Removal of cadmium from a liquid effluent by ion flotation

The removal of Cd using sodium dodecylsulfate (SDS) as collector was studied by ion flotation at laboratory scale. The effect of frothers (iso-propanol and methyl-isobutyl-carbinol (MIBC) and ionic strength (NaCl and Na2S04) were also studied, as well as characterization of the sublate by scanning electron microscopy (SEM) and the surface tension of the initial solutions. In the presence of SDS, the maximum recovery obtained at a stoichiometric metal to collector ratio of 1: 3 was 99.1 %, however a large volume of wet foam was produced. The best recovery (89.2%) with a dry foam was obtained at a stoichiometric ratio of 1:2. The introduction of frothers (iso propanol and MIBC) in the system produced the highest recovery of Cd at a concentration of 0.1% v/v, where the flotability was 98.8% and 97.7% for iso-propanol and MIBC respectively. An increase in magnitude of ionic strength from 4.7 × 10−4moles.dm−3to 4.7 × 10−1moles.dm−3 significantly decreased Cd removal. Surface tension testwork indicates a decrease in flotability of Cd as surface tension drops. The SEM/EDS studies showed that the morphology of the suhlate and the foam depends on the physico-chemical conditions of the system.