جستجوی مقالات مرتبط با کلیدواژه « نانوذرات مس » در نشریات گروه « علوم پایه »

Eco-friendly copper nanoparticles (NPs) were prepared from the interaction of a cheap and accessible precursor, blue alum with biomolecules (polyphenols, flavonoids, proteins, terpenoids and organic sulfur compounds) in the garlic extract as the reducing of copper(II) ions, and its protector and stabilizer. As-synthesized Cu NPs were characterized by conventional methods such as XRD, UV-Vis, FT-IR, SEM, TEM, TGA and EDX. Observing the absorption maximum at the wavelength of 580 nm in the UV-Vis spectrum of the suspension solution indicated the formation of copper nanoparticles due to its surface plasma resonance. The results of the XRD diffraction pattern showed that the average size of copper crystallite was 65 nm. The morphology of the synthesized sample by scanning electron microscope (SEM) showed that copper NPs were irregular spherical. Transmission electron microscopy (TEM) estimated the average size of copper particles to be 70 nm. The as-synthesized copper NPs were used as a nano-catalyst in the reduction process of methylene blue (MB) by sodium borohydride (NaBH4). The results showed that by increasing the amount of copper NPs, the rate of methylene blue reduction reaction increased. By adding 0.0010 g of as-synthesized copper NPs to a solution containing 25 mL of methylene blue 20 ppm and 25 mL of sodium borohydride 200 ppm, it reduced time of the reaction from 4 hours to 2 minutes and its efficiency was 77%. The complete reaction time of 25 mL of methylene blue solution with concentrations of 30, 40 and 50 ppm by 25 mL of sodium borohydride 200 ppm in the presence of 0.0010 g of copper NPs took 15, 25 and 28 minutes, respectively. The effect of solution pH showed that in a certain amount of nanoparticles, the reduction rate of methylene blue was higher in an alkaline environment.

This study aimed to isolate and identify bacteria from soils contaminated with copper and have access to a capable bacterial strain for producing copper nanoparticles (CuNPs). The present study showed the extracellular production of copper nanoparticles using strain Ta-31. The effect of various factors such as substrate, supernatant volume, enzyme inducer, and electron donor was investigated on the production process. The properties of synthesized nanoparticles were identified by using UV-Vis, FTIR, XRD, SEM, and EDS analysis. Moreover, the growth curve of strain Ta-31 was plotted in the presence and absence of an enzyme inducer (concentration of 0.1 mM copper sulfate). After the phylogenetic analysis, 16S rDNA gene sequences were determined, and their phylogenetic tree of the selected strain was plotted. The results showed that the best conditions for producing CuNPs, glucose 1% as an electron donor, 2 mM copper sulfate, and 20 ml supernatant had the best production. Strain Ta-31 arrived at the end of the log phase and the beginning of the stationary phase after 15 h. CuNPs were spherical and irregular, and the size of CuNPs was more in the range of 30-40 nm. According to the results, strain Ta-31 belonged to Staphylococcus pasteuri sp. with 99.88% similarity.

Copper nanoparticles (CuNPs) are used in various industries, including pharmaceutical and biomedical sciences, agricultural and food chemistry, electronics and environmental applications, due to their novel optical, chemical, photoelectrochemical, and electronic properties as well as antimicrobial activities. The aim of the present study was to evaluate the ability of endophytic bacteria to synthesize CuNPs.

Eighteen endophytic bacteria (CN1-CN18) were isolated from the root and crown rot of the bean. The agar dilution method was used to determe the intrinsic tolerance of endophytic bacterial isolates to copper ions. Characterization of CuNPs was performed using different methods including ultraviolet–visible spectroscopy (UV–Vis), field emission scanning electron microscope (FE-SEM), Fourier transform infrared (FTIR), X-ray energy diffraction spectroscopy (EDS), and powder X-ray diffraction (XRD). The antimicrobial activity of the copper nanoparticles was investigated by the agar well diffusion method.

The results of the study indicated that isolate CN10 was able to reduce CuCl2 to CuNPs. Based on the obtained phenotypic data and 16s rDNA sequence analysis (similarity above 99%), the isolate was identified as Pseudomonas grimontii. Additionally, spherical CuNPs with an average size of 24.8 nm were synthesized by resting cells of strain CN10 under 3 mM of copper chloride, pH 7.0, agitation 100 rpm, and 96 hours of incubation. The results of antimicrobial tests showed that the produced CuNPs exhibited the highest inhibitory effects on Xanthomonas campestris (19.2 mm) and the lowest inhibitory effects on Staphylococcus aureus (9.4 mm).

The current study is the first report on the synthesis of CuNPs using a resting cell of Pseudomonas grimontii. The results suggested the synthesis of CuNPs using endophytic bacteria as a promising tool for the production of CuNPs in a controlled shape and size.

Sulfur is one of the elements in fossil fuels that is converted to sulfur dioxide, which is one of the most important air pollutants, when burned in a car engine. In the present study, the adsorption capacity of an organic sulfurized compound from a diesel fuel model containing 300 ppm thiophene was evaluated using x13 zeolite modified with 3% by weight of copper metal. Moreover, the effect of three parameters of contact time (15, 30, 60, and 120 min), adsorbent value (0.5, 1, 2.5 and 3.5 g) and temperature (25, 40, 50 and 60 °C) was assessed in a discontinuous system. In order to activate the adsorbent surface cations, x13 zeolite was washed with deionized water and 0.1 M copper nitrate salt and then copper nanoparticles were loaded on it. The maximum adsorption capacity was 2.5 g of adsorbent at 60 min at room temperature, and the amount of thiophene for adsorption modified with copper nanoparticles increased from 300 to 138 ppm. The adsorption results showed that an increase of more than 2.5 g of adsorbent would not cause a significant change in the adsorption efficiency. In addition, FT-IR, SEM and N2 physisorption studies showed that the adsorbent would maintain its regular structure after nanoparticle loading. Finally, the modified zeolite showed better performance for desulfurization of the diesel fuel model.

Environmental pollutants in industrial effluents such as organic dyes and other chemical compounds have many destructive effects on human health, other living organisms, and the ecosystem nature. Toxic dyes are considered a major source of global environmental pollution problems. So, research on the removal and reduction of these pollutants is of great interest. In this study, first, nanocrystalline cellulose (NCC) was synthesized from microcrystalline cellulose using high‐ intensity ultrasonication as a mechanical method without any chemical treatment and the use of acidic corrosive substances. Then Cu/nano cellulose (Cu/NCC) nanocomposite was synthesized using nanocrystalline cellulose as support and ascorbic acid and hydrazine as reducers. The structure of as-prepared nanocomposite was characterized by various analyses such as ultraviolet spectroscopy (UV), infrared spectroscopy (IR), scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray powder diffraction (XRD). The catalytic activity of the nanocomposite was investigated in the removal reaction of methyl orange (MO) and 4-nitrophenol (4-NP) organic pollutants. The results demonstrated the catalytic removal of methyl orange and 4-nitrophenol in a short period (210-330 s) with a rate constant (0.0041 – 0.0063 s-1), respectively. The use of nanocrystalline cellulose as a substrate and ascorbic acid as a reducing agent in the synthesis process, which are environmentally friendly, and the appropriate catalyst efficiency, and reduction of dye removal time are the advantages of this work.

In today's life, due to changes in lifestyle and the industrialization of societies, the risk of increased environmental pollution, especially organic pollutants resulting from industrial effluents, threatens the health of humans and other living things. Accordingly, the effort to remove pollutants from industrial wastewaters has become one of the most important problems for many scientists around the world. Organic dyes are known as one of the most harmful and widely used pollutants in industrial effluents. Research has shown that 700,000 tons of dyes are produced every year, most of which are azo dyes - dyes with at least one azo group (R1 – N = N – R2) - is assigned (Ravikumar et al. 2018). Methyl orange as an azo anionic dye is the most widely used in the paper-making, printing, cosmetics, and dyeing industries. This dye is highly toxic, and due to its biodegradability, is one of the environmental hazards and has very destructive effects on human health and other organisms (Heidari & Aliramezani 2021; Ravikumar et al. 2018).4-Nitrophenol is one of the most widely used and resistant pollutants in various industries such as pharmaceuticals, paper production, petrochemicals, fungicides, pesticides, insecticides, preservatives, explosives, and dyes (Heidari & Karbalaee, 2019). Due to high toxicity, very high stability in the environment, and good solubility in water, compared to other phenol derivatives, it has many detrimental effects on the environment and the health of organisms. It causes severe irritation of the eyes, skin, and respiratory system. However, its reduced form, 4-aminophenol, is of great commercial importance as an intermediate for agricultural chemicals, pharmaceuticals, pigments, and other industrial products (Liu et al. 2016). On the other hand, using noble metal catalysts such as Au, Pt, Ag, Ni, due to their high catalytic activity and optimum selectivity, is very common. But the utilization of Cu due to the reasonable price, high efficiency, compatibility with the environment and body of living organisms, and very high stability has been suggested. (Jiang et al. 2018; Kgatle et al. 2020)In this work, nanocrystalline cellulose was produced from microcrystalline cellulose powder using a simple and green method without any toxic and common corrosive chemicals such as sulfuric acid. Copper metal composite based on nanocrystalline cellulose (Cu/NCC) was synthesized using ascorbic acid as a green reducing agent. It can be used as an effective catalyst in the catalytic reduction of organic pollutants of methyl orange and 4-nitrophenol in an aqueous solution.

• Synthesis of nanocrystalline cellulose First, 3 g of microcrystalline cellulose powder was weighed and 100 ml of deionized water was added to it. The mixture was stirred magnetically for 24 hours at room temperature. After placing it in an ice bath in an ultrasonicator for 15 minutes, then place the suspended mixture in a centrifuge for 4000 rpm, and dry at 60 °C (Heidari & Karbalaee, 2019). • Synthesis of cellulose/copper nanocrystalline composite (Cu / NCC) 0.2 g of the nanocrystalline cellulose with 20 ml of deionized water was mixed for 20 minutes, then 40 ml of 0.1% copper sulfate and 1 ml of 0.02 M ascorbic acid was gradually added and refluxed in an oil bath at 110 °C. After 20 minutes, 2 ml of NaOH 2 M was added and reflux for another 20 minutes. After the second 20 minutes, 1 ml of 35% hydrazine was added to the solution drop by drop, and a sharp change in color from light green to brick was observed, The mixture was refluxed for 30 minutes. The precipitate was removed and placed in a vacuum oven at 60 ° C for 24 hours to dry completely. To obtain the nanocrystalline / copper (CuNP / NCC) product (Goswami & Das, 2018). • Catalytic reaction of cellulose/copper nanocomposite in the removal of organic pigments: 0.25 ml of organic dye (methyl orange, 4-nitrophenol), 20 mM and 0.25 mL of 5 mM sodium borohydride, and 19 mL of deionized water were mixed, then 44 mg of catalyst was added. The UVVis absorption spectra were recorded at a constant time interval (30 s).

In summary, nanocrystalline cellulose was prepared using ultrasonication without any chemical treatment method. It was used as green and biodegradable support for copper nanoparticles synthesis. As-prepared nanocomposites showed the high catalytic activity for the reduction of organic pollutants such as methyl orange (MO) and 4-nitrophenol (4-NP) in a short time in the presence of excess sodium borohydride with pseudo-first-order kinetics. This nanocomposite as an environmentally friendly, green, and cost-effective catalyst expands the use of nanomaterials for environmental protection.

Nanotechnology as a modern science is rapidly expanding which can influx many biological aspects due to large extent. For this reason, concerns about the risks and consequences of this technology are rising in environment and especially in water resources. The purpose of this study is to investigate the effect of waterborn Cuo Nanoparticles on Oncorhynchus mykiss gill tissue, to detect a suitable biomarker for noticing Copper in Water Resources. Samples weighted 18±3 gr and exposure to Cuo Nanoparticels for a week with 25, 30, 50 and 100 ml/g doses. Physicochemical properties of water were 14±2 Cº temperature, 8-8.5 pH and 270 mg/l Caco3. At the end of 7 days, 9 fish were catch randomly from each treatment and second gill from left side of fish were removed for histological review. Hyperplasia, Oedema, Epithelial lifting in secondary lamella, lamellar aneurysm and Leukocyte infiltration was observed in gill tissues. In addition, the damage was determined at various concentrations of copper nanoparticles. Result showed that Cuo Nanoparticles, as copper ions, have significant adverse effects on gill tissues of O. mykiss and gills can be a suitable biomarker for copper in water resources. However, comparison of the extent and severity of injury stated that copper nanoparticles cause much less injury than copper ions.

Graphene with unique physico-chemical properties is known as a new phenomenon in material science. Combining the properties of graphene with other nanomaterials، results in exceptional nanocomposites. One route is the decoration of graphene sheets with nanocrystals. On the other hand application of zero valent metals for the wastewater treatment is a widely accepted technology. In this study the nanocopper decorated graphene composite was synthesized and characterized using different methods. The possibility of its application in the degradation of 4- (2-pyridylazo) resorcinol dye was investigated. The results showed that under optimal conditions، degradation of 50 ml dye solution (100 mg L-1) with 2 g L-1 of nanocomposite is achievable.