EMULSION LIQUID MEMBRANE PERTRACTION OF METAL IONS FROM AQUEOUS SOLUTIONS AND ELECTROPLATING EFFLUENT USING ROTATING DISK CONTACTOR

Abstract

Removal of chromium (III), copper (II), and zinc (II) from synthetic aqueous solutions and electroplating wastewater by an emulsion liquid membrane technique (ELM) was studied using a rotating disk contactor (RDC). Kerosene as diluent, Span 80 as surfactant, di-(2ethyl hexyl) phosphate (D2EHPA) as carrier, and 1 N H₂SO₄ solution as internal stripping phase were used for emulsion preparation. RDC provides relatively low shear to emulsion and thus minimizes rupture of the ELM. Various hydrodynamic and chemical parameters such as metal ion concentration in the continuous (feed) phase, pH of the continuous phase, carrier concentration, agitation speed, internal stripping agent concentration, and flow rate ratio of continuous phase to dispersed phase (treat ratio) have been experimentally investigated. The results showed that it is possible to remove more than 95% of all metal ions from aqueous solutions with a concentration factor of more than 35 and a removal of 68–74% of three metal ions from the electroplating effluent.

Keywords:

• Chromium (III)
• Copper (II)
• Emulsion liquid membrane
• Pertraction
• Rotating disk contactor
• Zinc (II)

Notes

For batch operation: surfactant concentration = 2.5% v/v, agitation speed = 300 rpm, external phase pH = 4.5, H₂SO₄ concentration in the internal phase = 1.0 N, agitation time = 16 min, carrier concentration = 2.0% v/v for chromium (III), 0.5% v/v for copper (II) and zinc (II). For continuous operation: surfactant concentration = 2.5% v/v, agitation speed = 400 rpm, external phase pH = 4.0, H₂SO₄ concentration in the internal phase = 1.0 N, agitation time = 55–60 min, carrier concentration = 2.0% v/v for chromium (III), 0.5% v/v for copper (II) and zinc (II).