited by the films, it can be concluded that the films are suitable as window materials in the fabrication of solar cell devices.

Nucleation and growth mechanism of cuprous oxide electrodeposited on ITO substrate

The electrodeposition mechanisms of cuprous oxide (Cu2O) from copper nitrate solutions on indium tin oxide (ITO) were investigated using the cyclic voltammetry and the chronoamperometry methods. Then the kinetics parameters, nucleation and growth mechanism were explored. The CV measurement showed that the electrodeposition of Cu2O takes place by cathodic reduction at potential −0.5 V versus saturated calomel electrode (SCE). Furthermore, the voltammograms at different scan rates revealed that the electrodeposition reaction of Cu2O is a quasi-reversible reaction controlled by the diffusion of copper ions. Moreover, the deposition mechanism of Cu2O on the ITO substrate determined by the Astley approach and confirmed by the Scharifker-Hills models follows an instantaneous three-dimensional (3D) nucleation controlled by diffusion with an average diffusion coefficient D of 0.549 10-6 cm2 s−1. The X-ray diffraction pattern of Cu2O film was indexed to cubic crystal structure. The scanning electron microscopy analysis indicated that the average size of the cuprous oxide particles is about 1.408 µm. The optical energy band gap (Eg) was calculated by Tauc’s plot for Cu2O is 2.16 eV. The theoretical analyses reveal that Cu2O has an energy band gap of 2.25 eV, which corresponds to experimental results.

Simultaneous Photocatalytic Esterification and Addition Reaction of Fatty Acids in Kemiri Sunan (Reutealis trisperma sp.) Oil over CuO/TiO2 Catalyst - A Novel Approach

A novel approach, namely photocatalytic esterification and addition reaction of unsaturated fatty acids using CuO/TiO2 catalyst has been investigated in kemiri sunan oil. The objectives of this study are to reduce the free fatty acid (FFA) content by using catalyst CuO/TiO2, characterization of the catalyst and the operation condition of reaction. The CuO/TiO2 catalyst was synthesized by the impregnation of TiO2 P25 powder with copper nitrate solution as a precursor and followed by calcination. The field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray Diffraction (XRD), and Transmission electron microscopes (TEM) result showed that copper oxide was highly dispersed on the TiO2 surface. The X-ray Photoelectron Spectroscopy (XPS) result showed that Cu is in the state of CuO (Cu2+), while Ti is in Ti4+ ( TiO2). The bandgap energy of CuO/TiO2 was smaller than TiO2 P25. It was found that the reactions conducted in the presence of CuO/TiO2 in a photoreactor under UV irradiation can perform esterification and addition reaction of the FFA, simultaneously. The optimum reduction of the FFA was under condition of 4% loading CuO/TiO2, 4 hours reaction time, 30:1 (mole/mole) methanol to oil ratio, 5% (w/w) catalyst amount. The conversion of FFA was at around 59%. The Gas Chromatography—Mass Spectrometry (GC-MS) results showed that the addition reaction of -eleostearic acid simultaneously occured at 100% conversion. Although the photocatalyst selectivity in FFA reduction was relatively low, but double bond reduction of -eleostearic acid (C18:3) was very high. The reduction of multiple double bond is considered as positive poin to improve the oxidative stability of the product. The simultaneous esterification and addition reactions mechanism has been proposed. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Plasma-solution synthesis of particles containing transition metals

The paper proposes a new method for the synthesis of powders containing transition metals using a plasma-solution system. The reactor was an H-shaped glass cell, the two parts of which were separated by a cellophane membrane. A discharge consisting of two discharges - with a liquid cathode and a liquid anode - a high voltage is applied to titanium electrodes located above the surface of the solution. Aqueous solutions of zinc, iron, cadmium, cobalt, nickel, and copper nitrates were used as the liquid phase. Under the action of the discharge on the liquid anode, in the region of contact of the discharge with the solution the formation of a colloidal suspension was observed. The kinetics of the process of synthesis of solid-phase particles in solution under the action of a discharge have been studied. The chemical composition and morphology of the formed solid phase have been established. The mechanisms of chemical reactions occurring in the solution under the action of plasma, and the mechanisms of formation of transition metal oxides in the process of calcining the synthesized powders have been proposed.