DISTRIBUTION THERMODYNAMICS OF METAL-COMPLEXES IN MICELLES OF NONIONIC SURFACTANTS

The complexation of cobalt(II), nickel(II), copper(II), and zinc(II) w ith thiocyanate ions has been studied in micellar solutions of nonioni c surfactant Triton X-100 by titration spectrophotometry and calorimet ry. The complexation has been also studied by varying length of POE (p olyoxyethylene) chain. With regard to Co(II), the [Co(NCS)(4)](2-), wh ich hardly forms in aqueous phase, is extensively formed in micelles. With Zn(II), the [Zn(NCS)(3)](-) and [Zn(NCS)(4)](2-) are formed in mi celles. With Ni(II), no complexation occurs in micelles. In the case o f Cu(II), the formation of [Cu(NCS)(2)] is concluded in both micelles and aqueous phase. The complexation behavior of [Co(NCS)(4)](2-) and [ Cu(NCS)(2)] depends significantly on the length of POE chain, suggesti ng that these complexes exist both in the relatively hydrophilic POE s ite and hydrophobic core site.