Extraction Methods and Processes

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Questions and Answers

What is the primary advantage of using counter current extraction over other methods?

It restricts the number of analytes that can be extracted.

It is less efficient and takes longer.

It minimizes the time for phase separation and reduces mixing problems. (correct)

It allows for more extensive mixing of the phases.

In continuous extractions, what role does the solvent play in the extraction process?

It is added only once at the beginning of the process.

It flows continuously to extract analytes from the mixture. (correct)

It aids in phase separation between solute and solvent.

It is used in a batch-like fashion, similar to batch extraction.

Which extraction method is characterized by adding the feed solution in parts and completing each stage before moving to the next?

Synergic extraction

Continuous extraction

Batch extraction (correct)

Counter current extraction

What characteristic distinguishes chelate extraction from other forms of extraction?

It requires the formation of complex structures with specific agents. Signup and view all the answers

Which of the following interactions is crucial for solvation processes?

Hydrogen bonding and Van der Waals forces. Signup and view all the answers

How does the extractability of neutral or organic solutes differ from that of chelated solutes?

Neutral solutes aggregate and require different systems for extraction. Signup and view all the answers

Which statement correctly describes ion-pair formation in extraction processes?

Ion-pair formation increases solubility of salts in organic solvents. Signup and view all the answers

What is a major problem associated with settlers in mining?

Emulsification during intense agitation Signup and view all the answers

Which of the following advantages does S.E. (Solvent Extraction) have over distillation?

Greater production capacity Signup and view all the answers

How does resonance affect chelate formations?

It delocalizes electron density, strengthening bonds Signup and view all the answers

What role does steric effect play in chelation?

It creates hindrances that reduce chelation strength Signup and view all the answers

Which solvent is mentioned as effective for extracting CO2 during biogas separations?

Selexol Signup and view all the answers

In terms of solvent solubility, what advantage do chelated compounds have?

Increased solubility in organic solvents Signup and view all the answers

What does S.E. isolate in the pharmaceutical industry?

Active pharmaceutical ingredients Signup and view all the answers

Which of the following statements best describes dispersed phase?

A phase that is distributed throughout another medium Signup and view all the answers

What benefit does S.E. provide in renewable energy applications?

High-purity methane extraction Signup and view all the answers

What does synergic extraction primarily enhance in the solvent extraction process?

Efficiency and selectivity Signup and view all the answers

Which of the following accurately describes a limitation of synergic extraction?

Risk of forming stable complexes Signup and view all the answers

In ion pair formation extraction, what role does the counterion play?

It forms a neutral ion pair complex with the target ion. Signup and view all the answers

Which of the following is an advantage of ion pair formation extractions?

Highly selective for certain ionic species Signup and view all the answers

Which example illustrates synergic extraction?

Tributyl phosphate and 2-thonoyl-trifluoroacetone for uranium extraction Signup and view all the answers

What role do salting-out agents play in the metal extraction process?

They reduce the solubility of solutes in water. Signup and view all the answers

Which of the following best describes the process of stripping in metal extraction?

It transfers extracted solutes back to the aqueous phase. Signup and view all the answers

Why are metal complexing agents used in extraction processes?

They bind interfering ions, enhancing analyte purity. Signup and view all the answers

What is a common characteristic of chelates used in extraction?

They are highly effective and selective for complex ion species. Signup and view all the answers

Which limitation is common to both chelation and solvation processes?

They require stable chelates or conditions. Signup and view all the answers

In what way do ion pairs enhance extraction efficiency?

They enhance the effectiveness for challenging molecular species. Signup and view all the answers

What is the primary purpose of backwashing in extraction procedures?

To remove impurities or excess solutes from the organic phase. Signup and view all the answers

What characterizes synergic extraction compared to other methods?

It requires a combination of extractants for increased efficiency. Signup and view all the answers

Which of the following extractants would NOT typically be used for polar species?

Cyanides Signup and view all the answers

Which statement best defines the term 'extraction cycle'?

The repeated use of extractants and stripping processes for recovery. Signup and view all the answers

What is the primary factor that the choice of organic solvent impacts in extraction efficiency?

Extent of solute transfer Signup and view all the answers

How does the pH of the aqueous phase affect solute extraction?

It alters the formation of metal complexes. Signup and view all the answers

Which extraction method is best defined by the concept of forming stable neutral soluble complexes with counterions?

Chelate Extraction Signup and view all the answers

What is a characteristic feature of synergic extraction?

Involves a combination of metal ions and counterions. Signup and view all the answers

Which type of extractant is known for its simplicity and selectivity by targeting neutral complexes?

Solvation Extractants Signup and view all the answers

What effect does acidity have on the extraction process?

It allows for control over extractable species formation. Signup and view all the answers

Which type of extraction method involves bulky hydrophobic groups for selective transfer to the organic phase?

Ion Pair Extraction Signup and view all the answers

What is the role of the counterion in synergic extraction?

It stabilizes the neutral metal complex. Signup and view all the answers

Which statement about organic solvents used in extraction is true?

They can be oxygenated or mineral acids. Signup and view all the answers

In terms of selectivity during extraction, what does the combined effect of two extractants accomplish?

Improves extraction efficiency significantly. Signup and view all the answers

Study Notes

Methods of Extraction

Counter current extraction is a multistage technique using a series of tubes to separate substances based on differences in density. Lighter phases enter from the bottom, and denser phases from the top (counter current). This method is based on distribution ratios, like in mixer-settler units. It requires less mixing time and is more efficient.
Batch extraction can occur in single steps or stages to extract analytes from samples. Solvent and extracted substances are removed after each process step, with fresh batches used as needed. This is common in laboratory settings for smaller-scale extraction.
Continuous extraction is more efficient for large-scale processes. Solvents are added continuously, and analyte extraction happens continuously without stopping. This method is used in industries where continuous operation is needed, although countercurrent methods are usually applied to avoid mixing issues.

Process of Extraction Systems

Chelate extraction involves the formation of chelates for extraction
Solvation: Solvent molecules surrounding and interacting with solute particles to enhance dissolution.
Ion-pair formation: Oppositely charged ions combining to form neutral complexes, increasing solubility in another solvent.
Synergistic extraction: Two or more extractants working together to improve extraction efficiency and selectivity.

Chelate Extraction

Metals can be extracted by forming a stable chelate complex with a chelating agent. The chelate complex is typically more soluble in an organic solvent than the original metal ion.
Chelating agents are compounds with multiple functional groups that can coordinate with metal ions to form stable complexes.
Chelate extraction is an important method in industries, laboratories, and environmental science.

Factors Affecting Extraction Efficiency

Choice of solvent: Matching the solvent's properties with the desired extraction characteristics. Consider properties like solubility, reactivity, toxicity, safety, and cost.
pH of the aqueous phase: It influences metal complexes and their extraction abilities.
Acidity: Aqueous phase acidity affects the ionic species of the solute and affects the extraction process.
Steric effects: Bulky groups on ligands or near metal atoms hinder proper coordination.
Resonance effects: Electron delocalization in ligands can enhance metal-ligand bond strength and increase the stability of the complex.

Industrial Applications of Solvent Extraction (S.E)

Hydrometallurgy: Extracting and refining metals from ores.
Nuclear waste treatment: Separating radioactive isotopes.
Biofuel separation: Extracting biofuels from biomass.
Waste Water Treatment: Removing or concentrating hazardous substances from water.
Pharmaceuticals: Isolating and purifying active pharmaceutical ingredients (APIs).
Food production: Some types of food production

Solvent Extraction, General

Importance of less solvent usage
Solvent extraction is useful for repeated use without adding fresh solvent.
Extraction is faster with automation than other methods.
Continuous solvent extraction involves continuously adding solvent, passing it through the mixture, and continuously extracting analyte solutes.
This is more efficient for large-scale operations.
Different types of equipment are used, including mixers, separators, condensers, and evaporators for optimal results.
The efficiency of solvent extraction depends on the properties of the solvents (solubility, miscibility, density differences), the physical/chemical properties of the extractants, and the conditions of the process
Specific considerations regarding the pH of the solution will also need to be taken into account

Solvent Extraction Principles

Principle of separation based on density differences or by other factors, such as selectivity towards particular compounds or components due to differences in chemical affinity between the components of the mixture and the solvent.
A mixing chamber containing feed solution and solvent, a settling chamber to separate the phases, coalescence areas for the merging of small droplets, weirs (splays) to allow the separation, and outlet ports to collect the separate phases.

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Description

This quiz covers various methods of extraction including counter current, batch, and continuous extraction systems. Learn about the principles behind each method and their applications in laboratory and industrial settings. Test your understanding of extraction techniques and their efficiencies.