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

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.

Nanometals-Containing Polymeric Membranes for Purification Processes

“…Some iron nanoparticles have negative properties towards microorganisms. They limit the transport of nutrients to bacterial cells, causing nutritional imbalance and metabolic weakening of bacteria, and they generate oxidative stress by producing some reactive oxygen species (ROS) with free radicals (Fenton or Fenton-like reaction), damaging cellular proteins, lipids, and DNA and eventually leading to bacterial death [ 149 ]. However, it should be remembered that, for some microorganisms, iron may be a factor necessary for their development and multiplication; therefore, depending on the composition of the biocenosis of the purified solution, both the composition of nanoparticles as well as their size and shape must be properly adjusted.…”

Influence of Multidimensional Graphene Oxide (GO) Sheets on Anti-Biofouling and Desalination Performance of Thin-Film Composite Membranes: Effects of GO Lateral Sizes and Oxidation Degree

“…After, the casting solution obtained was uniformly dispersed onto glass plate using a casting knife with the knife gap set at 200 µm (BYK, Geretsried, Germany). The PS support was immersed into water coagulation bath for 1 min at room temperature, and washed with water for 24 h. The PA layer was prepared using the interfacial polymerization method on PS support [23,64]. The PS support was immersed in aqueous MPD (2 wt %) solution for 2 min, and then was immersed in TMC (0.2 wt %) hexane solution for 1 min.…”

Biofouling of FeNP-Coated SWRO Membranes with Bacteria Isolated after Pre-Treatment in the Sea of Cortez

“…The other membrane was not coated (uncoated membrane) and used as blank for reference and comparison. The FeNPs were synthetized and characterized [18,19] according to the method of Baltazar et al [33] and Arancibia-Miranda et al [34]. The chemical structures and morphology of the FeNPs were characterized by X-ray Diffraction (XRD) using a Shimadzu XRD-6000 diffractometer (Kyoto City, Japan) and Scanning Electron Microscopy (SEM) using a Nova NanoSEM-200 (FEI Company, Hillsboro, OR, USA).…”

“…This can also be associated with the oxidative stress that has been shown to be caused by the generation of ROS by FeNPs, leading to damage of cellular DNA, lipids and proteins, causing bacterial death [46,47]. The existence of this latter mechanism also suggests that the Fenton reaction facilitated by the FeNPs can cause the death of different bacteria, not only of Bacillus halotolerans MCC1 [19,46], since the FeNPs in the presence of dissolved oxygen and water form hydrogen peroxide and Fe +2 ions. The hydrogen peroxide and Fe +2 then, in turn, initiate the Fenton reaction cycle, which produces several ROSs with strong biocidal effects.…”

“…However, these NPs are expensive and difficult to synthetize; therefore, their use as a membrane coating increases desalination costs. Iron nanoparticles (FeNPs) are a promising coating agent, as they cost less than other NPs, are easy to synthesize and have a biocide effect by promoting Fenton or Fenton-like reactions, producing oxidative stress by generating reactive oxygen species (ROS), disrupting lipids, proteins and DNA, and eventually causing bacterial death [17][18][19].…”