12 research outputs found
ナノ構造が制御された球状炭素微粒子の合成とエネルギー貯蔵デバイスへの応用
広島大学(Hiroshima University)博士(工学)Doctor of Engineeringdoctora
Videos on Carbon Particle Formation Prepared via Spray Pyrolysis
These videos demonstrate the nanostructured carbon particle formation mechanism prepared through ultrasonic spray pyrolysis based on the self-assembly behavior of phenolic resin and polystyrene latex (PSL). By adjusting the attractive or repulsive forces between the phenolic resin and PSL particles, the morphology of the prepared carbon particles can be precisely controlled. Strong electrostatic attraction between the highly positively charged PSL and phenolic resin resulted in hollow carbon particles, while the electrostatic repulsion occurred in the presence of negatively charged PSL formed porous carbon particles. Depending on the requirements of different applications, using our strategy will in turn guide the synthesis of nanostructured carbon particles with desirable architectures and compositions.
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Enhanced Protein Adsorption Capacity of Macroporous Pectin Particles with High Specific Surface Area and an Interconnected Pore Network
There has been much interest in developing protein adsorbents using nanostructured particles, which can be engineered porous materials with fine control of the surface and pore structures. A significant challenge in designing porous adsorbents is the high percentage of available binding sites in the pores owing to their large surface areas and interconnected pore networks. In this study, continuing the idea of using porous materials derived from natural polymers toward the goal of sustainable development, porous pectin particles are reported. The template-assisted spray drying method using calcium carbonate (CaCO3) as a template for pore formation was applied to prepare porous pectin particles. The specific surface area was controlled from 177.0 to 222.3 m2 g-1 by adjusting the CaCO3 concentration. In addition, the effects of a macroporous structure, the specific surface area, and an interconnected pore network on the protein (lysozyme) adsorption capacity and adsorption mechanism were investigated. All porous pectin particles performed rapid adsorption (∼65% total capacity within 5 min) and high adsorption capacity, increasing from 1543 to the highest value of 2621 mg g-1. The results are attributed to the high percentage of available binding sites located in the macropores owing to their large surface areas and interconnected pore networks. The macroporous particles obtained in this study showed a higher adsorption capacity (2621 mg g-1) for lysozyme than other adsorbents. Moreover, the rapid uptake and high performance of this material show its potential as an advanced adsorbent for various macromolecules in the food and pharmaceutical fields
Multifunctional, Hybrid Materials Design via Spray-Drying : Much more than Just Drying
Spray-drying is a popular and well-known "drying tool" for engineers. This perspective highlights that, beyond this application, spray-drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray-drying, the confined space of a liquid droplet is narrowed down, and its ingredients are forced together upon "falling dry." As detailed in this article, this enables the following material formation strategies either individually or even in combination: nanoparticles and/or molecules can be assembled; precipitation reactions as well as chemical syntheses can be performed; and templated materials can be designed. Beyond this, fragile moieties can be processed, or "precursor materials" be prepared. Post-treatment of spray-dried objects eventually enables the next level in the design of complex materials. Using spray-drying to design (particulate) materials comes with many advantages-but also with many challenges-all of which are outlined here. It is believed that multifunctional, hybrid materials, made via spray-drying, enable very unique property combinations that are particularly highly promising in myriad applications-of which catalysis, diagnostics, purification, storage, and information are highlighted
Controllable Synthesis of Porous and Hollow Nanostructured Catalyst Particles and Their Soot Oxidation
The introduction of macroporous structures into three-way
catalysts
(TWCs) through polymer template-assisted spray drying has attracted
attention because of its enhanced gas diffusion and catalytic performance.
However, the surface charge effect of polymeric template components
has not been investigated to control the structure of the TWC particles
during synthesis. Thus, this study investigated the effect of template
surface charges on the self-assembly behavior of TWC nanoparticles
(NPs) during drying. The self-assembly of TWC NPs and polymer particles
with different charges produced a hollow structure, whereas using
the same charges generated a porous one. Consequently, the mechanism
of particle self-assembly during drying and final structure particle
formation is proposed in this study. Here, porous TWC particles demonstrated
a faster oxidation of soot particles than that of hollow-structured
particles. This occurred as a result of the larger contact area between
the catalyst surface and the solid reactant. Our findings propose
a fundamental self-assembly mechanism for the formation of different
TWC structures, thereby enhancing soot oxidation performance using
macroporous structures
Multifunctional, Hybrid Materials Design via Spray‐Drying: Much more than Just Drying
Spray-drying is a popular and well-known “drying tool” for engineers. This perspective highlights that, beyond this application, spray-drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray-drying, the confined space of a liquid droplet is narrowed down, and its ingredients are forced together upon “falling dry.” As detailed in this article, this enables the following material formation strategies either individually or even in combination: nanoparticles and/or molecules can be assembled; precipitation reactions as well as chemical syntheses can be performed; and templated materials can be designed. Beyond this, fragile moieties can be processed, or “precursor materials” be prepared. Post-treatment of spray-dried objects eventually enables the next level in the design of complex materials. Using spray-drying to design (particulate) materials comes with many advantages—but also with many challenges—all of which are outlined here. It is believed that multifunctional, hybrid materials, made via spray-drying, enable very unique property combinations that are particularly highly promising in myriad applications—of which catalysis, diagnostics, purification, storage, and information are highlighted
Synthesis of Submicron-Sized Spherical Silica-Coated Iron Nickel Particles with Adjustable Shell Thickness via Swirler Connector-Assisted Spray Pyrolysis
Silica-coated iron nickel (FeNi@SiO2) particles
have
attracted significant attention because of their potential applications
in electronic devices. In this work, submicron-sized spherical FeNi@SiO2 particles with precisely controllable shell thickness were
successfully synthesized for the first time using a swirler connector-assisted
spray pyrolysis system, comprising a preheater, specific connector,
and main heater. The results indicated that the thickness of the SiO2 shell can be tuned from 3 to 23 nm by adjusting the parameter
conditions (i.e., preheater temperature, SiO2 supplied
amount). Furthermore, our fabrication method consistently yielded
a high coating ratio of more than 94%, indicating an excellent quality
of the synthesized particles. Especially, to gain an in-depth understanding
of the particle formation process of the FeNi@SiO2 particles,
a plausible mechanism was also investigated. These findings highlight
the importance of controlling the preheater and SiO2 supplied
amount to obtain FeNi@SiO2 particles with desirable morphology
and high coating quality
One-Step Aerosol Synthesis of SiO<sub>2</sub>‑Coated FeNi Particles by Using Swirler Connector-Assisted Spray Pyrolysis
Silica-coated soft magnetic particles are essential for
some powder
magnetic cores consisting of primary (coarse particles) and secondary
(fine particles) soft magnetic particles in the advancement of electric
devices. Herein, we report the first investigation on the direct synthesis
of submicron-sized silica-coated FeNi (FeNi@SiO2) particles
as the secondary particle using a connector-assisted spray pyrolysis
route. Provided by computational fluid dynamics calculation in applying
different connector types, i.e., T-shaped and swirler, we found that
the mixing performance between FeNi and HMDSO vapor in the swirler
connector played an important role in resulting heterogeneous nucleation,
which is crucial for obtaining the higher coating ratio (CR) and fewer
undesired nanoparticles than that of the T-shaped connector. The as-prepared
submicron-sized FeNi@SiO2 particles (353 nm) with the highest
CR (95.9%) demonstrated a remarkable DC bias characteristic (Isat) and eddy current loss values on a powder
magnetic core, promising the practical application in manufacturing
soft magnetic components
Controlling the Magnetic Responsiveness of Cellulose Nanofiber Particles Embedded with Iron Oxide Nanoparticles
2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized
cellulose
nanofiber (TOCN) particles, an innovative biobased material derived
from wood biomass, have garnered significant interest, particularly
in the biomedical field, for their distinctive properties as biocompatible
particle adsorbents. However, their microscopic size complicates their
separation in liquid media, thereby impeding their application in
various domains. In this study, superparamagnetic magnetite nanoparticles
(NPs), specifically iron oxide Fe3O4 NPs with
an average size of 15 nm, were used to enhance the collection efficiency
of TOCN-Fe3O4 composite particles synthesized
through spray drying. These composite particles exhibited a remarkable
ζ-potential (approximately −50 mV), indicating their
high stability in water, as well as impressive magnetization properties
(up to 47 emu/g), and rapid magnetic responsiveness within 60 s in
water (3 wt % Fe3O4 to TOCN, 1 T magnet). Furthermore,
the influence of Fe3O4 NP concentrations on
the measurement of the speed of magnetic separation was quantitatively
discussed. Additionally, the binding affinity of the synthesized particles
for proteins was assessed on a streptavidin–biotin binding
system, offering crucial insights into their binding capabilities
with specific proteins and underscoring their significant potential
as functionalized biomedical materials