Littérature scientifique sur le sujet « Nanorods' purification »

Gold nanorods with localized surface plasmon resonance (LSPR) can be chemically synthesized. We systematically investigated the effects of reaction parameters and centrifugation on the fine tuning of the rod dimension in scale-up production (80–100 mL). Nanorods of absorption bands from 600–1050 nm were fabricated with precise control of the aspect ratio (AR) from 1.5 to 8.9. Although all chemicals are important in directing the nanostructure, silver ion concentration and seed/Au3+ ratio were the most effective variations to adjust the absorption wavelength. With a single surfactant under the influence of silver nitrate, short nanorods up to AR of 5 were synthesized with corresponding maximum absorption wavelength at 902 nm. To achieve higher aspect ratio with absorption band beyond 1,000 nm, two-surfactant growth solution was sought to further elongate the rod length. Centrifugation speed and times were found to exert significant influences on the final rod dimension, which is important during the purification process. In a relatively large quantity nanorod synthesis, even distribution and sufficient mixing of chemical ingredients play an essential role in determining the yield, uniformity, and stability of the final nanorod formation.

To make full use of urban household balcony space, an urban aquaponics system for balconies was constructed to investigate the purification effects of four different substrates (volcanic stone, ceramic pellets, ceramic rings, and nanorods) and six plants (mung bean sprouts, hollow cabbage, water celery, lettuce, leek, and water chestnut) on fish culture wastewater. Through the determination of contaminants such as nitrogen and phosphorus and through the use of 16SrDNA sequencing technology, the substrate material and plant combinations with the best purification effects were screened. The results show that volcanic stone and nanorods have strong purification capacities. Compared to the other substrate types, there were more unique bacterial species on the surface of volcanic stone, among which amoeba species were the most dominant (92.42%). Among the six tested plant species, mung bean sprouts had the highest contribution to nitrogen uptake (94.96%), and water chestnut had the highest contribution to phosphorus uptake at 12.07%. Finally, the combination of nanorods and water celery was the best at purifying the wastewater. This study provides a theoretical basis and new ideas for the construction of urban aquaponics systems on balconies, which will help to achieve green farming and the efficient utilization of water resources.

High surface area zinc oxide material in nanorod morphological structure was synthesized using an ultrasonic technique in the presence of polyvinyl pyrrolidone as stabilizing agent. The crystallite, morphology, and surface area of the prepared white powder material were identified using XRD, SEM, and BET techniques, respectively. X-ray analysis confirms the high purity of synthesized ZnO. The evaluated specific surface area of prepared ZnO was 16.7 m2/g; this value guarantees high efficiency for water purification. The feasibility of synthesized ZnO nanorods for phosphorus sorption from aqueous solution was established using batch technique. Nano-zinc oxide exhibits high efficiency for phosphorus removal; the equilibrium state was recorded within 90 minutes. The most effective hydrogen ion concentration of the polluted solution was recorded at pH = 1 for phosphorus decontamination. The equilibrium of phosphorus sorption onto ZnO nanorods was well explained using both Langmuir and Temkin isotherm models. The calculated maximum monolayer sorption capacity was 89 mg/g according to Langmuir isotherm at 27°C. In order to explain the phosphorus sorption mechanism onto the prepared ZnO nanorods, three simplified kinetic models of pseudo-first order, pseudo-second order, and intraparticle diffusion rate models were tested. Kinetics was well fitted by pseudo-second order kinetic model with a contribution of intraparticle diffusion.

ZnO nanorods (NRs) films, nitrogen-doped (ZnO:N), and ZnO doped with nitrogen and decorated with silver nanostructures (ZnO:N-Ag) NRs films were vertically supported on undoped and N doped ZnO seed layers by a wet chemical method. The obtained films were characterized structurally by X-ray diffraction. Morphological and elemental analysis was performed by scanning electron microscopy, including an energy dispersive X-ray spectroscopy facility and their optical properties by Ultraviolet-Visible Spectroscopy. Analysis performed in the NRs films showed that the nitrogen content in the seed layer strongly affected their structure and morphology. The mean diameter of ZnO NRs ranged from 70 to 190 nm. As the nitrogen content in the seed layer increased, the mean diameter of ZnO:N NRs increased from 132 to 250 nm and the diameter dispersion decreased. This diameter increase occurs simultaneously with the incorporation of nitrogen into the ZnO crystal lattice and the increase in the volume of the unit cell, calculated using the X-ray diffraction patterns and confirmed by a slight shift in the XRD angle. The diffractograms indicated that the NRs have a hexagonal wurtzite structure, with preferential growth direction along the c axis. The SEM images confirmed the presence of metallic silver in the form of nanoparticles dispersed on the NRs films. Finally, the degradation of methyl orange (MO) in an aqueous solution was studied by UV-vis irradiation of NRs films contained in the bulk of aqueous MO solutions. We found a significant enhancement of the photocatalytic degradation efficiency, with ZnO:N-Ag NRs film being more efficient than ZnO:N NRs film, and the latter better than the ZnO NRs film.

High-efficiency, cost-affordable and environmentally sound catalysts are urgently needed for indoor air purification. Herein, we report the first investigation on room-temperature removal capabilities of AMoO 4 ( A = Ni and Co ) and derived molybdate– Pt composites with uniform nanorod morphology. The HCHO removal or oxidation capabilities and mechanisms are also compared and rationalized, which, we hope, can form a solid basis for potential applications of molybdate for indoor air purification.

Rod-shaped gold nanoparticles, namely gold nanorods (GNRs) have recently attracted a widespread attention due to their unique optical properties and facile synthesis. In fact, GNRs exhibit two distinct localized surface plasmon resonances (SPRs): the transversal mode in the visible region (TSPR) and the longitudinal one in the upper visible or nearinfrared part of the spectrum (LSPR) that correspond to the oscillations perpendicular or parallel to the rod length direction, respectively. In particular, the LSPR can be tailored to a particular wavelength: there is a linear relationship between the absorption maximum of the LSPR band and the mean aspect ratio (AR, ratio between the length and the width of the rod) of GNRs, which can be tuned during the synthesis. Other factors of impact on the frequencies of both TSPR and LSPR bands are the refractive index of the environment and the degree of particle aggregation. In addition, the surface of GNRs can be functionalized with a variety of molecules, providing stability and biocompatibility. All these features make GNRs ideal platforms for several applications and, in particular, for biomedical applications such as sensing, photo-acoustic imaging, photothermal treatment of cancer and drug delivery. However, several problems are connected to the synthesis and purification of GNRs, as well as to their use for biomedical applications. All these issues are addressed within the present PhD thesis, with special attention for GNRs which are well suitable for protein sensing, the photothermal treatment of cancer, and the realization of nanocapsules as drug delivery systems. Specifically, in the Introduction, a brief history of gold nanoparticles and gold nanorods, together with the synthetic procedure with an insight into the growth mechanism of GNRs, their optical properties and their biomedical applications, are addressed. In Chapter 1 the issues connected to the most common synthesis of GNRs (e.g. the difficulty to obtain relatively small GNRs and the precise control of the LSPR) are illustrated. Therefore a simple and reproducible method for the synthesis of small-sized GNRs with a good control over the LSPR is reported. A modified method for the purification of small GNRs from reaction by-products (i.e. spherical and cubic nanoparticles or aggregates) is accurately described in Chapter 2 with particular attention to the quantification of the separation. Chapter 3 is focused on the realization and characterization of functionalized GNRs for therapeutic applications. Although the available literature is inconclusive, particle size may modulate critical parameters such as: the cellular penetration, the intracellular localization, the biodistribution, features that depend on specific surface area, including the rate of interaction with proteins, residual toxicity of contaminants, the ratio between absorption and scattering of the particles and the efficiency and stability of photothermal conversion. Specifically, this chapter offers an extensive survey on the size related biological effects of functionalized GNRs (i.e. PEGylated GNRs), with special attention for the cytotoxicity and cellular uptake of GNRs on a panel of cellular models. In Chapter 4, the possibility to tune the interactions between GNRs with proteins is illustrated by direct monitoring the LSPR of GNRs, which is highly sensitive to changes in the refractive index. In particular, the effect of the insertion of charged groups in PEGylated GNRs on their protein interactions is reported, providing useful hints for protein sensing applications. Finally, in Chapter 5 is focused on the generation of nanosized capsules through self assembling of GNRs to be used for the delivery of hydrophobic anticancer drugs. These GNR-stabilized nanocapsules could provide highly localized release of anticancer therapeutics, maximizing the therapeutic efficacy and minimizing off-target effects. These studies could provide the basis for future pre-clinical animal studies that could lead to an important new therapeutic strategy for tumors.