Abstract

The improvement of reverse osmosis (RO) membranes represents a field of great interest, on a consolidated RO desalination and water treatment industry. Biofouling is a problem of high industrial impact, due to the negative incidence of microorganisms in the membrane modules, impairing the RO process. Copper is a very important raw material at the scientific-technological level due to its biocidal properties. Thus, for example, modifiers derived from copper, could be used to deal with biofouling in-situ. In this study, a route of surface modification of commercial membranes, through chemical functionalization and incorporation of copper derived nanoparticles to confer anti-biofouling properties, is proposed. Surface modifications were performed on commercial TFC-RO BW30 type membranes using a fourstep route: (i) surface activation by N-Hydroxysuccinimide reactive ester (NHS ester) formation on the carboxylate sites, (ii) grafting with polyethyleneimine (PEI) by direct reaction with the NHS ester sites, (iii) surface functionalization with chelating poly-phosphonic acid (Diethylenetriaminepentakis(methylphosphonic acid), DTPMP) and (iv) incorporation of colloidal copper oxide nanoparticles, previously optimized in another study. The surficial changes, groups formed and present species after each stage of the modification were systematically studied. The effects of surface treatment on the morphology of the active layer were verified. Operating performance tests were performed under brackish water treatment conditions, using a flat plate RO setup. Subsequently, biocidal tests were performed on the samples. The results show effectiveness in surface modification at all stages. Operational results show similar behavior to unmodified samples under brackish water RO filtration conditions (J=42.66±10.53 LMH; R=97.5±1.5 %; 1000 ppm NaCl, 600 psi, 25°C) and biocidal effectiveness against bacteria (49% vs. E. Coli). The surface-modified TFC membranes in this work show a potential utility against biofouling problems without affecting operational performance.