1. GUJARAT POWER ENGG. RESEARCH INST.
Subject: crystallization of material
Presented by :-
Soni Yash ( )
Suthar Bharat ( )
Suthar Rajat ( )
Tapodhan Satyam ( )
Guided by:- prof. hitesh panchal

2. Purpose of Crystallizer
Used to recover pure solids from solution
Highly desirable end product because of:
Exceptional purity
Ease of handling
Long shelf life
One of the final treatment steps in the purification and concentration of insulin
98% of the insulin must be crystallized
Kyla

3. Mechanism of Crystallization
Crystal nucleation and amorphous precipitates are in competition during supersaturation conditions
Nucleation favored by slowly exceeding the equilibrium point of saturation
permits time for the protein structure
to orient in a crystalline lattice
Kyla
(picture is of crystal nucleation)
Supersaturation:  mention that MEGAN will explain what supersaturation is in a couple of slides

4. Continuous or Batch Design
Benefits of Continuous
Can maintain solution in supersaturated state
Large fluidized bed for crystallization
Minimizes operation costs
Minimize down time (startup and shutdown)
Benefits of Batch
Good when have low concentration of product, high viscosity or many impurities
Can produce high quality crystal
Kyla
Supersaturation: when the concentration of solute exceeds its solubility limits
 Required for crystallization to occur

5. Methods of Crystallization
Supersaturation: liquid (solvent) contains more dissolved solids (solute) than can ordinarily be accommodated at that temperature
Can be achieved by several methods:
Cooling
Evaporation
Solvent addition
Precipitant Addition
Megan
Supersaturation: when the concentration of solute exceeds its solubility limits

6. Cooling Method
Concentrated solution gradually cooled below saturation temperature (50-60°C) to generate a supersaturated state
Yields well defined micron-sized crystals
Shell and tube heat exchanger is used to cool solution
Megan
Supersaturated state  induces crystallization
Heat exchanger is used to cool solution because it is naturally hot from heat of feed and heat of crystallization
* Gradual cooling will prevent trapping of impurities inside crystal (yellow triangles in picture)

7. Cooling Method Advantages: Disadvantages: High purity downstream
Temperature change does not always have a positive effect on supersaturation in proteins
Protein stability may be at risk
Solubility can be relatively insensitive to temperature at high salt concentrations
Cooling will only help reach supersaturation in systems where solubility and temperature are directly related
Megan
Explanation of Disadvantages…. ?

8. Evaporation Method
Solute dissolves in solution when heated to a certain temperature (75°C)
Slowly cooled until crystals precipitate
Shell and tube heat exchanger is used to heat and cool solution
Megan
* Picture is of shell and tube heat exchanger

9. Evaporation Method Advantages: Disadvantages:
high purity levels downstream
Disadvantages:
Vaporization chamber requires high pressures
Protein viability very sensitive to high temperatures
Megan

10. Solvent Method Solvents are generally good protein precipitants
Their low dielectric constants lower the solvating power of their aqueous solutions
Requires acidic solvent
For crystallization, an insulin protein falls out of solution at isoelectric point pH
Megan
Not sure about pH range… somebody check this please!!

11. Solvent Method Advantages: Disadvantages:
Proteins viability not at risk due to temperature change
Disadvantages:
Possible protein contamination due to insufficient downstream solvent recovery

12. Addition of Zinc Ions
In the presence of zinc ions, insulin proteins orient to form hexamer structures
Zinc ions render insulin insoluble which results in micro-crystallization and precipitation
Human Insulin Hexamer with Zinc ion
Megan
Picture: Human Insulin Hexamer with Zinc ion

13. Seeding Techniques
Primary nucleation is the first step in crystallization - growth of a new crystal
Can bypass primary nucleation (creation of new crystals) by "seeding" the solution
Secondary nucleation is crystal growth initiated by contact
Accelerated by "seeding" adding existing insulin crystals to perpetuate crystal growth
Megan

14. Crystal Size and Growth Rate
Crystal size distribution is important for the production process; affects:
downstream processing
solids transport
caking and storage properties of the material
Correct crystal size vital for economic production
Crystals produced in commercial crystallization processes are usually small
30 to 100 um in diameter
Rachel

15. Crystal Size and Growth Rate
Assumptions:
Continuous
Constant-volume
Isothermal
Well-mixed
Relates population density and crystal size
Rachel
Mechanism of crystal growth to determine crystal growth

16. Crystallizer Design
Addition of acidic solvent to decrease pH to achieve supersaturation
Addition of Zinc ions to initiate Insulin precipitation
Implementing of “seeding” technique
Minimize heat variation to maintain protein stability
Washing and extensive solvent recovery downstream
Rachel

17. Design Equations
Rachel

18. Engineering Drawing
Rachel

19. Crystallizer Suppliers
GEA Niro Inc.
Companies in over 50 countries
Copenhagen, Columbia, Germany, USA
GEA Kestner Evaporator/Crystallizer
Swenson Technology Inc.
Illinois, USA
HPD Inc.
Jana
These are for protein crystallizers!! Which differs greatly from chemical crystallizers

20. Alternative Processes
For special drug purposes and when a zinc-free product is needed
Alternative processes that can be used include:
Isoelectric Precipitation
Gel Chromatography
Ultrafiltration
Kyla

21. Isoelectric Precipitation
Protein purification procedure that can be used with crystallization or on its own
The pH of a mixture is adjusted to the pI of the protein to be isolated to selectively minimize its solubility
Kyla
pI = isoelectric point (?)

22. Gel Filtration Chromatography
Molecules are separated according to their size and shape
Filtration column is filled with porous beads
Solution passes through column
Elution through the gel occurs in order of decreasing molecular masses
Kyla

23. Ultrafiltration
Ultrafiltration used to concentrate macromolecular solutions
Forced under pressure or by centrifugation through a semipermeable membranous disk
Solvent and small solutes pass
through the membrane, leaving
behind a more concentrated
macromolecular solution
Kyla
Picture = ultrafiltration membrane

24. Thank you