Chlorination of natural organic matter: kinetics of chlorination and of THM formation

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阅读量：

125

作者：

H Gallard，UV Gunten

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摘要：

The kinetics of the formation of trihalomethanes (THMs) and of chlorine consumption for the chlorination of natural organic matter with an excess of chlorine (50 μM > [Cl 2] o>210 μM) was investigated. THM precursors could be divided into a fast and a slowly reacting fraction. Long term chlorine demand and the formation of THM could be described by second order kinetics. Rate constants were between 0.01 and 0.03 M 1 s 1 in the pH range 7–9 for surface waters and humic materials extracted from surface waters. A groundwater gave a higher rate constant of 0.124 M 1 s 1. Resorcinol-type structures were tested with respect to kinetics and yield of THM formation. They could possibly be responsible for the fast reacting THM precursors, which represent 15–30% of the THM precursors of natural waters. Additional classes of compounds that might contribute to the initial THM formation include readily enolizable compounds such as β-diketones and β-ketoacids. Experiments with phenol showed that slowly reacting THM precursors may consist of phenolic compounds. The influence of pretreatments (UV/visible irradiation, ozone and chlorine dioxide) on chlorine demand and THM formation from NOM was also studied: UV/visible irradiation does not alter THM formation but leads to a higher chlorine demand. Preoxidation with ozone leads to a lower THM formation with an unaltered chlorine demand and preoxidation with chlorine dioxide reduces THM formation and the chlorine demand.

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关键词：

Chlorination Natural organic matter THM precursors Chlorine demand Kinetic model

DOI：

10.1016/S0043-1354(01)00187-7

被引量：

561

年份：

2002