Factors Affecting On Solvent Extraction

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 modifying the                       oxidation state

      •For example: Reduction of Fe3+ to Fe2+.

     •Extraction of iron from the chloride solution 

        can be stopped by reducing Fe3+ to Fe2+

    


4.Masking Agents. 


•Some of the metals can interfere in the chemical reaction and create their interference in the reaction. 

• Masking Agents are the metal complexing agents which inhibits particular metals from taking part in chemical reaction and hence their interference can be stopped. 

 •For Example: Extraction of Aluminum in

  presence of Iron with 8- hydroxyquinoline. 

 • Here, Fe is masked with alkali cyanide to

  form stable ferrocyanide complex. 

• Some of the masking agents are listed

   below:

  Tartarate, Citrate, Fluoride, Cyanide and 

   EDTA are commonly used as a masking

   Agents .   


  5.Modifiers 

•Modifiers are the additives which are

 added to the organic phase to increase

 the solubility of the extractant in solvent. 

•Generally high molecular weight alcohols

 are used as modifiers. 

 •For Example. Polyvinyl alcohol etc. 


  6.Synergistic Agents

  •These agents are generally used for

    the enhancement of extraction process. 

  •Synergistic Agents are added to the organic

    phase in order to enhance the extraction     

    process . 

  •For example: 

 Neutral Organophosphorous compounds 

 added to acidic Organophosphorous

 compounds exerts synergistic efffect. 

 All these factors are affecting on the solvent           extraction. 

 


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