High Nanoparticle Concentrations Research Articles

Investigation of electronic and optical properties of nano-Ag produced from heterocyclic compounds by green chemistry reactions

The synthesis of nanoparticles using biological molecules has become one of the current research areas due to the high toxic content, poor stability, and expensive production technologies of nanoparticles synthesized by physical and chemical technologies. With the approach called green synthesis, nanoparticles that do not contain toxic substances have been produced in a method that does not harm the environment and human health. The number of polyphenol compounds in the ethyl alcohol/water extract of propolis collected from the Muğla-Türkiye region was determined. The synthesis and characterization of silver nanoparticles were carried out using the ethyl alcohol/water extract of propolis. The descriptions of the synthesized nanoparticles were made using ultraviolet-visible absorption and attenuated total reflection-Fourier transform infrared. Scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction methods were used for morphological examinations. Which polyphenol compound in the propolis content is effective in the synthesis of nanosilver particles was investigated with a Gaussian 16 package program. The electronic properties of the compounds were obtained by density functional theory using boundary orbitals theory, molecular electrostatic surface potential, and nonlinear optical properties. Epigallocatechin gallate, Kaempferol, and Quercetin are effective in obtaining nano-Ag and can be used as organic optical material in technology.

Performance enhancement of flat plate solar collector using ZrO2-SiC/DW hybrid nanofluid: A comprehensive experimental study

It is becoming very difficult for the industrial and technological sectors to meet the ever-escalating fuel and energy demands of a growing population. Experts and scholars have emphasized studying the feasibility of using renewable energies specifically solar energy. In this regard, huge efforts have been invested lately to study the effects of adding nanofluids in solar-based devices. The hybrid nanofluid in this work is prepared by dispersion of ZrO2-SiC particles in distilled water (DW). The nanofluid is employed into a Flat plate solar collector (FPSC) to identify the performance change of the collector. The study is conducted in solar energy laboratory, Gödöllő, Hungary. Next, various instruments are employed to evaluate the nanofluids’ stability and thermo-physical properties. Consequently, the ASHRAE standard 93–2003 is followed during the evaluation of the efficiency of solar collectors filled with nanofluids at mass flow rate of 0.025, 0.033, and 0.041 kg/s. The outcomes of the experiment revealed that the solar collector system showed greater energy and exergy efficiencies in the presence of a nanofluid as compared to the exergy and energy efficiencies shown by the system-based distilled water. The results indicated that at zero value of [(Ti – Ta)/GT], volume fraction of 0.1 % and mass flow rate of 0.041 kg/s, the collector showed maximum thermal efficiency equalling 75.21 %. Hence, nanofluid addition leads to a 31.64 % enhancement in thermal efficiency. It was found that the solar collector exergetic performance was evaluated which indicated a decline in exergy efficiency at a higher mass flow rate and also indicated a rise in the exergy efficiency at a higher concentration of nanoparticles in the nanofluid. At the concentration of 0.1 %, the system yielded maximum increase of about 28.31 % in the exergy efficiency.

Investigation of Dynamic-Mechanical-Thermal Analysis of Innovative Hybrid Carbon/Glass Fibers Reinforced by GNPs and Al2O3 for Marine Structures

AbstractMarine structural applications face numerous challenges related to environmental load, corrosion, and fatigue under varying time and temperature conditions. One of the major challenges faced by marine structural applications is dynamic mechanical thermal analysis (DMTA). In this study, innovative hybrid carbon/glass fibers (CGF) reinforced with different contents (1.5 wt. % and 3 wt. %) of dual nano-powders, including graphene nanoplatelets (GNPs) and aluminium oxide (Al2O3), were developed as reinforcements inside the epoxy matrix. The nanocomposites were fabricated using a hand lay-up technique, resulting in a nanocomposite sheet with dimensions of 300 mm length, 200 mm width, and 2.3 mm thickness. DMTA test specimens were prepared with dimensions of 50 mm length, 10 mm width, and 2.3 mm thickness. To ensure accuracy, three replicates were conducted for each condition, and the average values were calculated for analysis. Before DMTA, the prepared nanocomposites were analyzed using optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) to compare the influence of incorporating dual nano-powders. DMTA was carried out at different temperature values (ranging from 10 °C to 105 °C) and times (ranging from 5 to 575 min) at 1 Hz frequency with a heating rate of 4 °C/min and a nitrogen flow rate of 20 ml/min. The main objective of this study was to investigate the influence of incorporating dual nano-powders such as GNPs and Al2O3on various dynamic mechanical properties including storage modulus, loss modulus, damping factor (DF), and glass transition temperature (Tg) of the hybrid carbon/glass fiber-reinforced epoxy composites. The fabricated hybrid CGF composite with 1.5% wt. GA nanoparticles exhibited higher values for the DF of 0.68 and the Tg of 73.4 °C. However, increasing the nanoparticle content to 3% wt. GA led to a deterioration in the DF (0.54) and a reduction in Tg (27.8 °C) due to decreased bonding between the carbon fibers (CF) and glass fibers (GF) caused by the higher nanoparticle concentration. The complex modulus (E*) values demonstrated expected trends with temperature and time for the CGF-1.5% wt. GA composite, indicating acceptable behaviour. In contrast, the CGF-3% wt. GA composite exhibited lower E* values, indicating a decrease in stiffness and mechanical properties compared to the CGF-1.5% wt. GA composite. Microstructural observations after DMTA revealed a uniform scattering of nanoparticles in the CGF-1.5% wt. GA sample, while the CGF-3% wt. GA sample demonstrated improved scattering of Al2O3nanoparticles on the surface. The microstructural analysis further indicated a brittle nature with high resistance to crack initiation and propagation in the CGF-1.5% wt. GA composite.

A novel study on the influence of graphene-based nanofluid concentrations on the response characteristics and surface-integrity of Hastelloy C-276 during minimum quantity lubrication

In present investigation, the impact of nanoparticle concentration on the machining accomplishment of Hastelloy C-276 has been examined in turning operation. The outputs like temperature, surface roughness, chip reduction coefficient (CRC), tool wear, and friction coefficient along with angle of shear have been estimated. The graphene nanoparticles (GnP) have been blended into soybean oil in distinct weight/volume ratio of 0.5, 1 and 1.5%. The experimental observations revealed that higher concentration of nanoparticles has enhanced the heat carrying capacity of amalgamation by 12.28%, surface roughness (27.88%), Temperature (16.8%), tool wear (22.5%), CRC (17.5%), coefficient of friction (46.36%) and shear angle (15%). Scanning electron microscopy identified nose wear, abrasion, adhesion and loss of tool coating. Further, lower tool wear has been noticed at 1.5% concentration, while the complete failure of insert has been reported during 116 m/min, 0.246 mm/rev having 0.5% concentration. ANOVA results exhibited that surface roughness is highly influenced by speed rate (41.66%) trailed by feed rate (28.16%) and then after concentration (13.68%). Temperature is dominated by cutting speed (69.31%), concentration (14.53%) and feed rate (13.25%). Likewise, tool wear was majorly altered by cutting speed (67.2%) accompanied by feed rate (23.90%) and thirdly concentration of GnP (5.03%).

Unveiling the Hidden Value of Cotton Gin Waste: Natural Synthesis and Hosting of Silver Nanoparticles.

Cotton gin waste presents a significant challenge in the cotton ginning industry due to its abundant generation and limited disposal options. In this study, we explored the potential of cotton gin waste as a naturally occurring source material that can synthesize and host silver nanoparticles. The noncellulosic constituents of cotton gin waste served as effective reducing agents, facilitating the conversion of silver ions into silver atoms, while its porous structure acted as a microreactor, enabling controlled particle growth. A simple heat treatment of cotton gin waste powder in an aqueous silver precursor solution actualized the in situ synthesis of silver nanoparticles, without the need for additional chemical agents. Remarkably, a high concentration of silver nanoparticles (14.7%) with an average diameter of approximately 27 nm was produced throughout the entire volume of cotton gin waste. Electron microscopic images of cross-sectioned cotton gin waste confirm the internal formation of nanoparticles. Rietveld refinement analysis of X-ray diffraction patterns showed that the majority of the nanoparticles possess a cubic silver crystal structure. By leveraging the well-known biocidal properties of silver nanoparticles, the resulting silver nanoparticle-filled cotton gin waste holds promise for novel antimicrobial and antifungal material applications.

Exposure to silver and titanium dioxide nanoparticles at supra-environmental concentrations decreased sperm motility and affected spermatozoa subpopulations in gilthead seabream, Sparus aurata.

Marine pollution by nanoparticles (NPs) can be reprotoxic for fish and disturb successful reproduction of wild populations. In gilthead seabream (Sparus aurata), a mild effect on sperm motility was observed after exposure to high concentrations of silver NPs. Considering the great heterogeneity traits within a sperm sample, it is possible that NPs affect spermatozoa accordingly, modulating subpopulation profile. Thus, this work aimed to analyse NP effects in sperm motility in general and considering spermatozoa population structure, using a subpopulation approach. Seabream sperm samples from mature males were exposed for 1 h to increasing concentrations of titanium dioxide (1, 10, 100, 1000 and 10,000 μg L-1) and silver (0.25, 25 and 250 μg L-1) NPs, including Ag NP and Ag+, dissolved in a non-activating medium (0.9 % NaCl). Concentrations chosen include realistic (10-100 and 0.25 μg L-1, respectively, for TiO2 and Ag) and supra-environmental values. The mean particle diameter was determined as 19.34 ± 6.72 and 21.50 ± 8.27 nm in the stock suspension, respectively, for titanium dioxide and silver. After the ex vivo exposure, sperm motility parameters were determined using computer-assisted sperm analysis, and sperm subpopulations were later identified using a two-step cluster analysis. Results revealed a significant reduction in total motility after exposure to the 2 highest concentrations of titanium dioxide NPs, while curvilinear and straight-line velocities were not altered. Exposure to silver NPs (Ag NP and Ag+) lowered significantly total and progressive motilities at all concentrations, while curvilinear and straight-line velocities were significantly lower only at the highest concentration. Sperm subpopulations were also affected by the exposure to both titanium dioxide and silver NPs. In both cases, the highest levels of NPs triggered a decrease in the percentage of fast sperm subpopulations (38.2% in TiO2 1000 μg L-1, 34.8.% in Ag NP 250 μg L-1, and 45.0% in Ag+ 250 μg L-1 vs 53.4% in the control), while an increase on slow sperm subpopulations. A reprotoxic effect was proven for both NPs, but only at supra-environmental concentrations.

Influence of Nanofluid Flooding on Oil Displacement in Porous Media

Hydrocarbon displacement at the pore scale is mainly controlled by the wetness properties of the porous media. Consequently, several techniques including nanofluid flooding were implemented to manipulate the wetting behavior of the pore space in oil reservoirs. This study thus focuses on monitoring the displacement of oil from artificial glass porous media, as a representative for sandstone reservoirs, before and after nanofluid flooding. Experiments were conducted at various temperatures (25 – 50° C), nanoparticles concentrations (0.001 – 0.05 wt% SiO2 NPs), salinity (0.1 – 2 wt% NaCl), and flooding time. Images were taken via a high-resolution microscopic camera and analyzed to investigate the displacement of the oil at different conditions. In addition, contact angle measurements on quartz surfaces were also conducted at similar conditions to understand the flow behavior in the porous media. Further, zeta potential and particle size distribution measurements were conducted to examine the stability of the injected nanofluids. Results revealed that the injection of nanofluids into oil-wet pore space can significantly enhance the recovery rate of hydrocarbon by altering the wettability of the porous media. However, salinity, particularly at high nanoparticles concentration (≥ 0.005) can dramatically reduce the efficiency of nanofluid. Further, increased aging time can improve the ability of nanofluid to alter the wettability of the surface, and thus more oil can be displaced. Thus, nanofluid can efficiently enhance oil recovery if correctly formulated.

Preparation of glass nanofibers to reinforce polymethyl methacrylate toward persistent photoluminescent bricks

Polymethyl methacrylate (PMMA) was subjected to a reinforcement process by using electrospun glass nanofibers (GNF) to produce durable and transparent bricks. Photoluminescent and photochromic GNF@PMMA bricks were prepared by physical incorporation of lanthanide-activated aluminum strontium oxide (LASO) nanoparticles (NPs). Both CIE (Commission internationale de l'éclairage) Lab parameters and photoluminescence analysis were investigated to verify transparency of GNF@PMMA with the capability to change to green under UV lighting. The photochromic property was instantaneously reversible for GNF@PMMA hybrid bricks with low concentrations of LASO NPs, demonstrating fluorescence emission. GNF@PMMA with high concentrations of LASO NPs exhibited persistent photoluminescence afterglow emission with slower reversibility. An emission peak was detected at 517 nm upon excitation at 365 nm. Both hydrophobicity and ultraviolet shielding improved as LASO NPs content increased. Both of X-ray diffraction (XRD) and transmission electron microscopic analysis (TEM) were applied to examine the morphological features of LASO NPs and GNF to show diameters of 10–19 nm and 100–250 nm, respectively. Electrospinning technology was applied to prepare GNF, which were used to reinforce PMMA bricks as a roughening agent to improve their mechanical properties. Different analytical methods were utilized to analyze GNF and GNF@PMMA bricks for their morphological features. The scratching resistance of LASO NPs-containing GNF@PMMA bricks improved as compared to LASO NPs-free GNF@PMMA.

In-situ aligning magnetic nanoparticles in thermoplastic adhesives for contactless rapid joining of composite structures

Magnetic nanoparticles of high magnetic susceptibility, such as magnetite (Fe3O4), have been used for wireless heating of adhesives and composites through the magnetic hysteresis loss mechanism, but the high concentrations of nanoparticles needed to meet heating performance targets can degrade mechanical properties. Herein, we present an in-situ aligning method to enhance the heating efficiency of magnetite nanoparticles in a nylon thermoplastic matrix without adversely affecting its mechanical strength. A composite adhesive was made by dispersing Fe3O4 nanoparticles in a nylon matrix followed by hot melting. Experimental results show that by subjecting the adhesive to an alternating magnetic field during the hot-melt process, its heating rate can be improved by 200% compared to that without applying the magnetic field. The improvement in the heating performance has been identified to stem from the alignment of the ease axis of the magnetic nanoparticles. This in-situ aligning technique enables better induction heating performance with the same amount of Fe3O4 nanoparticles, avoiding the agglomeration problem of high nanoparticle concentrations. Moreover, this technique makes it possible to develop high-performance self-heating thermoplastic adhesive for reversible bonding and self-healing solution with a wide range of applications, such as bonding and debonding of composites, temporary attachment of systems, and recyclable bonded structures.

Chitosan-Based Composite Membranes with Different Biocompatible Metal Oxide Nanoparticles: Physicochemical Properties and Drug-Release Study.

Chitosan (CS) composite membranes were prepared using different biocompatible metal oxide nanoparticles (NPs): titanium dioxide (TiO2); iron oxide (Fe3O4); and aluminum oxide (Al2O3). For each nanoparticle, the CS-based composite membranes were prepared with two NPs contents in the CS solution, high (H) and low (L) NPs concentrations. To establish both concentrations, the NPs saturation point in the CS polymeric matrix was determined. The influence of NP concentrations on the physicochemical properties of the CS films was assessed. The prepared CS membranes were characterized with different techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential. It was found that the addition of NPs in the CS matrix improved both swelling and mechanical properties. Nanocomposite CS membranes could be prepared using Al2O3 NPs. Swelling experiments revealed different pH-sensitive mechanisms, which might be beneficial in biomedical applications since solute permeation through CS-based composite membranes could be controlled by adjusting environmental conditions. When aspirin transport (ASA) through the prepared membranes was carried out in different release media, SGF (simulating gastric fluid) and SIF (simulating intestinal fluid without enzymes), it was observed that the Fickian diffusion coefficient (D) was conditioned by the pH of the release solution. In SGIT (simulating gastrointestinal transit) medium, a transition time (ttrans) was detected due to the shrinkage of the CS polymeric chains, and the drug release depended not only on the Fickian's diffusion but also on the shrinkage of the biopolymer, obeying Peppas and Sahlin equation.

Mixed convection and thermal radiation effects on non-Newtonian nanofluid flow with peristalsis and Ohmic heating

Introduction: This investigation explores the heat and mass transfer properties of a non-Newtonian nanofluid containing graphene nano-powder and ethylene glycol during peristalsis. The rheological characteristics of the nanofluid are determined using the Carreau-Yasuda model, and various factors such as viscous dissipation, Lorentz force, Ohmic heating, and Hall effects are taken into account. Mixed convection and thermal radiation effects are also considered in the analysis, and the problem is mathematically described using the long wavelength and low Reynolds number approximations.Methods: The resulting nonlinear system is solved using numerical methods to obtain the solutions. The dominant effects of mixed convection and thermal radiation are given particular attention, while the influences of other parameters are discussed in relation to these dominant effects.Results and Discussion: The results demonstrate that increasing the Brinkman number, heat source, and thermal slip parameter leads to higher nanofluid temperatures. However, the heat transfer rate decreases with a higher Hall parameter. The velocity near the center of the channel increases for higher values of the concentration Grashof and Hall parameters. Furthermore, an increase in the Hall and Brownian motion parameters results in a higher concentration of nanoparticles. These findings have practical implications in various fields, including materials science, chemical engineering, and biomedical engineering.

Depth Dose Enhancement in Orthovoltage Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study.

This study was to examine the depth dose enhancement in orthovoltage nanoparticle-enhanced radiotherapy for skin treatment by investigating the impact of various photon beam energies, nanoparticle materials, and nanoparticle concentrations. A water phantom was utilized, and different nanoparticle materials (gold, platinum, iodine, silver, iron oxide) were added to determine the depth doses through Monte Carlo simulation. The clinical 105 kVp and 220 kVp photon beams were used to compute the depth doses of the phantom at different nanoparticle concentrations (ranging from 3 mg/mL to 40 mg/mL). The dose enhancement ratio (DER), which represents the ratio of the dose with nanoparticles to the dose without nanoparticles at the same depth in the phantom, was calculated to determine the dose enhancement. The study found that gold nanoparticles outperformed the other nanoparticle materials, with a maximum DER value of 3.77 at a concentration of 40 mg/mL. Iron oxide nanoparticles exhibited the lowest DER value, equal to 1, when compared to other nanoparticles. Additionally, the DER value increased with higher nanoparticle concentrations and lower photon beam energy. It is concluded in this study that gold nanoparticles are the most effective in enhancing the depth dose in orthovoltage nanoparticle-enhanced skin therapy. Furthermore, the results suggest that increasing nanoparticle concentration and decreasing photon beam energy lead to increased dose enhancement.

Heat transfer analysis of a hybrid nanofluid flow on a rotating disk considering thermal radiation effects

This study investigates heat transfer in a hybrid nanofluid that flows due to a rotating disk. The nanofluid contains copper and dioxide nanoparticles in water and is affected by a constant magnetic field. The study accounts for heat generation/absorption and thermal radiation and solves the governing equations using similarity transformations and the Shooting Method. The research reveals that the higher nanoparticle concentration in a fluid result in increased radial and azimuthal velocities due to improved convective heat transfer. This leads to higher fluid velocity and lower local skin friction coefficient. Heat generation/absorption and thermal radiation have a strong influence on the heat transfer process. Higher nanoparticle concentration, variable thermal conductivity parameter, and radiation parameter cause an increase in the temperature of the hybrid nanofluid. The local Nusselt number increases with an increase in the variable thermal conductivity parameter but decreases with nanoparticle concentration while increases with the thermal radiation parameter. Results from a special case analysis, which excluded certain parameters, closely agree with previous studies, confirming the validity of the solution. These findings can be useful in understanding heat transfer in similar scenarios, especially in energy engineering and thermal management.

Designing effective plating baths for use in the pulse-reverse plating of copper nanocomposite coatings

ABSTRACT The development of the process to produce Metal Matrix Nanocomposite (MMNC) coatings can provide opportunity for the enhancement of mechanical and electrical properties. This research uses speciation-simulating software to screen formulations for producing nanocomposites by pulse-reverse plating (PRP). PRP is used as a controlled delivery mechanism to attract a high concentration of nanoparticles to the coating during the anodic pulse which are subsequently captured in the cathodic pulse. A disadvantage is that the anodic pulse generates passivating hydroxide layers leading to poor adhesion. Speciation plots assess the stabilising effect of chosen complexants (gluconate and glycine) within electrolytes with the aim of diminishing hydroxide formation. To confirm bath formulation effectiveness before nanoparticle incorporation, UV-Vis spectroscopy and electrodeposition were used. Gluconate and glycine both theoretically produce highly stable complexes and also produce uniform copper deposits supporting the stabilisation effect observed in theoretical studies. This work therefore supports the use of these complexants for future stages of this research.

High-Dose Exposure to Polymer-Coated Iron Oxide Nanoparticles Elicits Autophagy-Dependent Ferroptosis in Susceptible Cancer Cells.

Ferroptosis, a form of iron-dependent, lipid peroxidation-driven cell death, has been extensively investigated in recent years, and several studies have suggested that the ferroptosis-inducing properties of iron-containing nanomaterials could be harnessed for cancer treatment. Here we evaluated the potential cytotoxicity of iron oxide nanoparticles, with and without cobalt functionalization (Fe2O3 and Fe2O3@Co-PEG), using an established, ferroptosis-sensitive fibrosarcoma cell line (HT1080) and a normal fibroblast cell line (BJ). In addition, we evaluated poly (ethylene glycol) (PEG)-poly(lactic-co-glycolic acid) (PLGA)-coated iron oxide nanoparticles (Fe3O4-PEG-PLGA). Our results showed that all the nanoparticles tested were essentially non-cytotoxic at concentrations up to 100 μg/mL. However, when the cells were exposed to higher concentrations (200-400 μg/mL), cell death with features of ferroptosis was observed, and this was more pronounced for the Co-functionalized nanoparticles. Furthermore, evidence was provided that the cell death triggered by the nanoparticles was autophagy-dependent. Taken together, the exposure to high concentrations of polymer-coated iron oxide nanoparticles triggers ferroptosis in susceptible human cancer cells.

Method for nanoparticles uptake evaluation based on double labeled fluorescent cells scanned in enhanced darkfield microscopy.

We present a method that integrates the standard imaging tools for locating and detecting unlabeled nanoparticles (NPs) with computational tools for partitioning cell volumes and NPs counting within specified regions to evaluate their internal traffic. The method uses enhanced dark field CytoViva optical system and combines 3D reconstructions of double fluorescently labeled cells with hyperspectral images. The method allows the partitioning of each cell image into four regions: nucleus, cytoplasm, and two neighboring shells, as well as investigations across thin layers adjacent to the plasma membrane. MATLAB scripts were developed to process the images and to localize NPs in each region. Specific parameters were computed to assess the uptake efficiency: regional densities of NPs, flow densities, relative accumulation indices, and uptake ratios. The results of the method are in line with biochemical analyses. It was shown that a sort of saturation limit for intracellular NPs density is reached at high extracellular NPs concentrations. Higher NPs densities were found in the proximity of the plasma membranes. A decrease of the cell viability with increasing extracellular NPs concentration was observed and explained the negative correlation of the cell eccentricity with NPs number.

A critical assessment of nanoparticles enhanced phase change materials (NePCMs) for latent heat energy storage applications

Phase change material (PCM) laden with nanoparticles has been testified as a notable contender to increase the effectiveness of latent heat thermal energy storage (TES) units during charging and discharging modes. In this study, a numerical model is developed and implemented based on the coupling between an advanced two-phase model for the nanoparticles-enhanced PCM (NePCM) and the enthalpy-porosity formulation for the transient behavior of the phase change. Therefore, a porosity source term is added to the nanoparticles transport equation to account for the particles' frozen state in regions occupied by solid PCM. This two-phase model includes three main nanoparticles’ slip mechanisms: Brownian diffusion, thermophoresis diffusion, and sedimentation. A two-dimensional model of a triplex tube heat exchanger is considered and different charging and discharging configurations are analyzed. Compared to pure PCM, results show a substantial heat transfer enhancement during the charging and discharging cycle in which a homogeneous distribution of nanoparticles is considered as the initial condition. For this case, the two-phase model predictions are superior to the ones obtained with the classical single-phase model. In the case of multi-cycle charging and discharging, a significant deterioration of the heat transfer rate is observed using the two-phase model while such assessment is senseless using the single-phase mixture model due to the physical assumptions upon which this model is formulated. The two-phase model results reveal that, for a NePCM with high nanoparticles concentration (> 1%), the melting performance during the second charging cycle is reduced by 50% compared to the first one. This performance degradation is attributed to a noteworthy non-homogeneous distribution of the nanoparticles at the beginning of the second charging cycle. The dominant nanoparticles migration mechanism, in this scenario, is the one resulting from sedimentation effects.

43 Particle and VOC Emissions During the Thermal Processing of Plastics to make Filaments for 3D-Printing

Abstract Introduction 3D-printing is continuing to grow as an industry, which creates a demand for printing material. Studies on 3D-printing have shown that printers emit nanoparticles and VOC, depending on printing method, and some adverse health effects have been reported. Emissions during production of 3D-printer filament is less studied, and interesting as it can be likened to a larger material extrusion printer. Materials and methods Measurements were made at a factory producing 3D-printer filaments, using an array of instruments to characterise the emissions and exposure for the staff. Particle emissions were assessed using condensation particle counters (20nm-1um), DataRAM (0.1-10 um) and a particle sensor (0.35-40 um). VOC emissions and exposure were assessed using Tenax tubes and VOC sensors. Measurements were performed for 1-2 days, apart from sensors, which were placed at the facility for a full working week, including after a longer break . Results High concentrations of nanoparticles were found in the production rooms (25 000-100 000 pt/ml) and close to the extruder nozzle (100 000-500 000 pt/ml). Levels of nanoparticles were also high in office rooms near production(25 000-50 000 pt/ml). VOC sensors showed the same trend in all rooms, including offices and staff kitchen, indicating spread of emissions from the source and inadequate ventilation. The particle sensor also showed variation over the week in correlation with work performed. Conclusion Production of 3D-printer filaments emit nanoparticles and VOC. Inadequate ventilation can lead to high concentrations of nanoparticles. Sensors were a useful tool to show emission trends.

Reducing Soot Nanoparticles and NOX Emissions in CRDI Diesel Engine by Incorporating TiO2 Nano-Additives into Biodiesel Blends and Using High Rate of EGR

The developments in the field of nano-additives have increased in the recent years due to the desire to reduce the level of exhaust emissions in diesel engines. The soot characteristics of particulate matter (PM) and nitrogen oxides (NOX) were experimentally investigated using two concentrations of titanium dioxide (TiO2) as nano-additives (25 ppm and 40 ppm) blended with C20D (composed of 20% castor oil methyl ester and 80% diesel fuel) and 30% exhaust gas recirculation (EGR). The combustion of C20D + TiO2 increases brake thermal efficiency (BTE) by 2.8% in comparison with neat C20D, while a significant reduction was obtained in BSFC 6.5% and NOX emissions were maintained at a level parallel with diesel. The results indicated that the technique involving a high EGR rate and the addition of 25 ppm and 40 ppm of TiO2 nanoparticles to the C20D exhibits better reductions in NOX emissions by 17.34% and 21.83%, respectively, compared to the technique comprising the use of C20D + TiO2 and C20D. The reduction in the total concentration of PM via the addition of TiO2 nanoparticles to the C20D was 26.74% greater than neat C20D and diesel. In contrast, the incorporation of a high rate of EGR with C20D +TiO2 increased the PM concentrations by 16.85% compared to the technique without EGR. Furthermore, the high concentrations of TiO2 nanoparticles (40 ppm) in the C20D produced 19 nm smaller soot nanoparticles compared to the 23 nm larger soot nanoparticles produced from the low concentrations of TiO2 nanoparticles (25 ppm) added into the C20D. The current investigation reveals that the reduction in NOX emissions and the production of soot nanoparticles notably improved due to the synergic effect of EGR, the TiO2 nanoparticles, and biodiesel.

Activation of silver nanoparticles by hydrophilic encapsulation for antimicrobial powder coated surfaces

Silver nanoparticles (AgNP) are known as an antimicrobial agent, but they cannot be efficiently converted to active silver ions due to the lack of hydrophilic reaction environment when incorporated into a dry powder coating film. To make these agents effective in the powder coated surface, a novel encapsulation approach was proposed. Silver nanoparticles were first synthesized on the surface of synthetic zeolite A by in-situ chemical reduction method, which was followed by the addition of copper ions through ion exchange. The functionalized zeolite was then encapsulated with different water-soluble hydrophilic polymers to facilitate the generation of silver ions from nanoparticles. The encapsulated additives were incorporated into the resin system for making the antimicrobial powder coating film. The properties of the additives and films were carefully analyzed, and results show that appropriate loading of silver guarantees a high concentration and uniform distribution of silver nanoparticles on the zeolite surface. The strength of the encapsulation with the additive is found to depend on the cations present in the additives. Anionic polymer encapsulation is the most effective solution for releasing silver ions from antimicrobial coated surface. Excessive hydrophilicity is not beneficial to antimicrobial ability and brings cracks on the surface. Additives with non-polymeric hydrophilic encapsulation made from the precipitation of calcium nitrate and sodium phosphate also shows acceptable antimicrobial efficiency. The proposed hydrophilic encapsulation method can well facilitate the activation of silver nanoparticles and ensure an effective antimicrobial property of the powder coating film.