Adi Ben-David

Dr. Meyer L. Rosoff and Rev. Benzion Bauer Prize for Excellence in Water Research, 2005.

Unit of Environmental Engineering and Department of Desalination and Water Treatment,
Zuckerberg Institute for Water Research,
Jacob Blaustein Institutes for Desert Research,
Ben-Gurion University of the Negev

My name is Adi Ben-David. I was born in 1976 in Ramat-Gan, Israel, and grew up in Moshav Roi in the Jordan Valley. When I was a teenager my family and I moved to Netanya. During my childhood I was very interested in hiking and nature. After high school I joined the army and served in the intelligence corps. My job was to help soldiers with domestic or financial problems. As soon as I finished my army service, I saved some money and traveled for half a year to South America. In 1998 I enrolled at Ben-Gurion University for a bachelor's degree in geology. During my first degree I worked as a laboratory assistant in a water laboratory at BGU. I also taught geography and English to pupils with learning difficulties in the "Newe Midbar" school in Kibbutz Hatzerim, and later to students after school as part of the Branco-Weiss project. In 2002 I began studying for a master's degree at the Department of Environmental Engineering, together with the Department of Desalination and Water Treatment Research at BGU. As part of my research, I practice desalination of water solutes containing organic compounds through reverse-osmosis and nano-filtration membranes. I hope to continue my studies onto a Ph.D. on the same topic.

Description of research:

Interactions of Organic Compounds with Reverse Osmosis (RO) and Nanofiltration (NF) Membranes with Correlation to Rejection

Supervisors: Dr. Yoram Oren and Dr. Slava Freger

RO and NF membranes are used for water desalination, i.e. the removal of salts from different sources of water such as municipal and industrial wastes, and also to treat drinking water. Recently, these membranes have begun to be used for removal of organic components from water sources. These components build up as a result of permeation of wastes, fertilizers, pesticides, herbicides and other anthropogenic pollutants.
RO and NF membranes are capable of good rejection of small salts. However, many small organic molecules can easily pass through them. The rejection mechanism cannot be explained only by the size of the molecule, since there are also effects of some other thermodynamic factors, such as hydrophilic and hydrophobic properties, charge, polarity and partition coefficient.
The purpose of this research is to evaluate the contribution of the size of a molecule in relation to the partition coefficient as part of the rejection mechanism in the active layer of the membrane (the skin). The measurements use the ATR-FTIR method, where the membrane's active layer is separated from the supporting polysulfone layers which are being dissolved by organic solvents. The active layer is attached to an ATR crystal and the intensity of absorption of organic compounds to the active layer is then measured in different concentrations. The experiment tested organic substances from several groups (alcohols, aniline, hydroquinone, urea), which have low molecular weights but are still bigger than salt molecules. For each of the substances, its rejection by the membrane was tested in comparison to the rejection of salts by the same membrane.
Each of the above organic compounds was tested several times for its specific absorption peaks, with and without the active layer in various different concentrations. For every substance, a specific absorption isotherm was obtained, from which the partition coefficient, K, was calculated. The results indicate that the size of the molecule has a greater effect than the partition coefficient in the rejection mechanism. However, there is still a lot of research needed to attain a more accurate estimation of both factors and their relative contributions to the rejection mechanism.