Pervaporation membranes: preparation, characterization, and application

Pervaporation (PV) is applied in liquid mixture separation by using nonporous membranes. The feed liquid is directly in contact with one side of the membrane, and the permeation of target compounds through the membrane, in a vapour phase, is achieved by the difference in chemical potential gradient established by a difference in the partial pressure. The present chapter will focus on the membrane materials and their applications in PV. Organic and inorganic membranes can both be used in PV, and the choice of the most suitable membrane material is of fundamental interest for the success of the separation. Therefore, a section is devoted to the investigation of the proper material, on the basis of its chemical-physical properties, that must be selected for making membranes with the best performance in terms of selectivity and permeability. Then, the most common techniques applied for PV membrane characterization as well as the different module configurations, employed both at lab and industrial scale, are also discussed. Finally, the different types of membranes, on the basis of their application, hydrophilic PV, organophilic PV, and organic/organic PV, are evaluated and their performances are reported. The future trends and innovation of PV membranes are also foreseen and contextualized in the continuing growing membrane scenario.