![]() ![]() ![]() For an organic compound, it is relatively safe to assume that it will dissolve better in the organic layer than in most aqueous solutions unless it has been converted to an ionic specie, which makes it more water-soluble. The most important point to keep in mind throughout the entire extraction process is which layer contains the product. This often leads to the formation of emulsions. Other solvents such as alcohols increase the solubility of water in organic layers significantly because they are miscible with both phases and act as a mediator. The higher water solubility lowers the solubility of weakly polar or non-polar compounds in these solvents i.e., wet Jacobsen ligand in ethyl acetate. Oxygen containing solvents are usually more soluble in water (and vice versa) because of their ability to act as hydrogen bond donor and hydrogen bond acceptor. Water also dissolves in organic solvents: ethyl acetate (3 %), diethyl ether (1.4 %), dichloromethane (0.25 %) and chloroform (0.056 %). ![]() Commonly used solvents like ethyl acetate (8.1 %), diethyl ether (6.9 %), dichloromethane (1.3 %) and chloroform (0.8 %) dissolved up to 10 % in water. However, in some cases it is possible to accomplish a phase separation by the addition of large amounts of a salt (“salting out”). Ethanol, methanol, tetrahydrofuran (THF) and acetone are usually not suitable for extraction because they are completely miscible with most aqueous solutions. Solvents like dichloromethane (=methylene chloride in older literature), chloroform, diethyl ether, or ethyl ester will form two layers in contact with aqueous solutions if they are used in sufficient quantities. Since most of the extractions are performed using aqueous solutions (i.e., 5 % NaOH, 5 % HCl), the miscibility of the solvent with water is a crucial point as well as the compatibility of the reagent with the compounds and the solvent of the solution to be extracted. The liquids involved have to be immiscible in order to form two layers upon contact. Many liquid-liquid extractions are based on acid-base chemistry. Washing is also used as a step in the recrystallization procedure to remove the impurity containing mother liquor adhering to the crystal surface. Strictly speaking, the two operations are targeting different parts in the mixture: while the extraction removes the target compound from an impure matrix, the washing removes impurities from the target compound i.e., water by extraction with saturated sodium chloride solution. A standard method used for this task is an extraction or often also referred to as washing. These compounds have to be removed in the process of isolating the pure product. Hence, liquidliquid extraction could be a novel method for treatment of textile wastewater.After a reaction is completed, the solution often times does not only contain the desired product, but also undesired byproducts of the reaction, unreacted starting material(s) and the catalyst (if it was used). In developing countries, tonnes of wastewater is discharged without prior treatment. Novelty: Wastewater treatment is most important in today’s life because of excess urbanization and industrialization. Hence, the manuscript presented an overview on applications of liquid-liquid extraction systems in treatment of textile wastewater. One such method is liquid-liquid extraction-based systems. Findings: Even though a variety of methods are available for treatment of textile wastewater, certain methods remain neglected without much attention. Methods: Google Scholar database was used to collect literature on liquid-liquid extraction systems in treatment of textile wastewater between 20. Objectives: To present an overview on various extraction systems used in treatment of textile wastewater. ![]()
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