Sonication time reduction

Sathish Kumar et al. [45] prepared bimetallic Au-Ru nanoparticles by the simultaneous reduction of both Au3+ and Ru3+ ions by ultrasound irradiation at three different molar ratios (Au3+ Ru3+ 1 1, 1 3 and 1 5) in 4 h in the presence of PEG. A significant change in the absorption as a function of sonication time was observed for Au-Ru bimetallic particles (Fig. 6.10), which indicated the... 

Although the single bubble experiment in Fig. 14.10b and the aforementioned multi-bubble work of Didenko et al. does support the hypothesis that thermal conductivity is a defining parameter of SL emission intensity, an alternative explanation attributes the trend in multi-bubble systems to the gas solubility, rather than the thermal conductivity. If the SL data from Fig. 14.9 is re-plotted as a function of the gas solubility, as shown below in Fig. 14.11, a very good correlation is found. This explanation is supported by several studies by Okitsu et al. [42, 59]. They found sonochemical activity to obey the same trend for the rare gases as for thermal conductivity, SL luminosity and temperature, as described above. This is evident in Fig. 14.12, which shows the sonochemical reduction of Au(III) to colloidal gold as a function of sonication time for different gas atmospheres. 

The effect of ultrasonic treatment on com particles was examined by sonicating both cooked and raw corn slurry samples and the resulting particle size was compared with nonsonicated samples (controls). The peak of the particle size distribution curve shifted from 800 pm to around 80 pm following sonication at high-power levels for cooked corn slurry samples. In addition, the particle size reduction was directly related to the power level and sonication time. The particle size reduction at the... 

The cleavage by lithium of a P-C bond in tertiary phosphines gives the phosphide anion. The reduction is accelerated by a factor of 10 imder sonication, and gram quantities of substrates undergo the reaction successfully in a cleaning bath. From methyl diphenyl phosphine, the reaction is selective and only a P-aryl bond is cleaved. The sonication time increases with the amount of substrate. This reaction would probably be improved with the use of probe generators. 

The interaction graph for AB represents the trend of average value of resistivity for each of the reduction agents as the level of sonication increases from 1 to 20 h. For HCl (Bl), the average response value increases from 0.33 to 0.641 Q cm, when sonication time increases from 1 to 10 h, followed by a decrease to 0.365 G cm in the next phase as the sonication time increases from 10 to 20 h. For HBr (B2), the average resistivity increases from 0.056 to 0.076 Q cm for an increase in the sonication time from 1 to 10 h, followed by a sharp increase from 0.076 G cm to 0.347 Q cm for the increase... 

But in sonicated condition hexamminenickel(II) ions did not form, because of the degassing effect of the ultrasound leading to the removal of ammonia gas during the sonication process. Because of this reason the turbidity in sonicated sample did not come to the zero value (Table 9.8). Ultrasound was also effective in the reduction of crystallization time by 50% in Ni-chloro and by 25% in Ni-thiocyanato complex, which, however, remained the same in NiSO.4 solution as shown in Table 9.10. 

This approach frequently leads to the most active metals as the relatively short reduction times at low temperatures leads to reduced sintering of the metal particles and hence higher reactivity. Fujita, et aL(62) have recently shown that lithium naphthalide in tqluepe can be prepared by sonicating lithium, naphthalene, and N, N, N, N-tetramethylethylene-diamine (TMEDA) in toluene. This allows reductions of metal salts in hydrocarbon solvents. This proved to be especially beneficial with cadmium(49). An extension of this approach is to use the solid dilithium salt of the dianion of naphthalene. Use of this reducing agent in a hydrocarbon solvent is essential in the preparation of highly reactive uranium(54). This will be discussed in detail below. 

One of the new techniques that has emerged in recent years is sonication extraction. A short overview of the application of this method to alkylphenols and APEO has been given recently by Petrovic et al. [3]. The reduction in extraction time and solvent use for sonication compared with Soxhlet extraction are substantial, and recoveries are comparable or better. 

A comparison has been made of the efficiencies of conventional and ultrasonically assisted pollutant extraction procedures using model soil samples (granular pieces of brick) which had been deliberately contaminated with copper oxide at 51 ppm [50]. Analysis of the brick particles after 30 min sonication on a Vibrating Tray [51] revealed an average reduction in copper content to 31 ppm, a reduction of about 40%. Using a conventional mechanically shaken tray for the same time period the residual contamination was 48 ppm representing a reduction of only 6% (Tab. 4.6). 

Hydrostannylation This reaction with a tin hydride normally requires an initiator, usually AIBN but also B(C2H5)3 (14, 314). It can also be initiated with high intensity ultrasound, and such reactions show large rate acceleration (100-600 times) and take place even at temperatures of -50°. Sonication is also effective for radical reductions and cyclizations (last example). 

Rieke obtained activation of metals by an indirect method, the reduction of salts, most of the time the chlorides, with potassium or lithium.18 The method was further improved by effecting the reduction with lithium under sonication,19 which avoids the use of potassium, prolonged heating at relatively high temperatures, and a possible deactivation of the metal slurry by annealing. 

Ultrasound-assisted extraction (USE) is an effective method for leaching many analytes from different kinds of samples [52-55]. It is simple, fast, efficient, and inexpensive in comparison with conventional extraction techniques such as solvent extraction in the Soxhlet apparatus. Ultrasound-assisted solid-liquid extraction is an effective and time-saving extraction method. Sonication accelerates the mass-transfer process between two phases. Use of ultrasound results in a reduction in operating temperature, allowing the extraction of temperature-sensitive components. The ultrasound apparatus is cheaper and its operation is easier in comparison with other novel extraction techniques such as MAE. 

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