Formaldehyde formation from tertiary amine derivatives during chlorination.

Area of Science:

• Environmental Chemistry
• Water Quality Analysis
• Organic Contaminant Formation

Background:

• A 2012 water contamination incident in the Tone River Basin affected 870,000 people due to formaldehyde precursor discharge.
• Hexamethylenetetramine (HMT), a tertiary amine, was identified as a precursor leading to formaldehyde formation during water purification.
• Tertiary amines are known precursors to aldehydes upon chlorination, necessitating further investigation into potential sources.

Purpose of the Study:

• To investigate formaldehyde (FA) formation from 29 amine derivatives during chlorination.
• To identify potential causes of the 2012 Tone River Basin water quality accident.
• To quantify FA formation yields from various amine structures, including autolysis and chlorination of autolysis products.

Main Methods:

• Investigated FA formation from 29 amine derivatives under chlorination conditions.
• Quantified FA molar formation yields and FA weight formation yields.
• Assessed FA formation from autolysis and chlorination of autolysis products.

Main Results:

• Hexamethylenetetramine (HMT) exhibited the highest FA molar formation yield (440%) after 24h chlorination.
• Tertiary amines and hydrazines with N-methyl groups were potent FA precursors, with molar yields per N-methyl group ranging from 25% to 45%.
• HMT showed an exceptionally high FA weight formation yield (95 wt.%), with some tertiary amines and hydrazines exceeding 20 wt.%.

Conclusions:

• HMT and specific N-methylated tertiary amines and hydrazines are significant formaldehyde precursors in water treatment.
• The findings highlight the risk of industrial effluents containing these compounds leading to water quality issues.
• Understanding these precursor-product relationships is crucial for preventing future water contamination events.