pervaporointi

Pervaporation (Finnish: pervaporointi) is an advanced membrane separation technology that combines the selective transport of solutions through a membrane with the phase change of a component from liquid to vapor. In a typical pervaporation system, a feed mixture is presented to one side of a hydrophilic or lipophilic polymeric or inorganic membrane, and a vacuum or a sweep gas is applied to the permeate side. As a preferred component traverses the membrane, it evaporates within the membrane pores and is removed in the vapor phase. This process is particularly effective for separating azeotropic mixtures or concentrating volatile components that are difficult to isolate by conventional distillation.

The driving force behind pervaporation is a chemical potential gradient: the partial pressure of the transported component is lower on the permeate side, encouraging migration across the membrane. Membrane materials are chosen for their permeability and selectivity; common examples include expanded PTFE, polyvinylidene fluoride, and zeolite-filled polymers. Pervaporointi is used industrially for dehydration of organic compounds, removal of low-boiling impurities from fuels, and recovery of solvents in polymer processing. It offers lower energy consumption than distillation because the separation occurs below the boiling point of the components and the evaporation takes place inside the membrane itself.

Despite its advantages, pervaporation faces challenges such as membrane fouling, limited throughput, and material cost. Research is focused on developing more robust membranes, scaling up modules, and integrating pervaporation into hybrid processes to enhance overall efficiency. The technique continues to grow as a niche but valuable tool for fine chemistry, bioprocessing, and sustainable solvent management.