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Frontiers of Environmental Science & Engineering >> 2012, Volume 6, Issue 6 doi: 10.1007/s11783-012-0434-7

Abiotic association of phthalic acid esters with humic acid of a sludge landfill

1. State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; 2. The Academy of Science of Shandong Province, Jinan 250013, China; 3. State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210093, China

Available online: 2012-12-01

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Abstract

The abiotic association between phthalic acid esters (PAEs) and humic substances (HS) in sludge landfill plays an important role in the fate and stability of PAEs. An equilibrium dialysis combined with C-labeling was used to study the abiotic association of two abundant PAEs (diethyl phthalate and di- -butyl phthalate) with humic acid (HA) isolated from a sludge landfill with different stabilization times and different molecular weights. Elemental analysis and Fourier Transform Infrared Spectrophotometer (FTIR) suggested that high value of HA was related to the high aromatic content and large molecular weight of HA. The results indicated that the association strength of PAEs with HA depended on both the properties of the PAEs and the characteristics of HA. The values of the association were strongly dependent on solution pH, and decreased dramatically as the pH was increased from 3.0 to 9.0. The results suggested that non-specific hydrophobic interaction between PAEs and HA was the main contributor to the association of the PAEs with HA. The interactive hydrogen-bonds between the HA and the PAEs molecules may also be involved in the association.

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