在硝酸钠存在下以三元缔合物形态浮选分离钯(Ⅱ)

Floatation of Palladium(Ⅱ) as a Ternary Association Complex in Presence of Sodium Nitrate

在水溶液中,钯(Ⅱ)与硫氰酸铵、十六烷基三甲基溴化铵形成不溶于水的三元缔合物,在少量硝酸钠存在下,此三元缔合物沉淀浮于盐水相上层形成界面清晰的液-固两相,当溶液中十六烷基三甲基溴化铵、硫氰酸铵和硝酸钠的浓度分别为1×10-3mol.L-1,1.5×10-2mol.L-1,50 g.L-1,pH 3.0时,钯(Ⅱ)被定量浮选。而铬(Ⅲ)、锰(Ⅱ)、镍(Ⅱ)、铝(Ⅲ)、钼(Ⅵ)、锌(Ⅱ)、铁(Ⅱ)在该体系中不被浮选,对合成水样和钯镍电镀废液中钯(Ⅱ)进行定量浮选分离测定。

A water-insoluble ternary ionic association complex [Pd（SCN）4^2-]· 2[CTMAB^＋ ] was formed in a weakly acidic solution between the anionic complex Pd（SCN）4^2- and cation CTMAB＋, and after shaking with a definite amount of solid sodium nitrate （e. g. 0.5 g）, the association complex was floated on the surface of the water phase forming a clear interface between the liquid and solid phases. Based on these facts, quantitative separation of Pd（ Ⅱ ） from Cr（ Ⅲ ）, Mn（ Ⅱ ）, Ni（ Ⅱ ）, Al（Ⅲ ）, Mo（Ⅵ）, Zn（ Ⅱ ） and Fe（ Ⅱ ） by floatation was achieved on the following optimized conditions： （1） acidity of solution： pH 3. 0, （2） CCTMAB 1 ×10^-3mol·L^-1, （3） CCH4SCN 1. 5 ×10^-2mol·L^-1 , （4）ρNaNO3 50 g· L^-1 and （5） total volume of water solution： 10 mL. Rate of floatation of 100% and 99. 6G were obtained in tests of separation of Pd（ Ⅱ ） from binary ion mixtures and multi-ion mixtures containing the above mentioned metal ions respectively. The proposed method was applied to the separation and determination of palladium in Pd-Ni electroplating waste solution containing 1. 434 g · L^-1 of Pd（ Ⅱ ） and 2. 715 g · L^-1 of Ni（ Ⅱ ）. After the floatation separation, Pd（ Ⅱ ） was determined by the dithizone photometric method. Average amount of Pd（ Ⅱ ） found by 7 separations and determinations was 1. 423 g · L^-1, with value of RSD （n=7） 1.8% .