title: Mercury reduction studies to facilitate the thermal decontamination of phosphor powder residues from spent fluorescent lamps.
abstract: This work investigates the thermal release of mercury from phosphor powder of spent fluorescent lamps. The treatment conditions and the ability of various reducing agents (primarily sodium borohydride) to lower the overall heating temperature required to improve the release of Hg have been evaluated. Hg species in samples were monitored in a thermal desorption atomic absorption spectrometer system, and total mercury was analyzed in a cold vapor atomic absorption spectrometer. Sodium borohydride was the best reducing agent among the ones studied. However, citric acid presented a high capacity to weaken mercury bonds with the matrix. When the sample was crushed with sodium borohydride for 40 min in a mass ratio of 10:1 (sample:reducing agent) and submitted to thermal treatment at 300 degrees C for 2 h, the concentration of mercury in a phosphor powder sample with 103 mg kg(-1) of mercury reached 6.6 mg kg(-1).
authors: Chemistry Department, Federal University of Minas Gerais (UFMG), Cidade Universitária 30.123-970 Belo Horizonte, MG, Brazil.
authors: Walter Alves
authors: WA
authors: Durão
authors: Camila Andreva
authors: CA
authors: de Castro
authors: Cláudia Carvalhinho
authors: CC
authors: Windmöller
mesh_terms: D001894:Borohydrides; D003247:Conservation of Natural Resources / Q000379:methods*; D003666:Decontamination / Q000379:methods*; D004350:Drug Residues / Q000032:analysis*; D004866:Equipment Contamination / Q000517:prevention & control*; D005453:Fluorescence; D006358:Hot Temperature; D007202:Indicators and Reagents; D008029:Lighting / Q000295:instrumentation*; D049408:Luminescent Agents / Q000032:analysis; D008628:Mercury / Q000032:analysis*; D010084:Oxidation-Reduction; D013054:Spectrophotometry, Atomic
chemical_list: D001894:Borohydrides; D007202:Indicators and Reagents; D049408:Luminescent Agents; C025364:sodium borohydride; D008628:Mercury