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超声波萃取的原理
发表于:2020-11-19 分享至:

超声波萃取的原理

超声波是指频率为20kHz-50MHz的电磁波,它是一种机械波,需要能量载体一一介质来进行传播。其穿过介质时,会产生膨胀和压缩2个过程。超声波能产生并传递强大的能量,给予介质极大的加速度。这种能量作用于液体时,膨胀过程会形成负压。如果超声波能量足够强,膨胀过程就会在液体中生成气泡或将液体撕裂成很小的空穴。这些空穴瞬间即闭合,闭合时产生高达3000MPa的瞬间压力,称为空化作用。这样连续不断产生的高压就像一连串小爆炸不断地冲击物质颗粒表面,使物质颗粒表面及缝隙中的可溶性活性成分迅速溶出。同时在提取液中还可通过强烈空化,使细胞壁破裂而将细胞内溶物释放到周围的提取液体中。利用超声波的上述效应,从不同类型的样品中提取各种目标成分是非常有效的。

Ultrasonic wave refers to the electromagnetic wave with frequency of 20khz-50mhz. It is a kind of mechanical wave, which requires energy carrier -- medium to propagate.As it passes through the medium, it expands and compresses.Ultrasonic waves can generate and transfer powerful energy, giving the medium a great acceleration.When this energy is applied to a liquid, a negative pressure is formed in the expansion process.If the ultrasonic energy is strong enough, the expansion process will create bubbles in the liquid or tear the liquid into small holes.These holes are closed instantaneously, and the instantaneous pressure up to 3000MPa is generated when they are closed, which is called cavitation.In this way, the continuous high pressure is like a series of small explosions that continuously impact the surface of the particles and rapidly dissolve the soluble active components in the surface and cracks of the particles.At the same time, the intracellular solute can be released into the surrounding extractive liquid by the strong cavitation of the extractive liquid, which causes the cell wall to break.It is very effective to extract various target components from different types of samples by utilizing the above effect of ultrasound.

技术特点

与常规的萃取技术相比,超声波萃取技术快速、价廉、高效。在某些情况下,甚至比超临界流体萃取(SFE)和微波辅助萃取还好。与素氏萃取相比,其主要优点有:①成穴作用增强了系统的极性,这些都会提高萃取效率,使之达到或超过素氏萃取的效率;@超声波萃取允许添加共萃取剂,以进一步增大液相的极性适合不耐热的目标成分的萃取:④操作时间比素氏萃取短。

超声波萃取优于SFE体现在:0仪器设备简单,萃取成本低得多;@可提取很多化合物,无论其极性如何,因为超声波萃取可用任何一种溶剂。SFE事实上只能用CO2作萃取剂,因此仅适合非极性物质的萃取。超声波萃取优于微波辅助萃取体现在:①在某些情况下,比微波辅助萃取速度快;②酸消解中,超声波萃取比常规微波辅助萃取安全3多数情况下,超声波萃取操作步骤少,萃取过程简单,不易对萃取物造成污染。对于超声波萃取来说,提取前样品的浸泡时间、超声波强度、超声波频率及提取时间等也是影响目标成分提取率的重要因素。

Compared with conventional extraction technology, ultrasonic extraction technology is fast, cheap and efficient.In some cases, it is even better than supercritical fluid extraction (SFE) and microwave-assisted extraction.Compared with element extraction, its main advantages are: (1) acupoint effect enhanced the polarity of the system, these will improve the extraction efficiency, make it reach or exceed the efficiency of element extraction;Ultrasonic extraction allows the addition of co-extraction agent, to further increase the polarity of the liquid phase (3) suitable for the heat resistance of the target component extraction: (4) the operation time is shorter than the element extraction.

Ultrasonic extraction is superior to SFE in the following aspects :0 simple equipment, much lower extraction cost;Many compounds can be extracted, regardless of their polarity, because ultrasonic extraction can be done with any solvent.SFE can only be extracted with CO2, so it is only suitable for extraction of non-polar substances.Ultrasonic extraction is better than microwave-assisted extraction reflected in: (1) in some cases, faster than microwave-assisted extraction;(2) in acid digestion, ultrasonic extraction is safer than conventional microwave-assisted extraction 3 in most cases, ultrasonic extraction steps are less, extraction process is simple, not easy to cause pollution to the extraction.For ultrasonic extraction, the soaking time, ultrasonic intensity, ultrasonic frequency and extraction time of samples before extraction are also important factors influencing the extraction rate of target components.







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