No abstract

Bio-polyphenols that are present in tea, date fruits, chockolate and many other plants have been recognized as scaffold material for the manufacture of composite filtration membranes. These phenolic biomolecules possess abundant gallol (1,2,3-trihydroxyphenyl) and catechol (1,2dihydroxyphenyl) functional groups, which allow the spontaneous formation of a thin polymerized layer at the right pH conditions. Here, we report a facile and cost-effective method to coat porous membranes via the complexation of tannic acid (TA) and cupric acetate (mono hydrate) through co-deposition. The modified membranes were investigated by XPS, ATR/FTIR, water contact angle, SEM and water permeance for a structural and morphological analysis. The obtained results reveal that the modified membranes with TA and cupric acetate (CuII) developed a thin skin layer, which showed excellent hydrophilicity with good water permeance. These membranes were tested with different molecular weight polyethylene glycols (PEG) in aqueous solution; the MWCO was around 600 Daltons.

Utilization of sustainable and environmentally friendly solvents for the preparation of membranes has attracted growing interest in recent years. In this work, a polyester thin film composite solvent resistant nanofiltration (SRNF) membrane was prepared by interfacial polymerization on a cellulose support. The cellulose support was prepared by non-solvent induced phase separation from a dope solution containing an ionic liquid as an environmentally friendly solvent (negligible vapour pressure). The polyester film was formed via the interfacial reaction between quercetin, a plant-derived polyphenol, and terephthaloyl chloride. Alpha-pinene was used as a green alternative solvent to dissolve TPC while quercetin was dissolved in a 0.2 M NaOH solution. The interfacial polymerization reaction was successfully confirmed by Fourier Transform Infrared and X-Ray Photoelectron Spectroscopy while scanning electron and atomic fore microscopy were used to characterize the membrane structure. The composite membrane showed an outstanding performance with a molecular weight cutoff around 330 combined with a dimethylformamide (DMF) permeance up to 2.8 L. m-2 bar-1 hr-1. The membrane was stable in strong aprotic solvents such as DMF offering potential application in the pharmaceutical and petrochemical industries.

In this work, a novel thin-film composite membrane composed of a polyester film on a cellulose support was successfully synthesised. The polyester film was formed from the interfacial reaction between catechin, a bio-derived poly-phenol, and terephthaloyl chloride (TPC). The cellulose support was prepared by non-solvent induced phase separation from a weight cut-off of around 500 g mol -1 . The membrane was stable in DMF over 30 days with no significant change in performance. The membrane has potential application in the food and pharmaceutical industries.

Highlights  Tannic acid was used as an effective building block for solvent-resistant membranes.  NMP resistant membranes with a molecular weight cutoff below 800 g/mol were manufactured.  Cross-linked PAN was applied as support membrane.