This monograph is intended to provide a systematic presentation of theories concerning the adsorption of metal ions from aqueous solutions onto surfaces of natural and synthetic substances and to outline methods and procedures to estimate the extent and progress ofadsorption. As heavy metals and the problems associated with their transport and distribution are of serious concern to human health and the environment, the materials presented in this volume have both theoretical and practical significance. In writing this monograph, one ofour goals was to prepare a book useful to environmental workers and practicing engineers. For this reason, our presentation relies heavily on concepts commonly used in the environmental engineering literature. In fact, the volume was prepared for readers with a basic understanding of environmental engineering principles and some knowledge of adsorption processes. No prior familiarity with the ionic solute adsorption at solid-solution interfaces is assumed. Instead, introduction of the necessary background information was included. Generally speaking, metal ion adsorption may be studied in terms of three distinct but interrelated phenomena: surface ionization, complex formation, and the formation and presence of an electrostatic double layer adjacent to adsorbent surfaces. Analyses of these phenomena with various degrees of sophistication are xviii ADSORPTION OF METAL IONS FROM AQUEOUS SOLUTIONS presented, and their various combinations yield different models that describe metal ion adsorption.

Adsorption from aqueous solutions is important in many tech nological areas, like water purification, mineral beneficiation, soil conservation, detergency, and many areas of biology. Recently, adsorption of radionuclides from aqueous solutions has become the focus of attention in assessing the movement of radionuclides through a geologic medium from underground radioactive waste repositor ies. This volume provides a multidisciplinary overview of current work in the area of adsorption from aqueous solutions, and reviews the progress that has been made in the theoretical models for assessing adsorption. Adsorption of heavy metal ions and the effect of complex formation is treated extensively, as are the effects of surface chemical properties of the adsorbent, solution pH, and thermodynamic parameters important in the adsorption process. Adsorption of pesticides and organic polymeric species on different adsorbents are included and implications of adsorption of ions on dental materials are discussed. Also included are studies of the adsorption of radionuclides by geologic media under environmental conditions. The study of the chemical nature of the adsorbed species at the surface by X-ray photoelectron spectro sc.opy which often provides mechanistic information for the adsorption process is included for adsorbed metal ions on clay and mineral surfaces.

This state-of-the-art volume represents the first comprehensively written book which focuses on the new field of biosorption. This fascinating work conveys essential fundamental information and outlines the perspectives of biosorption. It summarizes the metal-sorbing properties of nonliving bacterial, fungal, and algal biomass, plus highlights relevant metal-binding mechanisms. This volume also discusses the aspects of obtaining and processing microbial biomass and metal-chelating chemicals into industrially applicable biosorbent products. Microbiologists, chemists, and engineers with an interest in new technological and scientific horizons will find this reference indispensable.