Effects Of Ultrasonic Parameters Research Articles

Enzyme-catalyzed synthesis and kinetics of ultrasonic-assisted biodiesel production from waste tallow

The use of ultrasonic processing was evaluated for its ability to achieve adequate mixing while providing sufficient activation energy for the enzymatic transesterification of waste tallow. The effects of ultrasonic parameters (amplitude, cycle and pulse) and major reaction factors (molar ratio and enzyme concentration) on the reaction kinetics of biodiesel generation from waste tallow bio-catalyzed by immobilized lipase [Candida antarctica lipase B (CALB)] were investigated. Three sets of experiments namely A, B, and C were conducted. In experiment set A, two factors (ultrasonic amplitude and cycle) were investigated at three levels; in experiment set B, two factors (molar ratio and enzyme concentration) were examined at three levels; and in experiment set C, two factors (ultrasonic amplitude and reaction time) were investigated at five levels. A Ping Pong Bi Bi kinetic model approach was employed to study the effect of ultrasonic amplitude on the enzymatic transesterification. Kinetic constants of transesterification reaction were determined at different ultrasonic amplitudes (30%, 35%, 40%, 45%, and 50%) and enzyme concentrations (4, 6, and 8wt.% of fat) at constant molar ratio (fat:methanol); 1:6, and ultrasonic cycle; 5Hz. Optimal conditions for ultrasound-assisted biodiesel production from waste tallow were fat:methanol molar ratio, 1:4; catalyst level 6% (w/w of fat); reaction time, 20min (30 times less than conventional batch processes); ultrasonic amplitude 40% at 5Hz. The kinetic model results revealed interesting features of ultrasound assisted enzyme-catalyzed transesterification (as compared to conventional system): at ultrasonic amplitude 40%, the reaction activities within the system seemed to be steady after 20min which means the reaction could proceed with or without ultrasonic mixing. Reversed phase high performance liquid chromatography indicated the biodiesel yield to be 85.6±0.08%.

Effects of ultrasound parameters on ultrasound-assisted ultrafiltration using cross-flow hollow fiber membrane for Radixastragalus extracts

In this study, the effects of ultrasonic parameters on permeate flux and fouling resistances in the ultrasound-assisted ultrafiltration (UAUF) process of Radix astragalus extracts with hollow fiber membrane (HFM) was investigated. Ultrasonic parameters such as frequency, power and irradiation mode all can significantly affect the flux and fouling during the UAUF process, though the ultrasound power intensity was attenuated to be 10% only from generator. Concentration polarization and cake layer were decreased effectively by the ultrasound irradiation, resulting in a high flux performance. Meanwhile, HFM was susceptible to the irradiation at high power and low frequency compared with a flat sheet membrane. Ultrasound can not only enhance the permeate flux in UAUF but also cause breakage of HFM at an unsuited ultrasound field. It can be applied to the ultrafiltration process with HFM at an appropriate power and frequency.

Effects of Different Ultrasonic Frequency on Total Phenolic Contents of Extracts from Navel Orange Residue

Effects of ultrasonic parameters (ultrasonic time, temperature and ultrasonic power) under different ultrasonic frequencies including 20, 60, 100 kHz on total phenolic contents (TPC) of extracts from citrus peel (CP) were analyzed. The results showed that TPC of extracts from CP increased significantly with increases of ultrasonic time, temperature and ultrasonic power under three ultrasonic frequencies.

Ultrasound-mediated gene transfection in vitro: Effect of ultrasonic parameters on efficiency and cell viability

Ultrasound (US)-mediated gene transfection in the presence of microbubbles is a recently developed and promising non-viral gene delivery method. Optimising the parameters used in ultrasonic transfection is urgently required in order to realise higher transfection efficiencies in clinical settings. This study examined the effect of ultrasound exposure parameters on plasmid DNA transfection in mouse embryonic fibroblast cell lines using perfluorobutane bubbles. Variations in US intensity (0–11 W/cm2), pulse repetition frequency (PRF, 50–50,000 Hz), duty ratio (10 to 50%), exposure time (0–120 s) and microbubble volume concentration (0 to 10%) were tested, and the microbubble volume concentration was also monitored during exposure. Through the experiments, the mechanism of how variations in parameters influence US-mediated gene transfection was discussed, which can provide a basis for future applications of ultrasound mediated transfection.

Influence of Cavitation on Ethanol Enrichment in an Ultrasonic Atomization System

Ethanol was separated from aqueous solutions through ultrasonic atomization. Ethanol enrichment was evaluated by determining ethanol concentration in condensates collected from atomized mist and vapor. The amount of collected mist and vapor accorded with the amount of liquid left from the atomization column. In the limited range of ethanol feed concentration below 30 mol%, the ethanol concentration in the condensates was affected by ultrasonic parameters such as frequency and input power. Ethanol enrichment was enhanced at higher frequencies and lower input power. The effect of ultrasonic parameters on ethanol enrichment was interpreted from the viewpoint of cavitation. Potassium iodide oxidation was conducted to examine the occurrence of cavitation, and the number of violently collapsing bubbles. The use of higher frequency and lower input power, which corresponded to enhance ethanol enrichment, resulted in a decrease in KI reactivity. This trend suggests that violently collapsing bubbles enhanced fragmentation of the bulk liquid where no separation mechanism works. Assuming that the surface excess of ethanol plays a significant role in the separation, possible routes of ethanol transfer from liquid to mist or vapor are suggested.

Application of Power Ultrasound in Cavitation Erosion Testing of Nano-Ceramic Particle/Polymer Composites

Cavitation erosion is predominant in pipelines for liquid transportation, causing damage to pipe wall, impeller and their accessories. The present study is focused on development of cavitation -wear resistant nano-ceramic particle-reinforced polymer matrix material; and on study of its feasibility to be used as lining material in hydraulic transportation. The polymer/nano composite is fabricated using power ultrasound in all three process steps: synthesis of nano-dimensional particles of white fused alumina (WFA) from micron size particles, optimized blending and finally reinforcement into poly methyl methacrylate (PMMA) matrix. The effect of ultrasonic parameters on nanocomposite/ virgin polymers (like polyethylene and polypropylene) is studied by measuring mass loss of the materials and suspension turbidity during exposure time. At low frequency (20-60 kHz), cavitation intensity is predominant; this effect is utilized for fabricating sub-micron particles, and for performing accelerated cavitation erosion tests. At high frequency, acoustic streaming is predominant; this effect is utilized for blending and reinforcing of the nano ceramic particles into polymer matrix. The size and quantity of the particles generated by cavitation erosion was analyzed by Laser Particle Size Analyzer (20 nm-1400 micron range). The nano-composite coupons were analyzed before and after the ultrasonic erosion test using SEM. It is concluded that lowfrequency sonication is a viable option for cavitaton erosion testing of ceramic/polymer composites.