Tailoring Activated Carbon Surfaces for Water, Wastewater and Hazardous Waste Treatment OperationsEPA Grant Number: R828157
Title: Tailoring Activated Carbon Surfaces for Water, Wastewater and Hazardous Waste Treatment Operations
Investigators: Karanfil, Tanju , Kilduff, James E.
Institution: Clemson University
Current Institution: Clemson University , Rensselaer Polytechnic Institute
EPA Project Officer: Lasat, Mitch
Project Period: June 1, 2000 through May 31, 2002 (Extended to July 31, 2004)
Project Amount: $223,978
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Engineering and Environmental Chemistry , Water , Land and Waste Management , Air
Granular activated carbon (GAC) treatment has been proven to be an excellent option for removal of a broad range of synthetic organic compounds (SOCs) from drinking water sources and industrial wastewaters. Despite the demonstrated effectiveness of GAC treatment, difficulties remain with regard to design of treatment systems, which are technically and economically optimal. The primary objective of this proposed research is to develop a fundamental understanding of how activated carbon surface chemistry influences adsorption of priority pollutants from complex solution matrices. Specifically, our goals are to: 1) elucidate how carbon surface chemistry influences adsorption mechanisms (e.g., dispersive, electrostatic, hydrophobic interactions) of SOCs and organic macromolecules; 2) investigate how sorbate molecular properties impacts adsorption by activated carbons with different surface chemistry; 3) examine the role of carbon surface chemistry on competitive (i.e., simultaneous adsorption and preloading) adsorption interactions between target pollutants and organic macromolecules in the background water matrices; and 4) provide a rational basis for selecting or preparing activated carbons for removal of SOCs and organic macromolecules from water and wastewaters.
The hypothesis guiding this study is that carbon surface chemistry plays a key role in the adsorption of target compounds, especially for small molecular weight organic priority pollutants, and, in some cases, may overwhelm the effects of pore structure. We provide several pieces of evidence in the proposal to support this hypothesis. Our results clearly indicate that a good understanding of interactions between carbon surfaces and priority pollutants can be a viable route to producing novel sorbents for economic design and effective application of adsorption processes in meeting our increasingly stringent water quality standards.
We propose a four-phase approach to systematically investigate our objectives: 1) prepare and characterize surface modified GACs and activated carbon fibers (ACFs); 2) investigate the roles of carbon surface chemistry and target compound molecular structure on the adsorption mechanisms of priority pollutants; 3) examine the interactions between natural organic matter (NOM) and activated carbon surfaces; and 4) elucidate competitions between NOM and SOCs during adsorption by different surfaces.
The surfaces of GACs and ACFs will be treated to prepare carbons with different surface chemistry having similar pore structure. ACFs will be used for a better control of the pore size distribution and investigation of the interactions in the micropore region. The treated carbons will be extensively characterized by using a variety of techniques (e.g., N2 and CO2 adsorption, water uptake, FTIR spectroscopy, acid-base adsorption). Single and multiple solute isotherm experiments will be conducted for a series of aromatic, aliphatic and well-characterized NOM isolates to examine the role of carbon surface chemistry and target compound molecular structure on the adsorption mechanisms.
The results of this project will provide fundamental information that is essential for: i) economic design and effective application of adsorption processes in meeting our increasingly stringent water quality standards while treating complex water and wastewater matrices; ii) development of new adsorbents or customization of commercially available carbon surfaces for specific applications; iii) enhanced recovery of the target compound(s) in waste minimization applications and for reuse of the separating media, thus, in optimization of process economics; and iv) development of more mechanistic isotherms, mathematical models and design protocols.