Oxides, filtration

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. 

FILTER SOLUTION TO REMOVE UNDISSOLVED CALCI-OXIDE. FILTRATE CONTAINS CALCIUM ACETATE. 

Anhydrous sodium trithionate is formed in about 80-85% yield when the sulfate-free oxidized filtrate is run slowly into 150ml of alcohol. The precipitated crystalline salt is washed on the filter with about 50ml of alcohol and dried in air. 

Electrochemical coprecipitation with iron electrodes may also be effective in removing As(V) from water (Table 7.1). Recently, Sagitova et al. (2005) developed an electrochemical unit for treating household water. The unit oxidizes As(III) to As(V). A sacrificial anode creates dissolved iron, which coprecipitates As(V) with iron (oxy)(hydr)oxides. Filtration of the iron (oxy)(hydr)oxides can lower the arsenic concentrations of the water to below 10pgL 1. 

The following were introduced into 288 ml of phenyl oxide 96.10 grams of 5,5-dimethyl-hydantoin, 170.86 grams of 2-nitro-5-chloro trifluoromethylbenzene and 89.40 grams of cupric oxide. The mixture was heated to 190°C for about 23 hours, then cooled to 20°C and filtered. The residue was characterized in the phenyl oxide filtrate by thin layer chromatography. The analytical results obtained for these 5 examples were identical to those obtained and indicated in French Patent No. 2,329,276. 

The nitrator contents are drawn off to the filter tank (1) (Fig. 110). The tank is lead-lined and equipped with a ventilating pipe for conducting away nitrogen oxide. Filtration is most effective with a 20-cm layer of coarse-grained dinitronaphthalene as a filter material, placed between perforated plates of sheet aluminium. 

Nearly all indigo is produced from N-phenylglycine (see Fig. 8.18) via fusion with potassium and sodium hydroxide, followed by treatment with sodamide [103]. The melt containing the dialkalimetal salt of indoxyl is subsequently dissolved in water, and indigo is formed by aerobic oxidation. Filtration and wash-... 

Aldushin, A. R, Ivleva, T. R, Merzhanov, A. G., Khaikin, B. I., and Shkadinskii, K. G., Combustion front propagation in porous exothermic metallic samples with oxidizer filtration. In Combustion Processes in Chemical Engineering and Metallurgy (Russ.) (A. G. Merzhanov, ed.). USSR Academy of Science, Chemogolovka, Russia, 1975, p. 245. 

A pilot plant study has been undertaken to optimize coagulation and flitiation pietieatment for asbestotiofoim flber removal from industrial waste water. Experiments were conducted to compare the effectiveness of simple sand filtration and magnesium oxide filtration. The first tests showed that magnesium oxide is an excellent medium to filter asbestos and operates longer than sand, flow rate being equal. 

Anonymous, Recovery of Precious Metal Catalysts with Supercritical Water Oxidation, Filtration and Separation (June 2003). 

Sediments, sludges, soils Acid digestion, oxidation, filtration/centrifugation AAS, ICP/AES Variable, depending on matrix 93+6% EPA 1986a, 1986b... 

Methyltri -n - propylstibonium hydroxide, (C3H7)g(CH3)SbOH, is prepared by dissolving the foregoing methiodide in cold water and shaking the solution with freshly prepared silver oxide. Filtration and removal of the solvent under reduced pressure gives the hydroxide as an oil. The base is soluble in water, absorbs carbon dioxide and reacts alkaline to litmus. It precipitates cupric, stannous, ferric, aluminium and zinc hydroxides from the respective salt solutions. 

We note that burning sometimes occurs throughout the sample, while under other circumstances it occurs only on the surface of the sample, though this is generally due to the effect of limited oxidizer filtration through the sides of the sample, which is not accounted for here. In this chapter we nevertheless restrict consideration to surface burning so that the process can be modeled in two dimensions. Our model thus describes solid flame propagation in a thin cylindrical annulus between two coaxial cylinders, as in the synthesis of hollow... 

The following treatment techniques are applied sedimentation hydroxide precipitation multi-stage precipitation wet oxidation filtration procedures. 

Researchers further optimized purification of a model ATRP reaction using the same automated parallel synthesizer that was outfitted with a solid-phase extraction (SPE) unit that utilizes silica gel or aluminum oxide filtration cartridges that can interface with synthesizer s liquid-dispensing system. The polymerization of MMA with p-toluenesulfonyl chloride (TsCl) as the initiator and CuCl/4,4 -dinonyl 2,2 -bipyridine (dNbpy) as the catalyst was chosen as a model reaction for this study. The PMMA pol5mier of this reaction was determined to have an MW of 12 000 Da and a PDI of 1.15. Sixty-four different purification conditions were analyzed by vaiying column materials, column lengths, and eluent collected. For the model reaction, a 1.5-cm-long artivated neutral or basic aluminum oxide column with 2 ml of THF eluent was optimal. 

Data recorded under both low (15%) and high (80%) relative humidity conditions show that the H-ZSM-5 (0.4N) sample yields improved EtO filtration performance relative to the nntreated material. The H-ZSM-5 (LON) sample prodnces similar breakthrongh curves to the untreated sample while the ethylene oxide filtration performance of the H-ZSM-5 (1.5N) sample is significantly rednced as compared to the imtreated sample. 

Besides oxidants in the gaseous state, metallic oxidants have also often been employed. Both zero-valent aluminum (ZVAl) (Wu et al, 2007) and iron (Lee et al, 2003) showed preferably oxidation performance for As(III). Leupin et al (2005) reported a positive effect in oxidation of As(III) and a very high removal rate was achieved from an aerated groundwater by filtration through sand and zero-valent iron. A demonstration experiment showed that using 4 oxidation/ filtration steps, a 5 0 mg As (total) solution was obtained from a solution of500 mg L As(III)... 

An example along the above lines may be the new solvent-spun fiber Tencel, by Courtaulds, which recently was introduced. It is claimed to have an environmentally clean process, with virtually total recycling of the solvent." The manufacturing process is said to involve the dissolving of pulp in hot amine oxide, filtration of the solution, and then spinning into a bath containing a dilute solution of the solvent. The bath removes the amine oxide from the fibers, which are washed and dried, and the removed solvent is reclaimed for further use. The final fiber is said to have a different molecular structure from that of normal rayon, and a smooth surface and a round cross section. The fiber is claimed to be stronger than cotton and normal rayon in both the dry and the wet states. 

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