Cloud Point Extraction And Separation Of Copper And Correlative Metal Ions

Copper exists naturally throughout the environment, soil, water and air, which alloy is widely used in electrical appliances, machinery, vehicles, shipbuilding industry and so on. Some copper alloy containing rare earths (REs), from the waste of which extract copper and separate with REs, has great value in application.In recent years, with the national economy developing, more and more extensive use of resources, while more and more of the ores have been mined out, of which cobalt ore is associated minerals,depending primarily on the exploitation of the main ore. In the world the vast majority of produced cobalt is a by-product from producing copper, nickel, sulfur mines and clay-type mines. Of cobalt ore more with copper, nickel was isomorphous exist in the same kinds of minerals, in the ore dressing process nickel and cobalt can not be separated. So the separation of copper and nickel (cobalt) has very important application value.Liquid-liquid extraction has been widely used in separation and preconcentration of metal ions. However, this technique exhibits important restrictions and drawbacks related to the use of expensive, toxic and inflammable organic diluents. An interesting alternative to traditional liquid-liquid extraction is the cloud point extraction, firstly developed in 1977. It offers the advantages of safety, low cost, high concentration efficiency, low toxicity, easy disposal of surfactants, less environmental pollution and simple procedure. Cloud Point Extraction (CPE) has been attracted considerable attention in the last few years mainly because it is in agreement with the"green chemistry"principles without volatile organic solvents and no pollution to the environment. It is based on the solubility of neutral surfactant aqueous solutions and cloud point phenomenon, by changing experimental parameters to cause the phase separation, so the hydrophobic material and hydrophilic material can be separated. As a new means of separation and enrichment of CPE, with the excellency of high efficiency extraction, large enrichment factor, simple, safe, economical, easy to realize the unite use, obtained very great concern and attention; while in the field of the separation and purification of biological macromolecules, separation and determination of small organic molecules and separation and enrichment of metal ions etc are widely used.CPE has been studied for the extraction and preconcentration metal ions after the formation of sparingly water-soluble complexes. Various ligands have been used for this goal, e.g. quinolinol, 1-(2-pyridylazo)-2-naphthol(PAN), 1-(2-thiazolylazo)-2-naphthol (TAN), 5-Br-PADAP , calixarenes and so on. Among these reagents, calixarenes are increasingly important in the field of supramolecular chemistry and crystal engineering, which are also well documented as efficient extractants of metal ions in CPE, while its application to CPE require both high complexation ability towards metal ions and high lipophilicity in order to dissolve into micelles. In this paper, C4AS was choosed as chelating agents to study the extraction of metal ions using TritonX-100.In the first part work, the extraction of Cu(II) and Ln(III) (La, Gd and Yb) complexes with p-sulfonatocalix[4]arene (C4AS), using CPE technique with TritonX-100 as non-ionic surfactant was studied, which basing on different complexing ability of copper ions and lanthanide ions with C4AS to form chelate complex, thereby selectively dissolved into the surfactant micelle phase. The efficiency of CPE can be affected by several parameters, such as Triton X-100 or C4AS concentrations, equilibration temperature, equilibration time, centrifugation time, pH, and NaCl concentration. Therefore, optimizing the various conditions of cloud point extraction is essential. Optimal conditions was obtained by experiment as follow: the pH of solution about 6.50; the volume concentration of TritonX-100 of 1.764%; the C4AS concentration of 2.28×10-3 mmol L-1; equilibrium temperature of 80℃and continuance time of 60min; centrifugation time of 3min, different molar ratios of lanthanides and copper on the separation coefficient were also studied. The result indicated that complexing capacity of C4AS with copper far higher than the lanthanide ions. This method can be applied to the separation of copper ions and lanthanide ions (La3+, Gd3+, Yb3+).The second part of this article, the extraction of Fe3+(Co2+,Ni2+) with p-sulfonatocalix[4]arene (C4AS), using CPE technique with TritonX-100 as non-ionic surfactant was studied. The following experimental parameters were carried through: different acidity (with or without C4AS), the concentration of C4AS on the extraction efficiency. The results showed that C4AS has poor complexing ability with the three metal ions. Then the different molar ratio of cobalt and copper on the separation coefficient was studied, results showed that the separation factor can reach 10 or more with the molar ratio from2 to 10, the copper ions and cobalt ions can be separated.Cloud point extraction technology in the extraction and enrichment of trace metal ions has the following prominent advantages: First, safety and low toxicity; surfactant recyclable or incinerated after use; no pollution to the environment. Second, high efficiency of extraction; large enrichment factor and the maximum extraction rate of up to 100%. Third, high extraction speed; short time-consuming and easy to operate. Fourth, small dosage of surfactant and low cost. Fifth, it is easy to use in conjunction with other analytical instruments, such as with flow-injection instrument, achieving separation, concentration and determination of automation of samples. Sixth, enables continuous analysis of large quantities.Cloud point extraction as a new sample pre-treatment and separation methods, which has been greatly developed in recent years, but the basic theory and practical application need to be continue in-depth studied. The mechanism of phase separation remains to be further explored and induced phase separation techniques also needed further development. At present the combined study of cloud point extraction and other instrumental analysis is also in-depth researched.In a word, cloud point extraction technology can be successfully combined with modern chromatographic separation technology, which has broad prospects for development.