Grantee Research Project Results
2014 Progress Report: Dentritic polymers as biocompatible dispersants for oil spill remediation
EPA Grant Number: R835182Title: Dentritic polymers as biocompatible dispersants for oil spill remediation
Investigators: Ladner, David A. , Whelton, Andrew J , Powers, Sean P , Ding, Feng
Current Investigators: Ladner, David A. , Whelton, Andrew J , Powers, Sean P , Ke, Pu-Chun
Institution: Clemson University , University of South Alabama , Purdue University
Current Institution: Clemson University , University of South Alabama
EPA Project Officer: Aja, Hayley
Project Period: May 15, 2012 through May 14, 2015 (Extended to May 14, 2016)
Project Period Covered by this Report: April 1, 2014 through March 31,2015
Project Amount: $500,000
RFA: Environmental Impact and Mitigation of Oil Spills (2011) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
Dendritic polymers recently have been shown to encapsulate polycyclic aromatic hydrocarbons (PAHs) and other hydrophobic materials. We hypothesize that similar interactions will occur with crude oil components, thus allowing oil to be dispersed. Our objective is to gain a fundamental understanding of the interactions of dendritic polymers with crude oil, taking toxicity and biodegradability into consideration. Our community outreach program objectives are to involve community groups in developing the research and in educating a broad audience about current and novel dispersants and their environmental impacts.
Progress Summary:
Research
Our current efforts are focused on the preparation of four manuscripts (Carpenter, et al., in preparation; Salehi & Whelton, in preparation; Wang, et al., in preparation; Salehi, et al., in preparation). The Carpenter, et al. paper reflects our ongoing work to determine the effects of varying salinity and water quality on dendritic polymer dispersants. We have found that salinity plays a role in polymer behavior, but at all salinities (0 ppt [ion-free water] to 35 ppt [seawater]) the polymers are able to disperse Louisiana light sweet (LLS) crude oil. Other water quality parameters such as pH, natural organic matter (NOM) concentration, hardness, and alkalinity are under investigation.
The Salehi & Welton paper is an investigation of the release of benzene, toluene, ethylbenzene, and xylenes (BTEX) volatile organic compounds (VOCs) when crude oil is dispersed, either by Corexit 9500 or by dendritic polymers. This investigation stems directly from questions asked by our community group representatives during our outreach workshops (described below).
The Wang, et al. paper will describe the molecular mechanisms of poly(amidoamine) (PAMAM) dendrimers as oil dispersants. Molecular modeling is being used to elucidate the mechanisms beyond what we have reported previously. These modeling simulations cover a variety of types of oil and use many more molecules than in previous simulations so that water-oil interfacial effects can be observed.
The Salehi, et al. paper is a combined investigation of effectiveness and toxicity for hyperbranched polymers. We used a range of molecular weights for hyberbranched polyethyleneimine (HPEI) polymers and evaluated their dispersion effectiveness on LLS crude oil. We also tested the toxicity toward Daphnia magna water fleas. Effectiveness and toxicity were both highly dependent on polymer molecular weight. Compared to Corexit 9500, some of the polymers had similar effectiveness, but lower toxicity.
The above in-progress papers build on work that we have previously published (Geitner, et al., 2014; Geitner, et al., 2013; Bhattacharya, et al., 2013; Geitner, et al., 2012; and Bhattacharya, et al., 2012). The most recent of these, Geitner, et al., 2014, is a combination of laboratory work and molecular modeling that elucidates the relationship between structure and function for dendritic polymer dispersants. The paper sheds light on the ways that pH and temperature affect structure, and thus dispersion performance. An example finding is that at pH values below neutral the internal polymer functional groups of PAMAM dendrimers become positively charged. If the external functional groups are negatively charged, there can be back-folding of polymer end groups. This decreases dendrimers’ ability to host hydrocarbons. The most able dispersants are those that retain an open structure.
Community Outreach
We have completed three workshops with four community groups. The participating organizations were:
- Hijra House in collaboration with the Mississippi Coalition for Vietnamese American Fisher Folks and Families (MSCVAFF), Biloxi, MS
- Be Ready Alliance Coordinating for Emergencies (BRACE), Pensacola, FL
- Mobile Baykeeper, Mobile, AL
- The Estuarium at the Dauphin Island Sea Lab, Dauphin Island, AL
The first workshop was a gathering to meet the community group representatives, learn about their past and ongoing initiatives, and educate them regarding oil spill research. The second workshop was an intensive laboratory experience and discussion session with the community groups. The third workshop was a collaborative effort between researchers and community groups to design a website and an exhibit for the Estuarium at the Dauphin Island Sea Lab.
Future Activities:
Research
The remaining research in this project is to evaluate several other dendritic polymer structures beyond those that have been tested already for oil dispersion. These include both dendrimers (well-ordered structures with equal numbers of branching points on each branch) and hyperbranched polymers (randomly ordered structures with a statistical, rather than well-defined, number of branching points). Polyester dendritic polymers are one material type that shows promise because it may be more biodegradable than PAMAM or PEI materials. Polyester polymers can be decorated with a variety of functional groups, which expands the structural possibilities.
Community Outreach
The community outreach program has two main activities left to complete: the website and the Estuarium exhibit. The website structure and layout has been drafted and can be viewed at http://oilspilldispersants.weebly.com/ The intent of the website is to disseminate knowledge about oil spills and particularly dispersants, to the broader public. We are using the ideas generated from community group representatives during our three workshops, and we will use photos and videos from those workshops. Video editing into short, captivating footage is one main subtask.
The second main community outreach task is the Estuarium exhibit. A physical exhibit will be created with two parts: a “live” demonstration of oil spill dispersants in action, and an interactive digital display.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
| Other project views: | All 18 publications | 7 publications in selected types | All 7 journal articles |
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Bhattacharya P, Conroy N, Rao AM, Powell BA, Ladner DA, Ke PC. PAMAM dendrimer for mitigating humic foulant. RSC Advances 2012;2(21):7997-8001. |
R835182 (2013) R835182 (2014) R835182 (Final) |
Exit Exit Exit |
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Bhattacharya P, Geitner NK, Sarupria S, Ke PC. Exploiting the physicochemical properties of dendritic polymers for environmental and biological applications. Physical Chemistry Chemical Physics 2013;15(13):4477-4490. |
R835182 (2013) R835182 (2014) R835182 (Final) |
Exit Exit Exit |
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Geitner NK, Bhattacharya P, Steele M, Chen R, Ladner DA, Ke PC. Understanding dendritic polymer-hydrocarbon interactions for oil dispersion. RSC Advances 2012;2(25):9371-9375. |
R835182 (2013) R835182 (2014) R835182 (Final) |
Exit Exit Exit |
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Geitner NK, Powell RR, Bruce T, Ladner DA, Ke PC. Effects of dendrimer oil dispersants on Dictyostelium discoideum. RSC Advances 2013;3(48):25930-25936. |
R835182 (2013) R835182 (2014) R835182 (Final) |
Exit Exit Exit |
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Geitner NK, Wang B, Andorfer RE, Ladner DA, Ke PC, Ding F. Structure–function relationship of PAMAM dendrimers as robust oil dispersants. Environmental Science & Technology 2014;48(21):12868-12875. |
R835182 (2013) R835182 (2014) R835182 (Final) |
Exit Exit Exit |
Supplemental Keywords:
oil spill, dendritic polymer, dendrimer, hyperbranched polymer, dispersant, molecular modeling, effectiveness testing, drop breakup, surface tension, surfactant, Corexit 9500, toxicity, biodegradation, biocompatibility, Daphnia magna, oyster, benzene, toluene, ethyl benzene, xylenes, hexadecane, phenanthrene, naphthaleneRelevant Websites:
Ladner Research Group: http://www.clemson.edu/ces/ladnergroup/projects.php Exit
Whelton Research Group: http://wheltongroup.org/ Exit
Ding Research Group: http://dlab.clemson.edu/ Exit
Under construction Community Outreach Web Site: http://oilspilldispersants.weebly.com/ Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.