Simultaneous determination of trace Cu2+, Cd2+, Ni2+ and Co2+ in zinc electrolytes by oscillopolarographic second derivative waves
(1. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
2. School of Information Science and Engineering, Central South University, Changsha 410083, China)
2. School of Information Science and Engineering, Central South University, Changsha 410083, China)
Abstract: Simultaneous determination of impurity metal ions in high concentration zinc solution is very important for zinc hydrometallurgy, and the purpose is to establish a method for determining the trace Cu2+, Cd2+, Ni2+ and Co2+ in zinc electrolytes at the same time using the second derivative waves of single sweep oscillopolarography. Factors affecting the derivative waves of the ions were researched in a medium of dimethylglyoxime (DMG)-sodium citrate-sodium tetraborate. The results indicated that the interferences of a high concentration of Zn2+ and most other coexisting ions on the determination can be eliminated; when the Cu2+, Cd2+, Ni2+ and Co2+ are in the ranges of 1×10-7-3×10-4, 6×10-7-2×10-4, 2×10-8-1×10-5 and 1×10-8-3×10-5 mol/L, respectively, the relationships between the peak currents of the second derivative waves and the concentrations are linear; the detection limits to determine the Cu2+, Cd2+, Ni2+ and Co2+ are 8×10-8, 2×10-7, 6×10-9 and 4×10-9 mol/L, respectively. Without any sample pretreatment, the method was used to directly determine the trace Cu2+, Cd2+, Ni2+ and Co2+ in actual zinc electrolytes with satisfactory results. The method is simple, sensitive and rapid.
Key words: zinc electrolyte; copper; cadmium; nickel; cobalt; second derivative wave