1994 — 2001 |
Roberts, A. Lynn |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Nsf Young Investigator @ Johns Hopkins University
9457260 Roberts This is an award to support research through a National Science Foundation Young Investigator Award to be performed by the Principal Investigator who was nominated and selected through procedures contained in NSF 93-148, Young Investigator Awards FY 1994 Program. This investigator's research plan involves work on the interactions of trace metal ions with inorganic ligands. These have important ramifications with respect to the manner by which metals exert their toxic effects such as influencing the mechanisms that are involved in formation of toxic methylated metal species by sulfate-reducing bacteria. This work involves development of techniques for investigating the mechanisms of electron transfer in reductive dehalogenation reactions of polyhalogenated alkanes. The treatment of contaminated soils and aquifers by stimulating abiotic or microbial reduction can result in byproducts that are relatively persistent and toxic as well as others that are readily biodegraded. Results of this research may be applied in engineering design of systems for remediation of contaminated soil and aquifers to avoid the formation of byproducts that are relatively persistent and toxic.
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0.908 |
2000 — 2003 |
Roberts, A. Lynn Fairbrother, Howard (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Zero-Valent Metal and Bimetallic Treatment of Halogenated Vapor-Phase Contaminants in Landfill Gases @ Johns Hopkins University
0086755 Roberts This research explores the use of zero-valent metals for treating vapor phase chlorinated organic contaminants commonly found in landfill gas. Specifically, the reactions of 1,2-dichloroethane and cis-1,2-dichloroethane (and their daughter products) with a variety of bimetallic reductants (or iron alone) will be studied. Batch and column tests will be conducted for screening and for determining performance, longevity, and reaction rates and products. Additional studies will focus on developing a better understanding of the molecular-scale chemical reactions that result in destruction of halogenated contaminants at metal particle surfaces. Batch and column studies will be complemented by surface chemical investigations, designed to provide information concerning trhe composistion of the reactive metal surface as it evolves under the influence of exposure to water, chlorinated contaminants and the minor gas-phase constituents, oxygen and hydrogen-sulfide. In addition to the intended application to landfill gas, applications of this research include controlling emissions from chemical production and manufacturing processes, as well as treating contaminants present in soils (removed via soil vapor extraction or bioventing). This grant is made pursuant to Solicitation NSF 00-49, New Technologies for the Environment.***
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0.908 |
2000 — 2006 |
Karlin, Kenneth (co-PI) [⬀] Meyer, Gerald [⬀] Roberts, A. Lynn Fairbrother, Howard (co-PI) [⬀] Goldberg, David (co-PI) [⬀] Goldberg, David (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Craems: Environmental Redox-Mediated Dehalogenation Chemistry @ Johns Hopkins University
This Collaborative Research Activities in Environmental Molecular Science (CRAEMS) Award to Johns Hopkins University is supported by the Special Projects Office of the Chemistry Division. The award supports studies by Gerald Meyer, Howard Fairbrother, David Goldberg, Kenneth Karlin and A. Lynn Roberts of dehalogenation chemistry by combining their expertise in synthesis, homogeneous and heterogeneous catalysis, biomimetic and bioinorganic chemistry, electrochemistry, surface science, and environmental chemistry. Specific goals of this multidisciplinary program are: 1) the development of new reductive and oxidative dehalogenation chemistries and the elucidation of their fundamental mechanisms; 2) application of these new findings to the sensing, remediation, and determination of the environmental fate of organohalide pollutants; and 3) provide a pedagogical platform that informs and educates the next generation of environmental chemists. The fundamental studies will emphasize oxidative and reductive cleavage of organohalides by copper (I) and metalloporphyrin complexes. Both stoichiometric and electrocatalytic processes will be studied. Photo-triggered and electrochemical dehalogenation will also be examined. Dehalogenation by bimetallic reductants and metal sulfide minerals will be explored. Finally, electron-beam-induced chlorocarbon reductive cleavage will be examined in water and ice media. Collaborations include those with two National Laboratories (Oak Ridge National Laboratory and Pacific Northwest National Laboratory) and with two industries (KDF Fluid Treatment Inc., and Environmental Technologies Group Inc.). To develop an understanding of environmental principles and processes at the molecular level, a new graduate course will be developed and taught. An outreach program involving underrepresented undergraduate researchers from nearby universities (Howard University and Morgan State University) will be implemented.
Seventeen of the top twenty-five organic pollutants in the U.S. are organohalides. Volatile organohalides also deplete ozone and change global climate. This interdisciplinary work aims at a molecular-level understanding of redox-mediated dehalogenation, from which "greener" chemical processes can be developed and pollution problems due to organic halides can be obviated. The educational aspects of this multidisciplinary program, in collaboration with government laboratories and industries, is designed to increase the awareness of students concerning real-world environmental problems and to provide hands-on experience.
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0.908 |
2005 — 2009 |
Abts, Leigh Bouwer, Edward (co-PI) [⬀] Donohue, Marc [⬀] Roberts, A. Lynn Etienne-Cummings, Ralph (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Track 1, Gk-12: Broader Impact From Graduate Students Transferring Engineering Principles (Bigstep) to K-12 Education @ Johns Hopkins University
Fellows will rotate through an internship with several distinct K-12 schools that serve disadvantaged children. Master Teachers who have been involved in research at JHU or who are currently participants in a Native American Math Science Partnership will work with the Fellows: to develop pedagogical skills to teach children with different learning styles; to enhance the content knowledge of district teachers; and to facilitate the creation of standards aligned content based on cutting-edge research. Each project will focus on topics from Environmental Engineering and Geography (EEG), including geology, hydrology, ecology, geomorphology, environmental chemistry, human factors (relations between human activities and environmental change). The Fellows will relate each project: (1) to standards, such as the American Association for the Advancement of Science.s Project 2061, Flow of Matter in Ecosystems;. (2) to compelling social issues as global climate change, and preservation of ecosystems; and (3) to the utilization of materials by students with physical limitations.
The intellectual merit lies in the potential to advance our understanding of how formal university-K-12 partnerships can improve teaching and learning by delivering challenging and relevant science, technology, engineering and mathematics (STEM) content to traditionally disadvantaged K- 12 students with a wide range of learning styles. A team of eminent scientists, future STEM faculty, leading K-12 teachers, and education experts will work as teams to use engaging EEG content and pedagogy to overcome barriers such as: students. unstable learning environments, curriculums that are in transition due to educational policy shifts, the lack of accommodations for students with physical disabilities, and the scarcity of resources.
Broader impact will be achieved through the development of sustainable K-12 curriculum and laboratory modules deployed by teachers prepared to deliver advanced, multi-disciplinary, and multi-contextual material spanning the STEM disciplines. An independent evaluator will gather information and report the findings on the feasibility of using EEG activities and instructional materials to improve the academic achievement of disadvantaged students with diverse needs.
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0.908 |
2006 — 2010 |
Bouwer, Edward [⬀] Roberts, A. Lynn |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Biotransformation of Selected Pharmaceuticals and Personal Care Products (Ppcps) in Biofilms @ Johns Hopkins University
0606880 Bouwer This project will investigate the removal of pharmaceuticals and personal care products (PPCPs) by biofilm processes, particularly those used in wastewater reuse, e.g., biological filtration, riverbank filtration, and soil aquifer treatment. This research will test the hypothesis that biofiltration is an effective treatment option for removing selected PPCPs from wastewater streams undergoing reclamation through soil passage and ground water recharge. This will be accomplished by investigating the transformation and removal of a variety of PPCPs in small columns intended to simulate riverbank filtration. These compounds can have ecological impacts, even at the concentration levels found in treated sewage effluents, and the results of this work could improve our understanding of their fate under scenarios of groundwater recharge and bank filtration, as well as direct treatment in biofilm reactors. Given the increasing use of PPCPs and their detection in many streams across the country, the proposal is timely and the results could have important public health consequences.
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0.908 |
2011 — 2016 |
Roberts, A. Lynn |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Role of Cl2o and Other "Overlooked Oxidants" as Halogenating Agents @ Johns Hopkins University
PI: A. Lynn Roberts Proposal Number: CBET-1067391 Institution: Johns Hopkins University Title: Role of Cl2O and Other "Overlooked Oxidants" as Halogenating Agents
Conventional wisdom has it that HOCl serves as the principal ?active? chlorinating agent in solutions of free available chlorine (FAC), widely used to disinfect drinking water and wastewater. Likewise, HOBr is almost invariably believed to represent ?the? active brominating agent. Although other species (such as Cl2O, Cl2, BrCl, BrOCl, and Br2O) are known to occur as minor constituents of FAC, they are generally believed to be present at concentrations so low as to be negligible. This overlooks the fact that minor constituents can dominate reaction rates if their inherent reactivity outweighs their lesser abundance. Results recently published by the PI?s group demonstrate that several ?overlooked? halogenating agents may force revision of this paradigm. The PI hypothesizes they could play critical roles in the rate-limiting steps for ?slow? formation of the disinfection byproducts (DBPs) that predominate in distribution systems. The speciation of Cl2O, Cl2, BrCl, Br2O, and BrOCl differs from that of HOCl/OCl- or HOBr/OBr-. Their existence could have profound implications on our understanding of the fundamental processes that govern the rates of DBP generation. For example, [Cl2O] will be proportional to [HOCl]2. To the extent that Cl transfer from Cl2O to an organic compound factors into the rate of DBP formation, the kinetics will not be first order in [HOCl] (and, hence, in [FAC] at constant pH). This calls into question the utility of ?apparent? rate coefficients and intrinsic second-order rate coefficients previously reported in the literature. A dependence on [Cl2O] implies that chlorination rates of compounds that themselves lack acid-base speciation should exhibit a (-2)nd order dependence on [H+] at pH above the pKa of HOCl. Finally, the existence of BrCl implies that rates of bromination will increase with [Cl-], and the high reactivity of BrOCl implies that rates of bromination will increase with [FAC] at constant [Br-]. These results could force reconsideration of water treatment practices: the PI?s calculations indicate that the chloride content of FeCl3 commonly added as a coagulant could increase chlorination rates more than tenfold.
The research team intends to examine the kinetics of reaction(s) of an array of organic compounds, with an emphasis on species hypothesized to play a role in the rate of ?slow? DBP generation. They will carefully model the influence of solution conditions on the rate of parent compound loss and reaction product formation, including important DBPs. The suite of target compounds will also include partially halogenated species whose further halogenation has been proposed to represent rate-limiting steps in DBP formation. Finally, undergraduate and high school researchers, working in collaboration with a PhD student, will examine the influence of solution conditions ? especially [FAC] and [Cl-] as a function of pH ? on the rate of DBP formation on chlorination (or bromination) of natural organic matter. The results could assist in formulating improved recommendations for strategies to reduce DBP generation, thereby protecting public health.
Beyond the advancement of scientific discovery, graduate and undergraduate training, and public health aspects of this work, the project will enable K-12 outreach activities, and will broaden the participation of underrepresented groups. Specifically, this project will allow the PI to offer research internships (summer plus ensuing academic year) to students from Baltimore Polytechnic Institute, Baltimore?s magnet science, math, and engineering public high school. Such interns will work closely with undergraduate and PhD student participants, fostering in all participants an appreciation of diverse learning perspectives. Finally, the PI will continue her practice of engaging 5th-7th graders in environmental research by mentoring the research projects required as part of the FIRST Lego League (FLL) annual robotics challenge. Recent projects have included experiments at Johns Hopkins University related to carbon sequestration and research on self-composting toilets.
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