ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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Measurement and Variability of Crude Urease Enzyme for Enzyme Induced Carbonate Precipitation (EICP) Applications

Description
Two challenges in the implementation of enzyme induced carbonate precipitation(EICP) are the cost of enzyme and the variability of the enzyme. Urease enzyme costs can be lowered drastically with the use of crude extract from plant materials, but experience has shown variability in the source of the crude urease enzyme, the crude urease…

Two challenges in the implementation of enzyme induced carbonate precipitation(EICP) are the cost of enzyme and the variability of the enzyme. Urease enzyme costs can be lowered drastically with the use of crude extract from plant materials, but experience has shown variability in the source of the crude urease enzyme, the crude urease enzyme extraction methods, and the concentration of the EICP solution can cause significant variability in the efficacy of the EICP solution. This thesis examines the variability in the efficacy of crude enzyme derived from jack beans (Canavalia ensiformis) and sword beans (Canavalia gladiata), two of the most commonly used sources of urease enzyme for EICP. The sources of variability investigated herein include the crude extraction method (including the effect of the bean husks on extraction) and different chemical constituent concentrations. These effects were assessed using enzyme activity measurements and precipitation efficiency tests. The activity tests were performed via spectrophotometry using Nessler's reagent. The precipitation tests looked at the influence of chemical constituent concentrations of 0.67 M calcium chloride and 1 M urea with non-fat dry milk in the EICP solutions and a higher concentration solution with chemical constituent concentrations of 2 M for both calcium chloride and urea with non-fat dry milk. The high concentration solution was selected based on preliminary testing results to maximize carbonate precipitation in one cycle of treatment. Significant sources of a decline in activity (and increase in variation) of the crude urease enzyme were found in extraction from sword beans with husks, high chemical constituent concentrations, and juicing instead of cheesecloth filtration. This thesis also examines the accuracy of commonly used correlation factors for converting electrical conductivity to urease enzyme activity. Crude jack bean and sword bean urease enzyme activity measurement via electrical conductivity was found to have a correlation coefficient that differed from the previously reported correlation when compared to activity measured via the more accurate spectrophotometry using Nessler’s reagent measurements.
ContributorsPearson, Rayanna (Author) / Kavazanjian, Edward (Thesis advisor) / Khodadadi Tirkolaei, Hamed (Committee member) / Salifu, Emmanuel (Committee member) / Arizona State University (Publisher)
Created2022
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The Properties and Longevity of Crude Urease Extract for Biocementation

Description
Urease, an amidohydrolase, is an essential ingredient in the emerging engineering technique of biocementation. When free urease enzyme is used this carbonate precipitation process is often referred to as enzyme induced carbonate precipitation (EICP). To date, most engineering applications of EICP have used commercially available powdered urease. However, the high…

Urease, an amidohydrolase, is an essential ingredient in the emerging engineering technique of biocementation. When free urease enzyme is used this carbonate precipitation process is often referred to as enzyme induced carbonate precipitation (EICP). To date, most engineering applications of EICP have used commercially available powdered urease. However, the high cost of commercially available urease is a major barrier to adoption of engineering applications of EICP in practice. The objective of this dissertation was to develop a simple and inexpensive enzyme production technique using agricultural resources. The specific objectives of this dissertation were (i) to develop a simple extraction process to obtain urease from common agricultural resources and identify a preferred agricultural resource for further study, (ii) to reduce the cost of enzyme production by eliminating the use of a buffer, centrifugation, and dehusking of the beans during the extraction process, (iii) investigate the stability of the extracted enzyme both in solution and after reduction to a powder by lyophilization (freeze-drying), and (iv) to study the kinetics of the extracted enzyme. The results presented in this dissertation confirmed that inexpensive crude extracts of urease from agricultural products, including jack beans, soybeans, and watermelon seeds, are effective at catalyzing urea hydrolysis for carbonate precipitation. Based upon unit yield, jack beans were identified as the preferred agricultural resource for urease extraction. Results also showed that the jack bean extract retained its activity even after replacing the buffer with tap water and eliminating acetone fractionation, centrifugation, and dehusking. It was also found that the lyophilized crude extract maintained its activity during storage for at least one year and more effectively than either the crude extract solution or rehydrated commercial urease. The kinetics of the extracted enzyme was studied to gain greater insight into the optimum concentration of urea in engineering applications of EICP. Results showed higher values for the half-saturation coefficient of the crude extract compared to the commercial enzymes. The results presented in this dissertation demonstrate the potential for a significant reduction in the cost of applying EICP in engineering practice by mass production of urease enzyme via a simple extraction process.
ContributorsJavadi, Neda (Author) / Kavazanjian, Edward (Thesis advisor) / Khodadadi Tirkolaei, Hamed (Committee member) / Hamadan, Naser (Committee member) / Delgado, Anca (Committee member) / Arizona State University (Publisher)
Created2021