ANS:A - liquid extraction

Liquid-liquid extraction, also known as solvent extraction or simply extraction, is a separation process used to selectively transfer one or more components from a liquid phase into another immiscible liquid phase. This process is commonly employed in chemical and industrial processes for purification, concentration, or separation of desired components from a mixture. Here's how liquid-liquid extraction generally works:

1. Selection of Solvents: Two immiscible solvents are chosen: the feed solvent (containing the mixture to be separated) and the extracting solvent (into which the desired components will be transferred).
2. Contacting Phases: The feed solvent and the extracting solvent are mixed together in a separation vessel, such as a mixer-settler, extraction column, or centrifuge. Due to their immiscibility, they form two distinct phases: the organic phase (extracting solvent-rich phase) and the aqueous phase (feed solvent-rich phase).
3. Transfer of Components: The desired component(s) selectively transfer from one phase (usually the aqueous phase) into the other phase (usually the organic phase) based on their solubility and affinity for the respective solvents. This transfer is facilitated by the difference in solubility and partition coefficients between the components in the two phases.
4. Separation: After the transfer of components has occurred, the two phases are allowed to settle or are separated using mechanical means, such as decantation or centrifugation. The phase containing the desired components (now enriched in the extracting solvent) is collected as the extract, while the phase containing the remaining components is referred to as the raffinate.
5. Further Processing: The extract and raffinate phases may undergo additional processing steps, such as further extraction stages or downstream processes, to achieve the desired purity or concentration of the desired components.

Liquid-liquid extraction is widely used in various industries for a range of applications, including:

• Separation of organic compounds from aqueous solutions
• Recovery of valuable metals from ores or industrial waste streams
• Purification of pharmaceuticals and fine chemicals
• Removal of impurities from petroleum products
• Production of food and beverage ingredients

Overall, liquid-liquid extraction offers a versatile and efficient method for separating and purifying components from complex mixtures, making it a valuable technique in chemical engineering and industrial processes.