Senior Honors Projects, 2010-current

Date of Award

Spring 2015

Document Type

Dissertation/Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Chemistry and Biochemistry

Advisor(s)

Yanjie Zhang

Abstract

Hofmeister series is a set of ions in order of their abilities to affect physical properties in aqueous solutions. Franz Hofmeister was the first to discover the specific ion effects on protein solubility in aqueous solutions. Although the Hofmeister phenomena are general, their mechanisms are still not fully understood. Herein, we use optical tensiometry by a pendant drop method to study the Hofmeister anion effects on the surface tension of water. It has been observed that the surface tension of water increases linearly as the salt concentrations increase. The effects of salts follow a specific trend with respect to the surface tension increments: SO42- > CO32- > H2PO4- > F- > Cl- > Br- > I- >NO3- > ClO4- > SCN-. Using the same method, the effect of solution pH and amino acids ions on the surface tension of different amino acid solutions is also being investigated. So far the surface tension measurements of glycine, L-alanine and L-serine suggest that the surface tension increases due to the abundance of ionic species comparing to the neutral species and the hydrophobic chains. These studies will provide us with some valuable data that would help further the understanding of the behaviors of salts and amino acids at the air/water interface.

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