| dc.contributor.author | Hammed, Ademola Monsur | |
| dc.description.abstract | Recovery and reuse of enzymes can reduce the high enzyme costs that are challenging for cellulosic biorefineries. Attaching enzymes to magnetic nanoparticles to make magnetic nanobiocatalysts (MNBCs) can facilitate enzyme recovery and reuse. One approach for MNBC synthesis is by attaching enzymes to flexible polymer molecules to form polymer-enzyme conjugates (PECs) which in turn can be attached to superparamagnetic iron-oxide nanoparticles (SPIONs). However, this approach can be complex and unscalable. The research objective is to develop a scalable process to produce effective, recoverable and reusable cellulolytic MNBCs.
PECs were produced and tested before incorporation into MNBCs in order to test efficacy and reusability. The effects of different biomass pretreatment methods, temperature, pH and solid loading on PEC efficacy were determined. Hydrolysis conditions affect PEC and free enzyme (FE) efficacy equally suggesting that attachment to the polymer did not interfere with substrate-enzyme interaction. PEC has higher efficacy than FE at higher substrate loading offering potential for processing more substrate per batch. The recovered PECs were effective for subsequent hydrolysis and reduced enzyme requirement to 40% of free enzyme needed in the first stage.
A tubular electrochemical system (TES), an electrochemical reactor containing electrolytes flowing through a cathode tube with an inner anode rod, was developed to overcome scalability and sustainability challenges of SPION synthesis. The effects of current density, electrolyte concentration, electrolyte feeding strategy, and flow rate on TES productivity and SPION characteristics were determined. TES productivity and SPION characteristics were both affected by the reaction conditions. Increasing electrolyte flow rate caused a decrease in average SPION size and size-distribution. The flow rate can be used to control SPION size distribution and shape. Gradual addition of more electrolyte resulted in 75% increase in SPION yield.
Silica coating of SPIONs improves SPION longevity and adsorption capacity. A single-step process for silica-coated SPION (Si-SPION) synthesis using TES was developed. The coating agent (Na2SiO3) concentration did not affect Si-SPION morphology, but increasing Na2SiO3 concentration reduces SPION productivity. The Si-SPIONs did not dissolve in an acidic environment for 48 h and were suitable support for MNBC synthesis. The MNBCs were recovered and reused four times. | en_US |
| dc.publisher | North Dakota State University | en_US |
| dc.rights | NDSU Policy 190.6.2 | |
| dc.title | Process Development for Effective, Recoverable and Reusable Magnetic Nanobiocatalysts for Biomass Hydrolysis | en_US |
| dc.type | Dissertation | en_US |
| dc.type | Video | en_US |
| dc.date.accessioned | 2022-06-07T19:05:34Z | |
| dc.date.available | 2022-06-07T19:05:34Z | |
| dc.date.issued | 2021 | |
| dc.identifier.uri | https://hdl.handle.net/10365/32701 | |
| dc.subject | biometric cellulosomes | en_US |
| dc.subject | enzyme immobilization | en_US |
| dc.subject | lignocellulose hydrolysis | en_US |
| dc.subject | membrane recovery | en_US |
| dc.subject | nanobiocatalyst | en_US |
| dc.subject | tubular reactor | en_US |
| dc.rights.uri | https://www.ndsu.edu/fileadmin/policy/190.pdf | |
| ndsu.degree | Doctor of Philosophy (PhD) | en_US |
| ndsu.college | Agriculture, Food Systems and Natural Resources | en_US |
| ndsu.college | Engineering | en_US |
| ndsu.department | Agricultural and Biosystems Engineering | en_US |
| ndsu.program | Agricultural and Biosystems Engineering | en_US |
| ndsu.advisor | Pryor, Scott | |
