Search

In this study, highly antimicrobial CuNPs were integrated into a hydrophilic polydopamine (PDA) coating and immobilized on a RO TFC membrane via a mild and facile reduction approach to form a stable and durable dual-functional layer. Based on the XDLVO analysis, the introduction of PDA increased the membrane-foulant total interaction energy (ΔG mwf ) to 14.13 mJ/m 2 , resulting in improved anti-adhesive properties as demonstrated by a 37% decrease in BSA adsorption for the modified membranes. The well dispersed and high loadings of CuNPs induced by PDA conferred strong bacterial toxicity to the modified membranes, reducing the viability of E. coli by 76%. Furthermore, the presence of catechol groups on PDA favors the formation of covalent bond with CuNPs, thus prolonging the durability of the copper-based anti-biofouling membranes. The combination of PDA coating and CuNPs functionalization imparts the membrane with simultaneous anti-adhesive and anti-microbial properties, leading to a substantial reduction in biofouling propensity in dynamic biofouling experiments. Specifically, the flux decline due to biofouling observed for the modified membranes significantly decreased from 65% to 39%, and biofilm thickness and TOC biomass were 58%, and 55% lower, respectively. This study provides a facile and versatile strategy to construct high performance RO membranes with excellent anti-biofouling functionality., (Copyright © 2022. Published by Elsevier Ltd.)

The early stage of aggregation of cerium oxide nanoparticles (CeO 2 NPs) in anion solutions was inspected in the absence and presence of extracellular polymeric substance (EPS) with a help of time-resolved dynamic light scattering (DLS). The aggregation kinetics and attachment efficiencies were calculated according to measured hydrodynamic diameter across a range of 1-500 mM NaNO 3 and 0.01-100. mM Na 2 SO 4 . The aggregation of CeO 2 NPs in both NaNO 3 and Na 2 SO 4 solution conformed with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. In NaNO 3 solution, the critical coagulation concentrations (CCC) of CeO 2 NPs was calculated to be about 47 mM; in Na 2 SO 4 solution, CeO 2 NPs showed a re-stabilization process and thus there was no CCC value. SO 4 2- had intenser effects on CeO 2 NPs aggregation than NO 3 - might because of the distinction between their polarization, consisting in Hofmeister series. The presence of bound EPS (B-EPS), tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) in NaNO 3 solutions all lead to significant decrease in CeO 2 NPs aggregation. Steric repulsive force produced by absorbed EPS on CeO 2 NPs might take main responsibility in stabilizing CeO 2 NPs. Besides, Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) model successfully predicted the energy barrier between CeO 2 NPs with B-EPS, TB-EPS and LB-EPS as a function of NaNO 3 concentration. Furthermore, the difference in impeding the CeO 2 NPs aggregation with B-EPS, TB-EPS and LB-EPS may be caused by the divergence in molecular weight and component mass fraction especially protein content. These results might subserve the assessment on the fate and transport behaviors of CeO 2 NPs released in wastewater treatment plants., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Changes in solution chemistry and transport conditions can lead to the release of deposited MnO 2 nanoparticles from a solid interface, allowing them to re-enter the aqueous environment. Understanding the release behavior of MnO 2 nanoparticles from naturally occurring surfaces is critical for better prediction of the transport potential and environmental fate of MnO 2 nanoparticles. In this study, the release of MnO 2 nanoparticles was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), and different environmental surface types, solution pH values and representative macromolecular organics were considered. MnO 2 nanoparticles were first deposited on crystal sensors at elevated NaNO 3 concentrations before being rinsed with double-deionized water to induce their remobilization. The results reveal that the release rate of MnO 2 depends on the surface type, in the decreasing order: SiO 2 > Fe 3 O 4  > Al 2 O 3 , resulting from electrostatic interactions between the surface and particles. Moreover, differences in solution pH can lead to variance in the release behavior of MnO 2 nanoparticles. The release rate from surfaces was significantly higher at pH 9.8 that at 4.5, indicating that alkaline conditions were more favorable for the mobilization of MnO 2 in the aquatic environment. In the presence of macromolecular organics, bovine serum albumin (BSA) can inhibit the release of MnO 2 from the surfaces due to attractive forces. In presence of humic acid (HA) and sodium alginate (SA), the MnO 2 nanoparticles were more likely to be mobile, which may be associated with a large repulsive barrier imparted by steric effects., (Copyright © 2020. Published by Elsevier B.V.)

Engineered nanoparticles (ENPs) will inevitably enter wastewater treatment plants (WWTPs) due to their widespread application; thus, it is necessary to study the migration and transformation of nanoparticles in sewage treatment systems. Extracellular polymeric substances (EPSs) such as polysaccharides, proteins, nucleic acids, humic acids and other polymers are polymers released by microorganisms under certain conditions. Intracellular polymeric substances (IPSs) are microbial substances contained in the body with compositions similar to those of extracellular polymers. In this review, we summarize the characteristics of EPSs and IPSs from sewage-collecting microbial aggregates containing pure bacteria, activated sludge, granular sludge and biofilms. We also further investigate the dissolution, adsorption, aggregation, deposition, oxidation and other chemical transformation processes of nanoparticles, such as metals, metal oxides, and nonmetallic oxides. In particular, the review deeply analyzes the migration and transformation mechanisms of nanoparticles in EPS and IPS matrices, including physical, chemical, biological interactions mechanisms. Moreover, various factors, such as ionic strength, ionic valence, pH, light, oxidation-reduction potential and dissolved oxygen, influencing the interaction mechanisms are discussed. In recent years, studies on the interactions between EPSs/IPSs and nanoparticles have gradually increased, but the mechanisms of these interactions are seldom explored. Therefore, developing a systematic understanding of the migration and transformation mechanisms of ENPs is significant., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The early stage of aggregation of cerium oxide nanoparticles (CeO 2 NPs) in anion solutions was inspected in the absence and presence of extracellular polymeric substance (EPS) with a help of time-resolved dynamic light scattering (DLS). The aggregation kinetics and attachment efficiencies were calculated according to measured hydrodynamic diameter across a range of 1–500 mM NaNO 3 and 0.01–100. mM Na 2 SO 4. The aggregation of CeO 2 NPs in both NaNO 3 and Na 2 SO 4 solution conformed with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. In NaNO 3 solution, the critical coagulation concentrations (CCC) of CeO 2 NPs was calculated to be about 47 mM; in Na 2 SO 4 solution, CeO 2 NPs showed a re-stabilization process and thus there was no CCC value. SO 4 2− had intenser effects on CeO 2 NPs aggregation than NO 3 − might because of the distinction between their polarization, consisting in Hofmeister series. The presence of bound EPS (B-EPS), tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) in NaNO 3 solutions all lead to significant decrease in CeO 2 NPs aggregation. Steric repulsive force produced by absorbed EPS on CeO 2 NPs might take main responsibility in stabilizing CeO 2 NPs. Besides, Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) model successfully predicted the energy barrier between CeO 2 NPs with B-EPS, TB-EPS and LB-EPS as a function of NaNO 3 concentration. Furthermore, the difference in impeding the CeO 2 NPs aggregation with B-EPS, TB-EPS and LB-EPS may be caused by the divergence in molecular weight and component mass fraction especially protein content. These results might subserve the assessment on the fate and transport behaviors of CeO 2 NPs released in wastewater treatment plants. Image 1 • The early stage of aggregation of cerium oxide nanoparticles (CeO 2 NPs) in anion solutions was firstly inspected. • The effect of extracellular polymeric substance extracted from active sludge on CeO2 NP aggregation kinetics was accessed. • The DLVO model and EDLVO model were used to analysis the mechanism of CeO 2 NPs aggregation behavior theoretically. [ABSTRACT FROM AUTHOR]