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Zeolite-polyamide thin film nanocomposite membranes were coated onto polysulfone ultrafiltration membranes by interfacial polymerization of amine and acid chloride monomers in the presence of Linde type A zeolite nanocrystals. A matrix of three different interfacial polymerization chemistries and three different-sized zeolite crystals produced nanocomposite thin films with widely varying structure, morphology, charge, hydrophilicity, and separation performance (evaluated as reverse osmosis membranes). Pure polyamide film properties were tuned by changing polymerization chemistry, but addition of zeolite nanoparticles produced even greater changes in separation performance, surface chemistry, and film morphology. For fixed polymer chemistry, addition of zeolite nanoparticles formed more permeable, negatively charged, and thicker polyamide films. Smaller zeolites produced greater permeability enhancements, but larger zeolites produced more favorable surface properties; hence, nanoparticle size may be considered an additional "degree of freedom" in designing thin film nanocomposite reverse osmosis membranes. The data presented offer additional support for the hypothesis that zeolite crystals alter polyamide thin film structure when they are present during the interfacial polymerization reaction.

Assessing nanomaterialsfor human health and ecotoxicological impact can be well aided by using high-throughput laboratory methods.

A simple, analytical method for predicting transport of uncharged organic solutes through nanofiltration (NF) and reverse osmosis (RO) membranes is presented in this paper. The method requires characterization of key solute and membrane parameters-namely, solute size, membrane pore size, and solute-membrane affinity. All three parameters can be experimentally determined from relatively simple permeation tests and contact angle analyses. The parameters are fed into an analytical model of solute transport, which accounts for hindered convection and diffusion of solutes in the membrane pores, as well as the combined effects of steric exclusion and solute-membrane affinity on solute partitioning from the feed solution into the membrane pores. Overall model predictions for organic solute rejection agreed well with experimental data for three different solutes and two different polymeric NF membranes. Further, the model demonstrates the dramatic influence of solute-membrane affinity on organic rejection by NF and RO membranes. Solute transport predictions made assuming only steric exclusion significantly overestimated rejections for solutes with strong affinity for membrane polymers and similarly underestimated rejections for solutes that were strongly repelled by membrane polymers.

Rapid growth in nanotechnology is increasing the likelihood of engineered nanomaterials coming into contact with humans and the environment. Nanoparticles interacting with proteins, membranes, cells, DNA and organelles establish a series of nanoparticle/biological interfaces that depend on colloidal forces as well as dynamic biophysicochemical interactions. These interactions lead to the formation of protein coronas, particle wrapping, intracellular uptake and biocatalytic processes that could have biocompatible or bioadverse outcomes. For their part, the biomolecules may induce phase transformations, free energy releases, restructuring and dissolution at the nanomaterial surface. Probing these various interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings. This knowledge is important from the perspective of safe use of nanomaterials. [ABSTRACT FROM AUTHOR]

High-throughput screening was employed to evaluate bactericidal activities of hybrid Ag-TiO2 nanoparticles comprising variations in TiO2 crystalline phase, Ag content, and synthesis method. Hybrid Ag-TiO2 nanoparticles were prepared by either wet-impregnation or UV photo deposition onto both Degussa P25 and DuPont R902 TiO2 nanoparticles. The presence of Ag was confirmed by ICP, TEM, and XRD analysis. The size of Ag nanoparticles formed on anatase/rutile P25 TiO2 nanoparticles was smaller than those formed on pure rutile R902. When activated by UV light, all hybrid Ag-TiO2 nanoparticles exhibited stronger bactericidal activity than UV alone, Ag/UV, or UV/TiO2. For experiments conducted in the dark, bactericidal activity of Ag-TiO2nanoparticles was greater than either bare TiO2 (inert) or pure Ag nanoparticles, suggesting that the hybrid materials produced a synergistic antibacterial effect unrelated to photoactivity. Moreover, less Ag+ dissolved from Ag-TiO2 nanoparticles than from Ag nanoparticles, indicating the antibacterial activities of Ag-TiO2 was not only caused by releasing of toxic metal ions. It is clear that nanotechnology can produce more effective bactericides; however, the challenge remains to identify practical ways to take advantage of these exciting new material properties. [ABSTRACT FROM AUTHOR]