Sedimentation ,Centrifugation & extractions
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Questions and Answers

What happens to larger particles in a centrifuge compared to smaller ones?

  • They pass through with the clarified liquid.
  • They have lower settling velocities.
  • They remain suspended in the liquid.
  • They accumulate at the outer edge of the bowl. (correct)

Which statement best describes the inside structure of a disc stack centrifuge?

  • It contains closely spaced disks shaped like cones. (correct)
  • It operates without any central rotation axis.
  • It has a singular, flat base for solid accumulation.
  • It is a vertical cylinder with no internal components.

What is a feature of nozzle discharge centrifuges?

  • They only have one nozzle for liquid discharge.
  • They can only be used for solid materials with less than 10% content.
  • They enable continuous discharge of solids and liquid. (correct)
  • They require manual operation to remove solids.

In which industries are centrifuges commonly used?

<p>Brewing industry and edible oil refining. (B)</p> Signup and view all the answers

What modification allows for controlled discharge of solids in a centrifuge?

<p>Implementing self-opening nozzles controlled by timers. (D)</p> Signup and view all the answers

What is the primary mechanism of sedimentation?

<p>Gravity allowing denser solids to settle. (D)</p> Signup and view all the answers

Which separation process is used to separate immiscible liquids and solids from liquids?

<p>Centrifugation (C)</p> Signup and view all the answers

What type of product is typically obtained through centrifugation?

<p>Thick paste or concentrated suspension (A)</p> Signup and view all the answers

What is a key characteristic of a tubular bowl centrifuge?

<p>It consists of a narrow bowl rotating about a vertical axis. (D)</p> Signup and view all the answers

What determines the separation of immiscible liquids in centrifugation?

<p>The centrifugal force applied (C)</p> Signup and view all the answers

Which operation is typically more expensive in terms of equipment cost?

<p>Centrifugation (D)</p> Signup and view all the answers

What is the main application of centrifugation in the dairy industry?

<p>To separate cream from skim milk (B)</p> Signup and view all the answers

In what scenario would centrifugation be preferred over filtration?

<p>When filtration proves ineffective (D)</p> Signup and view all the answers

What is the primary role of the liquid in solid-liquid extraction?

<p>To carry out the separation process (B)</p> Signup and view all the answers

Which factor does NOT control the operation of liquid-liquid extraction?

<p>Temperature of the mixture (D)</p> Signup and view all the answers

What is the main product obtained when sugar is extracted from sugar beet?

<p>Sugar crystals (D)</p> Signup and view all the answers

In liquid-liquid extraction, what is necessary for the liquids being separated?

<p>They must be immiscible (D)</p> Signup and view all the answers

What medium is typically used to extract oil from natural products in a lab-scale liquid-liquid extraction process?

<p>Hexane (D)</p> Signup and view all the answers

Why are sugar beets cut into slices during the extraction process?

<p>To increase the surface area for extraction (C)</p> Signup and view all the answers

After extracting oil using hexane, what is the next step before reusing the solvent?

<p>Distillation (B)</p> Signup and view all the answers

Which of the following is an example of solid-liquid extraction?

<p>Extraction of coffee from coffee beans (C)</p> Signup and view all the answers

Flashcards

Sedimentation

The process where denser solids settle out of a suspension due to gravity.

Centrifugation

A process that uses centrifugal force to separate substances in a liquid.

Sedimentation vs. Centrifugation

Sedimentation uses gravity, while centrifugation uses centrifugal force to separate mixtures.

Immiscible Liquids

Two liquids that don't mix and separate into layers.

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Centrifugal Force

The outward force on a spinning object.

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Tubular Bowl Centrifuge

A type of centrifuge with a tall, narrow bowl for separating liquids and solids.

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Food Industry Use of Centrifugation

Centrifugation is used in food processing for tasks like separating liquids, and removing solids.

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Particle size relation to filtration and centrifugation

Centrifugation is effective for smaller and denser particles or mixtures often not feasible in filtration. Filtration is better for larger, non-dense particles.

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Solid loss in centrifuged effluent

If there is too much solid in the liquid being separated, the process might not be effective and the solid will remain in the final liquid.

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Disc Stack Centrifuge

A centrifuge with closely spaced cones (disks) inside a bowl, used to separate solids from liquids.

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Centrifugation

A process using centrifugal force to separate substances based on density differences.

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Continuous Centrifuge

A centrifuge that continuously separates solids and liquids.

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Nozzle Discharge Centrifuge

A type of continuous centrifuge that uses nozzles to expel solids and liquids.

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Solids Settling Velocity

The speed at which larger particles settle from a liquid in a centrifuge.

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Slurry Composition

Mixture containing up to 25% solids, often processed by the centrifuge.

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Self Opening Centrifuge

A modifed centrifuge where nozzle openings are controlled.

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Extraction

A process where a liquid is used to separate components from a solid or another liquid, usually by dissolving the desired component, then separating the liquid phases.

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Solid-Liquid Extraction

Extraction process where a liquid dissolves a component from a solid material, separating the liquid phase (containing the dissolved component) from the solid phase by gravity settling.

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Liquid-Liquid Extraction

Extraction from one liquid to another, using immiscible liquids.

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Immiscible liquids

Liquids that do not mix and form separate layers.

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Solvent Extraction

Extraction using a solvent to separate components.

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Edible oil extraction

Separation of oil from nuts, seeds, and beans, often using hexane as a solvent followed by solvent removal.

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Sugar Extraction from Sugar Beet

Extraction of sugar by using water as a solvent, often heated.

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Study Notes

Sedimentation

  • Solids in a suspension settle due to gravity.
  • Used in food processing to separate dirt, crystals, and/or dust from raw materials.

Centrifugation

  • Accelerates settling with a centrifugal field.
  • Separates immiscible liquids based on density differences.
  • Separates solids from liquids by moving solids to the bowl wall.
  • More effective for particles than sedimentation.

Sedimentation vs. Centrifugation Comparison

Feature Sedimentation Centrifugation
Separation Principal Gravity Centrifugal force
Employment Dilute suspensions of large, rigid solids When filtration is ineffective, or in more concentrated suspensions
Product Obtained Dry cake Paste or concentrated suspension
Expense of Equipment Less More
Particle Size Large particles Wide range
Removal of Insolubles Dilute, large, and rigid insolubles Effective across a broader range of particle sizes

Centrifugation Application

  • Immiscible liquids: Separates liquids of different densities. Example: separating milk into skim milk and cream.
  • Solids from liquids: Separates solids from liquids. Example: Fruit juice processing, clarifying cider, sugar syrups

Tubular Bowl Centrifuge

  • Tall, narrow bowl rotating vertically.
  • Suspension fed at the bottom; clarified liquid removed from the top.
  • Suitable for feeds up to 2% solid content.
  • Solids collected as a paste.
  • Intermittent operation.

Disc Stack Centrifuge

  • Short, wide bowl with closely spaced cones (disks).
  • Feed enters at the bottom, flows upward past disks.
  • Larger particles settle more easily.
  • Solids accumulate at the outer edge of the bowl.
  • Soluble material passes through.

Continuous Centrifugation

  • Nozzle discharge centrifuges allow for continuous operation.
  • Continuous discharge of solids (sludge) and clear liquid.
  • Used in various industries including brewing, wine making, and edible oil refining.
  • Can handle slurries up to 25% solids content.
  • Modifications include self-opening centrifuges for controlled nozzle openings. (e.g., based on solids buildup)

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Description

Explore the concepts of sedimentation and centrifugation, including their principles, applications, and comparisons. This quiz highlights the differences between these two methods of separation, focusing on efficiency, equipment expense, and particle size. Test your knowledge on their uses in various industries.

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