A Nano-Selenium Reactive Barrier Approach for Managing Mercury over the Life-Cycle of Compact Fluorescent Lamps
ABSTRACT Compact fluorescent lamps contain small quantities of mercury, release of which can lead to human exposures of potential concern in special cases involving multiple lamps, confined spaces, or young children. The exposure scenarios typically involve solid lamp debris that slowly releases elemental mercury vapor to indoor spaces. Here we propose and demonstrate a reactive barrier approach for the suppression of that mercury release, and demonstrate the concept using uncoated amorphous nanoselenium as the reactive component. Multilayer structures containing an impregnated reactive layer and a mercury vapor barrier are fabricated, characterized, and evaluated in three exposure prevention scenarios: carpeted break sites, disposal/recycling bags, and boxes as used for retail sales, shipping, and collection. The reactive barriers achieve significant suppression of mercury release to indoor spaces in each of thethree scenarios. The nanoselenium barriers also exhibit a unique indicator function that can reveal the location of Hg contamination by local reaction-induced change in optical properties. The article also presents results on equilibrium Hg vapor pressure above lamp debris, mathematical modeling of reaction and transport processes within reactive barriers, and landfill stability of nanoselenium and its reaction products.
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- "TCLP - leachable and 1 . 5% versus 0 . 08% SPLP - leachable for the used and new respectively . This is in agreement with previous studies with the explanation of gradual transformation of el - emental Hg to divalent soluble forms through oxidative re - action with phosphor ( Dang et al . , 1999 ; Raposo et al . , 2003 ; Lee et al . , 2009 ) ."
ABSTRACT: This article presents an original study on the releases of mercury (Hg) from broken compact fluorescent lamps (CFLs) under various environmental conditions. Leaching of Hg in liquids was examined using the U.S. En-vironmental Protection Agency's standard procedures Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure. Emission of Hg in vapor phase from broken CFLs was detected using an emission monitoring system. CFLs of eight different brands and four different wattages were tested. Results show that Hg contents in CFLs varied significantly with brand. Total amount of Hg contained in each CFL ranged from 0.1 to 3.6 mg, and only < 4% of the Hg was TCLP-leachable. Hg concentrations in TCLP extracts of all the new CFLs tested were lower than the regulatory level of 0.2 mg/L and thus the discarded CFLs do not fall into the hazardous waste category. Hg concentrations in Synthetic Precipitation Leaching Procedure extracts were lower than those in the TCLP extracts. Hg vapor emission test revealed that the CFLs continuously release Hg vapor once broken and the release can last over 10 weeks. Total amount of Hg vapor released from a broken CFL can exceeds 1.0 mg, which can cause Hg level in a regular room to exceed the safe human exposure limit under poor ventilation conditions. Results provide useful implications in guiding the handling and treatment of CFLs during and after use.Environmental Engineering Science 10/2011; 28(10). DOI:10.1089/ees.2011.0027 · 0.99 Impact Factor
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ABSTRACT: The ν4 band of trans-d2-ethylene (trans-C2H2D2) has been recorded with an unapodized resolution of 0.0063 cm−1 in the frequency range of 870–1100 cm−1 by Fourier transform infrared (FTIR) spectroscopy using a Bruker IFS 125R spectrometer. In the analysis of the band, no indications for perturbation were found. By fitting a total of 2121 infrared transitions of ν4 with a standard deviation of 0.00058 cm−1 using a Watson’s A-reduced Hamiltonian in the Ir representation, a set of accurate rovibrational constants up to four sextic terms for the v4 = 1 state was derived. The ν4 band is a C type with a band centre at 987.753336 ± 0.000039 cm−1.Chemical Physics Letters 08/2005; 411(1-3):43-45. DOI:10.1016/j.cplett.2005.05.112 · 1.90 Impact Factor
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ABSTRACT: Individualized medicine is the healthcare strategy that rebukes the idiomatic dogma of 'losing sight of the forest for the trees'. We are entering a new era of healthcare where it is no longer acceptable to develop and market a drug that is effective for only 80% of the patient population. The emergence of "-omic" technologies (e.g. genomics, transcriptomics, proteomics, metabolomics) and advances in systems biology are magnifying the deficiencies of standardized therapy, which often provide little treatment latitude for accommodating patient physiologic idiosyncrasies. A personalized approach to medicine is not a novel concept. Ever since the scientific community began unraveling the mysteries of the genome, the promise of discarding generic treatment regimens in favor of patient-specific therapies became more feasible and realistic. One of the major scientific impediments of this movement towards personalized medicine has been the need for technological enablement. Nanotechnology is projected to play a critical role in patient-specific therapy; however, this transition will depend heavily upon the evolutionary development of a systems biology approach to clinical medicine based upon "-omic" technology analysis and integration. This manuscript provides a forward looking assessment of the promise of nanomedicine as it pertains to individualized medicine and establishes a technology "snapshot" of the current state of nano-based products over a vast array of clinical indications and range of patient specificity. Other issues such as market driven hurdles and regulatory compliance reform are anticipated to "self-correct" in accordance to scientific advancement and healthcare demand. These peripheral, non-scientific concerns are not addressed at length in this manuscript; however they do exist, and their impact to the paradigm shifting healthcare transformation towards individualized medicine will be critical for its success.Pharmacological Research 08/2010; 62(2):57-89. DOI:10.1016/j.phrs.2009.12.011 · 4.41 Impact Factor