Cloud point extraction (CPE) utilizing polyoxyethylene 10 lauryl ether (C12E10) as the surfactant was carried out to separate and concentrate di(2-ethyl hexyl) phosphoric acid (D2EHPA) in its dilute aqueous solution.The CPE process was facilitated by decreasing the cloud point (CP) temperature of the solution with sodium sulfate.The influence of C12E10 concentration, settling temperature, pH value, and Ni2+ in the solution on the extraction efficiency (E) was studied.The results showed that extraction efficiency increased with the concentration of C12E10, temperature and pH value of the system.Trace Ni2+ in the solution has no obvious influence on extraction efficiency of D2EHPA when pH=7.00.Single-stage extraction efficiency larger than 85% has been obtained.
Extraction of p -aminophenol by D2EHPA, Alamine336 and their mixture were studied under various initial pH ranging 3-10.Both extractants extracted neutral form of p -aminophenol. When the pH value was between p K a1 and p K a2 ,a maximum distribution ratio appeared. This pH dependence can be explained by varying the molar fraction of neutral PAP with pH value. The mixed solvent of D2EHPA and Alamine336 had a higher distribution ratio than either Alamine336 or D2EHPA alone, i.e. ,the extraction of p -aminophenol with the mixed solvent showed the synergistic effect,and the molar concentration ratio of D2EHPA to Alamine336 at 1∶1.5 was the synergistic point.
