Sustainable additive manufacturing of polysulfone membranes for liquid separations

Membranes serve as important components for modern manufacturing and purification processes but are conventionally associated with excessive solvent usage. Here, for the first time, a procedure for fabricating large area polysulfone membranes is demonstrated via the combination of direct ink writing (DIW) with non-solvent induced phase inversion (NIPS). The superior control and precision of this process allows for complete utilization of the polymer dope solution during membrane fabrication, thus enabling a significant reduction in material usage. Compared to doctor blade fabrication, a 63% reduction in dope solution volume was achieved using the DIW technique for fabricating similarly sized membranes. Cross flow filtration analysis revealed that, independent of the manufacturing method (DIW vs. doctor blade), the membranes exhibited near identical separation properties. The separation properties were assessed in terms of bovine serum albumin (BSA) rejection and permeances (pressure normalized flux) of pure water and BSA solution. This new manufacturing strategy allows for the reduction of material and solvent usage while providing a large toolkit of tunable parameters which can aid in advancing membrane technology.