Extraction alkali

There are two main processes for clinker production a so-called wet process and a dry process. In the dry process the alkali raw materials are introduced in dry form into the kiln. In the wet process, these materials are introduced in the form of a slurry. Among other things, the type of process depends on the source of the kiln s raw materials. If a kihi extracts alkali raw materials from lakes then a choice for a wet process is logical, despite the disadvantage of its rather high energy use (5,000 MJ/toime versus 3,600 MJ/toime clinker), as in the dry process no water has to be evaporated. 

Crowns with Stilbene Fluorophores. Stilbenes undergo cis-trans isomerism on irradiation and this feature is exploited in (3.82). In the case of the frany-isomer, large ionic radius ions such as K+, and Cs, give fluorescent complexes whilst the smaller Lb and Na " cause quenching. UV irradiation to the dy-isomer causes a considerable change in the conformation of the crown ether substructure and increases its ability to extract alkali metals, including Lb and Na+, from water into benzene. 

Shinkai et al.111-151 synthesized a series of azobis(benzocrown ethers) called butterfly crown ethers , of which compounds 9 and 10 are examples. Their photoresponsive molecular motion resembles that of a flying butterfly. It was found that the proportion of their Z forms at the photostationary state increases remarkably with increasing concentration of Rb+ and Cs+, which interact with two crown rings in a 1 2 sandwich fashion. This is clearly due to the bridge effect of the metal cations with the two crowns, results that support the view that the Z forms make an intramolecular 1 2 complex with these metal cations. As expected, the Z forms extracted alkali metal cations with large ion radii more efficiently than did the corresponding E forms. In particular, the photoirradiation effect on 9 is quite remarkable for example, ( )-9 (n= 2) extracts Na+ 5.6 times more efficiently than (Z)-9 (n= 2), whereas (Z)-9(n= 2) extracts K+ 42.5 times more efficiently than ( )-9(n= 2). l ... 

It was shown long time ago that neutral and acidic solutions tend to extract alkalis preferentially from silicate glass the surface layer enriched in SiOj then slows down further corrosion because the alkalis have to be supplied to the surface from greater distances by diffusion. In contrast with this, strongly alkaline solutions (pH > 12)... 

The clay component is the main factor controlling the rheological properties and the slip stability. Some part in this respect, hovewer, can also be played by the other very fine components. From the frit particles, water extracts alkalis which affect the colloidal and rheological properties of the slip. Since the extraction is gradual, the suspension is allowed to stand for a certain time before application to stabilize its properties. 

Zintl also found that the most convenient way to produce the solutions of the anionic clusters in liquid ammonia is to extract alkali metal/post-transition element alloys in the solvent. However, detailed solid-state characterization of the clusters is very difficult using this technique, since poorly crystalline and often pyrophoric solids are obtained once the solvent is evaporated. These troublesome solids are alkali-metal ammoniates of cluster ions, " of which only [Li(NH3)4]3-[Li2(NH3)2Sb5] -2NH3 seem to have been completely structurally characterized, Furthermore, the ammoniates most often slowly revert back to the alloy upon further loss of ammonia. The last step involves transfer of electrons from the strongly reducing cluster anion back to the alkali-metal ion and thus represents a major synthetic obstacle. 

ABC extractants were found to possess attractive properties with regard to salt extraction. Extraction is efficient and selective. Compared with liquid cation exchangers, ABC extractants are less sensitive to acidity in the aqueous phase and extract alkali and alkaline earth metals better. Both the cation and the anion are extracted therefore, no acid or base addition is required for pH adjustment or for stripping. Extraction is reversible and provides for back-extraction of the extracted salt by water. Several potential applications of ABC extractants in salt extraction were studied, including MgCb recovery from concentrated seawater [2,4,5,7], separation of LiCI [6], removal of Fe from AlCl solutions [14,23], and recovery of ZnSO from zinc electrowinning bleeds [21]. 

The stability constants of the 1 1 alkali metal picrate complexes of diketone 18. heptacyclic terpyridyl 27 and flexible terpyridine 28 were estimated by hquid-liquid extraction, and the resulting log fj values for Na" " and are also given in Fig. 4. The affinities of 18 and 27 for these alkali metals are remarkably high for hosts containing only five or three ligand atoms, respectively. In water-saturated chloroform, pentadentate host 18 binds Na" and K more strongly than do most crown ethers. Compared to naphtho-18-crown-6 (26), 18 binds Na " 4000 times better, and K 40 times better. Even tridentate host 27 extracts alkali metal picrates into chloroform, whereas flexible model system 28 is ineffective under the same experimental conditions. The potent complexation... 

Methods for recovering lignin are the alkali process, the sulfite process, ball milling, enzymatic release, hydrochloric acid digestion, and organic solvent extraction. Alkali lignins are produced by the kraft (22) and soda (23) methods for wood pulping. These... 

Anti- and syn-isomers of 20 can extract alkali-metal cations from aqueous solutions, with binding of Cs" " by the syn-cryptophane giving the best results. The syn-cryptophane 29 has internal carboxylic acid groups that... 

Altwaiq, A. Khouri, S. J. Al-luaibi, S. Lehmann, R. Driicker, H. Vogt, C. (2011). The Role of Extracted Alkali Lignin as Corrosion Inhibitor. Journal of Materials and Environmental Science, Vol. 2, No.3, pp. 259-270, ISSN 2028-2508... 

Add S.O ml of the Extracting Alkali to each tube. Suspend the sediment by vigorously agitating the tubes with a buzzer and replace the tubes in the heater for exactly 30 min. Remove the tubes and centrifuge the contents for 10 min at 5000 rpm. Carefully withdraw the supernatant liquid with a capillary pipette attached to a vacuum source (Note ). 

For the removal of caesium from HLW to MLW, for instance, crown ethers (compounds 9 and 10, Figure 3) are well known for their ability to complex and extract alkali cations from acidic media. The stability of the complexes is linked to the relative size of the cavity of the crown ether as compared to the complexed... 

Crownopaddlane 26c bearing six ethereal oxygen atoms also more efficiently and selectively extracted alkali metal cations, compared with 18-crown-6 derivatives [29]. The intramolecular photocycloaddition was also applied to prepare three- and four-bridged crownophanes. The yields were moderate or excellent (52%, 93%) in spite of one-pot reactions. The cyclobutane rings acted to not only make the phanes rigid but also control the complexation behavior due to their bulkiness. 

---