Date of Award


Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)



First Advisor

Jason J. Evans

Second Advisor

Michelle Foster

Third Advisor

Marianna Torok


Anionic surfactants, such as linear alkyl benzene sulfonate (LAS) can inhibit enzyme activity in detergent formulations. The addition of a nonionic surfactant, such as an alcohol ethoxylate (AEO), can prevent the loss of enzyme activity caused by the LAS. This research was performed to assess if these general observations hold true in the specific case of Mannaway® mannanase detergent enzyme in the presence of LAS and Neodol 25-7® an ethoxylated alcohol. This study evaluates the hypothesis that free LAS, i.e. LAS not participating in an assembled micelle, causes the decreased enzyme activity and that presence of AEO catalyzes the formation of mixed LAS:AEO micelles, reducing the concentration of free LAS in solution and its adverse effect on mannanase activity. The effect of the formation of LAS:AEO mixed micelles on the enzymatic activity of mannanase and the concentration of free LAS in solutions were studied with a combination of tensiometric, potentiometric and enzymatic assays to provide experimental evidence of the link between mixed surfactant micelle formation, reduced free LAS concentration and mannanase activity. Results indicate that the formation of mixed micelles does cause a decrease of free LAS which allows for normal mannanase activity in the formulated mixture. This study proposes an equilibrium based model to calculate the concentration of free LAS activity in a mixed surfactant LAS:AEO solution and to predict the extent of an adverse effect of free LAS to mannanase activity.


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