Foreword ..................................................... xvii
Preface ....................................................... xxi
List of Contributors ........................................ xxiii
PART l Introduction ............................................. 1
1. Overview of Physical Adsorption by Carbons ................... 3
1.1. Introduction ............................................ 3
1.2. Physisorption on Nonporous Carbons ...................... 5
1.3. Physisorption by Porous Carbons ......................... 7
1.4. Concluding Remarks ..................................... 11
References .................................................. 12
2. Overview of Carbon Materials in Relation to Adsorption ...... 15
2.1. Introduction ........................................... 15
2.2. Structures of Elemental Carbon: Carbon Allotropes
and Polytypes .......................................... 17
2.3. The sp2 Carbon Forms: Graphitic, Graphitizable, and
Nongraphitizable Carbons ............................... 21
2.4. Structural Characterization of Carbon Materials:
The Basic Structural Units and Their Stacking and
Orientation Degrees .................................... 24
2.4.1. Planar Orientation .............................. 28
2.4.2. Axial Orientation ............................... 30
2.4.3. Point Orientation ............................... 34
2.4.4. Random Orientation .............................. 36
2.5. Conclusions ............................................ 42
Acknowledgments ............................................. 43
References .................................................. 43
PART 2 Fundamentals of Adsorption by Carbons ................... 51
3. Energetics of Gas Adsorption by Carbons: Thermodynamic
Quantities .................................................. 53
3.1. Introduction ........................................... 53
3.2. Classical Thermodynamics ............................... 54
3.3. Statistical Mechanics .................................. 59
3.4. Thermodynamic Quantities and Experimental Results ...... 66
3.5. Conclusions ............................................ 71
Acknowledgment .............................................. 71
References .................................................. 72
4. Monte Carlo and Molecular Dynamics .......................... 77
4.1. Introduction ........................................... 77
4.2. Overview of Computer Simulations ....................... 78
4.2.1. Selecting the Model ............................. 79
4.2.2. Initialization .................................. 83
4.2.3. Generating Configurations ....................... 83
4.2.4. Determining Properties from Configurations ...... 89
4.3. Conclusions ............................................ 97
References .................................................. 98
5. Models of Porous Carbons ................................... 103
5.1. Introduction .......................................... 103
5.2. Experimental Probes ................................... 104
5.3. Molecular Models of Carbons ........................... 106
5.3.1. Regular Porous Carbons ......................... 106
5.3.2. Disordered Porous Carbons: Simple Geometric
Models ......................................... 107
5.3.3. Disordered Carbons: More Realistic Models ...... 110
5.4. Adsorption, Diffusion, Reaction ....................... 121
5.5. Conclusions ........................................... 127
Acknowledgments ............................................ 128
References ................................................. 128
6. The Reasons Behind Adsorption Hysteresis ................... 133
6.1. Introduction .......................................... 133
6.2. Capillary Condensation Hysteresis and the Kelvin
Equation .............................................. 135
6.3. Hysteresis and Adsorption-Induced Strain of
Adsorbents ............................................ 136
6.4. Low-Pressure Hysteresis ............................... 137
6.5. Pore Network and Interconnectivity .................... 137
6.6. Some Peculiarities of the Adsorption Hysteresis
for Carbonaceous Adsorbents ........................... 138
References ................................................. 140
7. The Surface Heterogeneity of Carbon and Its Assessment ..... 147
7.1. Introduction .......................................... 147
7.1.1. The Adsorptive Potential ....................... 147
7.1.2. Thermodynamic Meaning of the Adsorption
Potential ...................................... 149
7.2. Theoretical Background ................................ 151
7.2.1. The Integral Equation of Adsorption ............ 151
7.2.2. Solving and Using the Integral Equation of
Adsorption ..................................... 152
7.3. The Application of Density Functional Theory .......... 153
7.3.1. The Deconvolution Method ....................... 154
7.4. Results for "Nonporous" Carbons ....................... 156
7.4.1. Synthetic Graphitic Carbons .................... 157
7.4.2. Natural Graphites .............................. 158
7.4.3. Carbon Blacks .................................. 159
7.5. Activated Carbons ..................................... 160
7.5.1. Assumed Structure .............................. 160
7.5.2. Example Applications of the Simple Model ....... 161
7.5.3. Advanced Activated Carbon Models ............... 163
7.6. Conclusions ........................................... 165
References ................................................. 165
8. Wetting Phenomena .......................................... 167
8.1. Introduction .......................................... 167
8.2. Wetting on Carbon ..................................... 175
8.3. Conclusions ........................................... 180
References ................................................. 181
9. Adsorbed Gases in Bundles of Carbon Nanotubes: Theory
and Simulation ............................................. 187
9.1. Introduction .......................................... 187
9.2. Endohedral Adsorption ................................. 190
9.2.1. General Remarks ................................ 190
9.2.2. Axial-Phase Transition ......................... 194
9.2.3. Other Endohedral Transitions ................... 196
9.3. Adsorption in Interstitial Channels ................... 198
9.4. External Surface. 202 Acknowledgments ................. 206
References ................................................. 206
10.Energetic Topography Effects ............................... 211
10.1.Introduction .......................................... 211
10.2.The Adsorptive Energy Surface ......................... 214
10.3.Generalized Gaussian Model ............................ 216
10.4.Simulations on Ideal Heterogeneous Systems ............ 221
10.5.Comparison Test for the GGM ........................... 223
10.6.Bivariate Model and Simulation Method ................. 225
10.7.Adsorption Results .................................... 227
10.7.1.Repulsive Interactions ......................... 227
10.7.2.Attractive Interactions ........................ 228
10.8.Scaling Behavior and Temperature Dependence ........... 230
10.9.Conclusions ........................................... 233
Acknowledgments ............................................ 234
References ................................................. 234
PART 3 Adsorption for Characterization of Carbon Materials .... 237
11.Porous Texture Characterization from Gas-Solid
Adsorption ................................................. 239
11.1.Introduction .......................................... 239
11.1.1.Carbon Structure ............................... 240
11.2.Potential Models ...................................... 240
11.2.1.Fluid-Fluid Potential Models ................... 241
11.2.2.Solid-Fluid Potential Energy ................... 244
11.3.Classical Methods for Pore Characterization ........... 246
11.3.1.Barrett, Joyner, and Halenda Method ............ 246
11.3.2.Broekhoff-de Boer Method ....................... 246
11.3.3.Dubinin Methods ................................ 247
11.3.4.Horvath-Kawazoe Method and its Modifications ... 248
11.3.5.Enhanced Potential Method of Do and
Coworkers ...................................... 250
11.4.Density Functional Theory ............................. 253
11.4.1.Introduction of DFT ............................ 253
11.4.2.DFT Applications to Pores (Slit and
Cylinder) ...................................... 255
11.5.Monte Carlo Simulations ............................... 257
11.5.1.Ensembles Used in Simulations of Adsorption .... 257
11.5.2.Monte Carlo Simulation for Slit Pores .......... 260
11.5.3.Monte Carlo Simulation for Cylindrical Pores ... 261
11.6.Additional Features ................................... 262
11.6.1.Energetic Heterogeneity ........................ 262
11.6.2.Pore Shape, Length, and Connectivity ........... 262
11.6.3.Numerical Inversion for Determining PSD ........ 262
11.7.Conclusions ........................................... 263
Acknowledgment ............................................. 264
References ................................................. 264
12.Porous Texture and Surface Characterization from
Liquid-Solid Interactions: Immersion Calorimetry and
Adsorption from Solution ................................... 273
12.1.Introduction .......................................... 273
12.2.Immersion Calorimetry of Carbons into Pure Liquids .... 274
12.2.1.Experimental ................................... 274
12.2.2.Thermodynamics of Immersion .................... 280
12.2.3.Applications ................................... 282
12.3.Characterization of Carbons by Adsorption from
Solution .............................................. 289
12.3.1.Thermodynamics ................................. 290
12.3.2.Applications ................................... 295
References ................................................. 297
13.Surface Chemical Characterization of Carbons from
Adsorption Studies ......................................... 301
13.1.Introduction .......................................... 301
13.2.Hydrophilic Carbon Surfaces ........................... 302
13.3.Surface Oxides of Carbon .............................. 304
13.3.1.Generation of Surface Oxides ................... 304
13.3.2.Functional Carbon Groups ....................... 306
13.4.Amphoteric Character of Carbons ....................... 308
13.4.1.Adsorption of Bases ............................ 308
13.4.2.Adsorption of Acids ............................ 312
13.5.Electrokinetic Phenomena .............................. 318
13.6.Effects on the Adsorption of Inorganic ions ........... 321
References ................................................. 323
14.Adsorption on Fullerenes ................................... 329
14.1.Introduction .......................................... 329
14.2.Adsorption for Porosity Characterization .............. 330
14.3.Adsorption in the Study of Surface Energetics:
Nonreactive Permanent Gases ........................... 332
14.4.Adsorption of Organic Gases and Vapors ................ 338
14.5.Oxygen Adsorption ..................................... 341
14.6.Adsorption Studies using IR Spectroscopy .............. 343
14.7.Hydrogen Adsorption: Gas Storage ...................... 346
14.8.Adsorption From Solution: Environmental
Applications .......................................... 351
14.9.Adsorption from Solution: Analytical Applications ..... 353
14.10.Adsorption from Solution: Colloidal and Biological
Systems ............................................... 357
14.11.Conclusions .......................................... 359
Acknowledgments ............................................ 359
References ................................................. 359
15.Hydrogen Adsorption in Single-Walled Carbon Nanotubes ...... 369
15.1.Introduction .......................................... 369
15.2.Experiment, Simulation, and Theory of Hydrogen
Storage ............................................... 370
15.2.1.Modeling of Physisorption with Classical
Potentials ..................................... 371
15.2.2.Ab Initio Modeling of Physisorption ............ 379
15.2.3.Ab Initio Modeling of Chemisorption ............ 384
15.3.Quantum Sieving ....................................... 385
15.4.Phase Transition Phenomena ............................ 391
15.5.Summary and Conclusions ............................... 393
Acknowledgments ............................................ 393
References ................................................. 394
16.Adsorption on Carbon Nanotubes: Experimental Results ....... 403
16.1.Introduction .......................................... 403
16.2.Hydrogen Storage ...................................... 404
16.3.Adsorption of Rare Gases and Simple Molecular
Species ............................................... 408
16.3.1.Methane ........................................ 409
16.3.2.Argon .......................................... 414
16.3.3.Helium ......................................... 417
16.3.4.Hydrogen ....................................... 419
16.3.5.Xenon .......................................... 420
16.3.6.Neon ........................................... 422
16.3.7.Tetrafluoromethane ............................. 422
16.3.8.Nitrogen ....................................... 424
16.4.Conclusions ........................................... 425
Acknowledgments ............................................ 426
References ................................................. 426
17.Adsorption on Activated Carbon Fibers ...................... 431
17.1.Introduction .......................................... 431
17.2.Preparation of ACFs ................................... 433
17.3.Characterization of ACFs .............................. 436
17.3.1.Adsorption on the ACF and Its Usefulness
to Understand Micropore Characterization ....... 438
17.3.2.Understanding the Activation-Pore Structure
Relationship of ACFs: Effect of Activating
Agent and Burn-Off Degree ...................... 444
17.4.Some Examples of ACF Applications ..................... 447
17.5.Conclusions ........................................... 449
Acknowledgments ............................................ 449
References ................................................. 449
18.Adsorption on Ordered Porous Carbons ....................... 455
18.1.Ordered Porous Carbons ................................ 455
18.1.1.Synthesis of Ordered Porous Carbons ............ 455
18.1.2.Applications of Ordered Porous Carbons ......... 457
18.2.Characterization of Ordered Porous Carbon by Gas
Adsorption ............................................ 458
18.2.1.General Features of the Nitrogen Adsorption
Isotherms ...................................... 459
18.2.2.Determination of the Pore Size Distribution .... 461
18.2.3.Adsorption Potential Distribution .............. 463
18.2.4.Verification of the Presence of Micropores
by the a-plot Method ........................... 469
18.2.5.Determination of the Specific Surface Area ..... 472
18.3.Conclusions ........................................... 474
Acknowledgments ............................................ 474
References ................................................. 475
19.Electrochemical Behavior of Carbon Materials ............... 479
19.1.A Brief Summary of Electrochemical Concepts ........... 479
19.1.1.The Electrochemical Interface .................. 479
19.1.2.Adsorption at Electrodes ....................... 481
19.1.3.Relevant Kinetic Parameters .................... 482
19.2.Thermodynamic Data for Carbon Electrodes .............. 484
19.3.Relevant Characteristics of Carbon Electrode
Materials ............................................. 485
19.3.1.Types of Carbons Used in Electrochemistry ...... 485
19.3.2.Structural Aspects ............................. 486
19.3.3.Surface Free Radical States .................... 486
19.3.4.Double-layer Properties ........................ 487
19.3.5.Roughness Factor ............................... 489
19.3.6.Fractality ..................................... 490
19.3.7.Intercalation of Ions in Graphite .............. 490
19.4.Chemically Modified Electrodes and Supramotecular
Configurations ........................................ 492
19.5.Electrochemical Kinetics on Carbon Electrodes in
Aqueous Solutions ..................................... 494
19.5.1.Direct Electrode Processes ..................... 494
19.5.2.Oxygen Electroreduction on Carbon Electrodes ... 495
19.5.3.Oxygen Reduction on Macrocyclic Transition
Metal Complexes on Graphite and Carbon
Surfaces ....................................... 499
19.5.4.Oxygen, Hydrogen, and Chlorine Electrode
Reactions ...................................... 499
19.6.Organic Electrochemistry at Carbon Electrodes ......... 501
19.7.Reactions on Biological Active Electrodes ............. 502
19.8.Corrosion Processes ................................... 503
19.9.Carbon Electrodes in Molten Salts ..................... 504
19.9.1.Cryolite-Al2Щ3 Melts ........................... 504
19.9.2.Halides-containing Melts ....................... 505
19.9.3.Oxygen-containing Melts ........................ 506
19.10.Carbon Electrode Manufacturing Techniques ............ 506
Acknowledgments ............................................ 507
References ................................................. 507
20.Self-Assembled Monolayers on C(0001) ....................... 513
20.1.Introduction .......................................... 513
20.2.Characteristic of the HOPG Substrate .................. 514
20.2.1.General Considerations ......................... 514
20.2.2.Nanoscopy Characterization of HOPG ............. 516
20.3.Self-Assembled Submonolayers and Monolayers ........... 521
20.3.1.Alkane Adsorption on C(oooi) ................... 521
20.3.2.Sulfur Atom Submonolayers on HOPG .............. 522
20.3.3.Alkanethiol Adsorption on C(oooi) .............. 522
Acknowledgments ............................................ 527
References ................................................. 527
PART 4 Applications of Adsorption by Carbons .................. 531
21.Removal of Inorganic Gases and VOCs on Activated Carbons ... 533
21.1.Introduction .......................................... 533
21.2.Adsorption of Inorganic Gases ......................... 534
21.2.1.Removal of Hydrogen Sulfide .................... 534
21.2.2.Removal of Sulfur Dioxide ...................... 542
21.2.3.Adsorption of Hydrogen Cyanide ................. 545
21.2.4.Adsorption of NOx .............................. 546
21.3.Adsorption of Volatile Organic Compounds .............. 549
21.4.Choice of Proper Carbon for a Desired Application ..... 553
References ................................................. 556
22.Gas Separation and Storage by Activated Carbons ............ 565
22.1.Introduction .......................................... 565
22.2.Activated Carbons for Gas Separation and
Purification .......................................... 567
22.3.Mechanisms of Gas Separation by Activated Carbons ..... 569
22.4.Examples of Gas Separation Processes .................. 570
22.4.1.Trace or Dilute Impurity Removal ............... 570
22.4.2.Production of Nitrogen from Air ................ 572
22.4.3.Production of Hydrogen and Carbon Dioxide
from Reformer Off-Gas .......................... 573
22.4.4.Nanoporous Carbon Membranes for Gas
Separation ..................................... 578
22.4.5.Sorption-Reaction Process for Removal of
Trace VOC ...................................... 581
22.4.6.Chemically Modified Activated Carbons for
Gas Separation ................................. 583
22.5.Adsorptive Process Design ............................. 585
22.6.Storage of Natural Gas on Activated Carbons ........... 587
22.7.Conclusions ........................................... 589
References ................................................. 590
23.Electrochemical Energy Storage ............................. 593
23.1.Introduction .......................................... 593
23.2.Lithium Insertion in Carbon Materials ................. 595
23.2.1.Principle of a Li-ion Battery .................. 595
23.2.2.Properties of Nanostructured Carbon Anodes ..... 597
23.2.3.Mechanism of Reversible Li Insertion/
Deinsertion in Disordered Carbons .............. 605
23.2.4.Conclusion ..................................... 607
23.3.Nanostructured Carbons as Components of
Supercapacitor Electrodes ............................. 607
23.3.1.General Properties of Supercapacitors .......... 607
23.3.2.Activated Carbons for Supercapacitor
Application .................................... 609
23.3.3.Mesoporous Carbons as Supercapacitor
Electrodes ..................................... 613
23.3.4.Carbon Nanotubes - A Unique Electrode
Component ...................................... 616
23.3.5.Conclusion ..................................... 621
23.4.General Conclusion and Perspectives ................... 621
References ................................................. 623
24.Adsorption of Inorganic Species from Aqueous Solutions ..... 631
24.1.Introduction .......................................... 631
24.2.Metal Ion Removal ..................................... 632
24.2.1.Adsorption of Metal Ions by Virgin Activated
Carbon ......................................... 633
24.2.2.Adsorption of Metal Ions onto Activated
Carbon Preloaded with Organic Matter ........... 638
24.2.3.Saturation of Activated Carbon by Organic
Matter and Metal Hydroxides .................... 639
24.3.Anion and Cation Removal .............................. 640
24.4.Reaction Between Activated Carbon and Oxidants ........ 641
24.4.1.Direct Reaction with High Concentration
Oxidants ....................................... 642
24.4.2.Reaction with Free Chlorine or Chlorine
Dioxide ........................................ 642
24.4.3.Dechlorination-dechloramination ................ 644
24.5.Catalytic Reactions with Modified Activated Carbon .... 645
24.5.1.Catalytic Reactions in the Presence of an
Oxidant ........................................ 645
24.5.2.Metal or Metal Oxide Impregnation .............. 645
24.5.3.Applications of Photocatalysis ................. 646
24.5.4.Specific Treatment of Sulfide or Hydrogen
Sulfide ........................................ 646
24.6 Conclusions and Trends ................................ 647
References ................................................. 647
25.Adsorption of Organic Solutes from Dilute Aqueous
Solutions .................................................. 653
25.1.Introduction .......................................... 653
25.2.Factors that Control the Adsorption Process ........... 655
25.3.Adsorption of Nonelectrolytes ......................... 658
25.4.Adsorption of Electrolytes ............................ 660
25.5.Adsorption of Natural Organic Matter .................. 668
25.6.Adsorption of Bacteria ................................ 671
25.7.Conclusions ........................................... 673
References ................................................. 674
26.Adsorption from Aqueous Solutions: Water Purification ...... 679
26.1.Introduction .......................................... 679
26.1.1.Conventional Water Treatment Processes ......... 679
26.1.2.Adsorption Processes ........................... 680
26.2.Factors Influencing the Application of Activated
Carbon in Drinking Water Treatment .................... 681
26.2.1.Characteristics of the Adsorbent and
Adsorbate ...................................... 681
26.2.2.Prediction of Adsorption Behavior .............. 684
26.2.3.Biological Removal ............................. 687
26.2.4.Natural Organic Material ....................... 688
26.3.Removal of Microcontaminants of Concern to
the Drinking Water Industry ........................... 689
26.3.1.Pesticides ..................................... 690
26.3.2.Industrial Chemicals ........................... 693
26.3.3.Pharmaceuticals and Personal Care Products ..... 695
26.3.4.Algal Metabolites .............................. 696
26.4.Removal of Natural Organic Material ................... 702
26.5.Conclusions ........................................... 703
Acknowledgments ............................................ 704
References ................................................. 704
27.Sorption of Viscous Organics by Macroporous Carbons ........ 711
27.1.Introduction .......................................... 711
27.2.Macropore Structure of Carbon Materials ............... 712
27.3.Sorption Capacity for Viscous Organics ................ 716
27.3.1.Heavy Oils ..................................... 716
27.3.2.Various Oils Other than Heavy Oils ............. 720
27.3.3.Biomedical Fluids .............................. 721
27.4.Kinetics of Sorption .................................. 722
27.5.Recovery of Heavy Oils ................................ 727
27.6.Discussion ............................................ 731
27.7.Conclusions ........................................... 732
Acknowledgments ............................................ 732
References ................................................. 732
Author Index .................................................. 735
Subject Index ................................................. 737
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