Ultrasonic irradiation treatment

Ultrasonic irradiation has been shown in laboratory studies [73] to increase dye exhaustion, enabling salt levels to be reduced. However, it seems doubtful whether the higher effectiveness is sufficient to merit development to overcome the problems involved in scaling-up the ultrasonic equipment to bulk-scale processing. For example, in one experiment using 5% salt at 65 °C, ultrasound treatment increased the dye exhaustion from 77% to 82%. 

Diadamantylsilylene Ad2Si formed from Ad2Sil2 upon treatment with lithium under ultrasonic irradiation was compared with that formed upon pyrolysis of a silirane (Scheme 14.39). ... 

Treatment of benzaldehyde with TiCU (lequiv.) and magnesium (l.Sequiv.) in TFIE at 25°C for 30min gives a mixture of 1,2-diphenylethene (43% yield) and dl- and OT ro-l,2-diphenylethane-l,2-diols (29% combined yields, dljmeso = AZiS ). The reaction conducted at 80°C produces the diphenylethene in 62% yield selectively. However, when catechol (1 equiv.) is added to the reaction mixture, pinacols are produced selectively in 76% yield dljmeso = 54/46) even at 80 °C. " Ultrasonic irradiation of a mixture of TiCU (15% in dilute HCl solution, 2 equiv.) and magnesium (4 equiv.) in EtOH accelerates the pincaol formation, but the diastereomeric ratio remains at a low level (dljmeso = 68/32). ... 

Fig. 12.2 Time dependencies of sonophotocatalytic reaction products from pure water. As powdered photocatalyst, Ti02-A (200mg, Soekawa, Commercial Reagent, rutile-rich type and specific surface area 1.9 m2/g) was used without further treatment. Liquid water (150 cm3, Wake, Distilled water for HPLC was used as reactant and was purged with argon, a Pyrex glass bulb (250-300 cm3) was used as a reactor and was placed m a temperature-controlled bath (EYELA NTT-1200 and ECS-0) all time. After the glass bulb was sealed, the irradiation was carried out under argon atmosphere at 35°C. Photo and ultrasonic irradiations were performed from one side with a 500 W xenon lamp (Ushio, UXL500D-O) and from the bottom with an ultrasonic generator (Kaijo. TA-4021-4611, 20C kHz 200 W), respectively.

Interestingly, the alkene to allene conversion can be carried out directly without isolation of the intermediate dihalocyclopropane. This process involves the treatment of the alkene with 1 equiv. of carbon tetrabromide and 2 equiv. of methyllithium in ether at -65 °C.163 Ultrasonic irradiation facilitates the formation of cyclopropylidenes, and therefore the allenes, from dihalocyclopropanes under the influence of Li, Na or Mg.1 The reactions are usually complete in 5-15 min. A report165 on the use of n-butyllithium complexed with the chiral tertiary amine (-)-sparteine, leading to optically active allenes, seems to be of questionable value. 

To explain the formation of the expected product of insertion into the H—Si bond of HSiEt3 in similar yields from different precursors, it was suggested that t-Bu2Si also arises by ultrasound-promoted lithio-dehalogenation of t-Bu2SiX2 (X = Cl, Br, I) see also Section II.E. This would represent the first example of a metal-promoted a-elimination of dihalosilanes. In a related study of the chemistry of diadamantylsilylene Ad2Si the reactive species formed from Ad2Sil2 upon treatment with lithium under ultrasonic irradiation was compared with that formed upon pyrolysis of a silirane, as shown in equations 36 and 3757. 

The work performed on DNB and NB illustrates two main problems with the use of ultrasound for contaminant degradation. First, under the given experimental conditions, the process is slow. Therefore, the fate of future applied research may rest in the ability to show favorable comparisons to other treatment processes in terms of both cost and efficiency. Second, as mentioned above, the agitation produced by ultrasonic irradiation initiates more volatilization than degradation. 

In routine analytical laboratories, the use of advanced oxidation processes (AOPs) is an emerging alternative to conventional sample treatments2 for analytical and environmental chemists. AOPs involve the in situ generation of highly potent chemical oxidants, such as the hydroxyl radical (OH ). Several processes have been applied in analytical sample pretreatment homogenous UV irradiation, either by direct irradiation of the sample or photolysis mediated by an appropriate chemical reagent ozone and ultrasonic irradiation. A variety of AOPs ensures compliance of specific treatment requirements with optimum treatment technologies (Table 5.1). 

The substances or materials have different capacity to be heated by microwave irradiation, which depends on the substance nature and its temperature. Generally, chemical reactions are accelerated in microwave fields [704], as well as those by ultrasonic (US) treatment, although the nature of these two techniques is completely distinct. 

As reported by Augugliaro et al. [64] the photocatalysis can be combined with chemical or physical operations. In the first case, when the coupling is with ozonation [65, 66], ultrasonic irradiation, photo-Fenton reaction or electrochemical treatment, which influence the photocatalytic mechanism, an increase of the efficiency of the process is obtained. 

To improve the photoprocess performance, diverse combinations of heterogeneous photocatalysis with chemical and physical operations have been proposed, including among others, photo-Fenton, ozonization, biological or electrochemical treatment, and ultrasonic irradiation these attempts were recently reviewed and analysed [107],... 

Table XI also compares the amino acid analyses of Merino 64 s wool with that of cuticle obtained by subjecting the wool to ultrasonic irradiation in 98 % formic acid (Bradbury and Chapman, 1964). The cuticle contained less arginine, aspartic acid, glutamic acid, leucine, and phenylalanine than whole wool, but more cystine, proline, serine, and valine. Cys-teic acid is probably formed during the ultrasonic treatment. These analyses cannot be accounted for quantitatively on the basis of a simple combination of low-sulfur and high-sulfur protein fractions, but the data suggest that the cuticle would not contain as much material in the a-helical conformation as the original fiber. The values obtained by Bradbury (1960) in an earlier examination of cuticle-rich material obtained by a mechanical descaling technique are in reasonable agreement with the values in Table XI.

The effects of ultrasonic treatment and ultrasonic irradiation on the extraction of cottonseed meal have been assessed [56], Results indicated that a combination of enzyme treatment and sonication produced a significantly greater yield of extracted protein than traditional methodologies. 

Polymeric, solid ATPH was adapted for [4-i-2] cycloaddition [64]. The polymer catalyst 66 was prepared by treatment of MesAl with the appropriate biphenol, followed by exposure to ultrasonic irradiation, and could be recovered quantitatively by simple filtration and reused (Scheme 6.44). The activity of the recovered 66 did not decrease even after seven uses. It is worthy of note that the [4+2] addition competes wifh fhe Tischenko reaction, which is a major path when solid alumina catalysts are used. 

Monoorganozinc halides (RZnX) can be synthesized by oxidative addition of organic halides to zinc metal. The oxidative addition rate is strongly affected by the reaction conditions (solvent, concentration) [16] and by activation of the zinc [15,17]. Zinc powder or zinc foil, which is activated by treatment with 1,2-dibromoethane and then with trimethylsilyl chloride, will oxidatively add alkyl iodides [18]. The reaction of alkyl bromides, on the other hand, requires more active zinc, which may be prepared by the reduction of zinc chloride with either lithium naphthalenide [19] or lithium metal under ultrasonic.irradiation [20, 21]. 

The complete deprotection of all acetonide groups of 180, ent-180,181 and 182 was attained by treatment with 50% TFA in CH2CI2 at room temperature under ultrasonic irradiation. The resulting porphyrin derivatives became insoluble in most organic solvents but they were soluble in methanol or ethanol and also in water, and this might be a useful feature in the areas of chiral recognition and asymmetric catalysis [144]. 

Ultrasonic irradiation can easily be integrated with existing, conventional treatment sjrstems, making it possible to simultaneously treat hazardous and nonhazardous waste streams. Successful development and deployment of this technology could conqiletely change the treatment of wastes generated in the DOE conqilex. 

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