Polyethyleneimine-facilitated high-capacity boronate affinity membrane and its application for the adsorption and enrichment of cis-diol-containing molecules

Membrane separation has notably important applications in many fields. Boronate affinity provides a method to specifically recognize cis-diol-containing molecules. However, there is no report on the preparation and application of boronate affinity membranes. In the present study, high-capacity boronate affinity membranes were synthesized by grafting polyethyleneimine (PEI) to regenerated-cellulose (RC) membranes and subsequently coupling 4-formylphenylboronic acid. Detailed physical characterizations using Attenuated Total Reflection Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed the success of the synthesis. The morphology of the membranes, which were characterized using an atomic force microscope (AFM), indicates that the membrane became smoother after the polymer was grafted. The boronate affinity membrane had high selectivity and a high adsorption capacity for cis-diol-containing molecules; its saturated adsorption capacity for catechol, salbutamol, dopamine and adenosine was 511, 103, 472 and 120 mu mol g(-1), respectively, which is much higher than that of most reported particulate or monolithic adsorbents. In addition, the membrane showed notably fast adsorption and desorption equilibration for the cis-diol-containing molecules. It was successfully used to enrich dopamine in urine samples with notably efficient reusability, which indicates its promising application in the pretreatment of real complex samples.