# crystallization

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Category: Education

## Presentation Description

AIMST,types of crystallizer,miers theory,crystal structure

## Presentation Transcript

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introduction Crystallization is the spontaneous arrangement of the particles into a repetitative orderly,i.e., regular geometric patterns. A crystal can be defined as a solid particle, which is formed by the solidification (crystallization) process (under suitable environment) in which structural units are arranged by a fixed geometric pattern or lattice.

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Crystal lattice is defined as an orderly arrangement of particles in three – dimensional space. The Three dimensional arrangement of particle in a crystal is also known as space lattice The smallest geometric portion, which repeat to build up the whole Crystal, is called a unit cell. A crystal is bounded by plane surface called faces The angle between the two perpendicular to the intersecting faces is termed as the axial angle Axial length can be defined as the distance between the centre of two atoms.

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CRYSTAL STRUCTURE AND EXTERNAL APPEARANCE All crystals are constructed from repeating units called unit cells. All unit cells in a specific crystal are the same size and contain the same number of molecules or ions arranged in the same way. There are seven primitive unit cells (Figure A): cubic, hexagonal, trigonal, tetragonal, orthorhombic, monoclinic and triclinic. Certain of these may also be end centred (monoclinic and orthorhombic), body-centred (cubic, tetragonal and orthorhombic) or face-centred (cubic and orthorhombic), making a total of 14 possible unit cells called Bravais lattices (Figure B).

(A)

(B)

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THEORY OF CRYSTALLIZATION

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Mier’s Supersaturation Theory Conditions for obeying mier’s theory 1.Solvent must be pure 2.Free from solid solute particle 3.Free from foreign solid matter 4.Free from entry of any particle 5.Soft crystal should not form during the process 6.Should not be any fluctuation in temp

Solubility curve

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Agitated Batch crystallizer EQUIPMENT

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Swenson walker crystallizer

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Krystal crystallizer

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Vacuum crystallizer

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Application Purification of drug Better processing characteristics Ease for handling Improved physical stability Improved bioavailability Sustained release

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