Transport of AgBr2−, PdBr42−, and AuBr4-in an Emulsion Membrane System Using K+-Dicyclohexano-18-crown-6 as Carrier

Abstract

Silver, palladium, and gold have been transported through a 1.5 M KBr/toluene/0.025 M MgS₂O₃ (or Mg(NO₂)₃) emulsion membrane system as AgBr₂ ⁻, PdBr₄ ²⁻ and AuBr₄, respectively, using K⁺-dicyclohexano-18-crown-6(DCl8C6) as carrier. The transport studies are carried out in AgBr₂ ⁻, PdBr₄ ²⁻, and AuBr₄ ⁻ single solutions and in AgBr²⁻/PdBr₄ ²⁻, AgBr²⁻/AuBr₄ ⁻, and PdBr₄ ²⁻/AuBr₄ ⁻ binary solutions. The presence of DC18C6 in the toluene membrane is found to greatly enhance ion transport. When MgS₂O₃ is in the receiving phase, AuBr_{4 -} is found to transport well even without DC18C6 in the membrane. The transport of AgBr₂ ⁻, PdBr₄ ²⁻, and AuBr₄ ⁻ is greater for those systems containing MgS₂O₃ in the receiving phase than for those with Mg(NO₃)². In binary studies with MgS₂O₃ in the receiving phase, PdBr₄ ²⁻ is transported selectively over AgBr₂ ⁻ and AuBr₄ ⁻ is transported selectively over either PdBr₄ ²⁻ or AgBr₂ ⁻.