摘要
本文研究了温度、银氨摩尔比,碱度及杂质金属离子对联氨还原银氨配合物以沉析银的反应,获得微量的Co(Ⅱ)、Mn(Ⅱ)、Fe(Ⅱ)特别是Cu(Ⅱ)离子,不仅能加快反应速度,且能有效地促进联氨按反应(A)进行四电子定向反应的比率,提高了银的还原沉析率,降低了联氨耗量。 N_2H_4+4Ag(NH_3)_2^++4OH^-=N_2+4Ag+8NH_3+4H_2O (A) N_2H_4+Ag(NH_3)_2^++OH^-=1/2N_2+Ag+3NH_3+H_2O (B) 通过正交试验,找出了影响联氨定向还原沉析银的各因素主次顺序为[NH_3],[Cu(Ⅱ)],温度,[NaOH],获得在起始浓度为0.0025mol/LN_2H_4和0.010mol/LAgNO_3的混合液中,联氨按四电子定向反应(A)的最佳条件是:Ag^+∶NH_3=1∶4(摩尔比),[Cu^(2+)]=4X10^(-5)mol/L,[NaOH]=0.010mol/L,在333K时搅拌反应10分钟,银的还原率在99.8％以上。
The effect of temperatuse, molar ratio of Ag(Ⅰ) to NH3, basicity, impurity of metal ions on the reaction of N2H4 with Ag(NH3)2+ has been studied. It is found that the transition metal ions, which have varied valence, such as Co(Ⅱ), Mn( Ⅱ ), Fe(Ⅱ ), especially Cu(Ⅱ), are the effective catalysts. In the presence of Cu(Ⅱ) ion, the rate of reaction is accelerated, and the relative amount of four-electson directional reaction of N2H4 (reaction A) is greatly increased.
N2H4+4Ag(NH3)2+4OH-=N2+4Ag+8NH3+4H2O(A)
N2H4+Ag(NH3)2+OH-=1/2N2+Ag+3NH3+H2O(B)
By using orthogonal test, the optium condition for the directional reaction of precipitation silver by the reduction of Ag(NH3)2+ with N2H4 is found. The order of each factor to influence the reaction is [NH3], [Cu( Ⅱ)], temperature, [NaOH]. In the mixture solution of the original concentration of 0.0025mol/L N2H4 and 0.010mol/L AgNO3, the molar ratio of Ag+ to NH3 is 1:4, 4×10-5mol/L Cu( Ⅱ ) and 0.010mol/L NaOH are selective, the reaction is carried at 333K, under stirring for 10 minutes, the percentage of the precipitating silver is above 99.8%.
出处
《杭州大学学报（自然科学版）》
CSCD
1989年第3期284-291,共8页
Journal of Hangzhou University Natural Science Edition
基金
国家自然科学基金资助项目
关键词
银
氨
配合物
联氨
还原
hydrazine
diamminesilver( I )ion: directional reaction
