A PEG-tannic acid decorated microfiltration membrane for the fast removal of Rhodamine B from water

A polyether sulfone (PES) microfiltration membrane was decorated by the deposition of mixture of polyethylene glycol (PEG) and tannic acid (TA). It was used as an adsorbent for the removal of Rhodamine B (RhB) from water and had a high removal ratio (>98.9%) at high flux up to 4777 L/(m2⋅h) in dynamic test. The mixture of PEG and TA formed a stable suspension but it transformed to a viscous mixture during permeating the narrow channel of membrane, which resulted in high dispersion of the TA within the membrane and good dye adsorption. The turbulence and high driving force in the dynamic test ensured good contact of dye and the adsorbent, which led to good dye removal, while in stationary adsorption test it had only moderate dye adsorption. Molecular dynamics study revealed the molecular weight of PEG had an effect on the aggregation morphology of PEG and TA, as well as the exposure of TA on the surface, leading to different removal performance. Our study provided a simple and quick method to prepare adsorbent for the fast removal of dye from water.