Final Report: Modified Natural Zeolite (Mnz) as a Selective Sorbent for Simultaneous Removal of Arsenites and ArsenatesEPA Grant Number: R831430
Title: Modified Natural Zeolite (Mnz) as a Selective Sorbent for Simultaneous Removal of Arsenites and Arsenates
Investigators: Sengupta, Arup K.
Institution: Lehigh University
EPA Project Officer: Richards, April
Project Period: October 1, 2003 through September 30, 2004
Project Amount: $50,000
RFA: New Technologies for the Environment (NTE) (2003) RFA Text | Recipients Lists
Research Category: Nanotechnology , Sustainability , Pollution Prevention/Sustainable Development
The newly promulgated arsenic maximum contaminant level of 10 μg/L in drinking water would require corrective action for about 4,000 water supply systems in the United States that serve small communities. In addition to being cost effective, the arsenic removal system for small communities should be operationally simple requiring minimal human intervention. The total dissolved arsenic concentration in groundwater may undergo changes over a period of time and both As(III) and As(V), referred to as arsenites and arsenates, may be present simultaneously in groundwater. Arsenic concentration in the treated water should remain less than 10 μg/L independent of any fluctuations of arsenic concentrations and relative distribution of arsenites and arsenates in groundwater. A simple-to-operate fixed-bed sorption process can be very effective in satisfying these goals. The general objective of this research project was to develop a suitable sorbent that is inexpensive and highly selective toward As(III) and As(V) and suitable for use in fixed-bed units requiring no pre- or posttreatment.
We successfully dispersed hydrated iron oxide (HFO) nanoparticles within natural zeolite. Zeolites, however, have negatively charged aluminosilicate groups. Because of the Donnan exclusion effect, modified natural zeolite (Mnz) did not offer high As(V) or As(III) removal capacity. Mnz, however, exhibited high sorption affinity toward dissolved copper and zinc ions.
Commercial anion exchange resins, once dispersed with HFO nanoparticles, offered both As(V) and As(III) removal capacity. This new sorbent also was amenable to efficient regeneration and reuse. In fact, zirconium oxide nanoparticles, once appropriately dispersed within an anion exchanger, also offer high arsenic selectivity. Activated carbon, alginate, cellulose beads, chitoson, diatomaceous earth, and other materials have been used to support metal oxide nanoparticles, but they fail to take the synergistic advantage of the Donnan membrane effect and hence, they cannot offer arsenic removal capacity as high as anion exchanger as the support material.
Very recently, we successfully dispersed iron oxide nanoparticles within thin, cylindrical ion exchange fibers. The resulting hybrid ion exchange fibers have high arsenic removal capacity with high sorption/desorption kinetics. Hybrid fibers also can be woven into a tea-bag like configuration and may find many point-of-use applications.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other project views:||All 2 publications||1 publications in selected types||All 1 journal articles|
||Cumbal L, SenGupta AK. Arsenic removal using polymer-supported hydrated iron(III) oxide nanoparticles: role of donnan membrane effect. Environmental Science & Technology 2005;39(17):6508-6515.||