Michihiko Fujine

Gas absorption accompanied by complex chemical reactions — III Parallel chemical reactions

Abstract Gas absorption accompanied by the parallel chemical reactions is discussed from the view-point of the film theory. The approximate solutions for the ratio Φ are derived by the same method described in our previous papers and compared with the analytical or numerical solutions for several cases. The difference of the ratio Φ between the approximate and the exact solutions is only a few per cent.

Gas absorption accompanied by complex chemical reactions- I Reversible chemical reactions

Abstract A solution based on the film theory is presented for gas absorption accompanied by a generalized, reversible chemical reaction of the form γAA+γBB⇋γEE+γFF. The approximate solution for the ratio of mass transfer coefficients, Φ, is derived and compared graphically with the exact numerical solutions for several limiting cases. It is shown that the error of this approximate method is less than several per cent.

Gas absorption accompanied by complex chemical reactions - II Consecutive chemical reactions

Abstract Based upon the film theory, the approximate solutions for gas absorption accompanied by two consecutive chemical reactions of the forms γ A A +γ B B →γ C C + Product,γ A′ A′ +γ C C →γ C C →γ B B and γ A A +γ B B →γ C C ,γ A A +γ ′ C C Product, are derived and compared with the numerical solutions. For the case of equal diffusivities, the approximate and numerical solutions agree with each other within a few per cent.

Gas absorption accompanied by complex chemical reactions-IV: Unsteady state

Abstract For gas absorption accompanied by ( m,n )-( p,q )-th order reversible, consecutive and parallel chemical reactions, the approximate solutions based on the penetration and surface renewal theories are derived under the condition of equal diffusivities, and compared with the approximate solution based on the film theory to manifest the generalized solution being suitable for three theories. For the case of reversible chemical reaction, the approximate solution based on the penetration theory is compared with the numerical solution to examine the accuracy of Hikita and Asais approximation in the unsteady state. It is found that the division of the approximate solution from the numerical solution is only a few per cent.

Behavior of the reaction plane movement in gas absorption accompanied by instantaneous chemical reactions

Abstract The absorptions of sulphur dioxide and hydrogen sulphite into jelly containing sodium sulphite or sodium hydroxide aqueous solutions were investigated by measuring the movement of reaction plane denoted by change of the color tone of indicator, and the experimental results were compared with the analytical solutions based on the penetration theory. The deviation of the color-change plane from the reaction plane was found to be negligibly small. The reaction between sulphur dioxide and sodium sulphite was found to be expressed by Model (1). The absorption process of hydrogen sulphide into sodium hydroxide solution was confirmed to be referred to Model (2). The reaction between sulphur dioxide and sodium hydroxide was verified to be a two-step consecutive instantaneous chemical reaction by substantiating the presence of the second reaction plane.

Mass Transfer of Ion Accompanied by Instantaneous Chemical Reaction in a Diaphragm Cell

ダイヤフラムセル内で 25℃の水溶液中における塩酸-水酸化カリウム, 塩酸-水酸化リチウム, 硫酸-水酸化カリウム系の3種類の中和反応を行なわせ, 瞬間反応を伴う場合のイオンの移動について実験的に研究した。一方, 境膜モデルに準拠した理論解として各反応成分がイオン拡散に従う場合と分子拡散に従う場合の2通りについてそれぞれ求め, 実験結果と比較した。まず実験結果をイオン拡散とした場合の理論解と比較したことろ, 各成分の拡散係数に無限稀釈水溶液における値を使用したにもかかわらず本実験範囲内 ([OH-濃度]/[H+濃度]≦8)では, ±5%の誤差内で一致することが認められた。他方, 分子拡散に従うとした場合の理論解との比較においても, 実験結果はイオンとしての拡散係数と分子としての拡散係数の違いが小さい場合には ±8%の誤差内で一致するのが認められた。しかし H+のように他のイオンと対になって分子として拡散する場合の拡散係数とイオンとして拡散する場合の拡散係数の間に大きな違いがある場合には, 分子拡散として考えると [OH-濃度]/[H+濃度] が大きくなる程, イオン拡散とした場合よりも実験結果との違いが大きくなるのが認められる。このようなことから物質移動現象をより正確に表わすためにはイオン拡散として考えた方がより妥当であるものと思われる。

Concentration profile of sodium ion in gas absorption

Abstract In this work the absorptions of sulphur dioxide and hydrogen sulphide into jelly containing one of sodium chloride, sodium sulphite and sodium hydroxide aqueous solutions have been carried out. After a certain exposure time, the jelly was cut into slices in which the concentration of sodium ion was measured by a flame spectrometer. The concentration of sodium ion at the gas—jelly interface was considerably higher than that in the bulk except for the H 2 SNaCl system. Experimental results are compared with the analytical solution based on the molecular penetration theory in which the molecular diffusivity is replaced by the effective ionic diffusivity, and it is found that both dissociation and reaction effects influence the concentration profile of sodium ion in the liquid phase.