Composite membranes from bio-inspired catechol-amine coatings for pervaporation desalination

Compared with reverse osmosis, pervaporation is less influenced by the osmosis pressure of the feed solution, which endows it as an attractive desalination technology. Many researches focus on developing high-performance pervaporation desalination membranes. Bio-inspired polyphenol coatings are versatile tools for engineering membrane surfaces. Here, catechol-amine chemistry was the first time applied to construct dense composite pervaporation desalination membranes via a stepwise coating method. Tannic acid (TA) and polyethyleneimine (PEI) were chosen as typical materials. Fabrication parameters, including TA and PEI concentrations in the coating solution, pH, and thermal annealing, are crucial to the desalination performance of the resulting membranes. The TA-PEI interactions were studied by the UV–Vis absorption spectroscopy method. The membrane prepared at optimal conditions exhibits excellent desalination performance. The water flux was 43 kg/(m2·h) at 50 °C for the feed of 3.5 wt% NaCl solution (95 kg/(m2·h) at 70 °C). The intrinsic hydrophilicity of the selective layer material ensures the membrane processes of good antifouling performance. This work demonstrates the possibility and potential of applying bio-inspired catechol-amine chemistry to prepare pervaporation desalination membranes.