Nanoparticles In Distilled Water Research Articles

Comparison of the antimicrobial photocatalytic activities of SiO2 and Au@SiO2 nanostructures in water decontamination.

Photocatalytic disinfection of Escherichia coli suspension by silicon dioxide nanoparticles and silicon dioxide/gold nanocomposite in a batch reactor is investigated experimentally and results are compared. Silica nanoparticles were synthesized by Stöber method and pulsed laser ablation method was employed to prepare gold nanoparticles in distilled water. Composition of two nanoparticles species was carried out, using the second harmonic pulse of Nd:YAG laser, whose wavelength is in the absorption spectra of gold nanoparticles. Results confirm a decrease in the bandgap energy of silica nanoparticles after composition. Escherichia coli were selected as an indicator of the microbial water contamination. Disk diffusion method was used to evaluate the antimicrobial potential of SiO2 and Au@SiO2 nanostructures. Photocatalytic activities of both nanostructures were examined in dark, and under the irradiation of UV and visible light. In all conditions, the performance of Au@SiO2 nanocomposites was higher than SiO2 nanoparticles. In dark condition the higher biocidal nature and activity of Au nanoparticles and for the case of UV radiation, decreasing the bandgap energy and recombination rate of SiO2 nanoparticles after composition with Au increased the efficiency. For the case of visible light radiation, surface plasmon resonances effects, and local heat of Au nanoparticles were responsible for increasing the efficiency. RESEARCH HIGHLIGHTS: Doping large bandgap semiconductors nanostructures, such as silica with metal nanoparticles, such as gold will improve their photocatalytic activity to work in visible light. In this mechanism, gold nanoparticles act as effective traps to prevent the recombination of photogenerated electron-hole pairs. Other mechanisms, such as Schottky barrier formation, surface plasmon resonance absorption of gold nanoparticles, and biocidal nature of the gold nanoparticles are effective in increasing the efficiency of Au doped silica nanostructures.

A comparative experimental study on thermal conductivity of distilled water-based mono nanofluids with zirconium oxide and silicon carbide for thermal industrial applications: Proposing a new correlation

The main aim of this experiment was to determine the thermal conductivity of two nanofluids, ZrO2/DW and SiC/DW, under different temperatures and concentrations as compared to the base fluid. In this work, zirconium oxide and silicon carbide nanoparticles were obtained, and the nanofluids were prepared using a two-stage method by dispersing the nanoparticles in distilled water (DW) by the ultrasonic processor and a magnetic mixture. Field emission scanning electron microscopy (FESEM), Energy-dispersive x-ray spectrometer (EDX), Transmission Electron Microscope (TEM), and X-ray diffraction (XRD) techniques were used to microstructural and characterize the nanoparticles. Stability of nanofluids were examined by zeta potential test. After that, thermal conductivity was measured using the thermal hot wire method using a KD2-Pro thermal analyzer at temperatures ranging from 20 to 60 °C. Solid volume fractions (φ) of 0.025%, 0.05%, 0.075%, and 0.1% were used. The results showed that the thermal conductivity of the nanofluid was enhanced with increased volume fractions and temperature. The highest recorded thermal conductivity was at the highest temperature 60 °C and solid volume fraction 0.1%. The thermal conductivity enhancement for ZrO2/DW at the volume fraction of 0.1% was 20.455%, and that of SiC/DW was 30.303%. The enhancement was compared to that of the base fluid, distilled water. Finally, based on experimental data, A new mathematical correlations were obtained by curve-fitting. The correlations were used to estimate the thermal conductivity of ZrO2/DW and SiC/DW nanofluids at different solid volume fractions and temperatures. The results obtained were compared to a correlation to determine their accuracy. The deviations from the presented correlations were 1.49% and 1.2% for ZrO2/DW and SiC/DW, respectively. The comparison between experimental results and correlation outputs showed a good agreement which signifies that the results were accurate.

Thermal performance evaluation of parabolic trough collector having different inserts and working with hybrid nanofluid

This study emphasizes the comparative investigation of the thermal capacity of parabolic solar trough collectors with spherical-shaped balls and two types of elliptical inserts (longitudinal orientation). Hybrid nanofluid is the heat-carrying liquid obtained by mixing CuO and Al2O3 nanoparticles in distilled water. Analytical investigations are conducted for 1% vol. concentration of hybrid nanoparticles in distilled water for varying proportions. Computational analysis is chosen to obtain thermal as well as flow trends in the tube receiver. The outcomes disclosed that 13.3%, 10.02%, and 16% improvements are noted for thermal efficiency, Nusselt number, and thermal performance index with elliptical inserts of minor diameter 12 mm in the receiver, respectively, than spherical ball inserts. The highest pump work of 35 W is associated with spherical inserts at 0.033 kg/s.

Generation of gold and silver nanoparticles using laser ablation of thin bimetallic films and bulk targets in water

Generation of gold and silver nanoparticles by laser ablation in water without the addition of surfactants is very attractive due to the purity of such nanoparticles. However, such nanoparticles face the problem of long-term stability, which severely limits their applicability. Here, we demonstrate the generation of hybrid gold-silver nanoparticles using the laser ablation of thin-film composites on a glass substrate in water, and compare with the laser fabrication of nanoparticles by using bulk targets of silver and gold. Thin-film method allows the formation of stable hybrid Au–Ag nanoparticles in distilled water without any stabilizers and additional ligands with an opportunity to regulate the nanoparticle composition using different metal ratios, layer order, and thickness of films. The stability and optical properties of the hybrid nanoparticles depend on the used laser pulse energy. This study demonstrates that the thin film method produces nanoparticles with higher stability compared to the bulk target method. These outcomes are encouraging for the creation of better-performing, stable, and clean nanoparticles that can be used in a variety of applications in biomedicine, sensors, integrated circuits, filters, batteries, covid-19 tests, solar cells, dual-energy mammography (DEM), computed tomography (CT), and other components of optical and electronic devices.

Preparation and Characterization of Silver Nanoparticles (AgNPs) by Pulsed Laser Ablation in Liquid

In this study, the technique of pulsed laser ablation in liquid (PLAL) is used to prepare colloidal silver (Ag) nanoparticles in distilled water (D.W.). The optical properties and the synthesis of the nanoparticles are characterized by UV-visible spectrophotometer, photoluminescence (PL), infrared Fourier transforms (FT-IR), and transmission electron microscopy (TEM) measurement. The optical characteristics of (Ag) nanoparticles are investigated using (UV–vis) analysis on all colloidal samples, which reveal a large peak at wavelengths of (405–410 nm) for silver nanoparticles created using PLAL technology. The infrared Fourier transforms (FT-IR) study determines the functional groups of silver nanoparticles in D.W. The silver nanoparticles (AgNPs) have a spherical form, and their diameters range from 12 to 20 nm, according to the transmission electron microscopy (TEM) measurements. The photoluminescence (PL) data reveal two peaks, one in the visible region, which is responsible for the production of silver nanoparticles, and the other in the UV region, where the size of the nanoparticles grows as the number of laser pulses increases.

Experimental Study on Convective Heat Transfer Enhancement of Automotive Radiator with Graphene-Nanoplatelet Suspension

In the present work, an experimental investigation has been conducted to analyse the effects of graphene-nanoplatelet (GnP) suspension on the thermal performance of automotive radiator. GnP nanofluids are prepared by dispersing the nanoparticles in distilled water with a concentration of 0-0.3 vol.%. The thermophysical properties of water-GnP nanofluid have been studied with different volumetric concentrations and temperatures. The present study shows that convective heat transfer performance of the automotive radiator could be enhanced by increasing the nanoparticle suspension, heating power, air flow and Reynolds number. The maximum thermal performance enhancement of 275% is achieved for 0.3 vol.% GnP nanofluid at the highest rated heating power. It is also evident that the suspension of nanoparticle has the most significant effect in enhancing the convective heat transfer of automotive radiator, followed by the effects of heating power, air velocity and Reynolds number.

Experimental investigation on pH and stability of distilled water ethylene glycol mixture with graphene nanoplatelets

An efficient heat transfer medium improves the overall efficiency of the equipment, and the main difficulty is with making well-dispersed nanoparticles in base fluids. The current research is focused to study the effect of different surfactants on nanoparticle dispersion and enhancement through property modifications. The stability and pH value of various surfactants with varying sonication duration were studied and compared with the graphene nanofluids. The graphene nanofluids were prepared by a two-step method by dispersing 0.1 wt% graphene nanoparticles in distilled water and ethylene glycol with a ratio of 70:30. The surfactants namely Cetyltrimethylammonium bromide (CTAB), Polyvinylpyrrolidone (PVP K-30), and Polysorbate 60 (Tween 60) of each 0.1 wt% were used for stabilizing the nanofluids. The duration of the sonication process was set as 60, 90, and 120 min respectively followed by the magnetic stirring for 60 min duration. The stability behavior of nanofluids was studied through visual inspection, UV spectrum, and zeta potential techniques, and the corresponding pH values were measured to correlate with the performance of the heat transfer equipment. The results showed that the dispersion of graphene nanofluids strongly depends on the type and amount of dispersant in the absolute value of zeta potential. Finally, the optimum conditions were found based on the enhanced stability, pH, and sonication time of graphene nanoplatelets in distilled water-ethylene glycol mixture with Polyvinylpyrrolidone (PVP K-30) as a surfactant for the battery thermal management systems (BTMS) in electric vehicles.

Parameter optimization and surface integrity aspects in MWCNT-based nano-PMEDM process of Inconel 718

This study examines the effects of Inconel 718's Nano PMEDM process parameters on Material Removal Rate (MRR), Tool Wear Rate (TWR), Surface Roughness (SR), and the integrity of surface and subsurface layers. It also examines the concentration of MWCNT nanoparticles in distilled water as a dielectric medium. Peak Current, Pulse on Time, and Powder Concentration were input variables in 20 experimental runs utilizing the Central Composite Design (CCD) of Design of Expert (DOE). To create and evaluate empirical models for MRR, TWR, and SR, response surface methodology (RSM) and ANOVA were used. According to the results of the improved RSM, the best responses for MRR, TWR, and SR are 0.012 g/min, 0.001 g/min, and 5.098 µm, respectively. These were accomplished by cutting parameters of 1.5 g/L for powder concentration, 307.967 s for pulse on time, and 19.925 Amps for peak current. GA optimization produced slightly different optimal values for MRR, TWR, and SR: 0.012 g/min, 0.003 g/min, and 5.229 µm, respectively. 20.178 Amps for Peak Current, 398.753 seconds for Pulse on Time, and 3.66 g/L for Powder Concentration were the suggested ideal cutting conditions for GA optimization. In the validation tests, both the GA-predicted outcomes and RSM-optimized values closely matched the experimental results.

Синтез, свойства и применение композитных наночастиц, полученных при окислении водой электровзрывного нанопорошка Al/AlN/Cu

In this work, for the preparation of AlOOH/CuO/Cu composite nanoparticles, nanoparticles based on Al, Cu, their compounds (Cu2Al, Cu9Al4, Cu4Al, CuAl ) And AlN were first obtained and characterized. The regularities of the oxidation of Al/ AlN/Cu nanoparticles in distilled water have been investigated. The optimal parameters for the synthesis of AlOOH/CuO/Cu composite nanoparticles from Al /AlN/Cu nanoparticles have been determined. The morphology of the obtained nanoparticles is shown using electron microscopy. The composition of the precursor and oxidation products was determined by the method of qualitative X-ray phase analysis. The average size of nanoparticles was determined by statistical processing of TEM images of nanoparticles. To construct the diagrams by size, the sizes of at least 1500 nanoparticles were taken into account. The specific surface area was investigated by thermal nitrogen desorption. To determine the optimal synthesis parameters, the oxidation reaction was carried out at different temperatures: 40, 50, 60, 70, 80, 90 °C with an accuracy of maintaining the set temperature of ± 0.1 °C. During the oxidation reaction of Al/AlN/Cu with water, the pH of the reaction mixture was controlled. It was found that the optimum reaction temperature is 60 °C. As a result of the synthesis, porous structures are formed, consisting of nanolobes of fine-crystalline boehmite with a size of 100 – 300 nm and a thickness of 5 – 7 nm, combined into agglomerates, in the center of which copper-based compounds are located. The specific surface area of ​​the reaction products reaches 160 m2/g. The presence of AlN nanoparticles in the composition promotes a more complete conversion of copper and intermetallic compounds with the formation of CuO and Cu2O. It has been shown that the synthesized nanoparticles can be used as an antimicrobial component in the composition of hybrid materials based on polyvinylpyrrolidone and PEG alloy (400 and 20.000).

A study of morphology, UV measurements and zeta potential of Zinc Ferrite and Al2O3 nanofluids

Nanofluids are generally used as working fluids in heat exchangers and heat transfer equipments because of their unique and improved heat efficacy. But their poor stability due to sedimentation and agglomeration with passage of time has limited them to use in practical applications. Stability of the nanofluids can be increased by addition of surfactants, which induces repulsion between the nanoparticles. Present work focuses on morphology, UV measurements and zeta potential measurements of zinc ferrite and aluminium oxide/water nanofluids. Nanofluids were synthesized by homogeneous mixing of zinc ferrite and aluminium oxide nanoparticles in distilled water to obtain different weight concentrations of the nanofluids using Cetyl Trimethyl Ammonium Bromide as surfactant. Results showed that both the nanofluids offer best dispersion conditions as per zeta potential values, allowing quitehigh stability of the nanofluids. Highest values of absorbance i.e. 3.922 and 3.569 were obtained using 0.5 wt% of the Zinc ferrite and Aluminium Oxide/water nanofluids. Also, highest values of zeta potential i.e. 42.7 and 45.2 mV were obtained using 0.02 wt% of the Zinc ferrite and Aluminium Oxide/water nanofluids.

Estimation of Theoretical Models of Photophysical Processes for Fluorescein Laser Dye with Ag Nanoparticles

In this study, a novel theoretical method for the absorption and fluorescence spectral estimations has been presented. These estimations have been based on experimental measurements of absorption and fluorescence spectra for the solutions of Fluorescein laser dye with Silver (Ag) nanoparticles in distilled water. The used concentration was (1x10-5 M) for Fluorescein dye, while the mass amounts were (0.003g, 0.005g, 0.0065g, 0.008g and 0.0085g) for Silver nanoparticles. A spectral absorption enhancement was detected in the case of increased Silver nanoparticle masses, which specify that the doped Fluorescein dye with Ag nanoparticles has an important effect on the dye absorption spectra. On the other hand, each fluorescence emission spectrum for the dye has quenched as Ag nanoparticle's mass amounts have increased. The related amounts of mass increase as a consequence of Förster resonance energy transfer (FRET). The novel approach of theoretical estimations has been based on curve fitting using Logistic Power Peak (LPP) function to estimate theoretical models for the absorption and fluorescence spectra of these samples. These rated models have excellent matching profiles with the experimental profiles so that the estimated models can replace the experimental measurements.

Statistical optimization of Closed Loop Pulsating Heat Pipe parameters with R-410a and nanorefrigerant in air conditioning applications

ABSTRACT The present investigation is an attempt to study the effect of refrigerant with nanoparticles against conventional refrigerant in closed loop pulsating heat pipe (CLPHP). Here, a customized CLPHP was used in this study and nanorefrigerant was prepared using R-410a with graphene nanoparticles in distilled water as the novel working fluid. The process parameters for CLPHP with both refrigerants, optimized using the statistical tool Response Surface Methodology based on central composite design, were inclination angle (θ°) ranging between 85 and 95, and power (W) ranging between 90 and 110. In this study, thermal conductivity (Rth), thermal resistance (k) and temperature difference (Δ T) between evaporator and condensor were analyzed. The optimized parameters for standard refrigerant were found to be: inclination angle 92° and power 104 W whereas for nanorefrigerant the parameters were 88° and 102 W. The yields in terms of Rth, k and T for refrigerant were 0.015°C/W, 6284.33 W/mK and 10°C and those for nanorefrigerant were 0.0025°C/W, 32376.72 W/mK and 18°C. This investigation revealed that the R2 values were approximately 100% in both cases illustrating that the statistical evaluation was true to the experimental model and befitting the same. The complete results exhibited that in both cases thermal conductivity increased while thermal resistance decreased. Also, differences in temperature between evaporator and condensor was larger in CLPHP with nanorefrigerant while it was lower in CLPHP with R-410 alone. Hence, the overall study suggested that the efficacy of R-410a with graphene nanoparticles was 80.05% better than that of lone R-410a in CLPHP. In conclusion, this experiment evinced the positive utilization of nanorefrigerant as working fluid in CLPHP for air conditioning applications.

Preparation of GO/DW nanofluids for heat transfer applications

Water-based nanofluids were prepared by dispersing graphene oxide (GO) nanoparticles in distilled water (DW) followed by magnetic stirring and ultrasonication to get homogeneous and stable suspensions. Nanoparticles were characterized through Field Emission Scanning Electron Microscopy (FESEM) and X-ray diffraction (XRD). Three samples of 100 ml were prepared at a particle loading of 0.03, 0.1, and 0.3% by weight (wt.%). The thermal conductivity of each sample was measured at 30, 45, and 60 °C temperatures, to study the effect of particle loading and temperature. The results showed that enhancement in thermal conductivity varied from 11.3 to 50.5%. The maximum enhancement of 50.5% in thermal conductivity was found at 60 °C in the case of nanofluid with particle loading of 0.3 wt%. An equation is proposed for thermal conductivity which shows the linear relationship with both particle loading and temperature.

Characteristics of Bipolar Nanosecond Discharges in Air Formed in the Electrode System “BLADE-SURFACE of Nonmetallic Liquid -BLADE”

Curcumin The design of the device for producing a high-current, bipolar nanosecond discharge over the surface of a non-metallic liquid (water, electrolytes, alcohols, etc.) in air is given. Air pressure is ranged from 5 to 101 kPa. The distance between the tip of the blade and the surface of water or liquid (5% solution of copper sulfate in distilled water) was 4 mm, and the distance between parallel metal blades was 40 mm. The conditions for uniform plasma overlapping of the electrolyte surface between the metal blades are established. The spatial, electrical, and optical characteristics of the discharge are investigated. It is shown that the discharge under study allows obtaining colloidal solutions of copper nanoparticles in distilled water in a macroscopic amount (1 liter or more). The developed reactor is of interest for use in poisonous chemical solution disinfection systems, solutions based on dangerous bacteria and viruses for which the use of traditional systems with a point spark discharge or a barrier discharge becomes ineffective. The rector is also promising for the synthesis of colloidal solutions of transition metal oxide nanoparticles from solutions of the corresponding salts. These solutions can be used in micro-nanotechnology and for antibacterial treatment of plants in greenhouses, processing of medical instruments and materials.

The Establishment of a Theoretical Model for the Estimation of Some Photo-Physical Processes in Laser Dyes

In this study, a new theoretical method for the estimation of absorption and fluorescence spectra is accomplished. These estimations were established following experimental measurements of absorption and fluorescence spectra for the solutions of fluorescein laser dye mixed with titanium dioxide (TiO2) nanoparticlesin distilled water. The used concentration of fluorescein dye was 1x10-5 M, whereas the masses of titanium dioxide nanoparticles were 0.0003g, 0.0005g, 0.001g and 0.002g. An absorption spectra improvement was observed upon raising the mass of TiO2 nanoparticles, which specifies that doping the fluorescein dye with TiO2 nanoparticles have an essential influence on the dye absorption spectra. On the other side, all fluorescence spectra for the dye quenched as TiO2 nanoparticles mass was increased, because of the induced electron transfer. The new method of theoretical estimations was based on curve fitting using Logistic Power Peak (LPP) function to estimate theoretical models for the absorption and fluorescence spectra of thesesamples. The results revealed that these estimated models had exceptional matching shapes with the experimental shapes, so that the estimated models can substitute the experimental measurements.

Mechanistic study on silica nanoparticles-assisted guar gum polymer flooding for enhanced oil recovery in sandstone reservoirs

Nanoparticles-assisted polymer flooding has attracted the attention of researchers for its enhanced rheological properties and stability of the chemical slugs. The present work deals with the rheological properties of guar gum with and without silica nanoparticles in the temperature range from 25 °C to 75 °C. It is found that the viscosity of guar gum solution increases significantly with increasing concentration of silica nanoparticles. Imbibition experiments were performed with waxy crude oil-saturated sandstone cores using 2000 ppm brine, 4000 ppm guar gum solution, 0.2 wt% silica nanoparticles in distilled water, and 4000 ppm guar gum containing 0.2 wt% silica nanoparticles as test fluids for understanding the mechanism of wettability alteration in the presence of silica nanoparticles and guar gum. Mixture of 0.2 wt% silica nanoparticles and 4000 ppm guar gum shows higher oil recovery (∼36 % original oil-in-place) compared to other test solutions in imbibition experiments. Contact angles between crude oil and sandstone rock were measured in presence of 2000 ppm brine, 0.025 wt% silica nanoparticles in water, and guar gum (2000 ppm)-silica nanoparticles (0.025 wt%) mixture. Guar gum containing silica nanoparticles are effective in changing the contact angle towards water-wet state (Contact angle ∼115°) from oil-wet state (contact angle ∼72°). No significant phase change is observed during the phase behavior experiment except for light emulsion formation. Finally, core flooding experiments were conducted with guar gum, silica nanoparticles solution, and mixture of silica nanoparticles and guar gum for additional oil recovery to verify the effectiveness of the chemical slugs. Results showed that the addition of silica nanoparticles to guar gum solution improves the effectiveness of guar gum polymer by recovering 44.3 % of original oil-in-place. A comparative study was also conducted to show the performance of silica nanoparticles-assisted guar gum solution for additional oil recovery. Most of the research works have focused on the application of silica nanoparticles-induced polyacrylamide and xanthan gum chemical slugs in enhanced oil recovery. However, laboratory study based on the application of silica nanoparticles-induced guar gum solution in additional oil recovery adds some interesting findings to the literature compared to the existing information.

BIOCOMPATIBILITY STUDY OF α-Fe2O3 NANOPARTICLES PREPARED BY HYDROTHERMAL METHOD

Nanoparticles of alpha ferric oxide ([Formula: see text]-Fe2O3) were prepared by the hydrothermal method. Structural properties of [Formula: see text]-Fe2O3 were determined by XRD, SEM and AFM measurements. The particles had a good matching with standard pattern. Average particle size was about 90[Formula: see text]nm and the distribution extended from about 20[Formula: see text]nm to 120[Formula: see text]nm. Biocompatibility study of ferric oxide nanoparticles against bacteria, parasites, tumor cell line and normal cells was determined. No antibacterial activity was observed for the concentration, of ferric oxide nanoparticles in distilled water, up to 1.5[Formula: see text]mg/ml vs. E. coli and S. aureus. Moreover, MTT assay was used to determine the cytotoxicity against parasites and cells. Intermediate cytotoxicity (53.30%) of 1.5[Formula: see text]mg/ml of prepared nanoparticles was noted against L. tropica, while weak cytotoxicity of 5.20% was observed against L. donovani at the same concentration of ferric oxide nanoparticles. On the other hand, the prepared nanoparticles revealed low cytotoxicity (47.28%) against SR tumor cell line, while no cytotoxicity was shown against lymphocytes, as a model of normal cells.

Experimental Study for the Thermal Conductivity of Micro and Nano fluids by Using Copper and Titanium Oxide

In this article experimentally investigations have been carried out to study the effect of the size and type particles on the thermal conductivity of micro and nanofluids. The study investigated nanofluids and microfluids which containing copper (Cu) and titanium oxide (TiO2) as well as in the size and type of micro and nanoparticles in distilled water as base fluid with different particles size and concentrations. The experimental results emphasized the enhancement of the thermal conductivity due to the nanoparticles presence in the fluid greater than microfluids, also shown the effect of the particle size and concentration on the thermal conductivity. It has been recognized that the addition of highly conductive particles can significantly increase the thermal conductivity of heat – transfer fluids. Particles in the micro and nano – size range have attracted the most interest because of their enhanced stability against sedimentation and, as a result, reduction in potential for clogging a flow system. Furthermore the results showed that, they obtained thermal conductivities doubtlessly revealed that a size and type particle was a key factor affecting conductive heat transport in suspensions. These results show noticeable enhancement in the thermal conductivity were evaluated to be (7.66 %, 2.35 %) for the Cu, TiO2 – distilled water nanofluid while reaches to (3.23 %, 1.02 %) for the Cu, TiO2 – distilled water micro fluids at the concentration of (5 vol. %) and at the room temperature. Moreover thermal conductivity was increased for the nanofluids and microfluids which contains large particle size compared with that contains small particle size. A good agreement was found between the experimental obtained data for this paper and other results from published papers

Characterization of cobalt oxide nanoparticles produced by laser ablation method: Effects of laser fluence

Abstract The role of laser fluence in producing cobalt oxide nanoparticles in distilled water by laser ablation method has been studied experimentally. Output of a pulsed Nd:YAG laser of 1064 nm wavelength and 7 ns pulse width with 10 Hz repetition rate was employed to irradiate a high purity cobalt bulk in distilled water. According to results, size of produced nanostructures as well as their oxidation was strongly under the influence of laser energy. Although a high purity Co bulk was used as the target of laser irradiation in the experiment but produced nanoparticles were mainly cobalt oxides. X ray diffraction pattern indicates that produced nanostructures are Co3O4. The excitonic absorption peak of Co3O4 nanoparticles was occurred in UV region. Results show that with increasing the fluence of laser pulse, size of nanoparticles was decreased while their aggregation was increased noticeably.

A detailed investigation on the thermo-physical and rheological behavior of MgO/TiO2 aqueous dual hybrid nanofluid

Experimental study of thermo-physical properties and rheological behavior of MgO-TiO2/DW (distilled water) nanofluids with the weight percent of 50:50, 80:20, 20:80, 60:40 and 40:60 are presented in this paper. Dual Hybrid Nanofluids (DHNFs) were prepared by suspending MgO and TiO2 nanoparticles in distilled water in the presence of Sodium Dodecyl Sulfate (SDS) as a surfactant. The temperature dependence of the properties in the range from 15 to 60 °C was measured. All experiments were fulfilled at different solid volume concentrations (0.1–0.5 vol%). The stability time of nanofluids was more than 3 days. The experimental results showed that the thermal conductivity of DHNFs strongly depended on solid volume concentration and rarely enhanced with enhancing temperature. The highest enhancement of thermal conductivity of DHNFs related to solid volume concentration was found to be 21.8% for 80 wt% MgO-20 wt% TiO2 equivalent to 0.3 solid vol% at 60 °C. The dynamic viscosity of DHNFs increased with enhancing solid volume concentration and reduced with enhancing temperature. The rheological behavior of MgO-TiO2/DW DHNFs was Newtonian in all laboratory conditions. The specific heat capacity of DHNFs (80 wt% MgO-20 wt% TiO2) decreased by 1.08% with a solid volume concentration of 0.5%. The temperature had not much impact on density enhancement. Additionally, 3 empirical correlations were presented to predict the aforementioned properties of DHNFs and the calculated results of which are in good agreement with the experimental data.