Hybrid liquid membrane (HLM) system in separation technologies

A novel liquid membrane system, denoted hybrid liquid membrane (HLM), was developed for the separation of solutes (metal ions, acids, etc.). It utilizes a solution of an extracting reagent (carrier solution), flowing between membranes. The membranes, which separate the carrier solution from feed and receiving (strip) solutions, enable the transport of solutes, but block the transfer of the carrier to the feed or to the strip. Blocking the carrier is achieved through membranes hydrophilic/hydrophobic or ion exchange properties, or through their retention abilities, due to pore size. The HLM-facilitated transport mechanisms have been schematically described and theoretical models have been developed to predict the rate of transport in the different separation processes. The model was tested on titanium(IV) transport from hydrochloric acid solutions. Titanium was removed by countertransport from low acidic (pH = 0.65) solutions or by co-transport from high acidic (7 mol/kg HCl) solutions, using DEHPA in benzene as a liquid carrier (membrane) solution. The efficiency of titanium transfer was studied as a function of feed, carrier and strip flow rate. Mass transfer parameters obtained were compared with model calculated data. Module optimization characteristics are discussed.