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21 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Coagulation |
• The chemical process of reducing the zeta potential and destabilization of particles (Hendricks 229) |
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Flocculation |
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Why Use Coagulation? |
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Colloids |
• Small particles that do not settle due to an electric surface charge, usually negative.• The characteristic size range is 1 to 10 μm. |
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Colloid System |
Colloid System is a sol dispersions of small solid particles in a liquid medium (Hendricks 230) |
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Objectives of Coagulation |
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Types of Coagulation |
• Conventional coagulation • Sweep-floc coagulation • Enhanced coagulation • Heterocoagulation |
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Coagulation Mechanisms |
. Charge-Neutralization (pH < 6) • Sweep Floc (pH > 6) |
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Charge-Neutralization |
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Sweep Floc Coagulation |
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Double Layers |
Stern layer + diffuse layer |
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Stern Layer vs Diffuse Layer |
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Particle Stabilization |
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Particle Destabilization |
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DLVO Theory |
• Combines the van der Waals intermolecular attractive forces with the electrostatic repulsive forces.• The “net” potential due to addition of these two forces determines the strength of the colloid interactions. |
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Zeta Potential |
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Particle Transport Mechanisms |
Brownian diffusion (perikinetic flocculation) Transport in laminar shear (orthokinetic flocculation) Differential settling Turbulent transport |
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Destabilization Mechanisms |
Compression of the double layer (DLVO Theory) Counterions adsorption and charge neutralization Interparticle bridging Enmeshment in a precipitate Heterocoaguation |
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How to Destabilize Colloids? |
Add coagulant(s) Mixing |
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Coagulant |
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Coagulant Aid |
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