Abstract
Solvent extraction studies of copper and zinc have been carried out using Versatic 10 acid and Cyanex 272 separately from a model brass pickle liquor. Various parameters for the extraction and separation of copper and zinc such as effect of pH, extractant concentration, phase ratio etc. have been optimized. It was observed that copper was almost completely extracted into the organic phase comprising of 30% Versatic 10 acid at the equilibrium pH of 5.0 using the phase ratio of 1:1 whereas, zinc extraction was noticed at above pH 5.0. On the other hand the pH0.5 values were 3.5 and 4.6 for zinc and copper respectively with 20% Cyanex 272. The difference in pH0.5 value of 1.10 indicated the possible separation of Zn and Cu. By McCabe Thiele diagram number of stages required for the counter current extraction of copper and zinc has been determined for both the solvents. The stripping study showed that 1 mol/L H2SO4 was sufficient to strip metal ions in a single contact from each of the extractant.
Highlights
Brass tends to build up a black coating on the surface called tarnish which is essentially a type of corrosion that is caused by exposure to the air
The effect of pH on the extraction of copper and zinc was investigated in the pH range 2-7 using the phase ratio of 1:1
It was observed that extraction of metals increased with pH and copper was completely extracted into the organic phase comprising of 30% Versatic 10 acid at the equilibrium pH of 5.1 whereas, zinc extraction was noticed only at pH above 5.0 (Fig.1) which was almost completely(~99%) extracted into the organic phase at pH 7.0
Summary
Brass tends to build up a black coating on the surface called tarnish which is essentially a type of corrosion that is caused by exposure to the air. Cleaning of the surface becomes increasingly necessary. The cleaning process involves removal of rust and oxide impurities by dipping the material in dilute sulphuric acid solution, which is usually reused several times before its disposal as a waste. As a result the waste pickle liquor is loaded up with pollutant materials such as copper, zinc, chromium etc. Due to its environmentally hazardous nature it can not be disposed off without pretreatment. Recovery of these metals is coincident with the goals of waste management strategy since they could provide some economical benefits and solve the pollution problem too. To obtain valuable end-products like copper powder, copper oxide, zinc oxide and copper/zinc salt from such streams solvent extraction is considered an ideal technique which has been applied extensively
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