Introduction to Liquid-Liquid Extraction

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Questions and Answers

What is the primary goal of liquid-liquid extraction?

To separate solutes based on their solubility (correct)

To combine multiple liquids into a homogeneous mixture

To create a solid from a liquid solution

To increase the temperature of the solution

In a typical extraction process, what is referred to as the 'raffinate'?

The pure solvent used for extraction

The mixture before the extraction process

The residual liquid after solutes have been extracted (correct)

The liquid containing the desired solutes

What defines the 'extract' in liquid-liquid extraction?

The solid phase formed from the extraction

The solvent with the solute after extraction (correct)

The original solution before extraction

The stream containing the unwanted contaminants

Which of the following best describes a ternary system in the context of liquid-liquid extraction?

A system consisting of a solute, solvent, and carrier liquid Signup and view all the answers

What is a key advantage of using liquid-liquid extraction over distillation?

It can handle closed-boiling point mixtures Signup and view all the answers

In liquid-liquid extraction, what does the term 'feed' refer to?

The mixture containing solutes to be extracted Signup and view all the answers

What role does a solvent play in liquid-liquid extraction?

It selectively dissolves the target solute from the feed Signup and view all the answers

Which of the following is NOT a common application of liquid-liquid extraction?

Separation of proteins from DNA Signup and view all the answers

Which of the following industries primarily utilizes extraction processes for the separation of heat-sensitive liquid feeds?

Biochemical Industry Signup and view all the answers

What is the requirement for the distribution constant K when the desired product is in the extract stream?

K must be greater than 1 Signup and view all the answers

Which equipment type is commonly used for multi-stage extraction processes?

Mixer-settler Battery Signup and view all the answers

What is a major disadvantage of mixer-settlers?

Size and material inventory held up Signup and view all the answers

Which type of extraction is characterized by being able to cope with slurries and high interfacial tension?

Batch-wise Extraction Signup and view all the answers

What happens if the solvent in an extraction system is miscible with the feed?

A second separation process is typically necessary Signup and view all the answers

Which of the following is NOT a type of multi-stage extractor equipment?

Single Stage Mixer-Settler Signup and view all the answers

Which statement about extraction systems in the petroleum industry is true?

They separate feeds according to chemical type. Signup and view all the answers

Which component serves as the solute in a liquid-liquid extraction process?

Penicillin Signup and view all the answers

What is the main purpose of using solvent extraction in biotransformations?

To reduce product loss during extraction Signup and view all the answers

Which of the following is NOT a factor to consider when choosing a solvent for liquid-liquid extraction?

Color Signup and view all the answers

What is an example of a periodical extraction method?

Shaking a separatory funnel Signup and view all the answers

Which extraction method should be selected when there is a need for constant separation?

Continuous extraction Signup and view all the answers

What type of equipment is commonly utilized in liquid-liquid extraction processes?

Centrifugal extractors Signup and view all the answers

Which of the following factors enhances the selectivity of solvent extraction?

Selectivity criterion Signup and view all the answers

Why is the distribution coefficient important in solvent extraction?

It measures the concentration of solute distribution Signup and view all the answers

Study Notes

Introduction to Extraction

Liquid-liquid extraction, or solvent extraction, separates solutes from a liquid solution using an insoluble liquid.
Separation hinges on the solubility differences of solutes in the contacting liquids.
The feed is the original solution comprising solute A and carrier liquid C, while the solvent S is a pure liquid.
The result of extraction appears as two phases: the extract (solvent-rich) and the raffinate (residual liquid).

Purpose of Extraction

Used to separate mixtures with close boiling points that can't withstand high distillation temperatures.
Examples include recovering penicillin from fermentation broths with butyl acetate and acetic acid from aqueous solutions using ethyl acetate.

Liquid-Liquid Extraction

Comprises three components: carrier liquid (A), extracting solvent (B), and solute (C).
Essential for applications requiring solute transfer between two immiscible or partially miscible liquid phases.

Liquid-Liquid Equilibria (LLE)

Vital for equipping and designing extraction setups.
Equilibrium data assists in optimizing the selection of extraction systems and solvents.

Classification of Extraction Processes

Periodical extraction involves shaking separatory funnels.
Continuous extraction maintains a constant flow for separation.
Countercurrent extraction optimizes contact between phases for enhanced separation.

Choice of Solvent

Key factors include selectivity, distribution coefficient, and insolubility.
Consider recoverability of solute, density differences, interfacial tension, chemical reactivity, cost, viscosity, vapor pressure, flammability, and toxicity.

Advantages of Solvent Extraction

Allows selective extraction directly from fermentation broths and reaction mediums.
Reduces product loss due to degradation as solutes transfer to a different phase.
Adaptable across various operational scales, including packed extraction towers and mixer-settlers.

Application of Extraction

Widely employed in the petroleum industry for separating heat-sensitive liquid feeds by chemical type.
Significantly utilized in biochemical and pharmaceutical sectors for antibiotic separation and protein recovery.
Used in inorganic chemical processes for recovering high-boiling compounds like phosphoric acid and sodium hydroxide.

Distribution Law

At equilibrium, the solute concentration ratio in two phases relates by the equation CE/CR = K.
The distribution constant K must exceed unity for extract streams and be less than unity for raffinate streams.

Typical Extraction System in Industry

Extraction systems necessitate at least one distillation column or another separation process to recover solvents from the extract.
Additional distillation is required when solvents exhibit some miscibility in the feed to recover solvents from the raffinate.

Classification of Extractors

Extractors can be categorized as single-stage or multi-stage systems.

Types of Extractor Equipment

Single-stage extractors include mixer-settlers and decanters.
Multi-stage extractors involve mixer-settler batteries and mechanically agitated extractors like Scheibel and rotating disk contactors.

Mixer-Settler

Mixer-settlers are favored for reliability, operating flexibility, and high capacity in handling challenging systems.
They accommodate viscous liquids and solid-liquid slurries but may require substantial space and material inventory.
Operations can be continuous or batchwise, with mixer and settler configurations being integral or separate.

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Description

Explore the fundamentals of liquid-liquid extraction, a vital technique for separating solutes from solutions. This quiz covers key concepts such as the roles of feed, solvent, and the phases formed during the extraction process. Understand its applications, including the recovery of important compounds like penicillin.