06 b colloidsedl - Formation of surface charges on metal...

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Formation of surface charges on metal oxides in water tep 1: Step 1: Step 2: 1. Hydroxyl-formation on the surface 2. Protonation / deprotonation of surface hydroxyls 1 3. Adsorption of ions from solution
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Connecting surface charge and pH (e.g. α -Al 2 O 3 ) urface Surface charge oint of zero charge PZC 2 Point of zero charge PZC Isoelectric point IEP
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urface charge of ceramic materials at pH 7 Surface charge of ceramic materials at pH 7 aterial olarity of charge Comments Material Polarity of charge Al 2 O 3 Strong + ZrO 2 Zero to weakly + Depending on purity and Y 2 O 3 -content SiC Weak to strong - Depending on SiO 2 on surface Si 3 N 4 strong – SiO 2 on surface in the beginning, may Dissolution of SiO 2 change after 24 h occurs at high pH Diamond None 3
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epulsive Potential ( smotic) Repulsive Potential (osmotic) d κ 2 Ψ 0 constant surface potential ε dielectric constant of medium [ ] R e a V πεε + Ψ = 1 ln 2 0 0 ε 0 permittivity of vacuum a particle diameter κ inverse Debye length d separation distance 2 / 1 2 2 1000 A N
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This note was uploaded on 03/04/2010 for the course MSE 6448 taught by Professor Sigmund during the Spring '10 term at University of Florida.

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06 b colloidsedl - Formation of surface charges on metal...

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