Silicon-Phosphorus triple bond compound : Studies of multiple bond between heavy group 14 and group 15 elements

課題番号：1975002

Effect of Ground Shell Properties on Adsorption Characteristics for Cadmium Ions

貝殻の大部分は産業廃棄物として処理されており，産業上の有効活用が求められている．本研究では，アラゴナイト型のアコヤ貝殻，カルサイト型のホタテ貝殻を粉砕して，貝殻の比表面積や結晶性がCd2＋イオンの吸着量に及ぼす影響について検討した． 粉砕により作製した，比表面積が同程度の貝殻粉体（アコヤ貝殻は9.0 m2/g，ホタテ貝殻は12.3 m2/g）で比較すると，Cd2＋イオンの除去率はアコヤ貝殻で84％，ホタテ貝殻で23％であり，アコヤ貝殻（アラゴナイト）の方が高かった．また，カルサイト型のホタテ貝殻，および試薬炭酸カルシウムでは比表面積の増加に伴って高くなった．カドミウムイオン吸着前後の結晶構造を比較したところ，ホタテ貝殻では吸着の前後で結晶構造は変わらなかった．一方，アコヤ貝殻では，吸着後の試料においてアラゴナイト型炭酸カルシウムの他に，炭酸カドミウムのピークも検出された．以上のことから，Cd2＋イオンの吸着量が，物理吸着の場合には貝殻の比表面積に，イオン交換反応の場合には粒子の結晶性に大きく影響することを明らかにした．Because seashells, which are a waste product in the seafood industry, are not recycled, several studies have investigated effective uses for discarded shells. Herein we report the Cd2＋ ion adsorption performances of ground scallop and pearl shells. The effects of the specific surface area and the crystallite size on the adsorption capacities of Cd2＋ ions were estimated. We found that ground seashells have potential to adsorb Cd2＋ ions. We measured the removal ratio of Cd2＋ ions using ground shell particles with close to the same specific surface area. The removal ratio of the pearl shells（aragonite form, 9.0 m2/g）and the scallop shells（calcite form, 12.3 m2/g）was 84％ and 23％, respectively. The pearl shells with low crystallite size exhibited excellent adsorption performance compared to the scallop shells and reagent calcium carbonate. When the aragonite particles were immersed in aqueous solutions including Cd2＋ ions, the ions were easily fixed as cadmium carbonate. On the other hand, the adsorbed amount was positively correlated with the specific surface area of the calcite particles. The adsorbed amount of Cd2＋ ions for aragonite and calcite shell particles depended strongly on the crystallinity and the specific surface area of shells, respectively

Evaluation of Aerosol Penetration through a Cylindrical Tube by Langevin Dynamic

円管内を層流で流れるエアロゾル粒子の通過率を評価するため，粒子のブラウン運動を再現できるランジュバン動力学方程式によって粒子の軌跡を計算した．通過率の計算では，粒子の侵入距離として円管入口から入射した粒子が壁面に到達するまでに移動した軸方向最大距離（zMTD）と，粒子が壁面に沈着した点の入口からの軸方向距離（zDD）の二つの基準を設けた．これにより，古典的な研究と同様に，ある円管断面における粒子の全流束と円管入口での全流束の比として定義されている粒子の通過率と，粒子の壁面への沈着流束の分布の両方の評価が可能となった．Péclet数が1000より高い条件では，zMTDとzDDの差はほとんどなく，zMTDの分布から求めた通過率は，流れの方向の粒子の拡散を無視して移流–拡散方程式を解析的に解くことで得られた従来の通過率とよい一致を示した．Péclet数が1000より低い条件では，粒子の等方的なブラウン運動の性質が顕著になり，zMTDがzDDより大きくなる粒子の割合が増加した．zMTDの分布から得られた通過率は，流れの方向の粒子の拡散を考慮した移流–拡散方程式より得られた通過率と非常によい一致を示したが，zDDの分布より得られた粒子の沈着流束の分布と，通過率の傾きから得られた沈着流束の分布は一致しなかった．そのため，低Péclet数での粒子の輸送と沈着現象を評価するには，粒子の軌跡を直接計算する手法が有用であると考えられる．In order to evaluate aerosol penetrations through a fully developed laminar flow in a cylindrical tube, the trajectories of aerosol particles were calculated by a Langevin dynamics equation that can represent the Brownian motion of aerosol particles. In our calculations, two criteria of penetration distance were employed: the maximum distance that a particle travels in the axial direction before it is deposited on inner wall of the tube, zMTD; and the axial distance from the inlet of tube to the point of deposition, zDD. The distributions of these two penetration distances enable us to evaluate respectively the classical penetration, defined as the ratio of total particle flux over a cross section of tube to the total particle flux at tube inlet, and the distribution of deposition flux to the tube wall. At high Péclet numbers of Pe>1000, there is almost no difference between zMTD and zDD. The resulting penetrations calculated from the distribution of zMTD agree well with the conventional analytical solution of convective-diffusion of aerosols in which the diffusion of aerosol particles in the direction of flow is neglected. At low Péclet numbers of Pe<1000, the isotropic nature of Brownian motion of aerosol particles becomes obvious: the ratio of particles of which zDD is smaller than zMTD significantly increases. The distribution of zMTD successfully reproduces the results of aerosol penetration obtained by the numerical solutions of the convective-diffusion equation of aerosols without neglecting the diffusion in the direction of flow, but the deposition flux obtained by the distribution of zDD does not agree with the gradient of particle penetration, which is a numerical solution of convective-diffusion equation of aerosol particles. Consequently, it was concluded that the method of calculating the trajectories of particles directly was advantageous to evaluate the particle behavior at low Péclet numbers

科研費研究機関指定後の採択状況について

othe

Characterization of Conductivity of Graphite-phenolic Resin Composite and its Application to Heating Plywood

Functional plywood can produce constant heat by applying a voltage to the conductive bonding layer between wood sheets. Herein functional plywood was prepared by filling various microsized graphite particles (3.3-52.5μm in diameter) and nanosized carbon black (CB ; 29 nm) into a phenolic resin. To investigate the electrical conductivity, the resulting composite resin was coated onto a commercial glass slide. The effects of particle size, mass fraction of the conductive fillers (graphite and CB), and the weight ratio of graphite to the fillers (φ = graphite / (graphite + CB)) on the conductive properties of the composite resin, particularly the specific resistance and its variation coefficient, were estimated. A composite resin, which included at least 30 mass% of filler, yielded a relatively low variation coefficient for the specific resistance. Additionally, the composition of the resin had superior conductivity when the weight ratio was 55-66 mass% and the graphite particles were 22.9μm or less in diameter. The above experiment indicated heating plywood was produced. Consequently, its surface temperature was measured. With respect to particle size, the standard deviation in the surface temperature of the plywood corresponded to that of the conductive properties on the glass slide. Hence, the method proposed herein using a glass slide is suitable for conductive characterization to determine the appropriate conditions to prepare heating plywood