MODELING CHEMICAL AND PHYSICAL PROCESSES IN LEACHING SOLIDIFIED WASTES zq # n ?
Solidification is an important treatment process in hazardous waste management and will continue to be so until waste minimization and waste recycle processes are perfected for all hazardous wastes. It is generally recognized that immobilization of contaminants in solidified wastes occurs through both physical and chemical mechanisms. Standard techniques for analyzing contaminant leaching measure only an observed diffusivity that does not separate chemical and physical factors. The suitability of the standard data analysis procedure is reviewed and alternative models developed that describe the separate effects of chemical and physical processes. These models describe physical transport through a solidified waste matrix according to Fick's law. Chemical reactions of sorption/desorption and precipitation/ dissolution are described. The observed diffusivity that would be calculated by ignoring chemical processes is shown to depend on the true effective diffusivity and coefficients that describe the chemical phenomena.
Assessment of the loss of radioactive isotopes from waste solids to the environment. Part I. Background and theory
A report is given of several theoretical expressions based on mass transport phenomena that relate the radioactivity escaping from such solids to diffusion, dissolution processes, surface conditions, and radioactive decay. Representative available data for radioactive waste solids incorporated in cement, asphalt, ceramic, and glass media are analyzed using the theoretical expressions presented. These analyses show that an expression taking into account diffusion and concentration-dependent dissolution gives good agreement with the data for most of the products considered. In the main, these products can be categorized as waste solids of low solubility incorporated in inert matrices. The effective diffusivities obtained are in the range of mid 10$sup - 17$ to mid 10$sup -12$ cm$sup 2$/sec, the dissolution rate constants are in the range of high 10$sup -9$ to low 10$sup -7$ sec$sup -1$, and the surface transfer constants are in the range of low 10$sup -4$ to low 10$sup -3$ sec$sup -1$ for the products analyzed. Once determined, such parameters can be used to compare various waste products and to estimate releases from these products, in particular, long-term releases. (auth)
EFFECT OF TIME AND TEMPERATURE ON ACCELERATED CHEMICAL DURABILITY TESTS MADE ON COMMERCIAL GLASS BOTTLES
The effects of storage of solutions in glass bottles at room temperature are compared with the results of various accelerated tests with corresponding solutions in the first paper of this series. The acid tests at room temperature are in good agreement with those at higher temperatures. 
 
Relative resistances of glass bottles as shown by accelerated tests with water roughly parallel relative resistances appearing in room-temperature storage of unbuffered, neutral materials only if the various amounts of extraction are approximately the same at both temperatures. 
 
The tendency of bottles to produce flakes or insoluble matter in alkaline solutions bears no direct relation to the amount of soluble matter extracted by such solutions.