Construction of covalently-bonded tannic acid/polyhedral oligomeric silsesquioxanes nanochannel layer for antibiotics/salt separation

Abstract Nanoscale permeation channels are a key factor for molecules or/and ions separation in membrane field. In this work, molecular deposition strategy is designed to construct high-performance nanochannel separation layer for selective separation of small molecules. Herein, octaammonium polyhedral oligomeric silsesquioxane (8NH3Cl-POSS) and tannic acid (TA), two kinds of multifunctional molecules with a size of about 1 nm, were used to prepare robust and perm-selective composite membrane through covalently-bonded layer-by-layer (LbL) self-assembly method. The optimized TA-POSS composite membrane exhibited a narrowed pore size distribution from 0.3 to 1.6 nm with a high water permeance of 21 L m−2 h−1 bar−1. The membrane showed desirable rejection of antibiotics (>90%) and enabled to separate them from NaCl solution. In addition, TA-POSS composite membrane showed outstanding stability due to the high degree of crosslinking between TA and 8NH3Cl-POSS and their rigid structures. This work gives a novel and green strategy to construct nanochannel composite membranes, which can efficiently separate molecules and salt.