Hydrophobic oxygen complex

M(II)—02 and the dative structure, M(III)—02. So the second condition is that the oxygenated complex must be surrounded by a hydrophobic environment in order to suppress charge separation and to exclude water molecules from the vicinity of the oxygenated complex. 

The surface chemistry of activated carbons essentially depends on their heteroatom content, mainly their surface oxygen complex content, which determines the charge of the surface, its hydrophobicity, and the electronic density of the graphene layers. Thus, when a solid such as a carbon material is immersed in an aqueous solution, it develops a surface charge that derives from the... 

All these results show the importance of the carbon surface chemistry and pore texture on the adsorption of nonelectrolytic organic solutes. Thus, for hydrophobic carbons, which generally have a low content of surface oxygen complexes, the adsorption of organic molecules is by dispersion and hydrophobic interactions, and the pores involved in the adsorption depend on the molecular size of the adsorptive. Conversely, when the adsorbent s content of surface oxygen complexes increases or its hydrophobicity decreases, there is a preferential adsorption of water on these complexes, which reduces the adsorption capacity of the adsorbent. 

In another recent study, Chen and coworkers [11] also investigated the effect of surfece oxygen complexes, introduced by air and ozone treatments, on the adsorption of the commercial surfactants SDS, Darex II (anionics), and Tergitol (nonionic). Results revealed that the surfactant adsorption was strongly suppressed by surface oxidation. These authors proposed that surfactant adsorption primarily occurs on nonpolar carbon surface patches by hydrophobic interactions. Therefore, the oxidative suppression of surfactant adsorption was... 

AC, as well as being a unique material in terms of its variable microporosities, as well as being amphoteric, are also essentially hydrophobic and adsorb species from aqueous solution, apparently ignoring the presence of the water, provided the surfaces are relatively free of surface oxygen complexes (see below for some qualifications to this statement). 

In addition, surface oxygen complexes affect the surface hydrophobicity, which determines the hydrophobic interaction. Hydrophobic interaction or, more specifically, hydrophobic bonding, describes the unusually strong attraction between hydrophobic molecules and hydrophobic carbon surfaces. The surface hydrophobicity of carbon materials can be determined, for instance, by measuring their contact angle with test liquids of known surface tension, by inverse gas chromatography or by water adsorption. 

The structure of the major trimeric LHCII complex has been recently obtained at 2.72 A (Figure 7.3) (Liu et al., 2004). It was revealed that each 25kDa protein monomer contains three transmembrane and three amphiphilic a-helixes. In addition, each monomer binds 14 chlorophyll (8 Chi a and 6 Chi b) and 4 xanthophyll molecules 1 neoxanthin, 2 luteins, and 1 violaxanthin. The first three xanthophylls are situated close to the integral helixes and are tightly bound to some amino acids by hydrogen bonds to hydroxyl oxygen atoms and van der Waals interactions to chlorophylls, and hydrophobic amino acids such as tryptophan and phenylalanine. 

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