A technique to achieve any mass transfer occurrence that

converts a mixture of substances into two or more

individual product mixtures.

The main goal of separation process is to ____________.

Chemists use analytical separation methods while chemical

engineers are more concerned with the manufacture of chemicals

using economical, large-scale separation methods.

Rate of Separation – governed by mass transfer

Extent of Separation – limited by thermodynamic

equilibrium

The most widely utilized industrial

separation technique.

Widely used when distillation is impractical, especially when the mixture to be separated is temperature-sensitive.

For microporous membranes, separation is effected by differing rates of diffusion through the pores.

For nonporous membranes, separation occurs because of differences in both solubility in the membrane and the rate of diffusion through the membrane.

Usually in the form of granular material or packing. The active separating agent eventually becomes saturated with solute and must be regenerated or replaced periodically.

Types of Phase

◉ Gaseous phase – occurs only in one phase

◉ Liquid phase – often occurs in one phase

◉ Solid phase – crystalline phase, polymorphs

A graphical representation which details the form(s) the material takes under specific conditions. It illustrate the variations between the states of matter of elements or compounds as they relate to pressure and temperatures.

Single Point – the point on a phase

diagram at which the three states

coexist

Cryptic Point – the point on a phase

diagram at which the substance is

indistinguishable between liquid

and gaseous states

Predicts the number of phases that will coexist within a system at equilibrium.

◉ It does not apply in non-equilibrium situations.

F = C − P + N

There are three important criteria for different phases

to be in equilibrium with each other:

temperature,

partial pressure,

and Gibbs free energy (or chemical potential)

For equilibrium condition:

◉ Constant Operating Conditions

- There are no changes in temperature and pressure.

◉ Constant Saturated Conditions

- The composition of the components does not change anymore.

It shows how the equilibrium compositions of the components in a mixture vary with temperature at a fixed pressure.

◉ Dew Point

The temperature at which the saturated vapor starts to condense.

◉ Bubble Point

The temperature at which the liquid starts to boil.

◉ Homogeneous azeotrope – an azeotrope that contains

one liquid phase in contact with the vapor.

◉ Heterogeneous azeotrope – usually form two liquid

phases with widely differing compositions.

Azeotropic mixtures with a higher boiling point than its constituents.

◉ Also called minimum-boiling azeotropes

Azeotropic mixtures that has a boiling point lesser than its constituents.

◉ Also called maximum-boiling azeotropes

Two different phases are brought into intimate

contact with each other and then are separated.

Liquids with high vapor pressure require relatively little energy to increase the vapor pressure, thus they have low boiling points.

Liquids with low vapor pressure require considerably more energy to increase the vapor pressure, thus they have high boiling points.

◉ The temperature remains constant throughout the boiling process of a pure liquid.

◉ At the boiling point, the liquid and vapor are in equilibrium, if the composition of each phase remains constant, the temperature will remain constant.

Packed columns are called continuous-contact columns

while trayed columns are called staged-contact columns

because of the manner in which vapor and liquid are

contacted.

A method that uses the equilibrium curve diagram to

determine the number of theoretical stages (trays)

required to achieve a desired degree of separation.

The upper part of the tower above the feed entrance is called the rectifying/enriching section.

The point D is called the pinch point because the two

operating lines each pinch the equilibrium curve.

A method used to theoretically calculate the minimum number of

trays required for the separation of a binary feed stream by a

fractionation column that is being operated at total reflux.

Substances are tend to mix together naturally and spontaneously.

◉ All natural processes take place to increase the entropy, or randomness of the universe.

Caused by reducing the pressure of the feed with a valve.

When volatility differences between

species to be separated are so small

If the feed is all vapor and the stripping

section of the column is not needed to

achieve the desired operation.

Vaporization curve – the curve on a phase diagram which represents the transition between gaseous and liquid states

Sublimation curve – the curve on a phase diagram which represents the transition between gaseous and solid states

The condensed liquid is stored in a

holding vessel known as the ____________.

◉ Trays – force the liquid to flow back and forth horizontally while the vapor bubbles up through holes in the trays.

◉ Packings – passive devices that are designed to increase the interfacial area for vapor-liquid contact, without causing excessive pressure drop across a packed section.

Limits of Distillation

If f = 0: Start of vaporization “Bubble Point”

If f = 1: Complete vaporization “Dew Point”

Use to describe a physical and mechanical procedure occurring individually or parallel to chemical reactions.

Characterization of Solid Particles.

Crushed materials = 0.6 < 0 < 0.8

Abrasion Materials = O < 0.95

average size of crushed material which has passed through one screen and retained on a screen having smaller opening

Material that retain on the screening surface

Material that passes through the screening surface

the treatment of a material containing a natural amount of moisture or a material that has been dried before screening.

This law implies that the same energy required to produce a material from 100 mm to 50 mm is needed to reduce the same material from 50 mm to 33.3 mm. Efficiencies of about 0.1-2%

This law implies that the same energy required to produce a material from 100 m to 50 mm as is required to reduce the same material from 50 mm to 25 mm

Size Reduction is a process whereby small particles are agglomerated or otherwise brought together into larger, relatively permanent masses in which original particles can still be distinguished

Sintering is agglomeration induced by heat.

Compaction or enlargement - processes where the mixture of particulate matter is fed to a compression device which promotes agglomeration due to pressure

Stages in Agglomeration Rate Processes

The slow fluid flow is called STREAMLINE or LAMINAR FLOW whereas, in fast motion, fluid particles cross and re-cross the streamline and the motion is called TURBULENT FLOW.

Forces acting on a particle moving through a Fluid

The Sedimentor is a

A. Thickener - if the concentrated sludge is desired

B. Clarifier - if clear liquid is desired

SEDIMENTATION

Advantages

● Excellent Reproducibility

Disadvantages

● Cannot be used for emulsions or very dense materials that settle quickly

● Depends on the ambient temperature that affect viscosity

● Orientation of non-spherical particles also influences the results

DENSITY

The greater the density of the particles, the faster the particles to settle

SIZE

The smaller the particles are, the faster they settle

TEMPERATURE

The lower the temperature of the water is, the higher the viscosity, so the slower the particles to settle