T8 PM Measurement/ Estimation of Environmentally Relevant Physico-Chemical Properties
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 337-338

(ROT-1117-726142) Beyond K_ow and vapor pressure.

Roth, C.^{1, 2, 3}, Goss, K.-U.^{2, 3}, Niederer, C.^{2, 3}, Arp, H.-P.^{2, 3}, Schwarzenbach, R.^{2, 3}, ¹ Harvard University, Boston, MA, USA² Swiss Federal Institute for Environmental Science and Technology (EAWAG), Duebendorf, Switzerland³ Swiss Federal Institute of Technology (ETHZ), Zurich, Switzerland

ABSTRACT- Sorption of pollutants in various phase systems plays a key role for the transport and transformation in the environment. Many sorption processes between two specific phases have been examined, but only for a few compound classes. Results have often been evaluated with one-parameter linear free energy relationships (LFER) based on one compound descriptor, usually vapor pressure, water solubility, the octanol-water or the octanol-air partitioning coefficient. For many compounds, the experimental determination of these descriptors is error-prone and gives highly variable results. These LFERs also remain limited to the one compound class for which they were developed. Poly-parameter LFERs can overcome these shortcomings because they specifically consider the various types of interactions that govern each partition process: i.e. van-der-Waals and electron-donor/acceptor interactions. A comparison of both approaches shows that the poly-parameter LFERs have three important advantages: 1) for many compounds the required descriptors can be determined easier and with better precision, 2) the pp-LFERs successfully describe sorption for polar and non-polar compound classes alike and extrapolation to compound classes that have not been part of the calibration data set is much more reliable, 3) provides a method to describe and understand the variability of sorption properties in various compartments. The talk will illustrate these points with a large amount of experimental data, including a range of environmental compartments such as mineral and salt surfaces as well as various organic sorbents.

Key words: organic vapour partitioning, inverse gas chromatography, sorption model