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¡¾2006Taylor & Francis½ºÌ廯ѧÐÂÊé¡¿Particles in Water Ë®ÌåÖеĿÅÁ£Îï Particles in water : properties and processes Contents Chapter one Introduction..................................................................................1 1.1 Particles in the aquatic environment..........................................................1 1.1.1 Origin and nature..............................................................................1 1.1.2 Particle size ranges............................................................................2 1.1.3 Effects of particles in water .............................................................5 1.2 Colloidal aspects ............................................................................................5 1.2.1 Classification of colloids ..................................................................6 1.2.2 Stability of hydrophobic colloids ...................................................7 1.2.3 Particle separation processes...........................................................8 Further reading .......................................................................................................8 Chapter two Particle size and related properties.........................................9 2.1 Particle size and shape..................................................................................9 2.2 Particle size distributions ...........................................................................10 2.2.1 General..............................................................................................10 2.2.2 The log-normal distribution ..........................................................14 2.2.3 The power law distribution...........................................................17 2.3 Particle transport..........................................................................................19 2.3.1 Fluid drag .........................................................................................20 2.3.2 Diffusion ...........................................................................................22 2.3.3 Sedimentation ..................................................................................23 2.3.4 Effect of particle size.......................................................................25 2.4 Light scattering and turbidity....................................................................26 2.4.1 General..............................................................................................26 2.4.2 Turbidity and light transmission..................................................28 2.4.3 Rayleigh theory ...............................................................................30 2.4.4 Mie theory ........................................................................................33 2.4.5 Anomalous diffraction....................................................................37 2.4.6 Rayleigh-Gans-Debye scattering...................................................38 2.5 Measurement of particle size .....................................................................38 2.5.1 Direct methods (microscopy) ........................................................39 2.5.2 Particle counting and sizing..........................................................40 2.5.3 Static light scattering ......................................................................43 2.5.4 Fraunhofer diffraction ....................................................................44 ?2006 by Taylor & Francis Group, LLC 2.5.5 Dynamic light scattering................................................................44 2.5.6 Sedimentation methods..................................................................45 Further reading .....................................................................................................46 Chapter three Surface charge .........................................................................47 3.1 Origin of surface charge .............................................................................47 3.1.1 Dissolution of constituent ions .....................................................47 3.1.2 Surface ionization............................................................................49 3.1.3 Isomorphous substitution..............................................................51 3.1.4 Specific adsorption of ions ............................................................51 3.2 The electrical double layer .........................................................................52 3.2.1 The double layer at a flat interface ..............................................52 3.2.2 Charge and potential distribution in the double layer.............55 3.2.3 Spherical particles ...........................................................................57 3.3 Electrokinetic phenomena ..........................................................................58 3.3.1 The plane of shear and the zeta potential ..................................59 3.3.2 Electrophoresis and electrophoretic mobility.............................60 Further reading .....................................................................................................62 Chapter four Colloid interactions and colloid stability...........................63 4.1 Colloid interactions ?general concepts .................................................63 4.1.1 Importance of particle size ............................................................63 4.1.2 Force and potential energy............................................................64 4.1.3 Geometry of interacting systems..................................................65 4.1.4 Types of interaction.........................................................................66 4.2 van der Waals interaction...........................................................................67 4.2.1 Intermolecular forces ......................................................................67 4.2.2 Interaction between macroscopic objects ....................................67 4.2.3 Hamaker constants .........................................................................70 4.2.4 Effect of dispersion medium .........................................................72 4.2.5 Retardation .......................................................................................74 4.3 Electrical double-layer interaction ............................................................75 4.3.1 Basic assumptions ...........................................................................75 4.3.2 Interaction between flat plates and spheres ...............................76 4.4 Combined interaction ?DLVO theory ...................................................78 4.4.1 Potential energy diagram...............................................................78 4.4.2 Effect of ionic strength ?critical coagulation concentration....................................................................................80 4.4.3 Specific counterion adsorption .....................................................84 4.4.4 Stability ratio....................................................................................86 4.5 Non-DLVO interactions ..............................................................................88 4.5.1 Hydration effects .............................................................................88 4.5.2 Hydrophobic attraction ..................................................................89 4.5.3 Steric repulsion ................................................................................90 4.5.4 Polymer bridging ............................................................................91 Further reading .....................................................................................................92 ?2006 by Taylor & Francis Group, LLC Chapter five Aggregation kinetics.................................................................93 5.1 Collision frequency ?Smoluchowski theory ........................................93 5.2 Collision mechanisms..................................................................................94 5.2.1 Brownian diffusion ?perikinetic aggregation..........................95 5.2.2 Fluid shear ?orthokinetic aggregation ...................................102 5.2.3 Differential sedimentation ...........................................................105 5.2.4 Comparison of rates .....................................................................106 5.2.5 Effect of hydrodynamic interactions..........................................107 5.3 Form of aggregates ....................................................................................109 5.3.1 Fractals ............................................................................................ 110 5.3.2 Collision rate of fractal aggregates............................................. 113 5.3.3 Density of fractal aggregates....................................................... 115 5.4 Strength and breakage of aggregates ..................................................... 116 Further reading ................................................................................................... 119 Chapter six Coagulation and flocculation .................................................121 6.1 Terminology ................................................................................................121 6.1.1 “Coagulation?and “flocculation?..............................................121 6.1.2 Destabilizing agents......................................................................122 6.2 Hydrolyzing metal coagulants ................................................................123 6.2.1 Hydrolysis of metal cations.........................................................123 6.2.2 Polynuclear hydrolysis products................................................126 6.2.3 Action of hydrolyzing coagulants..............................................127 6.2.4 Charge neutralization by adsorbed species..............................127 6.2.5 “Sweep?flocculation ....................................................................129 6.2.6 Overview ........................................................................................131 6.2.7 Practical aspects.............................................................................132 6.3 Polymeric flocculants ................................................................................133 6.3.1 Nature of polymers and polyelectrolytes in solution .............133 6.3.2 Examples of polymeric flocculants ............................................135 6.3.3 Polymer adsorption ......................................................................137 6.3.4 Bridging flocculation ....................................................................139 6.3.5 Charge neutralization and “electrostatic patch?effects .........140 6.3.6 Kinetic aspects of polymer flocculation ....................................142 6.3.7 Applications ...................................................................................147 Further reading ...................................................................................................148 Chapter seven Separation methods ............................................................149 7.1 Introduction ................................................................................................149 7.2 Flocculation processes...............................................................................149 7.2.1 Rapid mixing .................................................................................150 7.2.2 Floc formation................................................................................151 7.3 Sedimentation.............................................................................................153 7.3.1 Basics ...............................................................................................153 7.3.2 Sedimentation in practice ............................................................154 7.3.3 Upflow clarifiers............................................................................156 ?2006 by Taylor & Francis Group, LLC 7.4 Flotation.......................................................................................................157 7.4.1 General............................................................................................157 7.4.2 Dissolved air flotation ..................................................................158 7.5 Filtration ......................................................................................................162 7.5.1 Deep bed filtration ........................................................................162 7.5.2 Membrane filtration......................................................................170 Further reading ...................................................................................................173 ÕÒÁËÒ»Ìì²ÅÕÒµ½£¬ÏÈÃâ·Ñ·ÖÏí http://d.namipan.com/d/9fabe1340 ... 7f513a83d0a3be03800 [ Last edited by dfq0730 on 2009-9-27 at 18:04 ]

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