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Factors Affecting on Solvent Extraction.   There are some important factors which affects solvent extraction are: 1.Salting Out Agents   2.pH value  3.Oxidation States   4.Masking Agent 5.Modifiers  6.Synergistic Agents.  1.Salting Out Agents •The extraction or extraction efficiency of metals may be increased by addition of high concentrated inorganic salt to the aqueous phase.  •The Process of addition of inorganic salt to the aqueous phase is called Salting Out Effect.   •This is due to strong efffect of the added salt on the activities of the species by the common ion effect.    2. pH Value •Solvent Extraction process is dependent upon pH of the solution.  •The extraction of the two metals may be achieved at different pH values.  •Two different metals required different pH for    their extraction.  3.Oxidation States       •Extraction process must be selective.       •The selectivity of extraction may sometimes               increased or decreased by modifyin

Applications of Solvent Extraction.  1.Determination of the iron as the  8-       hydroxyquinolate.  Fe3+ ion ( 50-200 μ gms) can be extracted from an aqueous solution with 1% solution of 8 hydroxyquinoline in chloroform by double extraction . The pH of the aqueous solution is between 2-10. At pH 2-2.5, Aluminum, Cobalt, Cerium do not interfere in the analysis.  Ferric oxinate a dark coloured solution in chloroform are formed,which absorb radiation at 470 mμ.  2.Determination of Uranium as a 8-hydroxyquinolate   Uranium can be extracted and determined from the the aqueous solution by adding 8-hydroxyquinoline as the 8-hydroxyquinolate (900μgm ) at pH 8. 8 and in the presence of EDTA The Oxinate complex absorb at 400 mμ.  3.Determination of Lead in the blood.  For the determination of Lead in the blood, after the organic matter is destroyed, then blood sample is treated with dithiozone chelating agent.  Metal chelate of lead is formed. and then it is extracted into Dichloromethane at pH

Solvent extraction Introduction, Principle and Features.  Introduction: There are many methods of analysis which involves separation of components of mixture, their purification and their estimation.  These two terms one is Separation and other is purification having different conditions.  Separation starts with material composed of large amount of one constituent and small amount of other constituents. In this process all the constituents obtained in the pure form.  Purification involves small amount of other constituents is removed to get the large constituents in pure form .  Methods used for separation of mixture of constituents.  1.Physical Method.  2.Chemical Method.  1.In physical method, the advantage of the differences in physical properties of the constituents is taken.  For example. Adsorption , Solubility, etc.  2.In chemical method, the advantage of the differences in chemical properties of the constituents is taken.  For example. Precipitation.  Principle of Solvent Ex

  Solvent extraction. Distribution coefficient and it's Limitations.  Distribution coefficient: According to Nerst Distribution law,  "When solute distributes itself between the two immiscible solvents or phases in contact and in equilibrium with each other, then the ratio of the concentrations of the substance in the two phases is constant at constant temperature. " Thus,  S1/S2=kD Where,  kD -is distribution constant or partition constant.  S1- is Concentrations of the solute in mols/ litre in organic phase ( phase 1) .  S2-is Concentrations of the solute in moles / litre in aqueous phase ( phase 2)  kD -is the independent of the total solute or either of the phases.  This law takes no account of the activities of various species.  Therefore it is applicable only for dilute solutions.  Limitations of Distribution Law.  1.The Solution must be dilute.  2.The temperature remains constant.  3.The two solvents are immiscible.  4.The molecular state of the solute remains t

  Distribution ratio is denoted by capital letter D.  •  It is the ratio of total concentrations of species in organic phase ( phase 1) to the total concentrations of species in aquous phase.(phase 2) .  •  Let us consider an example of benzoic acid   distributed between two immiscible solvents ether and water    We know that, Here benzoic acid is a solute and ether is organic solvent and water is aquous solvent.  • kD= [HBz-]e /[ HBz-]a Where,  • [HBz-]e stands for Concentrations of benzoic acid in the ether layer.  • [ HBz-]a stands for Concentrations of benzoic acid in the water layer.  As we know, In aquous medium Benzoic acid undergo partial ionization.  • HBz   ionises as    H+   + Bz-  • By applying law of mass actionaction, the ionization constant (Ka) of benzoic acid in aquous medium is written as,  • Ka  = [H+]a  [ Bz- ]a/ [ HBz]a  Where suffix a - on the right hand side stands for     aquous.  • The distribution ratio in the two immiscible solvents Ether and water is written