Photoreduction of Pb(II) Using TiO2 Catalyst Modified with Fe3O4 Nanoparticles

The TiO2/Fe3O4 nanoparticle has been successfully synthesized and the material is then applied as a photocatalyst to reduce Pb(II). The Fe3O4 was synthesized through sono-coprecipitation method using NH4OH as a precipitating agent. The coating TiO2 onto Fe3O4 was performed respectively via hydrolysis reaction and sol-gel process using ammonium sulfate and TTIP as a reagent of TiO2. This study investigated several parameters such as the effect of time, equilibrium state and material responsiveness toward ultraviolet light. The XRD measurement indicated the presence of Fe3O4 and TiO2 while TEM image displayed the photocatalyst had a nanosized particle with approximately 60 nm in size. An activity test at pH 4, the equilibrium of photoreduction process showed at 60 minutes. The kinetic parameter of Pb(II) reduction at various catalyst presented that TiO2/Fe3O4 nanoparticle had better reduction rate constant than that of TiO2. Reusing of TiO2/Fe3O4 photocatalysts showed the results of Pb (II) photoreduction were not significantly decrease and the results of photocatalysis were still better than TiO2.

Nanoceria and Its Biomedical Relevance

Nanoceria is a nanosized particle preparation of cerium oxide. It shows mixture of cerium in the 3+ and 4+ states on the nanoparticle surface, giving it interesting redox properties. Nanoceria shows effective biological antioxidant properties, which makes it a great candidate for biomedical applications. Many studies have shown promising results on therapeutic potential of nanoceria in diseases like cancer, diabetes, atherosclerosis, and neurodegenerative diseases. Meanwhile, other studies explored biodistribution and toxicity of nanoceria. This review article describes nanoceria, its relevant biomedical applications, and adverse effects, based on previously reported studies.

An Analysis of Nanoparticle Settling Times in Liquids

Aggregation and settling are crucial phenomena involving particle suspensions. For suspensions with larger than millimeter-size particles, there are fairly accurate tools to predict settling rates. However for smaller particles, in particular micro-to-nanosizes, there is a gap in knowledge. This paper develops an analytical method to predict the settling rates of micro-to-nanosized particle suspensions. The method is a combination of classical equations and graphical methods. Validated using the experimental data in literature, it was found that the new method shows an order of magnitude accuracy. A remarkable feature of this method is its ability to accommodate aggregates of nonspherical shapes and of different fractal dimensions.

Preparation and Characterization of Polystyrene/TiO2 Core-Shell Nanospheres via Suspension Technique

In the present work, at first, nanoTiO2particles in anatase form were effectively surface modified via reacting with NCO groups of 4,4-methylenediphenyl disocyanate (MDI). Secondly, a solution of azobisisobutyronitrile (AIBN) (0.1 g) in inhibitor-free styrene (10 g) was poured into a 150 mL flask containing poly (vinyl alcohol) (PVA) suspending agent (0.1 g) in deionized water (60 mL) under N2flow, while stirring. The reaction mixture was then heated to 80 °C, and stirred for another 1 h. Next, it was divided to two portions; one for the synthesis of pure PS, and the other for the synthesis of PS/TiO2nanocomposites. Each aqueous portion was individually mixed with dichloromethane in a separating funnel. For PS/TiO2nanocomposites, the organic phase was charged with nanoTiO2particles (MDI-treated and/or untreated) (0.05 g), and then fully homogenized using ultrasonic homogenizer. Methanol non solvent was eventually used to precipitate the products. All samples involving pure PS, PS/surface modified TiO2nanocomposite, and PS/surface unmodified TiO2nanocomposite were thoroughly washed, filtered, and dried in vacuum at 50 °C for 12 h. From SEM images a core-shell relation could be clearly detected between the nanoTiO2particles and PS matrix. Meanwhile, the surface modified TiO2was dispersed into the PS matrix with better homogeneity compared to that of unmodified one. Undoubtedly, beside the surface modification factor, PVA suspending agent as an effective nanosized particle stabilizer, too, played a basic role in this high homogeneity. Also, FT-IR and XRD analyses led to promising results.

Preparation of Graphene/Pd Nanoparticle Composites and their Hydrogen Storage

Pd (en)2Cl2can be intercalated into graphite oxide layers with high efficiency. The Pd (en)22+intercalated graphite oxide was firstly synthesized by mixture reaction of Pd (en)2Cl2and graphite oxide, then it was reduced in solution with NaBH4and thereafter the graphene/Pd nanosized particle composites were obtained. The graphene composites were characterized by XRD, FE-SEM, TEM, ICP and N2adsorption tests and their H2storage was also measured. The results show that the composites contain a large amount of Pd and have a regular mesoporous structure, and Pd particles with a diameter of 2-6 nm are evenly dispersed between graphene sheets and pillar the graphene sheets. The BET surface area of the composites is 230 m2/g and their H2storage reaches 3.4 wt.% at 77K and 0.11 MPa.