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Extramural Research

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Title of Talk:
Nanoscale Biopolymers With Tunable Properties for Improved Decontamination and Recycling of Heavy Metals

Abstract of Talk:
Heavy metal ions are major sources for pollution of the biosphere and they are usually found as co-contaminants in many superfund sites. Current technologies are inadequate to reduce metal concentrations to acceptable standards and to separate these heavy metals from a waste mixture for potential recycling. Our goal in this work is to develop a technology utilizing nanoscale metal-binding biopolymers with customizable properties for the differential sequestration and recovery of different heavy metals in a mixed-metal waste. Tunable biopolymers based on elastin-like polypeptides (ELP) will be generated to demonstrate this feasibility by specifically incorporating different metal binding domains into ELP biopolymers with dramatically different transition temperatures. Initial feasibility studies will utilize two different ELP building blocks containing either polyhistidine or synthetic phytochelatin as the metal-binding domain. Application of this technology for soil remediation will also be discussed. This technology serves as an example to provide an efficient and non-toxic solution to the removal and separation of heavy metal contamination.

Environmental Applications/Implications:
The biosynthetic approach is environmentally friendly and allows precise and independent control of the length, composition, and charge density of the interacting end blocks and metal-binding domains, thus allowing the flexibility in designing tunable biopolymers that can undergo transition from water-soluble into aggregate forms under a wild-range of conditions and such precise control is valuable to satisfy the needs of different process conditions. Comparing to conventional chemical chelators or chelating polymers, the proposed biopolymers is environmentally friendly since no toxic chemical is required for their synthesis and regeneration can be achieved easily. This strategy if successful, will provide a low-cost and environmentally benign technology for heavy metal removal.

Success Stories:
A new paper describing the use of a mercury-specific biopolymer for the selective removal of mercury from contaminated water has just appeared in Environmental Science and Technology. This new technology has been highlighted by Science News and by the Technology Solution section of Environmental Science and Technology.

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