Concentration Of Copper Nanoparticles Research Articles

Experimental investigation on spray cooling heat transfer properties of ethylene glycol-water-based nanofluids

Abstract Spray cooling is a practical solution for high heat flux heat dissipation problems. The spray cooling experiment was conducted with 50wt% ethylene glycol aqueous solution as the base liquid in this paper. The effects of the concentrations of copper nanoparticles, copper oxide nanoparticles, silica nanoparticles and surfactant Tween-20 on the heat transfer characteristics during spray cooling were investigated. The results showed that adding nanoparticles within a certain concentration range could enhance the effectiveness of spray cooling's heat transmission. Under the same conditions, adding copper nanoparticle has the best effect, followed by copper oxide nanoparticle, and silica nanoparticle has relatively poor effect. Among them, the heat transfer coefficient and heat flux of the nanofluid could be raised by 10.58% and 11.34% in comparison to the base liquid when the concentration of copper nanoparticles was 0.01wt%. As the concentration of nanoparticles rises higher, spray cooling's ability to transfer heat is hampered. Adding the surfactant Tween-20 could effectively improve the copper-water-ethylene glycol nanofluid's capacity for heat transmission. When the concentration is 3ppm, the heat transfer coefficient and heat flux of the nanofluid with Tween-20 were increased by 9.81% and 10.38% compared to the copper-water-ethylene glycol nanofluid.

Shielding properties of Li2B4O7:Dy3+,Yb3+ glass containing copper nanoparticles

Glass matrices of Li2B4O7 doped with Dy3+, Yb3+ and Cu were synthesized by melt quenching technique using different concentration of copper nanoparticles. The study and analysis are centered in shielding radiation. The samples amorphous nature was corroborated by X-Ray diffraction (XRD) and nanoparticles size distribution was obtained by transmittance electron microscopy (TEM). Optical characterizations used were absorbance and photoluminescence emission (PL). Radiation shielding theoretical properties: mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), mean free path (MFP) and effective atomic number (Zeff) are obtained using Phy-X/PSD software and analyzed for future applications in radiation security.

Field evaluation of the efficacy of copper nanoparticles against mites associated with orange trees.

Phytophagous mites are dangerous pests, causing economic losses to the world's crops. Nanotechnology is a promising field for pests and disease management, and enhancement of agricultural productivity. The aim of the study was to evaluation of the effectiveness of copper nanoparticles (CuNP) against all stages of eriophyid mite, the citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) and tetranychid mite, the citrus brown mite Eutetranychus orientalis (Klein) (Acari: Tetranychidae), and Tenuipalpid mite, the false spider mite, Brevipalpus obovatus Donnadieu (Acari: Tenuipalpidae). This includes its impacts on predacious mites, Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae), on orange trees under field conditions. Five different concentrations of copper nanoparticles (40, 80, 160, 240, and 320 ppm), as well as the control (well water) were examined. The obtained results indicated that the mortality rate of both phytophagous and predacious mites was associated with an increase in the concentrations of copper nanoparticles. Copper nanoparticles were significantly effective in killing P. oleivora, E. orientalis and B. obovatus with minimal effects on A. swirskii and E. scutalis. The mortality percentage was 15.24, 20.32, 46.32, 78.97 and 86.37% for P. oleivora, 6.87, 9.86, 28.91, 56.30 and 77.52% for E. orientalis and 8.38, 23.50, 48.83, 68.80 and 84.08% for B. obovatus while the mortality percentage was 0.00, 0.56, 5.83, 9.91 and 15.19% for A. swirskii and 0.44, 3.96, 6.93, 8.63 and 21.39% for E. scutalis one week after exposure to 40, 80, 160, 240 and 320 ppm of copper nanoparticles, respectively. Moreover, the results showed that copper nanoparticles caused a reduction in the percentage of eggs hatching. The percentages of larvae hatching from eggs were 96.29, 80.00, 64.13, 45.66 and 32.17% for P. oleivora, 97.38, 83.28, 69.41, 48.01 and 35.29 for E. orientalis and 96.60, 76.92, 56.38, 40.55 and 33.28% for B. obovatus one week after exposure to copper nanoparticles at 40, 80, 160, 240 and 320 ppm respectively, compared with the control (well water). According to the results, the use of copper nanoparticles significant effect on reducing the population of phytophagous mites associated with orange trees, with low detrimental effects on predatory mites.

Biosynthesis of Copper Nanoparticles From Seaweed Ulva lactuca and Their In Vitro Antioxidative Potential.

Marine macroalgae is consumed by individuals in several regions, including Scandinavia, Great Britain, Ireland, China, and Japan; in Japan, it is commonly referred to as aosa. Copper nanoparticles are primarily composed of copper and exhibit a size distribution ranging from 1 to 100 nm. Copper nanoparticles can be synthesized using chemical or natural means, similar to other nanoparticle variants. The nanoparticles in question have garnered significant attention owing to their historical utilization as coloring agents, as well as their contemporary applicability in medicine and antibacterial treatments. The objective of this study was to investigate the biosynthesis of copper nanoparticles derived from Ulva lactuca seaweed and explore their in vitro antioxidative potential. Seaweed samples (10 g) were mixed with 50 ml of distilled water and placed in a shaker for two days. Copper sulfate (10 mM) was mixed with 100 ml of distilled water to obtain a copper (Cu) solution. Cu nanoparticles were then synthesized by adding the aqueous extract to 100 ml of the Cu solution and mixing it in an orbital shaker at 180 rpm for 24 hours. They were observed both visually and via ultraviolet(UV) spectrophotometry to confirm their nanoparticle synthesis. The initial reading was performed using a UV-visible spectrometer at 300-800 nm. The sample was centrifuged at approximately 8000 rpm for 15 minutes, the pellet was removed, and the pellet was dried in a hot-air oven. The synthesized Cu nanoparticles were then investigated using in vitro antioxidant assays. The seaweed-derived copper nanoparticles exhibited a 1.2 peak absorbance at 580 nm. Various concentrations of copper nanoparticles (25, 50, 75, and 100 µg/ml) were tested for free radical scavenging. As the copper nanoparticle concentration increased, the scavenging ability on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals assay showed that the free radical scavenging activity increased in a dose-dependent manner. Similar to the DPPH assay, the total antioxidant and hydrogen peroxide (H2O2)assays showed increased free radical scavenging with increasing concentration. The application of Cu nanoparticles in the synthesis process has the potential to enhance the antioxidant activity of Ulva lactuca as evidenced by the observed increase in antioxidant capacity and defense against reactive oxygen species.

A universal adhesive containing copper nanoparticles improves the bonding and mechanical properties of resin cement–root dentin interface: an in vitro study

The aim of this study was to evaluate the anti-MMP activity of two concentrations of copper nanoparticles (CuNp) and the effect of their addition to a universal adhesive system on resin cement-radicular dentin in situ degree of conversion (DC), elastic modulus (EM), nanoleakage (NL), and push-out bond strength (PBS). Anti-MMP activity was evaluated for several MMPs. Seventy-two roots of endodontically prepared human lower premolars were randomly divided into six groups according to CuNp concentration (0% [control], 0.1%, 0.2%) and adhesive strategy (etch-and-rinse [ER] and self-etch [SE]). Fiber posts were cemented, DC was measured using micro-Raman spectroscopy, the EM of the hybrid layer and adhesive layer was measured using a nano-indenter, the NL was evaluated by scanning electron microscopy, and PBS was tested at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey’s test (α = 0.05). CuNp demonstrated anti-MMP activity (p < 0.01). CuNp containing-adhesives showed significant increased DC (p = 0.01), increased EM in the hybrid layer and adhesive layer (p = 0.001), decreased NL values (p = 0.001), and increased PBS (p = 0.0001). Adhesive strategy was not statistically significant (p > 0.47). Usually, a significant difference among root thirds was observed, except for DC and NL when CuNp 0.2% was evaluated. This is the first in vitro study showing that the incorporation of CuNp in an adhesive is an achievable alternative that can provide anti-MMP activity and improve the mechanical and bonding properties to root canal dentin.

Analysis of size and concentration of nanoparticles contained in cutting fluid during turning of 316L steel in minimum quantity lubrication conditions

The paper presents an important issue concerning the size and concentration of copper nanoparticles in a nanofluid. The influence of nanoparticles on the stabilization of the nanofluid, tool vibrations during turning of 316L stainless steel and the machined surface topography were described. Four sizes of Cu nanoparticles were used: 22 nm, 35 nm, 65 nm, 80 nm and four types of concentration: 0.25 %, 0.5 %, 0.75 % and 1 %. For all prepared types of nanoliquids, the ultrasonic dispersion was obtained after 50 min, and the nanoliquids with smaller nanoparticle sizes were the most stable. The lowest values of the initial parameters, both vibrations and selected parameters of 3D surface topography, were observed for the smallest size of Cu (22 nm) and a concentration of 0.5 %. The article presents how important is the problem of determination both the size and concentration of copper nanoparticles in the MQL method.

Effect of copper nanoparticle concentration on tribological performances of cylinder liner piston ring

AbstractThe performance of cylinder liner piston ring (CLPR) that worked under harsh conditions significantly affected the reliability of diesel engines. Nano‐copper lubricant additives have recently been introduced due to their good anti‐wear properties. This study aims to gain insights into the interactions between concentrations of nano‐copper lubricant additives and the tribological performance of CLPR. Tests are performed on a reciprocating sliding test rig under different operating conditions, and the tribological performances are characterized by the friction coefficient, wear mass losses, and morphologies of worn surface. The experimental results indicated that the optimal concentration of nano‐copper additives is 2 wt%. Additionally, deposition of the Cu nanoparticles on the worn surface during the friction process facilitates the formation of the mending layer. These findings would aid to provide a technical reference for the application of nano‐copper additives in diesel engines.

Numerical simulation on Cu–H2O nanofluid of destructive and generative reactions in a Darcian medium: application of wall suction and blowing

Application of – nanoparticles in a base fluid of water means the growth of thermal conductivity of Nanofluid. This physical behavior recommends the prospect of applying nanofluids in electronic cooling and advanced nuclear systems. The formulated leading equations are transformed to non-dimensional form by appropriate similarity transformations and finally solved numerically through Runge–Kutta Shooting method of 4th order. The novelty of the current investigation is to examine the impact of wall suction/ injection over the dual solutions by numerical simulation for time-independent, two- dimensional nanofluid flow along a semi-infinite porous stretching horizontal wall placed in a Darcian medium under the application of magnetic drag force. The significant outputs are portrayed in dual solutions for suction/injection and deliberated their salient effects of various emerging physical variables on velocity, temperature, and molar concentration of Copper nanoparticles in water base fluid. It is obtained that the nanoparticle concentration grows via larger destructive chemical reaction and lessens when generative chemical reaction is enhanced. This investigation leads to opposite behavior due to endothermic reaction. The significance of such investigation in Darcian porous medium have frequent applications in the major area of industrial and engineering technologies that covers the bio-engineering, rubber technology and material processing.

Effect of Size and Concentration of Copper Nanoparticles on the Antimicrobial Activity in Escherichia coli through Multiple Mechanisms.

Metal and metal oxide nanoparticles, including copper nanoparticles (CuNPs), display antimicrobial activities and are regarded as promising microorganism inhibitors. Here, we explored the antimicrobial activity of CuNPs in Escherichia coli (E. coli) using two particle sizes (20 and 60 nm) and five concentrations (1, 5, 10, 50 and 100 μg/mL). The result showed a concentration-dependent trend of bactericidal activities for both size groups, with 20 nm particles more effective than 60 nm particles at low concentrations. The membrane disruption caused by CuNPs was confirmed by electron microscopy, PI staining and protein leaking analysis. However, the results of reactive oxygen species generation and genomic DNA damage revealed that the size and concentration of CuNPs were factors affecting the induction of multiple bactericidal mechanisms simultaneously on different scales. Further results of annexin V-PI staining supported this hypothesis by showing the shifting composition of the early-, late- and non-apoptotic dead cells across the CuNP groups. Many CuNP treatment groups were rescued when four mammalian modulators-wortmannin, necrosulfonamide, Z-VAD-FMK, and SBI-0206965-were applied separately. The results suggest the possible existence of bacterial programmed cell death pathways in E. coli which could be triggered by CuNP treatments.

The Application of Copper and Silver Nanoparticles in the Protection of Fagus sylvatica Wood against Decomposition by Fomes fomentarius

Wood technology is constantly looking for environmentally friendly technological solutions. It seems that nanotechnology can provide green and environmentally friendly alternatives for wood protection. In this study, the antifungal activity of silver and copper nanoparticles against the white rot fungus Fomes fomentarius was investigated under in vitro conditions and with respect to the protection of Fagus sylvatica wood. In both experiments, 5, 25 and 50 ppm of nanoparticles were used. The results of the in vitro test showed selective antifungal activity of the nanoparticles. All concentrations of copper nanoparticles stimulated mycelial growth. The stimulation was inversely proportional to the concentration. Silver nanoparticles inhibited fungal colony growth at the highest concentration (50 ppm) and did not affect growth at concentrations of 5 and 25 ppm. Silver nanoparticles increased the rot resistance of beech wood, but only at the highest concentration. Decay caused by F. fomentarius was stimulated by copper nanoparticles at the highest concentration. Probably, the fungus used copper as a micronutrient for better growth and increased the activity of extracellular enzymes. Our results from in vitro tests are consistent with those obtained on beech wood specimens, showing that the concentrations of the two nanoparticles used were too low to protect the beech wood from decomposition by xylophagous fungus.

A Numerical Investigation of a Melting Rate Enhancement inside a Thermal Energy Storage System of Finned Heat Pipe with Nano-Enhanced Phase Change Material.

Thermal energy storage via the use of latent heat and phase transition materials is a popular technology in energy storage systems. It is vital to research different thermal enhancement techniques to further improve phase transition materials’ weak thermal conductivity in these systems. This work addresses the creation of a basic shell and a tube thermal storage device with wavy outer walls. Then, two key methods for thermal augmentation are discussed: fins and the use of a nano-enhanced phase change material (NePCM). Using the enthalpy–porosity methodology, a numerical model is developed to highlight the viability of designing such a model utilizing reduced assumptions, both for engineering considerations and real-time predictive control methods. Different concentrations of copper nanoparticles (0, 2, and 4 vol%) and wavenumbers (4,6 and 8) are investigated in order to obtain the best heat transmission and acceleration of the melting process. The time required to reach total melting in the studied TES system is reduced by 14% and 31% in the examined TES system, respectively, when NePCM (4 vol% nanoparticles) and N = 8 are used instead of pure PCM and N = 4. The finding from this investigation could be used to design a shell-and-tube base thermal energy storage unit.

Antibacterial Activity of Electrospun Polyacrylonitrile Copper Nanoparticle Nanofibers on Antibiotic Resistant Pathogens and Methicillin Resistant Staphylococcus aureus (MRSA).

Bacteria induced diseases such as community-acquired pneumonia (CAP) are easily transmitted through respiratory droplets expelled from a person’s nose or mouth. It has become increasingly important for researchers to discover materials that can be implemented in in vitro surface contact settings which disrupt bacterial growth and transmission. Copper (Cu) is known to have antibacterial properties and have been used in medical applications. This study investigates the antibacterial properties of polyacrylonitrile (PAN) based nanofibers coated with different concentrations of copper nanoparticles (CuNPs). Different concentrations of copper sulfate (CuSO4) and polyacrylonitrile (PAN) were mixed with dimethylformamide (DMF) solution, an electrospinning solvent that also acts as a reducing agent for CuSO4, which forms CuNPs and Cu ions. The resulting colloidal solutions were electrospun into nanofibers, which were then characterized using various analysis techniques. Methicillin-Resistant isolates of Staphylococcus aureus, an infective strain that induces pneumonia, were incubated with cutouts of various nanocomposites using disk diffusion methods on Luria-Bertani (LB) agar to test for the polymers’ antibacterial properties. Herein, we disclose that PAN-CuNP nanofibers have successfully demonstrated antibacterial activity against bacteria that were otherwise resistant to highly effective antibiotics. Our findings reveal that PAN-CuNP nanofibers have the potential to be used on contact surfaces that are at risk of contracting bacterial infections, such as masks, in vivo implants, or surgical intubation.

Melting of nano‐enhanced phase change material in a cavity heated sinusoidal from below: Numerical study using lattice Boltzmann method

AbstractNatural convection and melting of ice as a phase change material dispersed with copper nanoparticles are numerically investigated. Square cavity filled with nano‐mixture (Cu−ice) subjected to sinusoidal temperature distributions from the hot bottom boundary. The phase change process and heat transfer are formulated and solved using the enthalpy‐based lattice Boltzmann method. Home‐built numerical code is developed and validated. The effect of Rayleigh number (Ra = 104, 105, and 106) and copper nanoparticle concentration (ϕ = 0%, 1%, 3%, and 5%) on the flow characteristics and thermal performance of NePCM during the melting process is examined. According to the numerical results, the melting and charging times decrease by increasing the Rayleigh number. It is also observed that increasing the volume fraction of nanoparticle decrease melting time by up to 10%.

Exposure of Copper Nano-Particles (CuNPs) Impairs Developmental Stages and Hatchability in the Fresh Water Snail Indoplanorbis exustus (Planorbidae: Pulmonate)

Pollution of water bodies by humans, in our day-to-day activities impairs the quality of water, thereby making the water sources unsuitable for aquatic fauna and also for human health. Various sources of pollutants in excess may negatively affect the diversity of living organisms. The evolving growth of nanotechnology has attracted a great deal of attention due to its concern in assessing their environmental and health safety. The present study was conducted to investigate toxicity of copper nanoparticles (CuNP) on the development of fresh water snail Indoplanorbis exustus. Acclimatized snails were exposed to increasing concentration of CuNP for 96 h and acute toxicity experiment was carried out to determine LC50, followed by exposure of snails to sublethal concentrations of CuNP to observe developmental deformities and to estimate percentage hatchability and survivability of young ones. The projected LC50 value for 96h of CuNPs was found to be 5.8mg/L, followed by exposure to sub-lethal concentrations of 1/6th(0.96mg/L), 1/5th(1.16mg/L), 1/4th(1.45mg/L), and 1/3th (1.93mg/L). The highest concentration of (1.93mg/L;1/3thof LC50) retarded hatching and caused morphological deformities in the larvae. However, no significant difference was observed in the weight of embryos in 7 days. These results revealed that CuNP exposure at sub lethal concentrations exerted developmental stress.&#x0D; HIGHLIGHTS&#x0D; &#x0D; Most of the invertebrate models used in aquatic toxicity are from phylum Mollusca, the gastropods are considered as the best model organisms for NPs toxicity because they are adapted to various environmental disturbances due to their dual habitat, easy availability, high fecundity, small size, short generation time and adaptability.&#x0D; Snails, Indoplanorbis exustus were exposed to increasing concentration of copper nanoparticles (CuNPs) for 96 h and acute toxicity experiment was carried out to determine LC50, followed by exposure of snails to sublethal concentrations of CuNPs to observe developmental deformities and to estimate percentage hatchability and survivability of young ones&#x0D; The highest concentration of (1.93 mg/L; 1/3th of LC50) retarded hatching and caused morphological deformities in the larvae. However, no significant difference was observed in the weight of embryos in 7 days. These results revealed that CuNP exposure at sub lethal concentrations exerted developmental stress on snails&#x0D;

Investigation of optical properties and antibacterial activity of chitosan copper nanoparticle composites

ABSTRACT Chitosan (Cs) doped with different proportion of copper nanoparticles (CuNPs) has been prepared using the casting method in an oven at T = 333 K. The optical properties of Cs/CuNPs have been investigated using different techniques such as, UV-Vis and FTIR spectroscopy. Many optical parameters such as optical band gap energy, oscillation energy, dispersion energy and lattice dielectric constant of all samples have been estimated. FTIR spectra of Cs and Cs/CuNPs have been investigated and the results revealed that, a broadness of OH groups in Cs/CuNPs has been observed. XRD measurements showed that, average of the particle size is approximately ~ 8.11 nm. Measurements of swelling showed that, the maximum swelling decreases linearly with increasing concentration of copper nanoparticles. The antibacterial activity of chitosan and Cs/CuNPs samples has been investigated against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia colii). The results revealed that, irradiated samples with UV-irradiation exhibited a greater activity in comparison to the non-irradiated samples.

Environmental concentrations of copper nanoparticles affect vital functions in Ankistrodesmus densus

Nanoparticles (NPs) have unique properties, leading to their widespread application in industry, consequently increasing their concentration in aquatic ecosystems. Although environmentally significant concentrations are still low, they tend to increase because of the intense use, posing into risk microalgae communities. Microalgae are primary producers that support food chains in aquatic ecosystems; thus factors that interfere with their physiology can be propagated throughout the food web. The present research investigated the effects of copper nanoparticles (Cu-NPs) in the physiology of a cosmopolitan green microalgae, Ankistrodesmus densus. Here, we focused on environmental NPs levels, so an ample Cu-NPs range was used, 0.3–635 μg L−1. Considering that NPs dissolve into the medium releasing their constituent material, free Cu2+ ions were determined and considered as surrogate for NPs concentration, which varied from 2.1 × 10-9 to 8.4 × 10-9 mol L−1. The experiment was based in 72 h Cu-NPs exposure, and to access the physiology of A. densus, we monitored population growth, photochemistry of photosynthesis and the content of cell biomolecules (total proteins, carbohydrates and lipids). The results showed that 2.1 × 10-9 mol L−1 free Cu2+ was enough to decrease growth rate, but 2.5x higher Cu was necessary to affect the photosynthetic parameters. Inorganic carbon fixation rate calculated by absolute electron transport rates was affected. Considering cell biomolecules, total proteins accumulated at 6.5 × 10-9 and kept increasing up to 8.4 × 10-9 mol L-1 free Cu2+. Because this was not related to biomass formation, we suggest a possible association with cell detoxification mechanisms. The most clear finding that emerged from this study is that environmental Cu-NPs concentrations affect vital functions in the green microalgae A. densus. An implication of this is the possibility of facing problems related to a increase of NPs in aquatic ecosystems in the near future.

Copper nanoparticles: Green synthesis and managing fruit rot disease of chilli caused by Colletotrichum capsici.

The present study was focused on synthesis and characterization of copper nanoparticles to evaluate their efficacy against fruit rot pathogen of chilli crop. The green synthesis of nanoparticles was carried out by using extracts of Eucalyptus and Mint leaves. The synthesis of copper nanoparticles was confirmed by XRD, PSA, SEM and TEM. The average size of these particles synthesized by Eucalyptus leaf extract (CuNP-E) ranged from 10 to 130 nm, while as size of Mint leaf extract synthesized particles (CuNP-M) ranged from 23 to 39 nm, thus confirming their nano size. These green synthesized copper nanoparticles were evaluated against Colletotrichum capsici where Carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm served as standard checks. The mycelia inhibition of Colletotrichum capsici caused by copper nanoparticles was studied on PDA medium. CuNP-M @ 1000 ppm showed highest mycelial inhibition of 99.78% followed by 93.75% at 500 ppm and CuNP-E @ 1000 ppm compared to standard fungicides, carbendazim 50 WP @ 500 ppm (72.82%), and copper oxychloride 50 WP @ 2500 ppm (85.85%). The CuNP-M @ 500 ppm were significantly superior to carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm, but was statistically at par with CuNP-E @ 1000 ppm. This shows effectiveness of much lower concentration of copper nanoparticles compared to conventional fungicides. In detached fruit method, nanoparticles applied before inoculation of pathogen showed better results with regard to incubation period, lesion number and lesion size than after inoculation of pathogen. The present study reveals a simple, convenient, non-toxic and cost-efficient technique for the synthesis of nanoparticles and their effectiveness against Colletotrichum capsici. CuNP-M first time synthesized and evaluated against Colletotrichum capsici performed better than CuNP-E.

Microstructure and Dielectric Properties of Polyaniline Doped with Copper Nanoparticles

Polyaniline (PANI) has been prepared by the oxidation method in order to fabricate it with various concentrations of copper nanoparticles (CuNPs) which produced using the reduction method. Various techniques have characterized pure PANI and PANI doped CuNPs composites, such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS), which were provided important information about the structure and morphology of the fabricated polymer nanocomposites. The properties of dielectric permittivity (έ), dielectric loss (ἔ) and electrical conductivity (σ_AC) properties were studied at room temperature versus a range of frequency (15-150) kHz. The results demonstrated that the addition of copper nanoparticles to polyaniline matrix increases the dielectric permittivity property and it decreases with increasing the frequency to reach a fixed value. So, the electrical conductivity of studied samples decrease with increasing the frequency.

Intensification of thermal energy storage using copper-pentaerythritol nanocomposites for renewable energy utilization

Pentaerythritol is a solid-solid phase change material with a high enthalpy of solid-solid phase transition (260–280 kJ/kg) and low thermal conductivity (0.2–0.7 W/mK). Thus, it is imperative to improve the thermal conductivity of pentaerythritol. The use of copper nanoparticles as an additive to pentaerythritol is explored, resulting in the development of copper-pentaerythritol composites. The effect of key independent variables (concentration of copper nanoparticles = 0–0.25 wt%; temperature = 40–180 °C) influencing the thermophysical properties (thermal conductivity and enthalpy of solid-solid transition) of copper-pentaerythritol composites has been studied. Transient planar source method was used for the measurement of thermal conductivity, while differential scanning calorimetry was used for the measurement of specific heat and enthalpy of solid-solid transition. Copper-pentaerythritol composites possessed higher thermal conductivity than pure pentaerythritol and this could be attributed to phonon conduction and nanoparticle clustering. The composite containing 0.0625 wt% copper nanoparticles exhibited 14–22.5% enhancement in thermal conductivity with no loss of enthalpy for solid-solid phase transition. This resulted in the reduction of time for completion of the solid-solid phase transition by 35.8% and an increase in the rate of thermal energy absorbed by 35.6%.

Surface-enhanced Raman scattering and antibacterial properties from copper nanoparticles obtained by green chemistry

In this study, copper nanoparticles (CuNPs) were synthesized using the extract of Opuntia ficus-Indica and Geranium as a reducing agent. By transmission electron microscopy, the morphology of the nanoparticles was determined to be mostly spherical, with a particle size about 3–10 nm. The UV–Vis spectra displayed absorption bands between 525 and 550 nm, associated with the surface plasmon resonance in the CuNPs. The various particle sizes obtained were tested as SERS substrate with the pyridine molecule. Antibacterial activity of copper nanoparticles against Escherichia coli gram-negative bacteria was studied. Bacteriological inhibition tests were performed on nutrient agar plates supplemented with different concentrations of copper nanoparticles. The copper nanoparticles with a concentration of 150 μg/mL and a size distribution around 6 nm showed the largest bactericidal effectiveness against E. coli.