Interfacial Chemistry of Rocks and Soils

Noémi M. Nagy, József Kónya

• Publisher: CRC Press
• Year: 2021
• Print ISBN:
  9780367856823
• eBook ISBN:
  9781000465181
• Topic: Physical Sciences
• Subtopic: Environmental Science

Knowledge of the basic interactions that take place between geological materials and different substances is the first step in understanding the effects of adsorption and other interfacial processes on the quality of rocks and soils, and on driving these processes towards a beneficial or neutral result. Interfacial Chemistry of Rocks and Soils examines the different processes at solid and liquid interfaces of soil and rock, presenting a complete analysis that emphasizes the importance of chemical species on these interactions.

This Second Edition features novel results in the field and expanded coverage of the kinetics of interfacial processes. New content includes models of heterogeneous isotope exchange, sorption isotherms for heterovalent cation exchange, as well as sorption of anions by chemically modified clays.

Summarizing the results and knowledge of the authors' research in this field over several decades, this volume:

• Explores the individual components of the studied systems: the solid, the solution, and the interface
• Discusses the characteristics and thermodynamics of the interface
• Profiles the most important analytical methods in the study of interfacial processes
• Demonstrates transformations initiated by interfacial processes
• Outlines avenues of treatment that may solve geological, soil science, and environmental problems

Drawn chiefly from the authors' years of research at the Imre Lajos Isotope Laboratory in the Department of Physical Chemistry at the University of Debrecen in Hungary, this book discusses chemical reactions on the surfaces/interfaces of soils and rocks; examines the role of these processes in environmental, colloid and geochemistry; and explores the effects on agricultural, environmental and industrial applications.

1 Components of Soil- and Rock-Solution Systems

DOI: 10.1201/9781003020080-1

1.1 Solid: Soil and Rock

The crust of the Earth is made up of rocks and soils, the latter produced by the weathering of rocks. Therefore, rocks and soils contain the same chemical elements, and their mineral composition is also similar. In addition, soils contain organic matter.

Rocks are defined as incoherent, naturally formed substances, mostly composed of minerals. They can be classified as igneous, sedimentary, and metamorphic, depending on their origin. Rocks are stable in the conditions under which they were formed. When environmental conditions are changed, they become thermodynamically unstable. This happens on the surface of the Earth when the rocks interact with the atmosphere, hydrosphere, and biosphere. The formation of soils is the result of the interactions between the rocks and the atmosphere, hydrosphere, or biosphere. The mineral transformations, including weathering, have been extensively studied and described as interactions of the lithosphere, hydrosphere, atmosphere, and biosphere (Kabata-Pendias and Pendias 1985, p.15). These processes are not limited to the solid phase; the liquid phase is also involved and plays an important role. As in all chemical processes, these interactions are driven toward achieving a chemical equilibrium, that is, the species formed must be thermodynamically more stable under the particular conditions than the original material was. The same can be said for any substances getting onto the rocks and soils regardless of its source (e.g., anthropogenic or other), which tend to transform if they are thermodynamically unstable. Obviously, the environment is not a closed system; therefore, the laws of thermodynamics will only determine the direction of the processes but not their final results. Furthermore, kinetic barriers also limit achievement of the equilibrium. The soil is an intermediate stage of this thermodynamically driven process during which rocks transform into other stable species under changed conditions.

Soil consists of an abiotic (as mentioned earlier) and a biotic (derived from living matter) part. This book deals with the abiotic part, the components of which are shown in Figure 1.1.

FIGURE 1.1 Components of the abiotic part of soil.

Abiotic soil components form a three-phase polydisperse system. About 50 v/v% of soil is solid, 50 v/v% is soil solution, and air, depending on humidity. As seen in Figure 1.1, the solid phase consists of mineral and organic components (Section 1.1.2). The main constituents of the gas phase (soil air) is composed of vapor and gases of the air (nitrogen, oxygen, carbon dioxide, etc.), and other gases such as hydrocarbons, radon, anthropogenic pollutions, etc., depending on local conditions. The soil solution is made up of the water-soluble components of solid and soil air. Its composition is determined by the geological conditions (composition of rocks and soils) and influenced by natural and anthropogenic factors.

1.1.1 Mineral and Chemical Composition of Rocks and Soils

Minerals are natural, usually inorganic, substances with a definite and predictable chemical composition and physical properties (O’ Donoghue 1990). Some organic substances (e.g., oxalates, amber, etc.) are also considered as minerals.

Minerals are arranged by the Dana and Strunz classification systems (Gaines et al. 1997; Strunz 1941). The groups are as follows:

• Elements.
• Sulfides.
• Halogenides.
• Oxides and hydroxides.
• Nitrates, carbonates, and borates.
• Sulfates, chromates, molybdates, and tungstates.
• Phosphates, arsenates, and vanadates.
• Silicates.
• Organic compounds.

In the soil and rocks near to the surface, silicates, oxides, carbonates, sulf...

Table of contents

• Cover
• Half-Title
• Series
• Title
• Copyright
• Contents
• Preface to the First Edition
• Preface to the Second Edition
• Authors
• Chapter 1 Components of Soil- and Rock-Solution Systems
• Chapter 2 Interfacial Processes in Geological Systems: Studies on Montmorillonite Model Substance
• Chapter 3 Interfacial Reactions at Rock and Soil Interfaces
• Chapter 4 Experimental Methods in Studying Interfacial Processes of Rocks and Soils
• Index