I express my deep gratitude to Dr. G. Sekaran, Scientist and Head of the Department of the Environmental Technology Lab, CLRI who accepted my request for carrying out my project work. I owe my deep sense of gratitude to Dr. Evvie Chockalingam, for her valuable guidance, constant encouragement, innumerable suggestions, patience and care that she bestowed on me during the course of my project. I would like to thank Dr. G. Sekar, Associate Professor, Department of Chemistry, IIT- Madras, for allowing me to use the facilities available in his lab for my experiments. I would like to thank my project coordinator Dr.Shiny John Vairamon, Head of the Department of Chemistry. Finally, my heartfelt thanks to Dr.Muthuraman Pandurangan. He played a vital role in writing up this book. Without him this would not be possible. I would like to express my sincere gratitude to the editor who accepted the manuscript. Last but not the least I would like to thank my beloved mother and other family members for their constant support throughout the process. Special thanks to all my friends who encouraged and supported me always as ever.