In this study, metal oxide nanoparticles were synthesized inside hydrogels to examine the effects of immersion temperature, gel composition, initial metal ion concentration, and doped metal ions on particle formation and photocatalyst properties. When the immersion temperature was raised, the oxidation reaction of the metal hydroxide was promoted and the catalytic activity increased, but if it was raised too much, particles grew and agglomerated, and the catalytic activity decreased. In addition, it was clarified that the denser the network density of the polymer chain by changing the gel composition, the more the growth and aggregation of particles were suppressed, and the catalytic activity increased. Furthermore, the higher the initial solution concentration, the higher the particle content, and the increase in the catalytic activity. However, if the concentration is too high, the swelling degree decreases and the amount of metal ion intake decreases, resulted in the decrease of particle content to reduce the catalytic activity. It was also suggested that the catalytic activity may increase by reducing the average particle size due to the influence of different ion radii when doping other metal ions and suppressing the recombination of electrons and holes by doped metal ions.

The tape casting process is widely used in various industrial processes. A plasticizer is added to a slurry to improve moldability and provide flexibility to a sheet. These results in quality instability and an increase in CO₂ emissions. A soft-flocculated slurry was generated in this work employing polyelectrolytes as a dispersion and a linear polymer with a charge reversal to the charge of the dispersant at both terminals as a soft-flocculant. A well-dispersed slurry was prepared by adding dispersant beforehand. After that, a soft-flocculant was added to the well-dispersed slurry. By adding soft-flocculant, the well-dispersed slurry was changed to a gel state because of the crosslinking of dispersant. The resultant gel was soft and could easily be changed into a liquid by shaking. The soft-flocculated slurry was optimized by selecting the appropriate agent and controlling the additive amount of the agent. A tape was casted using the doctor blade method. As a result, a thin tape could be cast without the use of a plasticizer using an optimized soft-flocculated slurry. The quality of this tape was comparable to that of a conventional method. Furthermore, the cast tapes showed high homogeneity and good flexibility resistance to bending use.

Particle adhesion and deposition in dry powder processes can result in low quality and productivity. In this study, to establish a method for controlling the charge and motion of particles and for removing them without using fluid and/or mechanical external forces, dielectric particles deposited on an insulating plate were charged and levitated using ultraviolet (UV) irradiation in an upward electric field. The particles in the top layer irradiated by UV light were positively charged by photoemission and levitated by the Coulomb forces. The flux and motion of the levitated particles and the charge of each levitated particle were experimentally obtained. The results showed that approximately 40% of the levitated particles descended because of the change in particle charge due to negative charge clouds formed by the photoemission from the particle layers and the levitated particles. Furthermore, applying an upward electric field after UV irradiation, all the particles were levitated without descending because the negative charge clouds were not formed. In addition, more particles were levitated due to an increase in particle charge, but the continuous levitation did not occur.

Surface-enhanced Raman scattering (SERS) is a phenomenon in which Raman scattered light of molecules adsorbed on noble metal nanoparticles with a diameter of about 50 to 100 nm is greatly amplified by surface plasmon resonance on the metal surface. Since it is possible to detect trace components, it is expected to be applied to ultra-sensitive analysis in a wide range of fields such as the medical field and the biological field. In SERS, it is known that when particles form a dimer or a further aggregate, an extremely strong electromagnetic field called a hot spot is formed between these particles. Since the target molecule is selectively adsorbed between such particles, the SERS effect is expected to be further amplified in the aggregated particles due to the synergistic effect of these two. However, the relationship between the aggregation state of such particles and the surface enhancement effect has not been completely elucidated. In this study, we fabricated a nanoparticle multilayer film by atomizer and verified the SERS effect due to the aggregate structure of the particles. The SERS effect was obtained with the nanoparticle accumulated film that prepared by 70-nm Ag nanoparticles with colloid concentration of 4.3 × 10¹² particles mL^–1.

In the production of pharmaceutical solid formulations such as tablet, the spherical crystallization method, in which crystallization and granulation are carried out simultaneously in the same system, can integrate the downstream in the pharmaceutical production process, thus enabling high efficiency in pharmaceutical manufacturing. On the other hand, process enhancement such as filtration, drying, and formulation after crystallization has been an issue. To solve this problem, we developed a one-pot processing system with hybridized powder processing operations in addition to filtration and drying functions. This desktop-sized device has a highly functional rotating spherical chamber that can handle all the processes of filtration, drying, powder mixing, and wet granulation at once. In this study, we confirmed that the suspension of fenofibrate granules prepared by the spherical crystallization method can be processed by the one-pot powder processing equipment. It was also found that the wet granulation of acetaminophen granules was possible by spraying binder from the spray nozzle in this apparatus.

Effect of particle shapes on self-propelled motion of the particles suspended in solution was studied with three different shapes of polymer particles including spherical, dumbbell-shaped, and snowman-shaped particles. Iron oxide nanoparticles (NPs) with a catalytic activity to decompose hydrogen peroxide were homogeneously heterocoagulated with the differently shaped particles to examine the shape effect on the self-propelled motion without considering inhomogeneity in catalytic reaction caused by the NP distribution on polymer surfaces. Heterogeneous Fenton reaction to decompose hydrogen peroxide in the presence of ascorbic acid used as a reduction promotor was applied to the polymer particles supporting iron oxide NPs. Mean square displacements of particles in in the Fenton reaction system were measured to evaluate the self-propelled motion. The snowman-shaped particles supporting the NPs exhibited self-propelled motion more strongly than the other particles, indicating that both particle shape and catalytic distribution on particle surface should be precisely controlled for further development of particles with a strong self-propelled motion.

We attempted to develop the electroless plating technique on plastic substrate employing polydopamine (PDA), which showed the adhesive ability to various solid and reducing ability of metal cation. Polypropylene (PP) plate was preliminarily coated with PDA thin film via polymerization of dopamine. We prepared spherical submicron PDA particles by polymerization of dopamine catalyzed by ammonia, and attempted to integrate the prepared particles on the pretreated PP plate by dip-coating. The adhered amount of PDA particle was controllable by withdrawal rate and solvent of particle dispersion. The inter-particle bonding was formed by adding glutaraldehyde (GTA) for the purpose of strengthening particle layer. Electroless Ni–P plating was conducted on the sample plates coated with PDA particles and the adhesive force between metal plate and each sample plate was measured by peeling test. The results of peeling tests demonstrated the possibility for improving the adhesive force of metal plate by increasing the amount of adhered PAD particle and forming the interparticle bonding. However, the adhesive force of metal plate is not sufficiently strong for practical use and further investigation is needed.

This study was conducted to reveal the relationship between properties of porous membrane and process conditions, when membrane is manufactured via wetting process. Membrane in this study was manufactured using two kind of carbon black (XC-72r and Li-100) which have different specific surface area. Time of ultrasonic dispersion to disperse carbon black and heating temperature to evaporate medium were process conditions to be changed. The thickness, permeability and surface roughness were measured for obtained membrane. As a result, permeability increased to the thickness in the case used Li-100. On the contrast, it was almost constant to the thickness for the case of XC-72r. Although the surface roughness did not depend on the thickness obviously, it became larger for the membrane used the slurry of bi-modal particle distribution for carbon black than used the slurry mono-modal. Consequently, it was revealed that the tendency of permeability and surface roughness to the membrane was understood by the morphology and particle distribution in slurry of carbon black.

Recycling and reutilization of powdery/dust waste are becoming increasingly important not only for ensuring a sustainable environment, but also for decreasing the cost of waste disposal. In this regard, we have been examining component separation using a vibrating fluidized bed, based on the differences in the agglomeration properties of the particles in each component. In the proposed separation method, the knowledge of the agglomerate formation and destruction of fine particles in the fluidized bed is essential. In this study, the effects of particle properties on the agglomerate formation and destruction in the vibrating fluidized bed were investigated using custom-made apparatus. TiO₂ rutile, TiO₂ anatase, and ZnO powder were used as tested powders. Changes in powder layer height and pressure loss were measured. Based on the obtained results, changes in agglomerate size were calculated using Ergun equation, and agglomerate formation and destruction was evaluated.

In Discrete Element Method (DEM), it is common to reduce the particle stiffness artificially from the original material property to employ a large time step and reduce the computational cost. When simulating cohesive particles, however, the reduction of the particle stiffness can cause excessive energy dissipation due to the prolonged contact duration, which can make the particles become more cohesive than the original ones. Recently, several scaling laws for attraction force are proposed to overcome this problem. Although these scaling laws are effective for dynamic systems where particles are fully fluidized as a bulk body, they are not applicable to relatively static systems since the instantaneous force balance is not maintained. In the present work, a new approach to reduce the viscous damping coefficient instead of the attraction force is proposed. The proposed model is applied to simulate cohesive particles in a rotary drum, and it is confirmed that the static phenomena such as the particles sticking on the drum wall as well as the dynamic phenomena such as the dynamic angle of repose are well replicated at the same time, which is difficult to achieve with the conventional method.

After the accident in Fukushima Daiichi Nuclear Power Plant, evaluation of radioactive wastes in environment, such as Cs and Sr, is required extensively in Japan. Therefore, we aimed development of dosimeter exhibits adsorption property by using Ag-exchanged zeolites. In this study, we investigated emission property in Ag-exchanged FAU-Y and LTA zeolites before and after irradiation of ionizing radiation. In Ag-exchanged FAU-Y and LTA zeolites, the emission intensity increased with increase in absorption dose. This result indicates that Ag-exchanged FAU-Y and LTA zeolites are candidate for dosimeters.

As effective utilization of seawater resources, a development of the recovery method of Ca dissolved in concentrated seawater discharged from the salt manufacturing process is desired. In this study, a recovery method of Ca in the concentrated seawater by continuous crystallization of hydrocalumite (HC) using a Taylor vortex crystallizer was investigated. Furthermore, effects of the operation parameters during the continuous crystallization on the powder properties of HC particles was predicted by constructing a regression model using deep neural network.

In human respiratory system, fluid behavior is complicated and drug particle behavior is unknown, since drug particle shape is irregular and its drag force is different from sphere particle. In this study, behavior of irregular shape particles in cascade impactor throat was analyzed by using DEM–CFD. Drag force model of irregular shape particle was applied for DEM–CFD. Based on the numerical simulation, drag force model suggested by Bagheri and Bonadonna agreed well with the experimental results. Also, it was found that many particles remained at inlet of cascade impactor throat due to the recirculation vortex.

In order to reveal the mechanism of powder processes, the application of numerical simulation is required because it can provide a detailed information of particle behavior. To apply numerical simulation to industrial systems, it is essential to take into account the non-sphericity of the particles and the complex wall boundary. In this study, we developed a new numerical simulation method for the system with arbitrarily shaped boundaries and non-spherical particles by applying the wall model based on the signed distance function to non-spherical particles.

All-solid-state lithium-ion batteries are expected as next-generation batteries for electric vehicles due to high energy densities and high safety. Approaches to a further improvement of energy densities include the analysis of electrode structure. In this study, DEM simulations were performed to calculate under compression process. The effect of the particle size ratio and plasticity ratio on the packing property was investigated.

We numerically investigate the rheological property of wet granular materials. We show that wet granular materials behave like solids even below the jamming point of dry grains. For the pressure, the extended theory of dry granular materials and the simulation are in good agreement. On the other hand, it is confirmed that the behavior of the pair correlation distribution function was different between the dry and wet granular materials.

The production of carbon-based materials with controllable shapes and structures from biomass in accordance with sustainable development goals is of high interest and encouraged. In this work, the carbon spheres were successfully fabricated via a spray drying method followed by the carbonization process, using Kraft lignin as the carbon source and potassium hydroxide (KOH) as the activation agent. The spherical carbon particles could be precisely controlled from dense to hollow sphere by varying the KOH concentration. In addition, the produced carbon has a high specific surface area (2424.8 m² g^–1) and could be used as active electrode materials for supercapacitors.

In this work, the aluminum surface was modified with different characteristics by anodizing and etching techniques. Two-type of modified surface aluminum of oxide film type and spike type were introduced as an aluminum substrate with various preparation conditions. Then, the modified surface aluminum was coated with a synthesized zeolite particle using silane as a coupling agent and became a composite adsorbent with 25–200 μm of layer thickness. The adsorption isotherms of the aluminum composites were investigated at 30°C.

Non-precious Cu₂O and Cu loaded hydrogenated black TiO₂ nanoparticles were prepared, and the H₂ evolution and the removal of a water based organic pollutant under UV light were studied. The results revealed that the B-TiO₂/Cu₂O/Cu (TC6-350) sample exhibited an improved photocatalytic hydrogen evolution performance, about 47 times higher than that of the TiO₂, and photocatalytic degradation of the Rhodamine B aqueous solution about 2.2 times faster than the TiO₂. The enhanced photocatalytic activity can be attributed to the integration of energy band alignment, effective carrier separation, and low charge transfer resistance. In addition, the constructed B-TiO₂/Cu₂O/Cu nanocomposite exhibited light stability, making it a long-term competitive photocatalyst for H₂ evolution. Therefore, the B-TiO₂/Cu₂O photocatalyst is a promising candidate for a variety of photocatalytic applications.

Mesoporous zerovalent iron-magnetite nanocomposites were synthesized for the removal of arsenic from multi-component solution. Based on the findings, the As(V) was reduced to < 10 ppb and the coexisting ions had no significant effect on As(V) removal because their removal mechanism is considered to be outer-sphere complexes formation whereas As(V) was predominantly inhibited through inner-sphere complex formation. The adsorbent has strong potential for reuse since the removal performance of As(V) after fourth cycle was > 94%. The adsorbent was stable after As(V) removal and the overall results confirmed that the adsorbent is suitable for removal of arsenic in actual wastewater.