Metal oxide nanoparticles are used in a wide range of commercial products, leading to an increased interest in the behavior of these materials in the aquatic environment. The current study focuses on the stability of some of the smallest ZnO nanomaterials, 4 ± 1 nm in diameter nanoparticles, in aqueous solutions as a function of pH and ionic strength as well as upon the adsorption of humic acid. Measurements of nanoparticle aggregation due to attractive particle-particle interactions show that ionic strength, pH, and adsorption of humic acid affect the aggregation of ZnO nanoparticles in aqueous solutions, which are consistent with the trends expected from Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Measurements of nanoparticle dissolution at both low and high pH show that zinc ions can be released into the aqueous phase and that humic acid under certain, but not all, conditions can increase Zn(2+)(aq) concentrations. Comparison of the dissolution of ZnO nanoparticles of different nanoparticle diameters, including those near 15 and 240 nm, shows that the smallest nanoparticles dissolve more readily. Although qualitatively this enhancement in dissolution can be predicted by classical thermodynamics, quantitatively it does not describe the dissolution behavior very well.

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Graphene/cotton composite fabrics were successfully synthesized via a facile “dipping and drying” process followed by a NaBH4 reduction method.

Carbon nitride nanotubes were produced by using porous anodic aluminum oxide membranes as the template through a polymerization reaction between ethylenediamine and carbon tetrachloride. The synthesized nanotubes were systematically studied by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transform IR, X-ray photoelectron spectroscopy (XPS), elemental analysis, and thermogravimetric analysis (TGA). The so-called carbon nitride materials obtained from this method were in fact carbon materials doped with nitrogen, and were partially oxidized. The carbon nitride nanotubes were then loaded with Pt nanoparticles, which are mostly loaded at the outside wall of the nanotubes and show excellent catalytic ability in cyclohexene hydrogenation.

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