Fate of Malathion on Copper and Iron Piping Within a Water Distribution System.

摘要

Thermogravimetry, the study of mass loss as a function of temperature, has been used for oxidation, decomposition, and solid-state studies. This research used a thermogravimetric analyzer (TGA) coupled with Fourier transform infrared (FT-IR) spectroscopy in the study of copper and iron specimens exposed to malathion. Exposure to the malathion solution created a visible silver coating on copper and graphite-flake particles on iron specimens. Thermogravimetric mass loss curves revealed linear and nonlinear decomposition stages associated with mass loss reactions. Copper specimens exposed to malathion exhibited lower activation energy (Ea) values (2.28 to 4.40 kJ mol-1) than for copper specimens exposed to deionized water (10.42 and 12.87 kJ mol-1). Iron specimens exposed to malathion show lower Ea values (1.54 and 1.28 kJ mol-1) than for iron specimens exposed to deionized water (3.30 and 6.40 kJ mol-1). These results suggest association between malathion and lowered activation energies across all sample specimens. The FT-IR results indicate that specimens exposed to malathion may produce hydrogen sulfide. This research is the first to the author's knowledge to use TGA and FT-IR to test malathion adherence to metal surfaces. These results have application in water distribution piping analysis.