Removal of lead by complexation using a heteropolyanion and extraction of formed complex by emulsified liquid membrane

In the present work the complexation of lead (Pb2+) with the monovacant heteropolyanion of Dawson type (P2W15Mo2O61)10− was studied. The stability constant of the complex (P2W15Mo2PbO61)8− was calculated to be β = 2.5 × 106. The recovery of this complex from aqueous solutions using emulsion liquid membrane technique (ELM) with trietylamine as the carrier was also investigated. The effect of different parameters such as stirring speed, external phase pH, surfactant concentration, extractant concentration, phase ratio (O/A), treatment ratio (Vext/Vemul) and initial concentration of formed complex on extraction efficiency was examined. The extraction efficiency reached 90% for optimum operating conditions.