Page 580 - Materials Chemistry, Second Edition

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Universal Wastes 551

FIGURE 18.3 Form printed at the state level to encourage pesticide recycling (Ohio State Pesticide Education
Program). Reproduced with kind permission of the Ohio Department of Agriculture.

18.4.6 UNIVERSAL WASTE LAMPS
Fluorescent lamps work by passing an arc of electricity through mercury vapor in the lamp. The
charged mercury atoms emit ultraviolet (UV) light, which is absorbed by a phosphor powder coat-
ing on the inside of the cylindrical glass lamp. The energized phosphors subsequently emit a white
light. To generate the mercury vapor a small amount of elemental (liquid) mercury is added to each
lamp during manufacture. The mercury instantly vaporizes when the lamp is turned on and it recon-
denses when the lamp is turned off. Most types of high-intensity discharge lamps, i.e., mercury
vapor, metal halide, and high-pressure sodium, also contain mercury (EBN, 1997).