Development of Material for Chemical Separation using Hydrophobic Surface of Recycled Polyvinylchloride

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(1) Distribution behaviors of aromatic compounds containing phenol and its derivatives in water were investigated by mixing recycled polyvinylchloride (RPVC) from agricultural use. The distribution was found to increase in the order phenol<p-cresol<p-ethylphenol<p-propylphenol<p-buthylphenol. To find out the role of the plasticizer in the RPVC, the distribution coefficients of these aromatic compounds between di-2-ethylhexyl phthalate and water were determined to reveal that the hydorophobicity of the solute played important role for the distribution. The adsorption of PVC resin of these compounds was relatively small compared to the plasticizer. In conclusion, the hydrophobic substances in water were extracted to the plasticizer in the RPVC.(2) The surface of the RPVC was coated with trioctylmethylammonium chloride (TOMAC) by mixing its 50% THF-H_2O solution with RPVC. The TOMAC in water solution was estimated by ion-pair extraction method with picric acid. These results show that a considerable amount of TOMAC is soluble in water. But the solubility was depressed by the addition of such an electrolyte substance as NaCl, KNO_3 and HCl.(3) The distribution behaviors of gold (III), platinum (IV) and palladium (II) in 1M-HCl to RPVC loaded TOMAC were investigated. The rate of distribution was found to decrease as follows ; Au (III)>Pt(IV) >Pd(II). The distribution ratio of the metal ions such as Zn(II), Cu (II) and Fe (III) was small compared to that of precious metal ions. Elution of the adsorbed precious metal ions from RPVC was investigated using 0.1M thiourea solution. The recovery of Au ((III) was about 80%. On the other hand, the recoveries of Pd (II) and Pt (IV) were about 40% and 10% respectively under the same condition.