Extraction Effect of Cobalt、Nickel and Magnesium from Water by Complex Extractant P204-N235

The optimal extraction conditions for the extraction of cobalt, nickel and magnesium were studied by using P204 and N235 composite extractant. The experimental results demonstrated that all of the metals extraction efficiencies increased with the increase of the concentration of P204, oscillation time and the initial pH value of aqueous phase. Taking into consideration various factors, the optimum extraction conditions are chosen to be 20% volume concentration of P204, 10 min of vibration time and initial pH value of 5. The compound extraction agents have higher efficiencies for extraction of cobalt, nickel and magnesium than that of pure P204 under the same extraction condition. Based on the log D-logP204 spectra, all of the slopes were 3, suggesting that the final products of cobalt, nickel and magnesium after extracted by composite extractant are CoA₂(HA), NiA₂(HA) and MgA₂(HA), respectively. All of the slopes of logD-pH spectra were calculated to be 2, implying that the metals ions extraction mechanism by using compound extraction agents is the cation exchange reaction.