Water-bonding tubular membrane used in a 3D-printing dialyzer for diffusion dialysis

Tubular membrane used in diffusion dialysis (DD) is operated easily in simple structure with light weight. Nevertheless, some defects, including leakage, low membrane area and low packing density, still restrict the DD performances. Herein, inspired from bionic aspect, a water-bonding polyvinyl alcohol (PVA) tubular membrane is prepared, and then used in a 3D-printing dialyzer for a DD process. The tubular membrane shows a long length of 195 cm, and a satisfying tensile strength of 16.8 MPa and elongation at break of 306%. The 3D-printing dialyzer provides the tubular membrane with a smooth flowing channel, which is used to separate H2SO4/FeSO4 solution through batch and semi-continuous DD processes. Batch DD process shows an improved acid recovery ratio (RH) of 70.7% with the Fe2+ rejection ratio (ηFe) of 87.9% after 4 h. As for the semi-continuous DD process, the RH of 91.2% and ηFe of 86.1% can be obtained when the acid feed is flowing in the tubular membrane at 96 mL h−1. In addition, acid of 1.0 mol L−1 can be continuously (>10 h) recovered when the water is flowing at 196 mL h−1. Hence, long tubular membrane cooperated with the 3D-printing dialyzer can be potentially used in DD process to replace the traditional flat membrane dialyzers.