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1. CHAPTER ONE: INTRODUCTION to MASS TRANSFER
Minia University
Faculty of Engineering
Chemical Engineering Department
Course Title: Mass Transfer
Prof. Dr. Mohammad Shawky Prof. Dr. Mohammad Shawky Course Coordinator:
Week No. 1
Third Year
Course Code: CHE 312

2. Contents

Definition of Mass Transfer

Examples of Mass Transfer

Mass Transfer Operations

Basic Concepts:

Concentrations:

Molar Concentration

Mass Concentration

Mole Fraction

Mass Fraction

3. Introduction

Three fundamental transfer processes:
i)Momentum transfer (∆P)
ii)Heat transfer (∆T)
iii)Mass transfer (∆C)

4. Definition of Mass Transfer

The term mass transfer is used to denote the transference of a component in a
mixture from a region where its concentration is high to a region where the
concentration is lower.

Mass transfer process can take place in a gas (vapor) or in a liquid,

It can result from the random velocities of the molecules (molecular diffusion) or
from the circulating or eddy currents present in a turbulent fluid (eddy diffusion).

5. Examples of Mass Transfer

Consider a tank that is divided into two equal parts by a partition.
Initially, the left half of the tank contains nitrogen N
2 gas while
the right half contains O
2 at the same temperature and pressure.
When the partition is removed the N
2 molecules will start
diffusing into the air while the O
2 molecules diffuse into the N
2.

If we wait long enough, we will have a homogeneous mixture of
N
2 and O
2 in the tank.

6. Examples of Mass Transfer

7. Mass Transfer Operations
Salt
water
Salt
solution
Takes place easily
according to 2
nd
law
of thermodynamics
of increasing entropy
Salt
solution
salt
water
Difficult to take
place because it
needs external
energy

8. R  P
Stock
Separation
process
R
R  P
Separation process
to purify P
P
Feed
stream
Separation
Process
Output streams different
in composition
Separating matter
and/or energy

9. Separation of phases only
L + G
G
L
(Flash Drums)
L + S
L
S
(Filter or gravity settler)
Transfer of some components from one stream to another
L + most of A
Gas A
+ inert
L
A
Inert
+ some A
Heat
L (A +B)
V
L
V
most A + B
L
most B + A
Examples of Separation Processes

10. Classification of Separation Processes

Evaporation: evaporation of a volatile solvent from a nonvolatile solute, e.g.
water from nonvolatile solute (salt).

Drying: removal of volatile liquids, e.g. water from solid materials.

Distillation: components of a liquid mixture are separated by boiling due to
differences in vapor pressure.

Absorption: removal of a component from a gas stream by treatment with a liquid.

Membrane separation: separation of a solute from a fluid by diffusion of the
solute from a liquid or gas through a semi-permeable membrane barrier to the other
fluid.

Liquid-liquid extraction: removal of a solute from a liquid solution by contacting
with another liquid solvent that is relatively immiscible with the solution.

11. Separation processes

Adsorption: removal of a component (adsorbate) from a gas or liquid stream by
adsorption on a solid material (adsorbent).

Ion exchange: removal of certain ions in a solution from a liquid by an ion-
exchange solid.

Liquid-solid leaching: removal of a solute from a solid (containing the solute)
by treating with a liquid that dissolves out the solute from the solid.

Crystallization: removal of a solute, such as a salt from a solution, by
precipitation the solute from the solution.

Mechanical-physical separation: separation of solids, liquids, or gases by
mechanical means. E.g. filtration, centrifugation, settling, and size reduction.

12. Concentrations

14. Relation Between Partial Pressure and Concentration

15. for gas

16. Thank YouThank You