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Ion flotation is a process used in the recovery and purification of soluble compounds that form charged particles in aqueous solution. This process was first developed in the 1950s and has since been widely used in the mining, chemical, food, and pharmaceutical industries. The purpose of ion flotation is to separate one or more components from a suspension containing both charged and uncharged particles.
This separation technique is based on the fact that particles in aqueous solutions are held in suspension by electrostatic interactions between the charged particles and the surrounding liquid. When a reagent, called a collector, is added to the suspension, it binds to the surface of the charged particle. The bound particle then carries a negative charge and is drawn to a positively charged collecting medium. This allows the particles to be separated from the mixture, collected and removed from the solution.
The most commonly used reagents in ion flotation are cationic surfactants such as quaternary ammonium compounds, ethylene diamine tetraacetic acid salts, and alkyl alkylate esters. These cationic reagents interact with the anionic surface charge of the suspended particles, forming a negatively charged surface. This charged surface is then attracted to electrostatically opposite positive collecting medium.
In industrial applications, the collecting medium is often a fibrous material such as filter paper or diatomaceous earth which is charged with either a cationic or anionic material. Once the particles have been collected, they are retrieved from the collecting medium by a bleaching process or by the use of solvents.
Ion flotation has a number of advantages over other separation techniques including its high efficiency and lack of affinity for other compounds. In addition, ion flotation systems are relatively easy to implement and require little maintenance or maintenance costs. This makes ion flotation systems ideal for applications requiring large volumes of products.
However, ion flotation systems do have some drawbacks. The reagents needed to bind the suspended particles are relatively expensive, while the solvents used in the recovery process can also be expensive. Additionally, the charged surface formed on the suspended particles is only temporary, which means that the particles may bind to dirt and other impurities unless they are washed before re-use.
Despite these drawbacks, ion flotation is still a popular separation technique and is used for a variety of applications. It is especially well suited for recovering a wide range of compounds from water, such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls, as well as from oil and other petroleum based products. Furthermore, due to its high efficiency and low operating costs, ion flotation is often chosen as a preferred process for the recovery and purification of soluble substances.
