Preface ix

1. Introduction 1

1.1 Environment 1

1.2 World Water Distribution 2

1.3 Environmental Pollution 5

1.4 Chromium 11

1.5 Nickel 16

1.6 Objectives 20

1.7 Literature Review 20

1.8 Adsorption 31

1.9 Adsorption Forces 35

1.10 Adsorption Theories 36

2. Material and Methods 39

2.1 Adsorbent Collection and Storage 39

2.2 Adsorbent Modification 39

2.3 Preparation of Adsorbate Cr (VI) and Ni (II) Solution 40

2.4 Instrumentation 40

2.5 Batch Adsorption Experiment 41

3. Results and Discussions 45

3.1 Characterization of Silica Sand 45

3.2 Effect of Contact Time and Initial Concentration of Cr (VI) and Ni (II) 52

3.3 Effect of pH on the Removal of Cr (VI) and Ni (II) 56

3.4 Effect of Temperature on the Removal of Cr (VI) and Ni (II) 60

3.5 Effect of Adsorbent Dosage on the Removal of Cr (VI) and Ni (II) 66

3.6 Adsorption Isotherm 73

3.7 Adsorption Kinetics 79

3.8 Thermodynamic Studies 86

4. Conclusions 91

References 94

Yogesh Sharma is a professor in the Department of Applied Chemistry, Institute of Technology, Banaras Hindu University. Prior to this he was at the National Institute of Foundry and Forge Technology, Ranchi, where he was involved with consultancy and testing of metals and alloys, drinking water, and industrial effluents. Dr. Sharma has published widely on the removal of metallic species from aqueous solutions.