Anti-Biofouling and Desalination Properties of Thin Film Composite Reverse Osmosis Membranes Modified with Copper and Iron Nanoparticles.

M Armendariz Ontiveros,A Llanquilef,A García García,Y Quintero,M Morel,L Argentel Martínez,A Garcia

doi:10.3390/ma12132081

Abstract

The anti-biofouling and desalination properties of thin film composite reverse osmosis membranes (TFC-RO), modified by the incorporation of copper and iron nanoparticles, were compared. Nanoparticles of metallic copper (CuNPs) and an iron crystalline phase mix (Fe and Fe2O3, FeNPs) were obtained by oxide-reduction-precipitation and reduction reactions, respectively, and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Modified membranes (PA+0.25Cu-PSL and PA+0.25Fe-PSL) were obtained by incorporating these nanoparticles during the interfacial polymerization process (PI). These membranes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and contact angle measurements. Bactericidal tests by a Colony Forming Unit (CFU) were performed using Escherichia coli, and anti-adhesion properties were confirmed by fluorescence microscopy estimating the percentage of live/dead cells. The permeate flow and rejection of salts was evaluated using a crossflow cell. An increase of the membrane’s roughness on the modified membrane was observed, influencing the desalination performance more strongly in the presence of the FeNPs with respect to the CuNPs. Moreover, a significant bactericidal and anti-adhesion effect was obtained in presence of both modifications with respect to the pristine membrane. An important decrease in CFU in the presence of modified membranes of around 98% in both modifications was observed. However, the anti-adhesion percentage and reduction of live/dead cells were higher in the presence of the copper-modified membrane in comparison to the iron-modified membrane. These facts were attributed to the differences in antimicrobial action mechanism of these types of nanoparticles. In conclusion, TFC-RO membranes modified by the incorporation of CuNPs during PI represent one alternative material to attend to the biofouling impact in the desalination process.

Highlights

Reverse osmosis (RO) desalination is a possible alternative that reduces water scarcity rates worldwide [1]
Materials 2019, 12, 2081 interfacial polymerization process, which consists of a combination of an aqueous m-phenylenediamine (MPD) solution and an organic trimesoyl chloride (TMC) solution [3]
The adding of Cu nanoparticles (CuNPs) and FeNPs within the PA layer of the thin film composite reverse osmosis membranes (TFC-RO) membranes during the interfacial polymerization process increased the membrane roughness, thereby affecting the desalination performance, and this effect was more remarkable in the membrane modified with FeNPs

Summary

Introduction

Reverse osmosis (RO) desalination is a possible alternative that reduces water scarcity rates worldwide [1]. In order to avoid biofouling in the membranes, researchers have incorporated, on the PA layer, different inorganic nanoparticles (NPs) with antimicrobial properties, such as Ag, TiO2 , and ZnO, among others [6,7,8]. Some of these NPs are quite expensive because of the extraction process from the earth and are difficult to synthesize. It is necessary to use antimicrobial NPs that are easy to obtain from nature, easy to synthesize, and are added to TFC membranes without significant costs to the desalination process, such as copper and iron nanoparticles [9,10,11]

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