Researchers investigated how to remove a type of harmful chemical called nonachloro biphenyl using zero-valent iron in hot, pressurized water. They found that higher temperatures make the process faster. By using a special technique to analyze the chemicals, they saw that the nonachloro biphenyl changed into less harmful forms over time. After 90 minutes at 250°C and 100 atm, the amount of the harmful chemical decreased by two-thirds. The process followed a predictable pattern, showing that it can be controlled and understood.