Test Your Understanding of Solvent Extraction Principles and Techniques!

Solvent Extraction: Principles and Methods

• Solvent extraction is a process used to isolate organic compounds from their aqueous solutions by shaking them with a suitable organic solvent.
• The organic solvent selected should be much more soluble in the organic solvent than in water, and water and organic solvents should not be miscible to each other.
• Common organic solvents used in solvent extraction include ether, benzene, and acetone.
• The distribution law, also known as Nernst's distribution law, is based on the principle that if a solute "X" distributes between two non-miscible solvents "a" and "b," the ratio of the concentrations of "X" in the two solvents is a constant quantity.
• The partition coefficient or distribution constant (KD) is the constant value of this ratio.
• Solvent extraction involves taking the aqueous solution of the solute in a separating funnel, mixing it with the desired organic solvent, shaking it vigorously, and allowing it to remain undisturbed for some time.
• The solute is transferred from the aqueous layer to the organic layer as it is more soluble in an organic solvent.
• The amount of organic substance extracted depends on the number of extractions.
• The principle of extraction of polyaromatic hydrocarbons (PAHs) involves liquid/liquid extraction (LLE) and considers five chemical properties: vapor pressure, solubility, molecular weight, hydrophobicity, and acid dissociation.
• The method used for sampling, determination, and extraction of total petroleum hydrocarbons (TPHs) and PAHs involves using seawater and sediment samples, extracting them with methylene chloride, and measuring the results in µgL-1 or µgg-1.
• For water samples, the method involves taking 10-20 g of the sediment sample and extracting it in a Soxhlet extractor with methylene chloride.
• The results for water samples are expressed in µgg-1.