Dimethyl Isosorbide As a Green Solvent for Sustainable Ultrafiltration and Microfiltration Membrane Preparation

Dimethyl isosorbide (DMI)-a well-known biobased high boiling green solvent-was used for the first time in the preparation of poly(vinylidene fluoride)- and poly(ether sulfone)-based membranes. Preliminary thermodynamic (Hansen and Hildebrand solubility parameters, relative energy difference) and kinetic (viscosity) studies on DMI confirmed that this solvent possesses the required physical/chemical properties to be exploited in casting membranes. Membranes were prepared by nonsolvent induced phase separation (NIPS) and a combination of vapor induced phase separation (VIPS)-NIPS techniques varying the exposure time to humidity. This latter approach led to the formation of membranes with a porous architecture avoiding the use of any pore forming additive. The so-prepared membranes were, then, fully characterized in terms of morphology, polymorphism (in case of PVDF), wettability, thickness, porosity, pore size, and water permeability. The membranes revealed different structures and a tunable pore size in the range of ultrafiltration (UF) and microfiltration (MF) that render them ideal for applications in water treatment processes.