Separation of chemicals

In chemistry and chemical engineering, a separation process is a process that transforms a mixture of substances into two or more compositionally-distinct products.

Various types of separation processes

• Sedimentation, flocculation, or centrifugation followed by decantation - used when the mixture consists of substances of different densities. The less dense substances is poured off of the more dense one. Flotation is a variation where suspended solids are encouraged to float to the top of the fluid by rising air bubbles.
• Filtration. Mesh, bag and paper filters are used to remove large particulates suspended in fluids, eg. fly ash, while membrane processes including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, dialysis utilising synthetic membranes can separate micrometre-sized or smaller species.
• Centrifugation and Cyclones
• Distillation - used for mixtures of liquids with different boiling points, or for a solid dissolved in a liquid.
• Chromatography involves the separation of different dissolved substances as they travel through a material. The dissolved substances are separated based on their interaction with the stationary phase.
• Electrophoresis Organic molecules, such as protein are placed in a gel. A voltage is applied and the molecules move through the gel because they are charged. The gel restricts the motion so that different proteins will make different amounts of progress in any given time.
• Extraction
• Precipitation
• Fractional freezing
• Sieving
• Winnowing