实验室中的分离过程

对于人类消费，实验室使用或工业制造的所需纯度来说，它确实很罕见。在大多数情况下，您必须诉诸于随后的分离，以便将所需产物与其他不良杂质分离，以确认身份和定量估计。从大量的分离已经用于净化食物谷物，天然颜料，海水中的盐，醇蒸馏等。

Separation processes generally fall in two main categories, namely, physical and chemical. The article is an attempt to cover different separations which are of significance in routine laboratory operations.

身体分离

Physical separations are common in home, laboratories and industrial operations. Such separations are based on physical properties of different materials constituting the mixtures.

Shape and size –一个常见的例子是通过手工采摘将食品与小石头或土壤肿块等不需要的杂质分离。通过使用不同的网格筛来实现更精细的分离。

Colour –通过手动采摘不同颜色的颗粒，可以进行许多分离，例如干颜料颗粒。

过滤 -is a classical laboratory separation practice with which you would be familiar from your school days. Suspended solids or precipitates in solution are removed by filtration using filter papers secured in glass funnels.

Centrifuging –离心机提供更快，方便的方法，用于去除固体悬浮液，与古典过滤方法相比。含有悬浮颗粒的溶液以离心机中的高RPM速度旋转。在一段时间后，由于离心力，固体悬浮液在离心管的底部沉降，并且可以容易地与溶液分离。

Evaporation –通过简单地允许溶液在烧杯中蒸发或加热，可以从溶液中除去溶解的固体。溶剂蒸发或沸腾留下固体残余物。

蒸馏 -蒸馏导致在均匀混合物中以沸点的差异分离均匀的混合物中。蒸馏在粗石油精炼期间分离纯部分起着重要作用。

升华 -sublimation occurs when a material changes phase from solid direct to gas without melting to a liquid. Dry ice or solid carbon dioxide is a common example which changes to gaseous carbon dioxide at room temperature without liquefaction.

Another example is ammonium chloride which can be removed from a solid mixture by gently heating the mixture on a watch glass and collecting the pure ammonium chloride deposited as a powder on the inside wall of an inverted funnel covering the mixture.

离子交换 -ion-exchange is a process involving passing the mixture of charged species in a liquid through an ion exchange column which retains oppositely charged ions and permits the ions bearing same charge to pass through. It is used extensively in water purification.

溶剂萃取 -它用于将具有不同误导性的液体的混合物在分离漏斗中振动。该技术在分离在所选溶剂中具有不同溶解度的溶解固体物质也可用。

结晶 -pure compounds can be separated from a dissolved state in a solution by allowing the solution to cool gradually to room temperature after seeding the solution with a crystal of the pure compound.

化学分离

The basis of chemical separations is reactions producing insoluble precipitates which can be separated by physical processes subsequently. Such reactions generally fall in the following categories:

沉淀是溶液中不同化合物之间的反应，形成不溶性固体反应产物

复杂的形成产生由金属和络合剂之间的反应产生的不溶性产物。

色谱法

色谱法是一种成熟的分离技术，在世界各地的实验室中建立了其存在。它是一种独特的分离技术，可以涉及在载体流动相和固定相之间的溶质之间的物理化学相互作用。液相色谱通过发展进化薄层色谱法andHPLC.。固定阶段和探测器的广阔选择有助于解决药物，食品，化妆品，蛋白质，生物分子等组成部分。相似地manbetx官方提供石油级分的挥发性组分的分离，食品中的香料，化妆品和香水中的香味，环境污染物和法医调查。