Nanoparticle filtration

Shylesh, S., Wang, L. and Thiel, W.R. (2010) Palladium(II)-phosphine complexes supported on magnetic nanoparticles filtration-free, recyclable catalysts for Suzuki-Miyaura crosscoupling reactions. Advanced Synthesis and Catalysis, 352 (2-3), 425-432. 

Nanoparticle penetration has been measured with a wide range of filter media by using silver nanoparticles from 3 nm to 20 nm at three different face velocities in order to define nanoparticle filtration characteristics of commercial fibrous filter media. After size classification by using a nano-DMA, the particle counts were measured by an ultrafine condensation particle counter (UCPC) both upstream and downstream of the test filter in order to determine the nanoparticle penetration for each specific... 

Yun, K.M., Hogan, C.J., Matsubayashi, Y, Kawabe, M., Iskandar, E, Okuyama, K., 2007. Nanoparticle filtration by electrospun polymer fibers. Chemical Engineering Science 62, 4751-4759. 

Another method to synthesize hollow nanocapsules involves the use of nanoparticle templates as the core, growing a shell around them, then subsequently removing the core by dissolution [30-32]. Although this approach is reminiscent of the sacrificial core method, the nanoparticles are first trapped and aligned in membrane pores by vacuum filtration rather than coated while in aqueous solution. The nanoparticles are employed as templates for polymer nucleation and growth Polymerization of a conducting polymer around the nanoparticles results in polymer-coated particles and, following dissolution of the core particles, hollow polymer nanocapsules are obtained. 

The purification methods for metal nanoparticles involve (1) evaporation, (2) centrifugation, (3) extraction, (4) filtration, and (5) other methods. 

Conventional filtration cannot be applied to the separation in purification of metal nanoparticles. If the metal nanoparticles are protected by polymer, however, the membrane filter, which can cut off the pol5mer with certain molecular weight, can be used to separate the polymer protected metal nanoparticles. Free metal nanoparticles which are not protected by polymer can pass through the membrane. Ion filter like cellulose can be used to separate ionic species from the reaction mixtures. 

In order to obtain the optimal performance of CNTs in various applications, high purity CNTs will be required. Purification of CNTs generally refers to the separation of CNTs from other entities, such as carbon nanoparticles, amorphous carbon, residual catalyst, and other unwanted species. A number of purification methods including acid oxidation, gas oxidation, filtration, and chromatography have been developed to date. In many cases, various combinations of these methods are used to obtain high quality CNTs. 

Reszka et al. [168] used ultrahltration to separate free mitoxantrone from PBCA nanoparticles. The particle suspension was passed through a cellulose nitrate membrane with a pore size of 20 nm with magnetic stirring and pressurized nitrogen. The filtrate obtained was analyzed for free drug content. Recovery of the particles is not possible with... 

Different results on D. magna have been reported (Lovem and Klaper, 2006). Mortality has been described in presence of fullerene nanoparticles obtained by tetrahydrofuran (IHF) dispersion in water, subsequent filtration, and removal of the organic solvent. This effect was concentration-dependent, reaching total mortality at 880 ppb. On the contrary, C60 nanoparticles prepared by sonication gave nonuniform lethal effects, without concentration dependence. 

In this building-block approach, the components are synthesized separately and then hybridized via linking agents/methods that utilize covalent, noncovalent (van der Waals, n-n interactions, hydrogen bonding), or electrostatic interactions. The attachment of these building blocks often requires the chemical modification of at least one component to overcome the differences in surface chemistry. As a consequence deposition is often limited to the first layer. Excess nanoparticles can be removed by filtration or centrifugation. 

Kong, B.-S., J. Geng, and H.-T. Jung, Layer-by-layer assembly of graphene and gold nanoparticles by vacuum filtration and spontaneous reduction of gold ions. Chemical Communications, 2009(16) p. 2174-2176. 

In both procedures purification of the nanoparticles was carried out either by means of filtration of the suspension over a 0.2 pm cellulose acetate filter or by Eppendorf centrifuging for 15 min followed by resuspension in water up to a final suspension of the nanoparticles in PBS buffer (pH 7.2) or in physiological solution. Nanoparticles loaded with a fluorescent marker... 

After reduction, Pd nanoparticles in the range of 5.2 nm were obtained. Particle size could be controlled by the ratio of -OH groups to Pd. Hydrogenation of cyclohexene in toluene gave a TON of 20 000 corresponding to a TOP of 700 h atm(H2) at 75% cyclohexene conversion. The catalyst was easily separated from the product by vacuum distillation and/or dialysis or membrane filtration [76]. 

The suspension is filtered through a 150-mL medium-porosity fritted Buchner funnel to collect the solid, crude nanoparticles. The filtrate should be colorless. The product is triturated with the following solvent combinations to remove the tetraoctylammonium bromide ... 

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