Concentration/purification of Co(II) ions by reverse osmosis and ultrafiltration combined with sorption on clay mineral montmorillonite and cation-exchange resin KU-2-8n

Feasibility in concentration of the heavy metals by using cobalt, as an example, has been studied. It has been actualized a membrane reactor obtained by combining sorption on a clay mineral or a cation-exchange resin with pressure-driven membrane separation. The retention coefficient of Co(II) ions by the OPAM-KN membrane under the quasi-steady mode of continuous operation reaches 0.92 and 0.98, when the montmorillonite clay mineral and KU-2-8n cation-exchange resin are used, respectively. When a UPM-20 membrane is used, these indices are substantially lower: 0.08 when clay mineral montmorillonite is used in the pressure-driven processes and 0.60 when cation-exchanger KU-2-8n is used in the such a one. The information about the water state has been determined by the differential scanning calorimetry method. A conclusion about an effect of the sorbents with the different nature on the purification/concentration process in the so-called hybrid method has been done. This conclusion has been reached based on the data about the water state in the dynamic membranes formed by a clay mineral or a cation-exchange resin on the surface of the supporting OPAM-KN and UPM-20 membranes. It was determined by differential scanning calorimetry method that dynamic membrane formed from cation-exchange resin KU-2-8n is more firm and dense than dynamic membrane formed from montmorillonite. It explain the increasing of Co(II) ions retention coefficient. It was established that combination of the sorption processes and pressure-driven separation may be used for heavy metals concentration.