Effect of Hydrotropes on Solubility and Mass Transfer Coefficient of p-Nitrobenzoic Acid

Prakash, D. Gnana; Kumar, S. Thenesh; Gandhi, N. Nagendra

doi:10.3923/jas.2009.2975.2980

Cited by 11 publications

(1 citation statement)

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“…Hydrotropic extraction relies mainly on the addition of enough hydrotropes in the solution. The different hydrotropes can be identified by their formula -sodium salicylate, cumene sulfonate, vitamin C, sodium benzoate, and sodium xylene sulfonate being some examples of hydrotropes [54][55][56][57][58][59] -and they are characterized by their MHC. Different methods of hydrotropic extraction exist.…”

Section: Principles and Processmentioning

confidence: 99%

Water as Green Solvent for Extraction of Natural Products

Petigny

Özel

Périno

et al. 2015

Green Extraction of Natural Products

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IntroductionWater is the most abundant molecule on the earth, covering 70% of its surface. Life processes on this planet are crucially dependent on the presence of water. It is often recognized that water has tremendous benefits as a green extraction solvent because it is not only inexpensive and environmentally benign but it is also nonflammable and nontoxic, providing opportunities for clean processing and pollution prevention. The water molecule contains three nuclei, one modestly heavy (oxygen), and two light ones (hydrogen). Because of water's electronic structure, the oxygen atom has a slight negative charge on it and the hydrogen atoms have a slightly positive charge [1]. When water molecules are closed together, their positive and negative regions are attracted, these attractive forces are known as hydrogen bonds. The energy associated with a hydrogen bond is 8-40 kJ/mol. The O-H bond lengths are 0.9572 Å and the average HOH bond angle is 104.52 ∘ , slightly smaller than the tetrahedral angle (109.5 ∘ ). The molecule is very small with a hard sphere diameter of 2.75 Å. The smallness of the water molecule has important consequences for the hydration of solutes. The contours of the total electron density in the HOH plane of the water molecule indicate a shape not far from spherical. The water molecule has a dipole moment of 1.85 D with two partial positive charges on the hydrogen atoms and a single zone of negative charge on the oxygen atom.It is well known that water molecules are strongly associated in the liquid phase by H-bonding. Hydrogen bonds result dominantly from electrostatic interactions with a light contribution of covalent bond formation. The H-bond interactions in liquid water constitute a 3-D H-bond network with localized and structured clustering. Therefore, the liquid structure is not determined by hard-core repulsions between the individual water molecules but rather by intermolecular and directional H-bonding. The broad variation of H-bond angles further demonstrates the noncrystalline arrangement of the water molecules and appears to indicate that some bond angle distortion in the H-bonds is rather easily allowed in the liquid. It is important to recognize that intermolecular interaction Green Extraction of Natural Products: Theory and Practice, First Edition. Edited by Farid Chemat and Jochen Strube.

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Section: Principles and Processmentioning

confidence: 99%

Water as Green Solvent for Extraction of Natural Products

Petigny

Özel

Périno

et al. 2015

Green Extraction of Natural Products

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Functions of Hydrotropes in Solutions

et al. 2012

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Hydrotropes affect a several-fold increase of the solubility of sparingly soluble solutes under normal conditions. Their water-solubility can significantly enhance the solubility of organic solutes such as esters, alcohols, aldehydes, ketones, hydrocarbons, and fats. While the study of hydrotropes is pioneered by a biochemist, greater appreciation of their role and applicability has happened rather in chemistry and chemical engineering than in biology. Hydrotropes are widely used in drug solubilization, as extraction agents for fragrances, as agents to increase the rate of heterogeneous reactions, and for separation of close-boiling liquid mixtures through extractive distillation and liquid-liquid extraction. Applications of hydrotropy and its mechanism are discussed and the scope for future work is presented in this review.

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