Cloud-point extraction of trace copper in lipophilic complex form

A less-common extraction procedure, cloud-point extraction, was used with a lipophilic chelating agent (LLX(R) 54) to extract copper ion from aqueous solution. Surfactant solutions [0.2-2.2 %(w/w) of nonylphenoxypoly(ethylenoxy)ethanol] with a cloud-point of 48-52 degrees C, was used in conjunction with a lipophilic chelating agent, dodecyl benzoylacetone, RC(6)H(4)CO-CH2COCH3, to form a copper complex that would be extracted into the micellar phase. Extraction was optimal in a pH range of 5-11 with 95.5-98.6% of the copper extracted. The partition coefficient increased with increasing copper concentration and was in excess of 1000 when the initial copper concentration was 80 ppm. Unlike the cloud-point temperature and the extraction rate, extraction efficiency was only slightly related to surfactant concentration.