Ion-Exchange Minerals and Disposal of Radioactive Wastes A Survey of Literature By B. P. ROBINSON GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1616 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1962 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. CONTENTS Page Abstract___ _______________________________________________________ 1 Introduction._____________________________________________________ 2 Purpose and scope of study._______________--__--____-__-_-____- 2 Ion-exchange property of minerals.______________________________ 2 Radioactive waste disposal____________________________________ 3 Acknowledgements- ___________________________________________ 4 Adsorption and ion exchange: General.______________________________ 4 Colloid science ________________________________________________ 4 Colloids defined._______________________.__.______^___^___ 5 Classification of colloids.___________________________________ 5 Size of colloidal particles.__________________________________ 5 Examples of colloids.______________________________________ 5 Properties of colloids-,___________-__-_-___-_____---------_- 5 Structure and electric charge...________________________ 5 Stability of colloids.___________________________________ 6 Other references.._________________________________________ 9 Thermodynamics and adsorption._____________________^___-_____ 9 Free energy and equilibrium._______________________________ 10 Experimental studies_______________________________________ 10 Other references.__________________________________________ 12 Reaction kinetics._____________________________________________ 12 Function of kinetics________-____--------________-__----_:__ 12 Order of rate equations._.__________________________________ 12 Diffusion effect on reaction rate_____________________________ 13 Temperature effect and the Arrhenius equation._______________ 13 Partition functions________-_________-___--____-___--_--_- " 14 Experimental studies.______________________________________ 14 Reaction mechanisms._________________________________________ 17 Types of adsorption______-_____-___--____-___-_-_----_--_ 17 Physical _ __________-__________--._______--_---_----- 17 Chemisorption _______-_______________--___-_--___-___- 17 Other types_______________________________---__----__- 18 Adsorption equations and exchange equilibrium___^_________-.__-__ 19 Empirical equations._____________________________________ 19 Mass-action equations._____________________________________ 21 Kinetic equations__________________________-___-__-.--__-- 26 Surface tension_________________________________ _______ 28 Surface-active agents____________^___^______-__---_-__ 29 Gibbs' adsorption theorem..____________________________ 29 Experimental studies____________-___-___---__------_- 30 Clay minerals__.---_-___-.__---_--__---------.__-_-___--__---_-------_- 31 Definition of clay minerals.._-__-__________-.___-___----_---__-- 31 Origin of clays____________--_______-_-_-_-_---_-__--_-----_--_ 31 Classification and nomenclature-___---_--__--_-----_--__--------- 32 Classification systems-____---_-------_---_--------__------- 32 Nomenclature_ _ ___-__________-_____^.__--___--__----___- 34 Allophane.___________________________________________ 34 Kaolinite group._______-___-______-.___-____-__-__-___- 34 IV CONTENTS Clays minerals Continued Classification and nomenclature Continued Nomenclature Continued Page Halloysite ____________________________________________ 34 Montmorillonite_ _ _______--______-_--______--__--___- 35 Vermiculite. _ _____________-_____-__-_----_-_-_-_-_-___ 35 Elite____________________--_-_-__-_-____-______ 35 Chlorite_______________________________________ 35 Palygorskite-attapulgite-sepiolite. _______________________ 36 Composition and structure____________________________________ 36 Old concept_____________________________________________ 36 Modern concept____-_______-__--_-_-_-__---_---_----_--__^ 37 Modern studies of clay structures.___________________________ 37 Structure of allophane minerals______-____-__-_-_-_____-___ 40 Structure of kaolinite--__-------------------_--------__--_- 40 Structure of halloysite____________________________________ 43 Structure of montmorillonites-______________________________ 44 Structure of vermiculite.____________-___-_-______---__-____ 50 Structure of illites.____________-____-__----_-_-__--_-_-____ 51 Structure of chlorites___________________-__-__---_----_-_ 54 Structure of attapulgite-palygorskite-sepiolite_________________ 55 Structure of mixed-layer clay minerals_______________________ 56 Other cation exchange minerals____________________________________ 58 Origin and nomenclature________-_______-___-____-_-_-____-___- 58 Glauconite__ _ __-_____-___-___--__----_---__---_--___-___ 58 Ultramarines_ _ _-_-___-__--____-_--_--_---__-____-_----__ 58 Zeolites __________________________________________________ 58 Composition and structure____------_------__-------_-_--_------ 59 Glauconite. _ ____________________________________________ 59 Ultramarines_ _ __________________________________________ 59 Zeolites __________________________________________________ 59 Cation exchange and adsorption on clays and other exchange minerals. _ _ 60 Definition _____________________________________________________ 60 Cation exchange materials._____________________________________ 61 Early history_________________________________________________ 61 Cation exchange theories_____________________________________ 62 Adsorption of polar molecules and gases by clay minerals._____--___ 63 Uptake of polar molecules._________________________________ 63 Uptake of water___.________-___-____-_-__-___--___-__- 63 Uptake of ammonia _________________________________ 64 Organic polar molecules._______________________________ 64 Modern concept of cation exchange in clay minerals and exchange minerals.___________________________________________________ 64 Cation exchange in clay minerals.---_______-__--_-_____-____ 64 Cation exchange in glauconite_____________________________ 66 Cation exchange in ultramarines..___________________________ 66 Cation exchange in zeolites._________--_____----___-_-__--__ 67 Determination of cation-exchange capacity _____-__---___-___-__-_ 67 Ammonium method______________________________________ 68 Barium meth.od______________________-__---_------_-_----- 69 Radioactive tracer-chromatogram method ____________________ 70 Colorimetric method ____________ _________-_____-_-___-_-_--_-_ 70 Miscellaneous methods.________________________________________ 70 CONTENTS V Cation exchange and adsorbtion on clays and other exchange minerals Con. Page Replaceability of exchangeable cations___________________________ 71 Factors influencing cation exchange.----.------------------- 72 Binding forces_____________________-______--_---_-_- 72 Accessebility of the lattice ions-_-----------_----_------- 72 lonization of adsorbed cations____.__________-__-_-__-- 73 Relative size of ions_________-__-___.._-_-.__--.-------- 73 Particle size_______-_______________-________--*.-__--. 74 Temperature_____________-___-___-___._-___-___- 76 Valence._____________________________________________ 76 Atomic weight and atomic number_____-__-___--__-_--- 77 Concentration__ _ ____________________________________ 77 pH..__...__._. - ._.._.._______._--_-- 79 Clogging at cation exchange positions___-_____--__------- 79 Hydrolysis_________-_______________________. 80 Heat of wetting._________________-_-__-__--__--_---- 80 Anions _______________________________________________ 80 Complementary cations.__________________--_._--__--__ 81 Swelling_____________________________ 81 Zeta potential_______________________________________ 81 Cation fixation._______________________________________________ 81 Anion exchange in clay minerals___________-_-_-____--_-----_-------- 83 Types of anion exchange.__________-_-__-__-____--__-___--_--_- 83 Exchange anions and clays___________________________________ 83 Fixation of phosphate ions____________________________________ 84 Effect of grinding________________-___-_____-___--_--_---_ 84 Effect of temperature____________________----___--__------- 84 Effect of pH____________________________-_____--_--- 84 Anion and cation exchange in different clays________________-_---- 85 Factors interfering with the study of anion exchange.______-__-_--_ 85 Other references on ion exchange_____--__---_--___--_---_------- 86 Radioactive waste disposal________________________________________ 86 The problem____________._________..__.____._.___ 86 Radioactive waste defined________-.___-_______-_-----------_---_ 86 Radioactive elements____-___-___-______-___--_-_------ __ 87 Units of measurement of radioactivity.____________-____.__--- 87 Sources of radioactive wastes_________________________________ 88 Classification of radioactive wastes____________________________ 89 Gaseous wastes________-_______-_______-__----__-_--_---- 89 Liquid wastes_________________-___-_---__--------.--_---- 90 Solid wastes____________________-________-_--._------------ 90 Current methods of handling wastes.____________________________ 90 Proposed methods of handling wastes---------------------------- 92 Chemical methods--_..__________--__--_-----_--_----------- 92 Filtration__________________________________________ 93 Evaporation ______________________________________________ 94 Adsorption and ion exchange______________________________