Novel Anionic Clay Adsorbents for Boiler-Blow Down Waters Reclaim and Reuse

Sahimi, Muhammad ; Tsotsis, Theodore T.

University of Southern California

关键词: Boilers;    20 Fossil-Fueled Power Plants;    Recycling;    Demetallization;    Clays;   

DOI  :  10.2172/888921
RP-ID  :  none
RP-ID  :  FG26-04NT42177
RP-ID  :  888921

美国|英语

来源: UNT Digital Library

【 摘 要 】

Our goal in this study is to utilize novel anionic clay sorbents for treating and reclaiming/reusing power-plant effluents, in particular, boiler blow-down waters containing heavy metals, such as As and Se. Developing and using novel materials for such application is dictated by the challenge posed by reclaiming and recycling these too-clean-to-clean effluent streams, generated during electricity production, whose contaminant levels are in the ppm/ppb (or even less) trace levels. During the study model blow-down streams have been treated in batch experiments. Adsorption isotherms as a function of pH/temperature have been established for both As and Se. Adsorption rates have also measured as a function of concentration, temperature, pH, and space time. For both the equilibrium and rate measurements, we have studied the As/Se interaction, and competition from background anions. A homogeneous surface diffusion model is used to describe the experimental kinetic data. The estimated diffusivity values are shown to depend on the particle size. On the other hand, a model taking into account the polycrystalline nature of these adsorbent particles, and the presence of an intercrystallite porous region predicts correctly that the surface diffusivity is particle size independent. A mathematical model to describe flow experiments in packed-beds has also been developed during phase I of this project. The goal is to validate this model with flow experiments in packed-beds during the phase II of this project, to determine the adsorption capacity under flow conditions, and to compare it with the capacity estimated from the adsorption isotherms determined from the batch studies.