Introduction to Separation Techniques

Introduction to Separation

• Separation techniques are a common practice in daily life.

Why Separate Substances?

• Substances are separated to isolate useful components and remove non-useful or harmful impurities.

Separating Useful Components

• Useful components have different applications.
• Sieving at construction sites separates soil for Reinforced Cement Concrete (RCC) and stones for other purposes.
• Sieving wheat flour separates fine flour for bread and bran for other uses, such as mixing with milk.

Removing Harmful Components

• Stones are removed from wheat grains before consumption because stones are not edible.

Mixtures: The Subject of Separation

• Mixtures are substances combined without chemical interaction or forming new substances.
• Mixtures consist of two or more substances.
• Separation techniques target the different components within mixtures.

Separation Techniques: Hand Picking

• Hand picking is a manual method to remove components from a mixture.
• Separation can be based on color (e.g., separating Gems candies by color).

Selective Separating

• Separation can be based on size difference (e.g., removing stones from wheat grains).
• Separation can be be based on quantity; useful for small mixtures.
• Hand picking is best for solid-solid mixtures with distinguishable components.

Inconvenient Option

• Hand picking is inconvenient when particle sizes are small or the mixture quantity is large.
• It is convenient only when the quantity of the mixture is small.

Separation Techniques: Sieving

• Sieving is used for solid-solid mixtures.
• It works on the principle of size difference between components.
• Finer particles pass through the sieve, while larger particles remain on top.
• Sieving can be used as an alternative to hand picking for large mixture quantities.
• Sieving is used on construction sites to separate fine sand from stones.

Sieving Example

• During wheat flour sieving, fine flour passes through while the bran remains.
• Effective sieving requires a significant size difference between the desired substances.
• Sieving is ineffective when particles are the same size, as they either both pass through or both remain on top.

Separation Techniques: Threshing

• Threshing involves separating grains from stalks.
• It is another method for solid-solid mixtures.
• It involves beating stalks to release grains.

Explanation of Method

• Grains are attached to stalks through weak points.
• Beating (threshing) breaks this weak link, separating the grain from the stalk.
• Threshing can be done manually or with threshing machines.

Separation Techniques: Winnowing

• Winnowing separates the husk from seed grains.
• It is used for solid-solid mixtures.
• Separation is based on weight differences between components.

Weight Differential in Components

• Winnowing uses wind to separate heavier and lighter components.
• It separates the husk from the seed, where lighter components are blown away by the wind.
• Heavier components fall straight down.

Separation Techniques: Sedimentation and Decantation

• These are used for solid-liquid mixtures.
• The solid in the mixture must be INSOLUBLE in the liquid.
• Sedimentation: Heavy, insoluble solids settle down due to gravity when the mixture stands.
• Over time the things in the solution will settle naturally.
• For example, soil settles at the bottom of a soil and water mixture after standing.
• Decantation: Pouring out the liquid (supernatant) after sedimentation, leaving the solid behind.

Problems?

• Separating stones by hand is labor-intensive.
• Separating tiny materials in mud is difficult.

Replacing Previous Methods

• Filtration can replace sedimentation and decantation.

Separation Techniques: Filtration

• Filtration separates insoluble parts of a solution.
• The mixture passes through a filter (e.g., cloth).
• Solids remain on the filter, while the liquid passes through as purified liquid.

Better Filtration Techniques

• Filtration is an effective technique for separating two materials.
• This allows for very smaller materials to be filtered as well, which could not manually be separated.
• Use a strainer to hold back tea leaves when pouring tea.

Separation Techniques: Evaporation

• Evaporation is the process of a liquid turning into vapor.
• For example, water converting into water vapor.

Explaining Evaporation Method

• Seawater contains salt that can be separated.
• Salt is separated from the impurities in seawater.
• Workers pour seawater into small, shallow pits in the ground.

How does the Sea Water Evaporate?

• Water evaporates due to prolonged exposure to the sun and wind.
• Leaving salt and impurities from the seawater
• The leftover salt undergoes further purification and processing to make it safer for consumption.

Process Review

• Start with seawater in shallow pits.
• Expose the pits to sun and wind, so that water evaporates.
• The residue is salt and impurities.
• Impurities are further purified and processed before market sale.

Differences Note

• Boiling is not evaporation.
• Boiling uses artificial heat (e.g., from a stove).
• Evaporation is a natural process (e.g., from the sun).

Separation Techniques: Condensation

• Condensation is the conversion of vapor back into a liquid.
• For example, water vapor converting into water.
• Condensation can be combined with evaporation for distillation.
• Water converts to water vapor and back again.

Method Review

• Water is heated (boiled) in a kettle and escapes as steam (water vapor) from the spout.
• Ice on the spout causes the vapor to turn back into water.
• A similar process occurs with other materials.

Ginning Method

• Ginning is used when moving from fiber to fabric.

Using Multiple Methods

• Separating a mixture may require multiple methods (e.g., sand and salt mix).

Multiple Methods Explained

• Sand and salt are combined with water.
• Stirring dissolves both.

Problems you could run into

• Too much salt may prevent it from fully dissolving.
• The separation may be incomplete due to the quantity of salt.

Sedimentation Process

• Add water to the sediment to make it more solution friendly to separate, and let it sit.

Process Example

• The sand would settle, and the salt would dissolve.
• Separate via decantation (separating water/salt from sand)
• Heat the water to evaporate it.

Method 2. Shorter

• Add water and mix.
• Pour mixture through a strainer to trap dirt and collect only pure solution.

Can water dissolve any amount of substance it?

• There are limits to how much you dissolve.

SATURATED SOLUTION

• At a certain temperature and amount of a substance, only so much can dissolve.
• This can be understood via an analogy between sand and salt.

Analogy Review

• The amount of available water affects the potential to dissolve a substance

Solution Defined

• Solution = solvent + solute.
• A solvent is a mixture of whatever is being dissolved (e.g., water).
• All substances are considered solutions.
• An unsaturated solution has the potential for more solute to dissolve.
• A saturated solution has reached the limit of solute that can dissolve.
• Temperature can affect the saturation point.
• Super saturation is a technique to dissolve more solute than normally possible.

How to use SUPER SATURATION

• Dissolve more salt in water than it would normally hold.
• It will mix, become even stronger than ever before.
• This gives you a super solvent

Conclusion

• Separation techniques are diverse and useful.

Review Questions

• Which one would require "FILTRATION' style separation
• Corn and Milk.

Explanation of Method

• Water is a key factor, filtration is used for water and solids.
• Oil and water, being both liquids, would not use filtration.
• Water + solids will give you that result
• Corn Flakes + INsoluable, gives you the correct answers.

2. Which of the following methods is best, or one is more right.

Problem Introduction

• Consider Kidney Beans, Rice, etc.
• Which is easily separated via being lightweight

Correct Answer and why

• Rice Flex and Corn lightweight, so can separate with the specified method

3. The question pertains to an at home method to separate ghee from "SOMETHING"

Problem Intro

• Given what you did by accident?
• You made Ghe, out of butter. and not everything mixed in properly

Correct Answer?

• Filtration or Decantation is the best option
• Some people may pour out what has filtered down or use a cloth.
• So you need to move the solids away!
• Either of them work

Question 4

• Working on some chapatis!
• While prepping flour, a user notes some wheat
• Which method should remove them?

Correct Method

• Sieving separates by a distance

End Note

Question

• How can you complete GINNING by itself, give an example.
• Physics is an all-rounder, and will have your back the entire time.