Integrated use of liquid membranes and membrane contactors: Enhancing the efficiency of L-L reactive separations

Abstract

Separation processes combining facilitated transport membranes and membrane contactors offer several advantages such as the ability of liquid membranes to promote the uphill transport of target species by the coupling between mass transfer and chemical reaction, together with the benefits of using membrane contactors: large interfacial area, non-dispersive contact and independent flow of the fluid phases that can play an important role in process intensification. In this work, computer simulation techniques using previously validated mathematical models which take into account mass transfer and chemical reaction are employed: (i) to design the integration of liquid contactors in an already existing electroplating process and (ii) to quantify the degree of intensification provided by liquid membrane separation processes through the definition of suitable intensification indexes such as productivity/size ratio and modularity. The methodology has been illustrated through two different real applications in the context of surface treatment industry which were extensively analyzed in previous works: (i) the regeneration of trivalent chromium passivation baths by the on-site continuous removal of zinc and iron trap ions derived from the electroplating process and, (ii) the treatment of spent pickling hydrochloric acid generated in the hot-dip galvanizing process, with the aim of recovering the valuable zinc.