This Broadening Participation Research Initiation Grant in Engineering (BRIGE) provides funding for the development of low-environmental impact polymer to coat nanoscale particles for groundwater remediation. Plant-based polymers will be modified and their structure-property relationships will be studied to understand the impacts of various functional groups on dispersion, contaminant treatability, aquifer injectability, and subsurface mobility of coated nanoscale zero-valent iron particles. The results obtained from the experiments will be used to fine-tune the final architecture of biopolymers to coat the particles. The overall objective of this research is to study the impacts of manipulation of the biopolymer functional groups on dispersion, contaminant degradation, and transport behaviors of the coated iron particles as well as biodegradability of the polymer coatings.
If successful, this research will lead to the development of smarter and low-impact groundwater remediation tools which will benefit practitioners in environmental remediation. The findings from this research will elucidate the impacts of polymer architecture on aquifer transport of polymer coated nanomaterials. The biodegradation studies are expected to lead to the development of new polymer biodegradation test protocols and help in better understanding the degradation behavior of complex engineered nanomaterials in an aquatic environment. This research project will add to the body of knowledge in environmental engineering, polymer science, and nanotechnology as well in biomedical science. The biodegradable polymers synthesized within this project may find uses in drug and nutrient delivery in human and plants. The project will broaden the participation of underrepresented groups (Native Americans, first generation Americans, and women) in fundamental research. The high school students recruited for research in this project are expected to pursue higher education and careers in science and engineering. Programs organized among Native American middle/high school students and students with disabilities will help in inculcating the spirit of scientific research among them.
Nanoparticles are tiny particles which have amazing properties that can be exploited for our benefit. A nanoparticle is smaller than 100 nanometers (nm) and one nanometer is one billionth of a meter or 1000 times smaller than a micrometer. Because of their small size they agglomerate very easily and that is a problem for successful exploitation of the nanoparticles for our uses. One of the most important parameter in nanoparticles is their surface area per volume. The nanoparticle surfaces are very reactive and can breakdown or adsorb environmental toxins or contaminants very effectively. However, agglomerated nanoparticles are not very effective contaminant remediation. The objective of this research was to modify the surface of the nanoparticles using polymers such that the nanoparticles do not become agglomerated and maintain their individuality, and in the process they do not lose their surface areas due to agglomeration. The objective of this project was to make the nanoparticles disperse and swim well in water. It was hypothesized that the nanoparticles will swim to the contaminants in groundwater and remediate them effectively. To achieve dispersibility and contaminant affinity, a hydrophobic (water hating) backbone polymer was used and that was attached to a hydrophilic graft. An anchoring group was attached to the hydrophobic backbone such that the polymer with the graft can get attached to the target iron nanoparticles. As the modified nanoparticles will be used for groundwater remediation which will be eventually extracted for human consumption, the polymers used should be green and biodegradable. Commercially available edible soybean oil was used as the base material for one of the polymers. The oil was polymerized to form a straight-chain hydrophobic backbone and a hydrophilic polyethylene glycol (PEG) graft was used along with an acidic anchoring group. The new polymer was called an amphiphilic graft copolymer (APGC) and was used to coat the iron nanoparticles. The coated nanoparticles showed very good dispersion behavior and did not get settled down for more than two hours. The coated nanoparticles could degrade toxic compounds like trichloroethylene (TCE) and arsenic in water more efficiently than the uncoated (bare) nanoparticles. Biodegradation studies indicated that the APGC (alone and when coated onto iron nanoparticles) can be easily degraded by common bacteria. Because of the PEG group the APGC coated nanoparticles did not stick to the aquifer materials (sand) and now can be easily injected to the specific locations in an aquifer where grounwater contaminants are located. The project researchers also worked on food-grade starches (corn, wheat, rice, potato, and tapioca) and used them as nanoparticle surface modifiers. Tapioca starch with an acidic anchoring group was found to be the best candidate for nanoparticle surface modification for groundwater remediation applications. The starch modified nanoparticles could degrade TCE relatively effectively and the coated tapioca starch was highly biodegradable. A biopolymer derived from sea weeds was also used for decrease nanoparticle agglomeration. Biopolymer alginate is non-toxic, easily available, and inexpensive. Alginate was used to entrap and encapsulate nanoparticles and the entrapped/encapsulated nanoparticles could remediate aqueous arsenic, selenium, and phosphate. The uses of the new products developed within this research project are not limited to environmental clean-up alone. The APGC developed within this research project will find uses in drug delivery and in new generation smart batteries. APGC can also be used for modification of powders used in food (for example, cocoa powder) such that they can remain suspended for an extended period of time. The soybean oil-based polymer can be used in paints and as surface coating on metals and plastics. Some of the methodologies developed within this project (for example how to evaluate biodegradation of polymers) can now be used by researchers in polymer science. The starch-based surface modifiers can be used as emulsifying/dispersing agents in food products (chocolate drinks, cake mixes, and salad dressing). Three patent applications have been filed to protect intellectual properties developed within this project, and the products are at various stages of commercialization. Once commercialized, these product manufacturing units and associated industries are expected to create manpower training and employment opportunities. Nine graduate students, sixteen undergraduates, and nine high school students were trained on nanotechnology within this project. Four students worked on their doctoral degrees and four others worked on their master’s degrees during this project. The graduate students also had the opportunity to mentor undergraduate and school students in their research. Two additional undergraduate students, three K-12 teachers, and two Veteran K-12 teachers were involved in nanotechnology research during the project period. Female students and K-12 teachers, students of color, first generation Americans, and physically challenged students who form the underrepresented groups in engineering were specifically recruited to work in this project. Middle school nanotechnology teaching modules have been developed in collaboration with subject teachers in such a way that these modules blend into the regular courses in middle schools.
