Removal of cadmium(II) from wastewater with gas-assisted magnetic separation

In this study, a method combined low-field magnetic separation (MS) with flotation, named as gas-assisted magnetic separation (GAMS), was applied for the removal of cadmium from wastewater. With bubbles' assistance, the speed of magnetic separation can be greatly improved and the limitation of magnetic force on the capture distance can be overcome. Thus, GAMS is much more efficient and easily scalable than MS. In this work, ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres (EMPs) were synthesized as the adsorbent for cadmium. And GAMS was used to separate the EMPs and Cd-loaded EMPs. The effects of pH, gas flow rate, concentration of Cd-loaded EMPs, loading volume, and ionic strength on GAMS were investigated. The results indicated that the EMPs and Cd-loaded EMPs could be rapidly and remotely removed from the solution with GAMS. And the separation time decreased with the increase of gas flow rate and NaCl concentration, but grew with the rise of pH value, loading volume, and concentration of the EMPs. This work showed the great potential of GAMS in the area of water treatment.