Kinetic and mechanistic examinations of abiotic reductive transformation of halogenated methanes with bimeticallic nano-scale particles

• Main Author: Feng, Jing
• Other Authors: Lim, Teik Thye
• Format: Theses and Dissertations
• Language: English
• Published: 2008
• Subjects: DRNTU::Engineering::Environmental engineering::Water treatment
• Online Access: https://hdl.handle.net/10356/12228
• Institution: Nanyang Technological University

In this study, chlorinated and brominated methanes were chosen as the target compounds. Nano-scale Fe, Ni/Fe and Pd/Fe particles were synthesized by the wet chemical reduction method with sodium borohydride as the reductant. Batch reduction experiments were conducted to investigate reductive dehalogenation of the halogenated methanes with the different types of nano-scale particles. The reduction kinetics, pathways and the mechanisms of dehalogenation reactions with the nano-scale bimetallic particles are also examined. Both kinetic and mechanistic examinations are considered in establishing the major and minor transformation pathways. The reduction of the halogenated methanes to end products could follow both parallel and sequential pathways. The main non-halogenated end product was found to be methane. Based on the statistic analysis, two-parameter regression relationships were also established for the kinetics prediction for the dehalogenation reactions with the nano-scale particles. Meanwhile, the presence of amphiphiles (such as natural organic matters and surfactant) and an increase of pH value would inhibit the reduction rate of the halogenated methanes.