Synthesis of MWCNTs by chemical vapor deposition of methane using FeMo/MgO catalyst: role of hydrogen and kinetic study.

This study aims to investigate the role of hydrogen on CNTs synthesis and kinetics of CNTs formation. The CNTs were synthesized by catalytic chemical vapor deposition of methane over FeMo/MgO catalyst. The experimental results revealed that hydrogen plays an important role in the structural changes of catalyst during the pre-reduction process. The catalyst structure fully transformed into metallic FeMo phases, resulting in an increased yield of 5 folds higher than those of the non-reduced catalyst. However, the slightly larger diameter and lower crystallinity ratio of CNTs was obtained. The hydrogen co-feeding during the synthesis can slightly increase the CNTs yield. After achieving the optimum amount of hydrogen addition, further increase in hydrogen would inhibit the methane decomposition, resulting in lower product yield. The hydrogenation of carbon to methane was proceeded in hydrogen co-feed process. However, the hydrogenation was non-selective to allotropes of carbon. Therefore, the addition of hydrogen would not benefit neither maintaining the catalyst stability nor improving the crystallinity of the CNT products. The kinetic model of CNTs formation, derived from the two types of active site of dissociative adsorption of methane, corresponded well to the experimental results. The rate of CNTs formation greatly increases with the partial pressure of methane but decreases when saturation is exceeded. The activation energy was found to be 13.22 kJ mol-1, showing the rate controlling step to be in the process of mass transfer.

Fundamentals to Apply Magnetic Nanoparticles for Hyperthermia Therapy.

The activation of magnetic nanoparticles in hyperthermia treatment by an external alternating magnetic field is a promising technique for targeted cancer therapy. The external alternating magnetic field generates heat in the tumor area, which is utilized to kill cancerous cells. Depending on the tumor type and site to be targeted, various types of magnetic nanoparticles, with variable coating materials of different shape and surface charge, have been developed. The tunable physical and chemical properties of magnetic nanoparticles enhance their heating efficiency. Moreover, heating efficiency is directly related with the product values of the applied magnetic field and frequency. Protein corona formation is another important parameter affecting the heating efficiency of MNPs in magnetic hyperthermia. This review provides the basics of magnetic hyperthermia, mechanisms of heat losses, thermal doses for hyperthermia therapy, and strategies to improve heating efficiency. The purpose of this review is to build a bridge between the synthesis/coating of magnetic nanoparticles and their practical application in magnetic hyperthermia.

Recent Developments in Nanocellulose-Reinforced Rubber Matrix Composites: A Review.

Research and development of nanocellulose and nanocellulose-reinforced composite materials have garnered substantial interest in recent years. This is greatly attributed to its unique functionalities and properties, such as being renewable, sustainable, possessing high mechanical strengths, having low weight and cost. This review aims to highlight recent developments in incorporating nanocellulose into rubber matrices as a reinforcing filler material. It encompasses an introduction to natural and synthetic rubbers as a commodity at large and conventional fillers used today in rubber processing, such as carbon black and silica. Subsequently, different types of nanocellulose would be addressed, including its common sources, dimensions, and mechanical properties, followed by recent isolation techniques of nanocellulose from its resource and application in rubber reinforcement. The review also gathers recent studies and qualitative findings on the incorporation of a myriad of nanocellulose variants into various types of rubber matrices with the main goal of enhancing its mechanical integrity and potentially phasing out conventional rubber fillers. The mechanism of reinforcement and mechanical behaviors of these nanocomposites are highlighted. This article concludes with potential industrial applications of nanocellulose-reinforced rubber composites and the way forward with this technology.

Assessment of agricultural waste-derived activated carbon in multiple applications.

To minimize waste production and reduce reliance on fossil fuels, agricultural waste such as rice straw has been actively used in biochemical production. In Taiwan, cellulosic waste has been used in anaerobic digestion for bioethanol production. This process produces a large amount of biomass-associated sludge that may become a serious environmental issue. Therefore, in this study, the anaerobic digestion sludge was recycled for the production of activated carbon via pyrolysis and activation by KOH. Surface characterization showed increased surface area and development of microporous structure upon activation. The FTIR image showed that high temperature activation eliminated most functional groups in the activated carbon, except for CO and C-O groups. The results showed that the activated carbon could be used for pollutant adsorbents such as molecular dyes (methylene blue: 217 mg g-1) and metal ions (copper: 169 mg g-1) from aqueous solution. In addition, the as-synthesized activated carbon can be used for CO2 capture and capacitor. Instead of focusing on one single application, we proposed that centralized production of activated carbon could be used in various applications, while further modification could be adopted depending on the need of its specific application.

Production of bio-hydrogenated diesel by catalytic hydrotreating of palm oil over NiMoS2/γ-Al2O3 catalyst.

Catalytic hydrotreating of palm oil (refined palm olein type) to produce bio-hydrogenated diesel (BHD) was carried out in a continuous-flow fixed-bed reactor over NiMoS2/γ-Al2O3 catalyst. Effects of dominant hydrotreating parameters: temperature: 270-420°C; H2 pressure: 15-80 bar; LHSV: 0.25-5.0 h(-1); and H2/oil ratio: 250-2000 N(cm(3)/cm(3)) on the conversion, product yield, and a contribution of hydrodeoxygenation (HDO) and decarbonylation/decarboxylation (DCO/DCO2) were investigated to find the optimal hydrotreating conditions. All calculations including product yield and the contribution of HDO and DCO/DCO2 were extremely estimated based on mole balance corresponding to the fatty acid composition in feed to fully understand deoxygenation behaviors at different conditions. These analyses demonstrated that HDO, DCO, and DCO2 reactions competitively occurred at each condition, and had different optimal and limiting conditions. The differences in the hydrotreating reactions, liquid product compositions, and gas product composition were also discussed.

Preparation of magnetite hollow structure for drug delivery application.

Monodispersed Fe3O4 nanospheres with hollow interior and porous shell structures were synthesized without any template by refluxing iron precursor solution in a Teflon-line autoclave at 200 degrees C. Those nanoparticles exhibited a ferromagnetic behavior with a high saturation magnetization of 76 emu/g. The hollow structure was formed based on the assembly of many small particles to form large-sized spheres, followed by chemical conversion coupled with Oswald ripening process. Due to the differences in size, density and/or crystallinity between the outer and interior particles in the spheres, the inner particles migrated to the outer shell, resulting in the formation of the empty space inside nanostructures. The potential application of Fe3O4 hollow nanoparticles as a drug carrier was evaluated with Rhodamine6G as a model drug, showing a pH-dependent release profile due to the difference of proton concentration.

Application of TiO2-coated alumina beads to dielectric barrier discharge-photocatalyst hybrid process for NO and SO2 removals.

NO and SO2 removal by dielectric barrier discharge-photocatalyst (DBD-P) hybrid process was examined for various conditions of process variables. Alumina beads were coated with TiO2 thin film by a rotating cylindrical PCVD reactor and they were packed inside the cylindrical reactor. The NO and SO2 removal efficiencies can be enhanced by using a combination of dielectric barrier discharge and photodegradation by TiO2. The stronger the applied voltage is, the higher the pulse frequency is, or the longer the gas residence time is, the higher the NO and SO2 removal efficiencies become. By applying additional photocatalytic effect, NO removal efficiency increased more significantly than SO2 removal efficiency, because SO2 removal efficiency was already high by dielectric barrier discharge only. In this study, we found that the alumina beads coated with TiO2 thin film by a rotating cylindrical PCVD reactor could be used effectively to remove NO and SO2 by DBD-P hybrid process.

Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties.

Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO2 nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO2 samples, and one commercial Degussa TiO2 sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl2) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO2 isoelectric point was found to be dependent on particle size. As anatase TiO2 primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO2 nanoparticle IEP was found to be insensitive to particle crystal structure.

Enhanced stability and in vitro bioactivity of surfactant-loaded liposomes containing Asiatic Pennywort extract.

The objective of this work has been the microencapsulation of Asiatic Pennywort (AP) extract with lecithin from soybean. The effect of various quantities of non-ionic surfactant (Montanov82) on liposomes upon physicochemical characteristics as well as their in vitro bio-activities was investigated. An addition of surfactant resulted in a decrease in particle size and an increase in percentage AP entrapment efficiency of liposomes. The surfactant-loaded liposomes demonstrated higher stability than surfactant-free liposomes where higher percentage AP remaining of liposomes can be achieved depending on surfactant concentration. No significant difference was found on AP release profiles among varied surfactant concentrations, although a presence of surfactant resulted in prolonged AP release rate. Liposomal AP with 20% w/w surfactant or higher demonstrated low cytotoxicity, a stronger anti-oxidation effect and collagen production on dermal fibroblast cells when compared with free AP and surfactant-free liposomes, possibly due to better cell internalization and less AP degradation in cells.

Particle trajectories and temperature histories of TiO2 nanoparticles synthesized in diffusion flame reactor.

The computational analysis was developed to illustrate the gas temperature and velocity profiles in the oxy-methane diffusion flame reactor during the formation of TiO2 nanoparticles and the collection of the TiO2 nanoparticles by filter. The computational simulation shows that the increase in gas temperature and velocity is significantly affected by the increase in CH4 flow rate. The particle trajectory was calculated by using the model, which concerns the effects of thermophoretic force and gas velocity on the particle movement. The particles starting from different initial positions in radial direction will move in different trajectories. The particles following different trajectories have different temperature histories and also residence times in the gas phase. As the particles start at the initial position of the reactor which is further away from the central axis, they spend longer time in the gas phase and deposit on the higher position of filter. For particles starting at the initial position of the reactor which is further than 0.5 cm from the central axis, they move to deposit on the pyrex tube instead of filter. As the CH4 flow rate increases, the particles move further from the central axis, but it takes a shorter time for the particles to deposit on the filter. The particles synthesized at a higher CH4 flow rate show significantly higher temperature history than those particles synthesized at a lower CH4 flow rate. The temperature histories of particles in diffusion flame reactor can be quite important information to control the properties of TiO2 nanoparticles.

A simple method for bakers' yeast cell disruption using a three-phase fluidized bed equipped with an agitator.

A three-phase fluidized bed equipped with a turbine agitator was utilized as a simple device for disrupting bakers' yeast cells (Saccharomyces cerevisiae). The degree of yeast cell disruption was evaluated based on the number of broken cells and its validity was confirmed by the total amount of crude soluble proteins released and by microscopic observation. It was found that the equipment could yield 90% of yeast cell disruption. With the presence of glass beads, the degree of cell disruption became higher as agitating speed is increased. The disruption enhancement would be attributed to the grinding effect resulting from the interaction between yeast cells and glass beads. One-thousand micrometers of glass beads yielded a higher degree of disruption than larger ones. An increase in liquid flow rate hindered the degree of disruption because of shorter contact time although the shear rates in the yeast suspension would become more rigorous.

Characteristics of carbon nanoparticles synthesized by a submerged arc in alcohols, alkanes, and aromatics.

Fullerene-related carbon nanostructures can be synthesized by an arc-in-liquid system as a cost-effective technique. In this work, we investigated the effects of additional carbon sources from liquid media that were alcohols (C(m)H(2m+1)OH, m = 1-8), alkanes (C(m)H(2m+2), m = 6-7), and aromatic compounds (C6H6-C(n)H(2n), n = 1-2) on the product structures and the yield of nanocarbon-rich deposits. It was found that carbon nanoparticles (CNPs) that included multi-walled carbon nanotubes (MW-CNTs) and multi-shelled carbon nanoparticles were produced at high concentrations in the hard deposit at the cathode tip formed by the arc in the alcohols and alkanes, similar to that in a water environment. Importantly, not only graphite electrodes but also these organic compounds played a role of a carbon source to produce CNPs that led to an approximately 8-100 times higher yield than the arc-in-water system. There was a tendency that the increase in alcohol concentration and carbon content in the organic molecules positively affected the yield and production rate of the CNPs. However, the selectivity of MW-CNTs was significantly reduced when aromatic compounds were used. Structural analyses by dynamic light scattering and Raman spectroscopy revealed the dependency of the hydrodynamic particle sizes of CNPs and their crystallinity on the liquid components. For a discussion on the reaction mechanism, optical emission spectra of the arc plasma were analyzed to estimate the arc temperature. In addition, liquid byproducts were analyzed by a UV-vis absorbance spectrometer.

Modeling of experimental treatment of acetaldehyde-laden air and phenol-containing water using corona discharge technique.

Acetaldehyde-laden air and phenol-contaminated water were experimentally treated using corona discharge reactions and gas absorption in a single water-film column. Mathematical modeling of the combined treatment was developed in this work. Efficient removal of the gaseous acetaldehyde was achieved while the corona discharge reactions produced short-lived species such as O and O- as well as ozone. Direct contact of the radicals and ions with water was known to produce aqueous OH radical, which contributes to the decomposition of organic contaminants: phenol, absorbed acetaldehyde, and intermediate byproducts in the water. The influence of initial phenol concentration ranging from 15 to 50 mg L(-1) and that of influent acetaldehyde ranging from 0 to 200 ppm were experimentally investigated and used to build the math model. The maximum energetic efficiency of TOC, phenol, and acetaldehyde were obtained at 25.6 x 10(-9) mol carbon J(-1), 25.0 x 10(-9) mol phenol J(-1), and 2.0 x 10(-9) mol acetaldehyde J(-1), respectively. The predictions for the decomposition of acetaldehyde, phenol, and their intermediates were found to be in good agreement with the experimental results.