Physicochemical Characteristics of Humic Acid Aggregates Formed in Zero-Valent Iron Systems
(0) The influence of natural organic matter (NOM) on contaminant removal by Fe0 systems has been of increasing concern. Our recent studies have shown that, in addition to direct sorption on the Fe0 surfaces, humic acid complexation with dissolved iron released from Fe0 corrosion results in the formation of colloids (<0.1 m) and aggregates (>0.45 m) in solution depending on the type of background cations. This study investigated the physicochemical characteristics of humic acid in Fe0 systems, which helps advance our understanding on the application of Fe0 permeable reactive barriers (PRBs) in the vicinity of NOM-rich shallow aquifers. Fourier transform infrared spectroscopic analysis of the newly formed humic acid aggregates indicated the presence of innersphere complexation involving different oxygen-containing functional groups. The results of XAD-8 resin fractionation showed that both hydrophobic acid and hydrophobic neutral fractions were removed from solution, thus hydrophobic interactions also probably contributed to humic acid aggregation. High-pressure size-exclusion chromatograph revealed that average molecular weights of the dissolved fraction of humic acid increased with reaction time and that aggregation occurred across a wide range of molecular weight fractions. The presence of these humic acid aggregates provided additional hydrophobic domains for partitioning of trichloroethylene in solution, although the effects could not be quantitatively correlated to the physicochemical properties of various types of humic acids.
humic acid iron-humate aggregates permeable reactive barriers zero-valent iron.
Daniel C W.TSANG Irene M.C.LO Nigel J D.GRAHAM
Department of Civil and Natural Resources Engineering,University of Canterbury,Christchurch,New Zeal Department of Civil and Environmental Engineering,Hong Kong University of Science and Technology,Hon Department of Civil and Environmental Engineering,Imperial College London,UK
国际会议
2009 International Symposium on Environmental Science and Technology(2009环境科学与技术国际会议)
上海
英文
313-319
2009-06-02（万方平台首次上网日期，不代表论文的发表时间）