Oxidative cutting/purification

CNTs can be processed such as purification based on oxidation, cutting, and activation by forming carboxylic acid and hydroxyl groups on the surface of CNTs, which can further be linked with other biomolecules to realize special function (Ajayan et al., 1994). As shown in Fig. 9.19, ferritin molecules attached to the surface of CNTs via covalent bond, the nanocomposites with ferritin molecules-functionalized CNTs own better mechanical, thermal, and electronic properties... 

Most commercial products are mixtures because of the way they are manufactured. For instance many surfactant hydrophobes come from assorted products such as petroleiun alkylate cuts or triglyceride oils, with a molecular weight distribution that could be narrow or wide. Usually, a purification and separation of single isomeric species would be too costly and, in most cases, pointless. Moreover, the synthesis reactions involved in the surfactant manufacturing might be the intrinsic reason of the production of a mixture, such as in the case of polycondensation of ethylene oxide which results in an often wide spread ethylene oxide munber (EON) distribution. A residual content of some intermediates or by-products might also be a significant cause for mixture effects. 

Toluene, acetone and methyl ethyl ketone are, due to their cut-off values, not the first choice if UV detection is used to control the process. Tetrahydrofuran has to be avoided because for larger scale use it has to be stabilized with an anti-oxidant (butyl-ated hydroxytoluene) that will finally end up in the product, often making an additional purification step necessary. 

The Pb thus obtained is practically free of Se and Te as well as of all those elements whose sulfides have a lower solubility product than PbS. In addition, all colloidal impurities present in PblCHjCCXllg 3 HgO (for example, Au) are removed. The noble m al content after three purification steps is 10 g. Au and 10" ° g. Ag/g. Pb. Very pure Pb is strikii ly soft and easy to cut, and on melting is more resistant to air oxidation than the very pure commercial electrolsrtic material. 

Purification of H2 as an intermediate or final product is a pivotal process that cuts across the transportation fuels and chemical sectors. Over the past few decades, tremendous progress has been made in the development of selective polymeric, ceramic, metal, and composite membranes for H2 separation. Of particular interest has been development of highly permselective membrane systems to enable efficient, economic, and environmentally responsible production of power within the context of advanced gasification processes that employ combustion turbines and solid oxide fuel cells. 

In 1916 the first industrial process for synthetic production of acetic acid was commercialized. The process is based on the liquid phase oxidation of acetaldehyde. In the 1950s the petrochemical industry developed rapidly and the costs for refinery hydrocarbon cuts were very low. Therefore, the direct liquid-phase oxidation of butane and naphtha became the preferred synthetic route to producing acetic acid. However, the major disadvantage of this process is the significant amount of by-products (up to 50% of the feed is converted into by-products). Hence direct hydrocarbon oxidation to acetic acid requires complex purification units with high investment and operating costs. Today, only small amounts of acetic acid are still manufactured by this process. 

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