Graduation Year


Document Type




Degree Name

MS in Chemical Engineering (M.S.C.H.)

Degree Granting Department

Chemical Engineering

Major Professor

Venkat Bhethananbotla, Ph.D.

Co-Major Professor

Scott Campbell, Ph.D.

Committee Member

John Kuhn, Ph.D.


BTEX, Flory HUggins, Modified Flory Huggins, QCM


The environment around us has a great impact on human health. A polluted environment can adversely impact human health and cause diseases like cancer, skin diseases, breathing problems and many more and hence altering the quality of life. Hence it is very important to develop sensors that can efficiently detect these harmful substances from environment. Volatile organic compounds (VOCs) are carbon-based chemical substances that are volatile even at ambient temperature and pressure conditions which enter the atmosphere through industrial processes, building materials, etc.

Acoustic wave devices can detect very low concentrations (ppm, ppb) of organic compounds in the environment. A thin layer of chemically selective material is coated on the surface of the acoustic wave device for the collection of analyte molecules by sorption. The amount of sorption depends upon the physical and chemical properties of the film (typically a polymer) coated on the QCM.

Though the existing technology relates a change in frequency of the sensing element to the total amount of mass sorbed in the coated film. However, if the sorption is from a mixture, the masses of individual analytes cannot be determined from these measurements. The purpose of this work is to propose and test an algorithm for determining the weight fractions of individual analytes in the film from a knowledge of the total weight fraction of sorbed species at equilibrium. The algorithm is an extension of Barker’s method, which is routinely applied to vapor-liquid equilibrium of small molecules to determine concentrations (in this case, vapor-phase mole fractions) that were not directly measured.