Organic solutes adsorption, from aqueous dilute solutions

Adsorption of Organic Solutes from Dilute Aqueous Solutions... 

This chapter shows that a unified explanation can be given of the adsorption from dilute aqueous solutions of different organic solutes, from nonelectrolytes to electrolytes, polyelectrolytes, and bacteria. Thus, the adsorption process is a complex interplay between electrostatic and nonelectrostatic interactions. Electrostatic interactions depend on the solution pH and ionic strength. The former controls the charge on the carbon surface and on the adsorptive... 

Finally, Chapters 24—27 deal with the environmental apphcations of carbons as adsorbents for the removal of pollutants from aqueous solutions. These four chapters are highly complementary. Thus, Chapter 24, which addresses the problems associated with the removal of inorganic species, finds its alter ego in Chapter 25, which deals with the adsorption of organic solutes from dilute aqueous solutions. Both chapters provide insights into the fundamental reasons for the performance exhibited by a carbonaceous adsorbent. The global topic of water purification using carbons as adsorbents is addressed in Chapter 26, which... 

Hydrogels show a marvelous prospect for the procedure of metal-ions recovery from dilute solutions (Peter 1995, Varma et al. 2004). Recently, the adsorption of natural organic pollutants (such as humic acids) from aqueous solution using chitosan adsorbents has attracted intensive attention in environment and health fields (Ngah and Musa 1998, Wu et al. 2002, Yan and Bai 2005). Adsorbents, derived from a nature polymer, are required for environment-conscious technologies. The adsorptions of metal ions and humic acid from aqueous solutions onto radiation cross-linked chitosan derivatives were introduced here. 

Radke, C. J. Prausnitz, JM. (1972) Adsorption of organic solutions from dilute aqueous solution on activated carbon. Industrial Engineering Chemistry Fundamentals, 11,445 51. 

We have considered the surface tension behavior of several types of systems, and now it is desirable to discuss in slightly more detail the very important case of aqueous mixtures. If the surface tensions of the separate pure liquids differ appreciably, as in the case of alcohol-water mixtures, then the addition of small amounts of the second component generally results in a marked decrease in surface tension from that of the pure water. The case of ethanol and water is shown in Fig. III-9c. As seen in Section III-5, this effect may be accounted for in terms of selective adsorption of the alcohol at the interface. Dilute aqueous solutions of organic substances can be treated with a semiempirical equation attributed to von Szyszkowski [89,90]... 

The most common hydrophobic adsorbents are activated carbon and siUcahte. The latter is of particular interest since the affinity for water is very low indeed the heat of adsorption is even smaller than the latent heat of vaporization (3). It seems clear that the channel stmcture of siUcahte must inhibit the hydrogen bonding between occluded water molecules, thus enhancing the hydrophobic nature of the adsorbent. As a result, siUcahte has some potential as a selective adsorbent for the separation of alcohols and other organics from dilute aqueous solutions (4). 

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