|Ph.D Student||Segal Yael|
|Subject||Characterization of Organic Compounds and Fouling on|
Separation Membranes via Spectroscopy and
|Department||Department of Civil and Environmental Engineering||Supervisors||Professor Raphael Linker|
|Professor Emeritus Carlos Dosoretz|
|Full Thesis text|
The aim of this study was to develop a methodology for quantitative chemical analysis of membrane organic fouling using spectroscopy methods and chemometric analyses. Accordingly the study was divided into two stages. The first stage focused on quantitative estimation of organic compounds in a solution and consisted of three parts. The objective of the first part was to determine whether UV-Vis absorbance and/or EEM fluorescence could be used for quantitative determination of humic acid (HA) and bovine serum albumin (BSA) in the presence of alginic acid (AA). These compounds simulate natural organic matter (NOM), protein, and polysaccharide respectively. The objective of the second part was to determine the most appropriate chemometric methods for each spectroscopic technique. The objective of the third part was to determine how much could be gained by using advanced chemometric analysis rather than commonly-used single-band analysis methods. The second stage of this study focused on direct estimation of organic fouling of ultrafiltration (UF) membranes by photoacoustic spectroscopy. Solutions of BSA and AA were filtered using two UF membranes: Polyacrylonitrile 200 kDa and Polysulfone 30 kDa. The concentrations of BSA in the solutions were estimated by UV-Vis absorbance and a regression model obtained in Stage 1, and by total nitrogen (TN) measurements. The fouling was calculated by a simple mass balance and regression models between the membranes spectra and the fouling were obtained.
The main conclusion of the first stage of this work was that HA and BSA concentration can be accurately estimated using simple UV-visible absorbance (validation errors of 5% and 6% respectively). In addition, HA concentration can be accurately estimated using EEM fluorescence measurement, while BSA can be estimated only when HA is not present in the solution (validation errors of 5% and 6% respectively).
The fouling estimated using the mass balance correlated well with the photoacoustic measurement of the membranes (validation error of 10%). The total fouling of the PS membrane by BSA was much higher than the fouling of PAN membrane. The irreversible fouling of the PAN membrane was higher than the irreversible fouling of the PS membrane. The presence of AA created an additional reversible fouling of BSA on the PAN membrane.
The combination of spectroscopy methods with chemometric analysis proved to be very suitable for direct quantitative analysis of both solution composition and membrane fouling.