With the rapid development of nanotechnology and widespread use of nanoproducts, the ecotoxicity of nanoparticles (NPs) and their potential hazards to the environment have aroused great concern. Nanoparticles have increasingly been released into aquatic environments through various means, accumulating in aquatic organisms through food chains and leading to toxic effects on aquatic organisms. Nanoparticles are mainly classified into nano-metal, nano-oxide, carbon nanomaterials and quantum dots according to their components. Different NPs may have different levels of toxicity and effects on various aquatic organisms. In this paper, algae are used as model organisms to review the adsorption and distribution of NPs to algal cells, as well as the ecotoxicity of NPs on algae and fate in a water environment, systematically. Meanwhile, the toxic effects of NPs on algae are discussed with emphasis on three aspect effects on the cell membrane, cell metabolism and the photosynthesis system. Furthermore, suggestions and prospects are provided for future studies in this area.
This study prepares a new form of cellulose/graphene composite (CGC) by mixing dissolved cellulose with graphene oxide and reducing it with hydrazine hydrate. The composite particles achieve higher adsorption levels than five other sorbents (graphite carbons, primary secondary amine (PSA), graphite carbon black (GCB), cellulose, and graphene) for six triazine pesticides. The adsorption process only requires adding 30 mg of CGC for 10 mL of solution of triazine pesticides. The mixture is hand-shaken five times at pH 9. The equilibrium adsorption isotherm reveals that the Langmuir model describes the adsorption process better. Thermodynamic parameters indicate that adsorption is spontaneous, favorable, and endothermic in nature. Furthermore, the CGC is very stable and can easily be recycled using a simple organic solvent. The adsorption efficiency of the CGC is still over 85% after six times of recycling.
Biodegradable poly(ε-caprolactone) (PCL) and octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) nanocomposites were prepared at low ovi-POSS loadings via a solution casting method in this work. Scanning electron microscopy observation reveals not only the fine dispersion but also the crystallization of ovi-POSS in the PCL matrix. The overall isothermal melt crystallization kinetics, spherulitic morphology, crystal structure, and dynamic mechanical properties of neat PCL and its nanocomposites were studied with various techniques. The presence of ovi-POSS has enhanced the overall isothermal melt crystallization rates of PCL in the nanocomposites; however, the crystallization mechanism and crystal structure of PCL remain unchanged despite the ovi-POSS loading. In addition, the storage modulus of the nanocomposites has been enhanced significantly relative to neat PCL, while the glass transition temperature varies slightly irrespective of the presence of ovi-POSS.
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