Ind. Eng. Chem. Process Des. Dev. 1082, 27, 511-514
NM = forward extraction rate of copper, mol/cm2 s r = reaction rate, mol/L s RF = flow ratio (= Fw/Fo) V = total volume per stage, cm3 V, = volume of aqueous phase per stage, cm3 X = defined by eq 39 (Figures 1 and 2) x = distance from interface, cm Y = defined by 38 (Figures 1 and 2), cm/s Yl = defined by eq 40, cm/s Y2 = defined by eq 41,cm/s Y3 = defined by eq 42, cm/s YI(O) = (MR2)i y , ( k ) = (MR,) at x = kh ~ ~ ( =0 (HR)i 1 y 2 ( k ) = (HR) at x = kh y3(0)= d(MR,)/dx at x = 0 y 3 ( k )= d(MR,)/dx at x = kh Greek Letters = defined by eq 43 ai= defined by eq 36 7 = reaction rate parameter cy
(eq 44) qi = modified reaction rate parameter (eq 37) T~ = resistance time of aqueous phase per stage, s $o = volume fraction of organic phase Subscripts b = bulk e = equilibrium
511
H = hydrogen ion HB = monomer of active component of LIX63 HR = monomer of active component of LIX65N (HB),= dimer of active component of LM63 in organic phase (HR),= dimer of active component of LIX65N in organic phase i = interface in = entrance M = copper ion MR = copper mono-complex ion with LIX65N MR, = copper bis-complex with LIX65N N = last stage out = exit ( ) = concentration of chemical species, mol/L ( )* = concentration of chemical species in reaction zone, mol/L ( ,), = concentration of chemical species in mth stage, mol/L overbar = organic phase Literature Cited Kojlm, T.; Tomb, J.; Miyauchl, T. Kagaku Kogaku Ronbunshu 1979, 5 , 476. Kojima, T.; Miyauchi, T. Kagaku Kogaku Ronbunshu 1981a, 7 , 143. Kojlma, T.; Miyauchl, T. Kagaku Kogaku Ronbunshu 1981b, 7 , 200. Kojlma, T.; Miyauchi, T. Ind. Eng. Chem. fundam. 1981c, 2 0 , 14. Kojlma, T.; Miyaudhi, T. Ind. Eng. Chem. Fundem. I W d , 20, 20. KoJIma,T.; Miyauchi, T. Ind. Eng. Chem. fundam. 1982, In press. Taylor, R. Lecture at Shell Chem. Co. Ltd. Tokyo, Sept 12, 1978.
Received for review April 1, 1981 Accepted January 19, 1982
Studies of Copper Etching in Ferric Chloride Solutions Shln-lchi Habu’ Salesian Polytechnic Ikuei, Igusa, Suginami, Tokyo, Japan
Yoshlro Yoshihiro Meui Unlvers& Hlgashbmlta, Tama, Kawasaki, Japan
The reaction of a ferric chloride solution with copper metal under similar condiins to platemaking was investigated from the standpoint of mass transfer theory. The rate equation of copper dissolution was derived from a model of the reaction. The rate constant depends on various factors such as the diffusion coefficient of ferric ion, the mass transfer coefficient, the volume of an etching solution,and the thickness of a stagnant film next to the copper surface. The experimental results agreed well with the theoretical values.
Introduction In the graphic arts and printing industry, the gravure process covers an important area in the reproduction technology. The process of preparing the gravure cylinders (Cartwight and MacKay, 1956) or photoengraving plates (Burrows et al., 1964) is called “etching”. Various methods of etching have been developed, and the one applying the reaction of a solution of ferric chloride with copper has been used the most widely (Carthght and MacKay, 1956; Shaffert et al., 1949). In spite of this situation, the reaction of etching has not been fully explained. With the concept of a diffusion-controlled reaction, Salzberg et al. (1951) proposed an overall rate equation for the dissolution of a metal in a solution containing an oxidant. They proved 0198-4305/82/1121-0511$01.25/0
it to be correct for the dissolution of silver in dilute aqueous ceric sulfate solutions. However, it is uncertain that the Salzberg’s equation is also correct for the etching because the properties of the etching solution are quite different from that used in Salzberg’s experiment. In a previous paper (Habu and Yoshihiro, 1972), we proposed an empirical equation on the relationships between the rate of dissolution and the diffusion of cupric ions, but we did not explain the action of ferric ions to copper in detail. The purpose of the work herein reported was to determine whether the theory of mass transfer would give an explanation on the results obtained experimentally and would offer an insight into the mechanism of the reaction. 0 1982 American Chemical Society
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Ind. Eng. Chem. Process Des. Dev., Vol. 21, No. 3, 1982
If Dcu = DFe,this reduces to the stoichiometry expected for a homogenous reaction. Equation 7 can now be written :Ft*
.
I
dc dt
- = KA(a0 - 2bc) where
K=
c =
kDFe
V(2k8
+ DFe)
and
.Cu' ,
= DCu/DFe
(13)
If 2bc
