ADSORPTION

Question 1

EXPLAIN WHAT IS A FIXED BED ADSORPTION COLUMN?

Answer 1

• A FLUID STREAM PASSES THROUGH A STATIONARY LAYER OF ADSORBENT MATERIAL
• USED TO PURIFY GAS AND LIQUID MIXTURE BY REMOVING UNWANTED COMPONENTS

Question 2

WHAT ARE THEY KEY STRUCTURAL FEATURES OF THE COLUMN?

Answer 2

• ADSORBENT BED IS STATIONARY, MAXIMIZING CONTACT TIME BETWEEN ADSORBTATE AND ADSORBENT.
• COLUMNS ARE VERTICALLY ORIENTED TO INCREASE GRAVITATIONAL EFFTEC, ENHANCING DISTRIBUTION OF FLUID
• ADSORBENTS ARE LAYERED WITH VARYING GRANULE SIZES TO OPTIMIZE MASS TRANSFER RATE

Question 3

DEFINITION OF ADSORBATE AND ADSORBENT.

Answer 3

ADSORBATE : SUBSTANCE THAT IS DEPOSITED ON THE ADSORBENT
ADSORBENT : SURFACE OF A SUBSTANCE WHICH ADSORBATE ADSORBS

Question 4

APPLICATIONS OF LIQUID-PHASE ADSORPTION.

Answer 4

• SEPARATION OF FRUCTOSE FROM GLUCOSE USING ZEOLITES
• SEPARATION OF PARAFFINS FROM AROMATICS
• REMOVAL OF ORGANIC COMPOUNDS FROM WATER OR ORGANIC SOLUTIONS

Question 5

APPLICATIONS OF GAS-PHASE ADSORPTION.

Answer 5

• REMOVAL OF WATER FROM HC GAS
• REMOVAL OF SULPHUR COMPOUNTS FROM NATURAL GAS
• REMOVAL OF ODORS FROM AIR

Question 6

PHYSICAL PROPERTIES OF ADSORBENTS (4)

Answer 6

1. SMALL PELLETS, BEADS OR GRANULES
2. POROUS STRUCTURE
3. OFTEN OCCURS AS MONOLAYER, SOMETIMES SEVERAL LAYERS
4. HAVE ELECTROSTATIC PROPERTIES THAT ENCOURAGE MATERIALS TO ADHERE TO THE SURFACE

Question 7

WHAT ARE ADSORPTION ISOTHERMS?

Answer 7

• THE RELATIONSHIP BETWEEM THE CONCENTRATION OF A SOLUTE INA FLUID PHASE AND ITS CONCENTRATION ON THE SOLID PHASE.
• solid q (kg adsorbate/kg adsorbent)
• fluid c (kg adsorbate/m^3 adsorbent)

Question 8

WHAT ARE EXAMPLES OF COMMERCIAL ADSORBENT? (5)

Answer 8

• ACTIVATED CARBON (USED TO ADSORB ORGANIC)
• SILICA GEL (DEHYDRATE GASES AND LIQUID)
• ACTIVATED ALUMINA (DRY GASES AND LIQUID)
• ZEOLITES (DRYING, SEPARATION FOR HC)
• RESINS (ARSORB NONPOLAR ORGANICS)

Question 9

DESCRIBE THE ADSORPTION PROCESS.

Answer 9

1. WHEN BULK FLUID FLOWS THROUGH THE FIXED BED, THE SOLUTE DIFFUSES TO THE EXTERIOR SURFACE OF THE PARTICLE.
2. SOLUTE DIFFUSES INSIDE THE PORE TO THE SURFACE.
3. FINALLY IT IS ADSORBED.

Question 10

WHAT IS THE FORM OF ADSORBENT IN COMMERCIAL PROCESSES?

Answer 10

• SMALL PARTICLES IN A FIXED BEDW

Question 11

WHAT HAPPENS WHEN THE BED IS FULLY SATURATED?

Answer 11

• THE FLOW IS STOPPED AND THE BED IS REGENERATED THERMALLY SO THAT DESORPTION OCCURS.
• THE ADSORBATE IS RECOVERED AND THE ADSORBENT IS READY FOR ANOTHER CYCLE.

Question 12

EXPLAIN JUST SIMPLY WHAT HAPPENS.

Answer 12

• WHEN THE FLUID FLOWS THROUGH THE BED, THE SOLID PARTICLES (ADSORBENT) ADSORBS COMPONENTS FROM THE FLUID (ADSORBATE).