摘要
用旋转圆盘法考察了盐酸浓度对铜置换Pd(Ⅱ)反应速度的影响,发现在低盐酸浓度(0.01～0.1mol/L)时,反应速度极快,在液相中发生CuCl_2^-对Pd(Ⅱ)的化学还原,反应产物Cu与Pd的摩尔比为1:1,铜离子为二价;在较高酸度(3～5mol/L)时,反应速度显著变慢,置换反应仅在铜片表面进行,属于电化学反应机理,速率方程为10gC_0/C_t=2.723×10^(-3)t-0.002,产物Cu与Pd的摩尔比>2,铜离子为一价,且出现放氢副反应。
The effect of HCl concentration on cementation of Pd (Ⅱ) by Cu was investigated with the rotating disk technique.It was found that the cementation rates were very last when HCl concentration ranged from 0.01 to 0.1 mol/L with the mechanism of chemical reduction.Pd (Ⅱ ) was reduced by CuCl_2^- in aqueous phase.The molar ratio of copper ions to metallic palladium in products was 1: 1, copper ions were cupric.The rate decreased obviously when HCl concentration increased to 3～5 mol/L.The cementation occurred only on the surface of copper disk.This process was controlled by electrochemical reaction.The cementation rate model is expressed by the following equation.
log C_0/C_t=2.723×10^(-3) t-0.002
The molar ratio of Cu: Pd in the products was greater than two, copper ions were cuprous, and the cementation was accompanied with hydrogen evolution.
出处
《贵金属》
CAS
CSCD
北大核心
1993年第4期1-9,共9页
Precious Metals
关键词
钯
置换沉淀
铜
反应机理
盐酸
Palladium
Cementation
Copper
Reaction mechanism
