Outstanding Paper Award Subcommittee of Kagaku Kogaku Ronbunshu has assessed the 53 papers published in volume 43 in 2017, and the editorial board finally selected the four papers for Kagaku Kogaku Ronbunshu Outstanding Paper of 2017; these are the papers on “Preparation of Cation-Exchange Fibers with High Protein-Binding Capacities by Pre-Irradiation Induced Emulsion Graft Polymerization,” “Metal Hydroxide Formation in DMAPAA Hydrogel and Novel Metal Ion Removal Method,” “A Model for Non-Equimolar Binary Gas Diffusion through Pores in the Region of Molecular Diffusion,” and “Evaluation of Aerosol Penetration through a Cylindrical Tube by Langevin Dynamic.”

Bubble point pressure and dielectric spectra of propane+ethanol liquid mixtures were measured at 303.2 K. The bubble point pressure was measured by use of a static type apparatus. The experimental pressure increased with increase in the mole fraction of propane, and the tendencies were well correlated with NRTL equations. The dielectric constants decreased with the mole fraction of propane. Otherwise the dielectric relaxation times showed convex shapes for the mole fraction of propane. The excess dielectric constants and the excess inverse dielectric relaxation times showed negative values over the whole range of the propane concentration. These phenomena suggested that hydrophobic interactions and dipole–dipole interactions play important roles in determining the dielectric properties of propane+ethanol liquid mixtures at the experimental temperature and pressure.

Gas channeling and temporary defluidization occur during the operation of fluidized beds when the fluidizing gas is switched to one of higher density. These effects arise because the gas velocity in the emulsion phase falls below the minimum fluidizing velocity due to non-equimolar counter-diffusion between the emulsion phase and the bubble phase, a major factor in which is the difference between the average molecular velocities of the two gases. During defluidization, the pressure-drop decreases due to the channeling and recovers after reaching a minimum value. In this study, this change was divided into three processes, and a parameter for each process was correlated with particle size and density. Based on the correlations obtained, the range of particle properties that has the potential to induce defluidization was mapped. It was found that defluidization is inevitable for a fluidized catalyst bed with particles of less than 100 µm. Further, the effect of defluidization could be reduced by increasing the gas velocity after the switching, and defluidization could be avoided by gradually changing the gas composition when the fluidizing gas was switched.

A spouted bed plasma reactor was developed for the uniform and continuous surface treatment of 3D particles in combination with a spouted fluidized bed and plasma-generating device, and the effect of fluidizing conditions and plasma conditions on the surface reforming of PP particles with the reactor was evaluated based on the measured wettability of the particles before and after the plasma treatment. It was found that the PP particle surfaces are reformed uniformly by using the spouted bed plasma reactor. The fluidizing conditions and plasma conditions variously influenced the particle reforming. The wettability of PP particles improved significantly with better particle circulation in the whole bed and longer treatment time, while the voltage of the plasma did not affect the surface reforming. The improvement in wettability was attributed to the production of C=O functional groups associated with Ar plasma, and the effect of physical structural damage was found to be negligible.

For estimation of particle density and mixing ratio, settling experiments were carried out by the buoyancy weighing-bar method. The JIS Test Powders 2, GBL30 and GBM30, which had the same particle size distributions and different densities, were used as sample particles. Glycerol solution was used as dispersion liquid. The density of the glass beads measured by the buoyancy weighing-bar method was similar to that measured with a pycnometer. The density distribution of the glass beads mixtures could be estimated by the buoyancy weighing-bar method.

Iodine toxicity from kelp has become a significant concern due to the widespread use of kelp as a raw material for food products. Here, the removal of iodine from kelp by use of an anion exchange resin was examined. Due to its competitive adsorption on the resin, iodine is simultaneously removed from kelp and from the liquid phase according to the competitive adsorption equilibrium between kelp and the resin. With an extraction solvent chosen to prevent loss of kelp mass, the dissolution rate of iodine from kelp into the solvent exhibited a high correlation with the kinetic constant of iodine release from kelp, which was calculated from the leaf thickness-dependent transmission distance. In the adsorption of iodine by the anion exchange resin, a high correlation was also found between the experimental value and that obtained from the competitive adsorption model, and when 0.9 M mannitol was used as the extraction liquid to suppress the loss of kelp mass, the average removal rate of iodine was 95% or higher.

A combined process consisting of ultrasonic irradiation and stepwise addition of inorganic salts was proposed in order to develop an efficient pretreatment to upgrade the settling performance of activated sludge. The addition of the divalent cation Ca²⁺ followed by the addition of the trivalent cation Fe³⁺ induced the formation of extremely large flocs, which led to a significant increase in the rate of batch gravity settling. Comparison with the result obtained when the salts were added in reversed order revealed that the prior addition of Ca²⁺ is essential to the improvement of settling properties. Among various Fe³⁺ dosages following the Ca²⁺ dosage of 10 mM, the Fe³⁺ dosage of 3 mM showed the maximum initial settling rate of 21.0 mm/min, which was 350 times the value obtained for raw sludge. Moreover, this Fe³⁺ dosage was equally effective in improving the settling performance when the Ca²⁺ dosage was significantly reduced from 10 mM to the extremely low value of 0.3 mM. When the effect of the stepwise addition of Ca²⁺ and Fe³⁺ was examined for the supernatant and for the consolidated sediment separated from the ultrasonicated sludge by centrifugal sedimentation, it was found that the marked flocculation effect of stepwise addition of Ca²⁺ and Fe³⁺ was attributed not to intracellular polymer substances released into the bulk solution from cells disrupted by ultrasonication but to disrupted cells themselves.

Bioethanol production using sugarcane as a raw material is effective in reducing greenhouse gas emissions but may be problematic in competing for the raw material for sugar production. A simulation in an earlier study demonstrated that sugar and ethanol production can be both increased by simultaneously introducing two technologies, high yielding sugarcane varieties and sugar/ethanol combined production process, into a sugar mill. However, in order to introduce these technologies to a sugar mill, it is necessary to acquire data through a plant-scale demonstration. In this study, we conducted demonstration tests from sugarcane cultivation to sugar/ethanol combined production on a pilot scale on the island of Ie, Okinawa Prefecture, and obtained material balance data when seven types of sugarcane were used as raw materials. In addition, we clarified the effect of sugarcane ingredient composition on each process and demonstrated that simultaneous increase in production of sugar and ethanol can be achieved.

The effect of synthesis conditions on the structure of magnetic mesoporous iron oxide (MMIO) and the capacity of MMIO to adsorb bromophenol blue (BPB) were examined. MMIO with a relatively large surface area (70 m²/g) and composed of only Fe₃O₄ could be obtained by adjusting the pH of the surfactant aqueous solution to 5.5. The surface area decreased as the calcination temperature of MMIO increased in the range of 250–500°C, probably because the size of mesopores increased with the progressive sintering of Fe₃O₄ particles. In order to synthesize MMIO with a large surface area and composed of a single phase of Fe₃O₄, calcination at a low temperature of about 300°C was found to be necessary. It was also found that the added surfactant acted as a dispersant. The maximum amount of BPB adsorbed by MMIO (solution pH, 5.5; calcination temperature, 300°C) was achieved when the BPB solution pH was 4.0. The amount of BPB adsorbed at saturation was 34 µmol/g. To examine the mechanism of BPB adsorption on MMIO, the adsorption isotherm was analyzed with the Langmuir and Freundlich equations. The mechanism was found to be of the Langmuir type, with a monomolecular layer of BPB adsorbed on the surface of MMIO.

Biomass resources have attracted attention because they are renewable and can be converted into feedstock for producing valuable chemicals such as olefins and aromatics. The present study proposes a two-step operation for producing bio-oils or chemicals from biomass to improve the quality of product and catalyst life. The first step is fermentative production of oxygen-containing compounds such as butyric acid from molasses as biomass. In the second step, the product is converted catalytically to propylene. The feasibility of the two-step process depends on the fermentation step. To realize the efficient acid fermentation, conditions were studied for producing butyric acid in high selectivity in a short period. Under our optimized conditions, selectivity was improved from 25.4 to 73.5 C% and the fermentation period was shortened from 13.5 to 1.5 d. Catalytic conversion of the fermentation product over zeolite gave a propylene yield of 25 C%. The results clearly show feasibility of the two-step processes for propylene production from molasses.