Nanoparticle Mass Research Articles

Importance of mass and enthalpy conservation in the modelling of titania nanoparticles flame synthesis

In most simulations of fine particles in reacting flows, including sooting flames, enthalpy exchanges between gas and particle phases and differential diffusion between the two phases can be neglected, since the particle mass fraction is generally very small. However, when the nanoparticles mass fraction is very large representing up to 50% of the mixture mass, the conservation of the total enthalpy and/or the total mass becomes critical. In the present paper, we investigate the impact of mass and enthalpy conservation in the modelling of titania nanoparticles synthesis in flames, classically characterised by a high conversation rate and consequently a high nanoparticles concentration. It is shown that when the nanoparticles concentration is high, neglecting the enthalpy of the particle phase may lead to almost 70% relative error on the temperature profile and to relative errors on the main titania species mass fractions and combustion products ranging from 20% to 100%. It is also established that neglecting the differential diffusion of the gas phase with respect to the particle phase is also significant, with almost 15% relative error on the TiO mole fraction, although the effect on combustion products is minor.

Modelling the viscosity of carbon-based nanomaterials dispersed in diesel oil: a machine learning approach

The viscosity of a nanofluid is one of its fundamental thermophysical properties, and it is an important consideration in heat transfer applications. Although the viscosity can be reliably obtained from experimental measurements, the development of models to predict the viscosity is a faster and more convenient approach. This study focuses on creating a machine learning model for the viscosity of different carbon nanomaterials dispersed in diesel oil. The nanomaterials considered here include multi-walled carbon nanotubes, graphene nanoplatelets, and their hybrid combinations. A support vector regression-based model was developed and validated using 120 experimental data points in the temperature range 5–100 °C. The model inputs are the nanoparticle mass fraction, the fluid temperature, and the viscosity of the diesel oil. The developed model yields very good predictive performance on the training and testing datasets. The correlation coefficient and the root mean square error were 99.98% and 0.0076 Pa s, respectively, for the training dataset, and 99.99% and 0.0026 Pa s for the testing dataset. These results indicate that the developed model is extremely accurate for predicting the viscosity of carbon-based nanomaterials in a diesel oil medium, and it was found to outclass all existing models. This model could therefore be extremely useful in the design of heat transfer applications.

Optimisation of Zinc Oxide Nanoparticle Biosynthesis Using Saccharomyces Cerevisiae with Box-Behnken Design

Zinc oxide nanoparticles have wide applications as catalysts, antimicrobial agents, drug delivery agents, etc. because of their intrinsic properties. Various methods can be applied to synthesise nanoparticles, one of which is the biosynthesis process. Biosynthesis is more eco-friendly than chemical and physical methods. In the present study, the optimisation of zinc oxide nanoparticle biosynthesis using the yeast Saccharomyces cerevisiae was performed by applying a response surface method called the Box�Behnken design (BBD). Three factors were optimised in the present study, namely the concentration of zinc acetate as the precursor (X1), concentration of the S. cerevisiae fermentation broth (X2), and the incubation time (X3). The mass of zinc oxide nanoparticles (Y) was recorded as the response of the experiment. The product was then characterised by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and particle size analyser (PSA). The optimum conditions for the preparation of zinc oxide nanoparticles were found to be 0.3 M, 100% (v/v), and 24 h as the zinc acetate concentration, medium concentration, and incubation time, respectively. The FTIR analysis showed peaks at ~600 cm−1, which is characteristic for ZnO stretching. From the XRD result, the ZnO nanoparticles with hexagonal structure was confirm. The SEM/EDS analysis confirmed that the morphology was spherical and showed the major energy emission for zinc and oxygen. Moreover, the PSA analysis revealed that the smallest size was 218.6 nm (12%) when the synthesis was performed at the optimum conditions, while when the incubation time was prolonged for 120 h, the size decreased to 134.2 nm.

Hall current effects on a magnetic nanofluid layer under temperature gradient

In the Bénard convection governed nanofluid confined between two horizontal infinite free-free boundaries, the effect of Hall current is investigated when it is subjected to the constant vertical magnetic field. The Buongiorno mathematical model for hydromagnetic flow with Hall currents has been considered. The Brownian motion effects and thermophoresis of nanoparticles have been included in the energy equation. A realistic boundary condition based on zero nanoparticle mass flux at the walls is incorporated for the analysis. The impacts of Brownian motion, convective heat transfer, thermophoresis of nanoparticles and zero mass flux conditions are also deliberated through the behaviour of the related parameters. The parameters representing the model incorporate the consequences of newly introduced physically realistic boundary conditions and Hall currents. For comprehensive physical interpretation the embedded parameters have been plotted and deliberated graphically. It is found that Hall current is responsible to enhances the instability of the system and sets the convection earlier. A rigorous comparison has been made with the existing results. The results are shown graphically and verified numerically.

Molecular dynamics simulation of thermal and phonon transport characteristics of nanocomposite phase change material

Nanomaterials have been widely used to prepare nanocomposite phase change material (NPCM) and enhance its thermal conductivity. However, most of the studies are mainly focused on the thermal transport properties and the microscopic mechanism is still not clear. In this paper, molecular dynamics (MD) method was adopted to study both the thermal and phonon transport behaviors of NPCM (CuO/paraffin) to deeply reveal the influence mechanism of nanomaterials on PCM. The results show that the nanoparticle can enhance PCM thermal conductivity, and the enhancement effect is strengthened with nanoparticle mass fraction and NPCM temperature increasing. After that, phonon density of states was calculated to investigate the phonon scattering phenomenon in NPCM. The results show that the phonon scattering is very small in nanoparticle; then with the distance to nanoparticle surface increasing, the phonon scattering quickly increases; however, there exists a nanolayer around the nanoparticle, where the phonon scattering almost keeps constant. The weaker phonon scattering, the higher thermal transport performance. So, the existence of nanolayer caused by nanoparticle reduces the phonon scattering and promotes the heat transfer, which contributes to the thermal conductivity enhancement of NPCM

Effect of ink formulation on the inkjet printing process of Al–ZnO nanoparticles

This study focuses on the inkjet printing of aluminum-doped zinc oxide (AZO) spherical and platelet nanoparticle-based nanoflakes with typical sizes ranging from 700 to 800 nm. The AZO nanoparticles were synthesized by aqueous precipitation. The preparation of the solvent-based inks was performed with the control of the viscosity, ink stability, and nanoparticle dispersion. The results showed that the viscosity for nanoparticle dispersions slightly changes (from 6.9 to 8.7 cPs) when the nanoparticles mass concentration increases from 1.8 to 10%. In order to achieve thin films of AZO nanoparticles, we optimized the printing process by real-time monitoring of drop velocity with a stroboscopic camera. This technology involves direct patterning of a functional material by tiny MEMS-jets on a flexible and rigid substrate at specific locations. The lowest concentration of AZO nanoparticles corresponding to 1.8% enables printing several times during the nanoparticle dispersions and the clogging of printhead nozzles is less pronounced. In our conditions, the optimum voltage value is 25 V to achieve a drop velocity from 7 to 9 m/s. In the case of nanospheres with 10% of AZO nanoparticles, for a large dropspace (90 $$\mu$$ m), the individual printed droplets appear as a sequence of linear dots. When the drop spacing decreases to 75 $$\mu$$ m, isolated drops start to overlap and merge. Further decrease in the drop spacing eliminates scalloping and leads finally to a regular and continuous layer at 55 $$\mu$$ m.

Photoluminescence, thermal and surface properties of triarylimidazole-containing polyimide nanocomposite films.

In this work, a triarylimidazole-containing diamine 2-(4-methylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (MPBAI) was firstly synthesized and polymerized with 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) to prepare transparent polyimide (PI) films by means of thermal imidization. Then, inorganic nanoparticles including silica (SiO2), alumina (Al2O3) and silicon nitride (Si3N4) were separately introduced into the PI(MPBAI-CBDA) with different mass fractions of 0.02%, 0.10%, 0.50% and 2.50% to obtain three series of PI nanocomposite films. All these films were close to colorless and transparent, although the light transmittance showed a downward trend due to the introduction of nanoparticles. Moreover, as the content of inorganic nanoparticles increased, the fluorescence intensities of these films were increased. Comparatively, the improvement effect of nano-SiO2 was the most obvious. When the content of SiO2 was 2.50%, the maximum intensity of the fluorescence absorption peak was increased by 9.6 times, and the absolute fluorescence quantum yield reached 17.2%, about 5.2 times that of the original PI film. Moreover, the maximum absorption peak produced a red shift of 85 nm due to the addition of 2.50% Si3N4, which was probably caused by the weakening of fluorescence quenching effect and high permittivity. The nanocomposites exhibited high glass transition temperatures of around 300 °C and excellent thermal stabilities. The surface hydrophobicity was changed by adjusting the mass and type of nanoparticles. Thus, this work provided a simple way to improve the photoluminescence effect by introducing the nanoparticles. The functional films will be expected to be applied in some optical applications.

Investigating a single slope solar still with a nano-phase change material

The present paper investigates the performance of a conventional single slope passive solar still (CSS) under the influence of a paraffin based phase change material (PCM) and a nano-PCM (n-PCM) in terms of the fresh water production per day. To achieve this objective, three solar stills with the same dimensions were designed and fabricated. Among them, one still was left without any modification (CSS), another one was incorporated with paraffin as PCM (PCMSS), and third one was assimilated with an n-PCM (NPCMSS). Previously, the n-PCM was prepared by adding 0.5% mass of silica nanoparticles in paraffin. The experiments had steered on a hot and humid weather at Coimbatore, India during the month of April 2020. The results evidenced that the incorporation of PCM and n-PCM improved the fresh water production by 51.22% and 67.07%, respectively.

Electrochemical study of copper oxide and activated charcoal based nanocomposite electrode for supercapacitor

In this work, copper oxide (CuO) nanoparticles were synthesized at different temperature using chemical co precipitation method at room temperature. The synthesized copper oxide nanoparticles were mixed with activated charcoal powder to make nanocomposite for its application as electrodes material in ultracapacitor. Electrodes formed by synthesized nanocomposite at 600 OC show superior performance, which has been used as the optimized temperature for nanocomposite synthesis. Also nanoparticle and charcoal mass ratio1:1 was found to be optimum for electrochemical performance. The synchrotron X-ray diffraction (SXRD) pattern confirms the monoclinic structure of the synthesised CuO nanoparticles. Electrochemical performances of the synthesised nanocomposite electrode and prepared supercapacitor cell were studied using cyclic voltammetry, a.c. impedance spectroscopy and charge discharge methods with 1 M NaOH as an electrolytes. The specific capacitance of the fabricated supercapacitor cell A is constant upto 2000 cycles at 100 mV cm−2.

Mechanical and Microscopic Properties of Graphite/Laterite Nanocomposites

The effectiveness and improvement mechanism of graphite nanoparticles (GN) in strength properties and microstructure characteristics of regional laterite were analysed in this study. Dry density was also taken into consideration, and the effects of graphite nanoparticle (GN) content and dry density were mainly addressed. Triaxial tests, consolidation tests, and penetration tests were used to analyse the effectiveness of different dry densities and graphite nanoparticle mass ratios on the properties of laterite; microscopic methods such as scanning electron microscopy (SEM) tests were used to analyse the improvement mechanism. The results show that the increase in dry density can make the laterite more compact. The large specific surface area and nanoeffects of the graphite nanoparticles (GN) induce the attraction between soil particles after mixing, both of which make the laterite’s shear strength; compression index and impermeability have been enhanced to varying degrees. The microscopic tests showed that, as the content of graphite nanoparticles (GN) continues to increase, when it exceeds 1.0%, the attraction between soil particles increases and coarse particles are formed, which leads to the increase of the pores of the soil. In addition, the graphite nanoparticles have a certain degree of lubricity, a high amount of graphite nanoparticles enters the laterite soil layer, increasing the distance and gap between the layers, making it easy to separate the coarse particles from the coarse particles, and the strength increase is reduced. However, it is still stronger than that of the plain laterite.

An analytic study of the development of bioconvection in a suspension of randomly swimming gyrotactic microorganisms and nanoparticles

By formulating a mathematical model for randomly swimming gyrotactic microorganisms, the development of bioconvection in a suspension containing nanoparticles is studied. The modelled system of nonlinear partial differential equations are solved by using linear stability analysis, normal mode analysis and Galerkin weighted residual method to obtain secular equation containing parameters characterising the onset of bioconvection. The effect of thermophoresis and Brownian motion in the suspension of random swimming gyrotactic microorganisms has been analysed. The numerical results showing dependence of critical thermal Rayleigh number on bioconvection Rayleigh number, nanoparticle Rayleigh number, and nanoparticle Lewis number are also presented graphically. The analysis reveals that thermophoresis, nanoparticle mass diffusivity and volumetric fraction enhance the development of bioconvection. We also found that the impact of the thermal Rayleigh number on the bioconvection Rayleigh number is more significant than the nanoparticle Rayleigh number.

Experimental investigation of specific heat of aqueous graphene oxide Al2O3 hybrid nanofluid

The specific heat of aqueous graphene+Al2O3 (1:1) hybrid nanofluid was measured using the cooling method. The influence of nanoparticle mass fraction and temperature on the specific heat capacity of the hybrid nanofluids was investigated, the specific heat of the hybrid nanofluid was compared with that of aqueous graphene oxide nanofluid and Al2O3 nanofluid. A fitted formula of the specific heat of the hybrid nanofluid was proposed based on the experimental data. It indicates that the specific heat reduction ratio increases with increase of nanoparticle fraction and the maximum reduction ratio is 7% at 0.15 wt.% at 20?C. The mass fraction of nanoparticle affects the specific heat of hybrid nanofluid more significantly at lower temperature. Temperature impacts the specific heat more distinctly than the nanoparticle fraction. The specific heat increases with temperature and the maximum specific heat reduction ratio of the hybrid nanofluid diminishes from 7% at 20?C to 2% at 70?C at the mass fraction of 0.05%.

Mixed convective nanofluid flow over a non linearly stretched Riga plate

The present article concentrates on the heat and mass transfer characteristics of a mixed convective flow of an electrically conducting nanofluid past a slender Riga plate in the presence of viscous dissipation and chemical reaction. The heat and mass transfer characteristics are analyzed by a zero nanoparticle mass flux and convective boundary conditions. The thermophoretic and Brownian aspects for nanoliquid are proposed using Buongiorno's relations. The similarity quantities are utilized to obtain dimensionless forms of flow field equations. The resulting coupled nonlinear equations associated with the constituted boundary assumptions analytically proceed via optimal homotopy analysis method (OHAM). Various parameters causing the change in distributions of velocity, temperature, and concentration are graphically explained with relevant physical references. One of the important observations of the present study is, for higher values of modified Hartmann number the velocity profile increases and temperature profile supreses and it is interesting to note that the contemporary numerical simulations offer confirmable accuracy in the existing literature, which authenticates the novelty of current investigation.

Nonlinear frequency behaviour of magneto-electromechanical mass nanosensors using vibrating MEE nanoplates with multiple nanoparticles

Nanomechanical mass sensors are promising candidates for low-cost, rapid and sensitive detection of ultrasmall particles such as biomolecules, bacteria and pollutant objects. This advanced mass sensors function based on the change in the vibration behaviour due to the nanoparticle attachment. A nonlinear continuum formulation is developed in this analysis for the large-amplitude vibrations of magneto-electromechanical mass nanosensors. The strain gradient influence and the effect of the nonlocality of stress components are incorporated into the nonlinear analysis via a higher-order scale-dependent theory of elasticity. The nanomechanical sensor makes use of vibrating magneto-electro-elastic (MEE) nanoplates with several possible locations for trapping nanoparticles. The nonlinear equations of the nanosensor are obtained and solved using Hamilton’s principle and perturbation technique, respectively. A verification study is performed by using available finite element results from the literature for graphene-based mechanical nanosensors. The nonlinear frequency shifts are obtained for different scale-dependent theories and various types of compatibility equations. The influences of the mass, position and number of nanoparticles on the frequency shift are studied considering the effects of stress nonlocality, strain gradient, mass moment of inertia, and geometrical nonlinearity.

Lecithin coating as universal stabilization and functionalization strategy for nanosized drug carriers to overcome the blood-brain barrier.

Lecithin coated cholesteryl oleate (ChOl) based nanoparticles (NPs) imitating natural lipoproteins represent a new and promising drug carrier strategy to cross the blood-brain barrier (BBB). In such systems lecithin serves as stabilizing as well as functionalizing agent and enables the adsorptive binding of apolipoprotein E3 (ApoE) as potential drug targeting ligand. The present work is focused on the effect of size reduction on the lecithin coating and ApoE binding. Furthermore, the transferability of this lecithin coating strategy to other NP cores, namely polylactic-co-glycolic acid (PLGA) and polylactic acid (PLA), is investigated in order to provide a universal strategy for a wide range of cores to overcome the BBB. The ChOl NPs' size was successfully reduced from 100nm to 70nm. Varying the core size of ChOl NPs illustrated, that the at least needed lecithin amount for sufficient stabilization could be calculated surface area dependently. However, the size reduction led to reduced dye loading per NP and increased ApoE need per NP mass. These effects turned out as huge disadvantages of smaller NPs by weakening the observed ApoE mediated effects. Nevertheless, the extended understanding of the lecithin coating could be used to transfer the concept to other core materials. PLGA and PLA NPs were investigated as alternative core materials for lecithin coating. PLGA was found to be unsuitable, whereas in the case of PLA sufficient stabilization and 100% adsorptive binding efficiency to ApoE could be achieved. The ApoE mediated effects of transcytosis at an in vitro BBB model by bypassing lysosomes were reproduced in even stronger quantities than with a ChOl core, proving lecithin coating as transferable strategy to disguise various NPs with a certain lipophilicity as lipoproteins.

Characterisation of particles within and aerosols produced by nano-containing consumer spray products.

Nanoparticles have been incorporated into a range of consumer spray products, providing the potential for inadvertent inhalation by users and bystanders. The levels and characteristics of nanoparticle inhalation exposures arising from the use of such products are important inputs to risk assessments and informing dose regimes for in vitro and in vivo studies investigating hazard potentials. To date, only a small number of studies have been undertaken to explore both the aerosols generated from such products and the metal nanoparticles within them. The objective of the current study was to add to the limited data in this field by investigating a range of nano-containing spray products available within the UK. Six products were selected and the nanoparticles characterised using a combination of techniques, including: inductively coupled plasma mass spectrometry (ICP-MS), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDX) and single particle ICP-MS (spICP-MS). The aerosol produced by these products, when sprayed within a glovebox, was characterised by scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS). A cascade impactor with thirteen stages (NanoMOUDI) was used with one product to generate information on the size specific nanoparticle elemental distribution within the aerosol. The results demonstrated the presence of solid nanoparticles (silver, gold or silica) in each of the products at low concentrations (<13 ppm). TEM and (sp)ICP-MS provided reliable information on nanoparticle size, shape, number and mass, while the light scattering methods were less effective due to the complex matrices of the products and their lack of chemical specificity. The aerosols varied significantly across products, with particle and mass concentrations spanning 5 orders of magnitude (10 - 106 cm−3 and 0.3–7600 μg m−3, respectively). The NanoMOUDI results clearly indicated non-uniform distribution of silver within different aerosol particle size ranges.

Improving the Performance of A Flat Plate Solar Collector Using Nanofluid as Working Fluid

Solar energy is the best alternative to limited fossil fuels. The foremost important means of utilizing solar energy are solar collectors. The most common types of solar collectors are flat plate solar collectors. A great deal of theoretical research has been conducted to enhance the flat plate solar collector efficiency. One effective way to increase the efficiency is by using an improved thermal properties fluid as nanofluid. In this paper, a numerical study has been made to enhance the efficiency and improve the performance of solar collector via the use of (Multi-Wall Carbon Nano Tube-water) MWCNT-H2O nanofluid instead of traditional fluid like water as working fluid under the weather of Mosul city / Iraq (36.3489° N, 43.1577° E). One dimensional dynamic model using implicit finite difference method was used. Solving energy conservation equations through the various layers of the solar system is the basis upon which the current model was based. Effects of nanoparticle volume fraction and mass flow rate on the working fluid stream temperature differences, and the thermal efficiency were studied. The mass flow rate was varied from 0.004 kg/s to 0.03 kg/s, while the volume fraction was varied from 0% to 6%. The results of "Nanofluid Based Flat Plate Solar Collector" were compared with the experimental results presented by [1]. The comparison established a good match between the current results and experimental results. The results showed an increase in the working fluid outlet and inlet temperature difference and collector thermal efficiency due to the addition of MWCNT nanoparticles. The temperature difference of "Nanofluid Based Flat Plate Solar Collector" was found 28.8⁰C at 0.014 kg/s and 6% in April, while it was 25 ⁰C at the same condition in the "Water Based Flat Plate Solar Collector case". Also, the thermal efficiency of "Nanofluid Based Flat Plate Solar Collector" was found 2.41% to 6.68% more than the "Water Based Flat Plate Solar Collector case".

Effects of heat sink structure on heat transfer performance cooled by semiconductor and nanofluids

On account of the low heat dissipation problem of common cooling systems, an experimental system with enhanced structures was set to improve the heat transfer of heat sink cooled by semiconductor and TiO2-water nano-fluids. The influences of structures (smooth surface, metal foam with PPI=30, cylindrical bulge (height: H=2 mm, staggered arrangement), cylindrical groove (depth: D′=2 mm, staggered arrangement)), nanoparticle mass fractions (ω=0.0–0.5 wt%), input power of the semiconductor (P=2 W, 4 W, 6 W), and Reynolds numbers (Re=414−1,119) on the flow and heat transfer properties of TiO2-water nanofluids were studied. The compositive thermal and hydraulic properties of the enhanced technologies were analyzed by thermal efficiency. Results indicated that the combination of semiconductor and metal foam shows the most excellent performance compared with other combinations and it can be enhanced by 48.1% at best. Nanofluids with ω=0.4 wt% display the best cooling capacity instead of the highest concentration. The cooling effect shows an increasing trend with the input power of the semiconductor.

Influence of the Concentration of Fe and Cu Nanoparticles on the Dynamics of the Size Distribution of Nanoparticles

The evolution of the size distribution of nanoparticles depending on the concentration of nanoparticles in a colloidal solution is investigated. The formation of new stable distributions shifted relative to the initial distribution is directly related to the processes of agglomeration of nanoparticles. Using successive two-fold dilutions of nanoparticles by 2–32 times, it was shown that the maximum of the nanoparticle size distribution shifts toward smaller sizes with a decrease in the concentration of nanoparticles, both for distributions by the number of nanoparticles and for distributions by mass of nanoparticles. Thus, with dilutions, the relative concentration of individual nanoparticles increases, while the number of particles in one aggregate decreases. A mathematical model has been created that predicts a change in distribution with a change in the concentration of nanoparticles in a colloid.

Effects of adding different concentrations of block copolymers in epoxy matrix nanocomposites with carbon allotropic nanoparticles

AbstractThis work investigates the role of different concentrations of a polyester‐polyurethane‐based block copolymer (BCP) on epoxy resin nanocomposites with allotropic carbon nanoparticles (graphene nanoplatelets [GNPs] or carbon nanotubes [CNTs]) on thermal, morphological, and mechanical properties, focusing on fracture toughness and its mechanisms. Amounts of BCP corresponding to 1x, 5x, and 10x the mass of nanoparticles were added. Nanocomposites with a low concentration of BCP (1x) were stronger than the neat epoxy, while high concentrations of BCP (10x) yielded a negative effect for both studied carbon nanoparticles. Fracture toughness (KIc) performed better at a 5x BCP concentration and this effect was greater for the system with CNTs. Likewise, for the GIc, the best results were seen in nanocomposites with 5x BCP, with a greater increase in the system with GNPs. In all nanocomposite systems with BCPs, the soft phase self‐arrangement mechanisms, that is, debonding/cavitation and consequent voids on the fracture surface, were verified.