colloidal dispersion

colloidal dispersion

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  seminar & MINIPROJECT ON COLLOIDAL DISPERSON The Seminar Report is submitted to BCDA COLLEGE OF PHARMACY & TECHNOLOGY Under guidance of PROF(DR). GAUTOM MUKHOPADHAY , Assistant Professor Presented By Sayani Saha B.Pharm , 4th sem University Roll No. 20101917030
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  COLLOIDAL DISPERSIONS  Dispersedsystem consists of: a) particle matter(dispersed phase) b)dispersion medium (continuous medium) CLASSIFICATION OF DISPERSED SYSTEM  Molecular Colloidal Coarse Dispersion Dispersion Dispersion Less than 1 µm 1 µm to 500 µm greater than 500 µm Particle undergo very slow diffusion don’t diffuse rapid diffusion eg: eg: colloidal silver eg : suspension O2 & glucose sol. & emulsion
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  Comparison of propertiesof colloidal sol Lyophilic (solvent -loving) Lyophobic (solvent -hating) Association (amphophilic) Dispersed phase Solvation Preparatio n Viscosity Effect of electrolyte Large organic molecules Lying within colloidal size Solvated Spontaneous by dissolving in solvent Viscosity increased as conc. Increased at certain conc. Gel sol gel formation Stable in presence of electrolytes. Desolvation and Inorganic particles such as gold or silver Little Needs special procedure Not greatly increased due to unsolvation Unstable due to neutralization of charges on particles Aggregates of small organic molecules or ions whose size is below the colloidal size Hydrophilic or lipophilic portion of the molecules is solvated depending on the medium Spontaneous when conc. of amphiphiles exceeds cmc. Increases as conc. Of amphiphiles increase as micelles no. increases and become asymmetric. Cmc is reduced and salting out occur at
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  Shape of colloidalparticles • The more extended the particle, the greater its specific surface and greater the opportunity for attraction. • Properties of colloids as flow, sedimentation rate and o.p. are all affected by the shape of the particles.
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  Classification of colloids Basedon dispersion medium and dispersed phase
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  Properties of colloids Physical Chemical OpticalKinetic Electrical
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  Physical properties  Heterogeneity: colloidal solution consist of two phase-dispersed phase and dispersion medium.  Stability: lyophilic sols in general and lyophobic sols in the absence of substantial conc. Of electrolytes are quite stable.  Colour: the colour of colloidal substances depend upon the colloidal particles present in it.
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  Chemical properties • Sourceof electro-negativity • Buffering capacity Kinetic properties • Brownian motion • Sedimentation • Diffusion • Viscosity • Osmotic pressure
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  Optical properties • Lightscattering • Ultra microscopy • Electron microscopy Electrical properties • Electrophoresis  Cataphoresis  Anaphoresis • Electro-osmosis
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  Coacervation Coacervation is achemical method for producing polymer droplets in suspension based on the separation of two liquid phases into one concentrated colloidal phase Peptization Peptization or Deflocculation is the process responsible for the formation of stable dispersion of colloidal particles in dispersion medium