Acidos Humicos

ANL-84-78
ANL—84-78 DE85 015539

HUMIC SUBSTANCES IN NATURAL WATERS AND THEIR COMPLEXATION WITH TRACE METALS AND RADIONUCLIDES: A REVIEW by Sam Boggs, Jr., David Livermore, and Martin G. Seltz

ARQONNE NATIONAL LABORATORY, ARQONNE, ILLINOIS Operated by THE UNIVERSITY OF CHICAGO lor U Μ U. S. DEPARTMENT OF ENERGY under Contract W-31-109-Ene»38

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DISCLAIMER
This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of anyinformation, apparatus, product, or process disckxed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, rccommendatiofi, or favoring by the United States Government or any agency thereof. The views andopinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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TABLE OF CONTENTS Page ABSTRACT I. II. INTRODUCTION DISTRIBUTION AND CHARACTERIZATION OF DISSOLVED HUMIC SUBSTANCES IN NATURAL WATERS A. B. D. Dissolved Organic Carbon Content of Natural Waters Types of Organic Carbon Compounds 1

4 4 5 7 8 8 9 912 17 17 19 19 22 23 24 24 24 24 25 25 25 26 27 27 27 28 29

C. General Characteristics of Humic Substances Chemical Composition and Structure of Humic Substances 1. Elemental Composition 2. Oxygen-Containing Functional Groups 3. Chemical Structure E. Origin of Humic Substances in Natural Waters and Soils F. Methods for Isolating and Purifying Humic Substances 1. Extraction and Fractionation ofHumic Substances from Soils 2. Purification of Soil-Derived Humic Substances 3. Extracting Humic Substances from Water G. Methods for Analyzing and Characterizing Humic Substances 1. Spectrophotometry in the Ultraviolet and Visible Regions 2. Infrared Spectrophotometry 3. Nuclear Magnetic Resonance Spectrometry 4. Electron Spin Resonance Spectrometry 5. X-Ray Analysis and Electron Microscopy 6.Viscosity Measurements . 7. Surface Tension Measurements 8. Molecular Weight Measurements 9. Degradation Methods III. INTERACTION OF HUMIC SUBSTANCES WITH METALS A. General Concepts 1. Metal .Complexes 2. Chelate* 3. Types of Ligande

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TABLE O CONTENTS (contd) F Page B. S t a b i l i t i e s of Metal Complexes and Chelates 1. 2. 3. C< D. S t a b i l i t y Constants for Metal ChelatesThe Importance of S t a b i l i t y Constants Factors Influencing the S t a b i l i t y o f Metal Complexes 29 29 34 . . . . . « 34 37 41 41 41 42 42 43 43

Types of Metal-Organic I n t e r a c t i o n s Techniques for Studying Metal-Organic I n t e r a c t i o n s 1. 2. 3. 4. 5. 6. Potentiometric T i t r a t i o n Ion-Exchange Equilibrium . . . . Equilibrium D i a l y s i s Gel F i l t r a t io n Chromatography I o n - S e l e c t i v e Electrodes Calculation of S t a b i l i t y Constants from Experimental Data

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Influences of Metal-Ligand Concentrations and Environmental Variables on the S t a b i l i t y o f Metal-Organic Complexes 1. 2. 3. 4. 5. Influence of Metal Type Type of Organic Matter Metal and Organic Acid Concentrations E f f e c t s of pH E f f e c t s of IonicStrength

45 46 47 48 48 49 51 51 52 54 54 62 76 78 80 81 82 84

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COMPLEXING OF RADIONUCLIDES BY ORGANIC SUBSTANCES A. B. C. Introduction Complexing of Radionuclides with Synthetic Organic Compounds Complexing of Radionuclides with Humic Substance* 1. 2. D. Complexity of S o i l Humic Substances with Radionuclides Complexing of Radionuclides by Dissolved Humic Substances in Surface Waters and...