Separation of Cadmium and Zinc by Supported Liquid Membrane Using TOPS‐99 as Mobile Carrier

What is it about?

The separation of cadmium and zinc from a dilute aqueous sulphate media using supported liquid membrane technique has been studied. The microporous polypropylene film Celgard- 2400 was used as the solid support for the liquid membrane and TOPS-99 as the mobile carrier. Effect of different parameters such as flow rate, pH of feed solution, extractant concentration in membrane phase, acid concentration in strip solution, Cd(II) and Zn(II) concentration in feed solution on metal ion flux was studied. It was observed that flow rate of 100mL/min was sufficient to minimise the resistance due to aqueous boundary layer at the feed solution membrane interface. The zinc flux increased with increase of pH from 1.5 to 3.5 and then decreased with further increase of pH. The cadmium permeation started at a higher pH i.e. 3.0 and increased with increase of pH up to 3.5 followed by a plateau. Also with increase of TOPS-99 concentration in membrane phase up to 200 mol/m3, JZn increased and then decreased. The separation factors for cadmium and zinc were calculated at different experimental condition and were reported.

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Why is it important?

Separation of zinc and cadmium was carried out by liquid membrane technique using TOPS-99, produced by Heavy Water Plant, Talcher, India, as mobile carrier. Also equilibrium studies with shake flask were carried out. Following conclusions were drawn from the above studies. a The slope analysis studies of log D vs. equilibrium pH and log D vs. log [TOPS-99] indicates that 2 moles of the hydrogen ion and extractants were involved with 1 mol of the extracted metal species of both zinc and cadmium. b The zinc flux increased with increase of pH from 1.5 to 3.5 and cadmium flux increased from 3.0 to 3.5. The extraction of cadmium below pH 3.0 was minimum. c Also JZn increased with increase of extractant concentration up to 200 mol/m3 and then decreased. d It was observed that maximum separation factor of 53.854 was obtained with 0.765 and 0.89 mol/m3 of zinc and cadmium in feed solution. e. The best separation of cadmium and zinc is obtained at pH 2.25, 200 mol/m3 of TOPS –99 and 1260 mol/m3 of H2SO4 in strip solution.

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