Vreugdenhil, Andrew J

The oil sands industry is producing large volumes of tailings waste reaching 2 billion cubic meters by 2034 In this study, the industrial standard flocculant, high molecular weight PAM, was grafted from the surface of activated carbon (AC). This material was designed to increase the flocculant's hydrophobicity and density. Different molecular weight PAM was grafted from AC with different AC contents and particle sizes (AC-PAMs). The AC-PAMs were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). The AC-PAMs achieved molecular weights 107 – 5,600 kg/mol and AC content of 0.2 – 5.8% on <0.1 and 0.1 – 0.5 mm AC particle diameters. AC-PAM achieved higher solids contents up to 51 wt% using AC-PAM with 5.1 wt% AC due to the grafting from a hydrophobic AC core. To summarize, our work shows the successful grafting of PAM from AC and its potential as a flocculant for mature fine tailings.

Author Keywords: activate carbon, atom transfer radical polymization, flocculation, grafting-from, polyacrylamide, surface-initiated polymerization

N-Heterocyclic Carbenes (NHCs) have significantly impacted organometallic chemistry as ligands in transition metal catalysis, offering strong electron-donating properties and high bond dissociation energies. However, their structural versatility is limited by the scarcity of commercial precursors and challenging modification procedures. Furthermore, we have investigated its coordination to transition metals; copper, silver, and palladium. We further demonstrate the effects of its steric parameters by utilizing the Suzuki-Miyaura cross-coupling of aryl chlorides using [(RO-NHC)Pd(allyl)Cl] as precatalysts. This study demonstrates increased catalyst activity with bulkier ligands in Suzuki-Miyaura cross-coupling reactions. We also present simplified procedures for copper NHC complexes using triethylamine with no requirements for special equipment and techniques. Preliminary investigations towards a more economical approach to measuring the electron donating abilities of NHCs were conducted using CuI and AgI cyanide complexes as probes. The outcomes of this research may contribute to the growing research in the applications of NHCs as ligands in catalysis.

Author Keywords: Catalysis, Ligand synthesis, N-Heterocyclic carbenes, Organic Chemistry, Organometallic Chemistry, Transition metal catalysis

Innovative strategies to manage copious waste streams by upcycling feedstocks to valorized products which are then used in environmental remediation applications is an attractive circular economy model. This thesis explores this approach using waste wood generated from the milling of Chlorocardium rodiei (greenheart), a tropical hardwood species abundant in Guyana. We evaluate the thermochemical conversion of this feedstock, using phosphoric acid as the activant, to super activated carbons with surface areas of more than 2200 m2/g. Owing to the presence of surface heteroatoms, these adsorbents are amenable to further surface modifications including base-treatment, O-functionalization and N-functionalization. Using a facile oxidation procedure and shrimp waste-based dopants, we increase oxygen and nitrogen content by 8-fold and 5-fold respectively. These increases are realized without catastrophic loss of surface area and porosity as generally occurs with many reported functionalization approaches. Functionalized materials demonstrated efficient removal of both metal ions and the chlorinated herbicides 2,4-dichlorophenoxy acetic acid and paraquat. Pristine and base-washed ACs removed more than 90% of iron, aluminum and manganese from natural pit-lake waters. O-functionalized adsorbents also showed excellent removal efficiencies for aluminum and lead but only removed moderate amounts of manganese. Nitrogen-enriched composites fabricated with the addition of commercial chitosan removed 67% 2,4-D and 89% paraquat from model solutions at environmentally relevant concentrations of 4 ppm and 40 ppm respectively. Their versatility is further demonstrated in their ability to remove both herbicides from binary mixtures albeit to different extents. Shrimp chitin-based composites were most effective at removing 2,4-D from model solutions with a maximum adsorption capacity of 101 mg/g. Both surface area and surface nitrogen had strong influences on the adsorption capacity of adsorbents. Mechanistically, physisorption interactions predominate the synergistic or antagonistic interaction between N-functionalized composites and herbicide species. These green adsorbent materials, fabricated from sustainable biopolymers, are promising candidates for diverse environmental remediation applications.

Author Keywords: adsorption, Environmental remediation, N-functionalization, O-functionalization, tropical hardwood waste, waste valorization

This thesis presents the design, synthesis, and evaluation of activated carbon polyacrylamide (AC-PAM) composites for oil sands tailings remediation, integrating flocculation and adsorption functionalities. Surface-initiated atom transfer radical polymerization (SI-ATRP) was employed to graft high molecular weight PAM brushes onto petroleum coke and commercial activated carbon, with SARA-ATRP yielding the most uniform architecture (Mn ≈ 5.2 kg/mol, Đ ≈ 1.25). Flocculation tests using mature fine tailings (MFT) revealed superior sedimentation and dewatering with SARA-ATRP composites, outperforming conventional PAM at lower dosages. Adsorption studies using benzoic acid and model naphthenic acids showed selective uptake governed by polymer brush morphology and molecular structure, with Dubinin–Radushkevich isotherms best capturing the behavior of ARGET-ATRP composites. Post-flocculation assays confirmed reduced metal and polymer contamination, validating dual-function efficacy. These findings underscore petcoke's viability as a sustainable substrate and highlight controlled polymerization as a critical driver for tuning composite performance in industrial water treatment.

Author Keywords: Activated Carbon, Adsorption, Atom Transfer Radical Polymerization, Dubinin–Radushkevich, Isotherm, Polyacrylamide

The generation of polymer brushes by surface-initiated polymerization techniques has become a powerful tool for the creation of hybrid materials. Governed by the type and amount of polymer used in the modification, the chemical and physical properties of a surface can be tailored by polymer grafting. In this study, a commonly used polymer flocculant, polyacrylamide (PAM), was grafted onto the surface of activated carbon (AC). This hybrid material was designed with the intent of combining the functionalities of both the activated carbon and the polymer flocculant, potentially acting in a synergistic manner. The PAM grafted AC (AC-PAM) was examined as a flocculant in the treatment of mature fine tailings (MFT). AC-PAM was synthesized by surface-initiated activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). This was accomplished by pre-functionalizing the surface of activated carbon by oxidation, followed by the attachment of an ATRP initiator. From this surface, SI-AGET ATRP of acrylamide monomers was performed. The resulting AC-PAM was characterized by FTIR, XPS, TGA, SEC, and BET analysis. Characterization results indicated the successful grafting of polyacrylamide from the surface of activated carbon. The AC-PAM was measured to contain approximately 10.6% PAM by weight, and the average-number molecular weight of the grafted polymer was 176,100 g/mol. The flocculation performance of AC-PAM and PAM were compared by performing settling tests with 5 wt% MFT. The optimal polymer dosage for PAM was found to be 10,000 ppm, producing an initial settling rate of 3.51 m/hr and a supernatant turbidity of 430 NTU. Comparatively, the optimal dosage for AC-PAM was found to be 20,000 ppm, producing a supernatant turbidity of 114 NTU and a fast initial settling rate of 27.54 m/hr. The improved flocculation performance is hypothesized to occur due to the effective increase in the molecular weight of PAM when grafted from the surface of activated carbon. In all, our work demonstrates the successful grafting of PAM from AC, as well as potential wastewater treatment applications for these types of hybrid materials.

Author Keywords: Activated carbon, Atom transfer radical polymerization, Flocculation, Grafting, Polyacrylamide, Surface-initiated polymerization

This thesis describes the synthesis, application and evaluation of a UV crosslinked 3-methacryloxypropyltrimethoxysilane-derived coating formulation. This is a two-component sol-gel system with 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS). Herein we show that if we change the co-solvent required for solubilizing MaPTMS from the more common methanol and ethanol to isopropanol we change the rate of hydrolysis from days or weeks to minutes. With the assistance of 2D 29Si-NMR we demonstrate that the system undergoes extensive condensation in twenty minutes. Using standard UV irradiation, the material can be extensively UV crosslinked with 70% of the methacryloxy functionality being consumed in 5 minutes upon irradiation in the presence of a photo-initiator. When this material is used to coat low carbon steel and immersed in an accelerated corrosion solution (dilute Harrison's solution); this material affords low carbon steel 25 hours of protection when crosslinked and 17 hours of protection when uncrosslinked.

The material was then used to encapsulate polyaniline (PANI), an intrinsic conductive polymer used in the corrosion protection of metal substrates. PANI has been encapsulated previously in sol-gel material, but due to the pH dependence of the solubility of PANI, it can not be encapsulated in more commonly chemically crosslinked sol-gel. As our system is UV crosslinked rather than chemically crosslinked, we were able to successfully demonstrate the inclusion of PANI into our coating system.

Finally, this thesis includes a thorough computational investigation into the structure and band gap of PANI. Through the analysis of the band gap it was shown that the structure of the polymer commonly displayed in literature is not the correct structure of the polymer. Our results suggest that when PANI is made electrochemically, the oligomer contains two quinoid units next to one another instead of the more usually represented regularly alternating benzoid and quinoid units. The results also suggest that when PANI is made using the oxidant ammonium persulfate, the polymer most likely contains a Michael adduct structure somewhere in the polymer chain which dominates PANI's electronic properties.

Author Keywords: 3-Methacryloxypropyltrimethoxysilane, Computational Chemistry , Corrosion , Polyaniline, Tetraethoxysilane

Connecting academia to industry is one important way to advance towards meeting the United Nations (UN) Sustainability Goals (SDGs).1 Sustainability can be applied to all industrial sectors with the SDGs being implemented by 2030.2 This research contributes to the SDGs by investigating a way to remediate an industrial waste stream in the egg-breaking industry. If adopted, this would reduce the amount of eggshell membrane (ESM) waste placed in landfill where it does not decompose properly. The work described in this thesis specifically targets extraction of collagen and hyaluronic acid (HA), two components of the ESM that are of commercial value in the cosmetic, pharmaceutical, and biomedical industries3,4 . Deliverables from this research include economically viable extraction methods, developed based on green chemistry approaches, that can be transferred from lab bench to industrial scale. The extraction development process was guided by the 12 Principles of Green Chemistry5,6,7 and the 12 Principles of Green Engineering.8 HA was most successfully extracted using a sodium acetate solution on ground ESM. Filtrate was collected, exhaustively dialyzed and lyophilized. High molecular weight HA was recovered. Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy and proton nuclear magnetic resonance (NMR) spectroscopy compared extracted material to reference HA identifying successful extraction. Collagen was extracted using acetic acid or pepsin enzyme digestion. Hydrophilic interaction liquid chromatography (HILIC) coupled with mass spectrometry (MS) compared amino acid composition of extracted materials to reference collagen material. FTIR-ATR spectra also supported successful extraction of collagen. This work identifies that HA and collagen can be conveniently extracted from ESM using an economical approach that can be implemented into egg-breaking facilities. This work highlights the benefits of connecting academia to industry to advance green chemical approaches while implementing sustainable practices into existing industry.

Author Keywords: collagen, eggshell membrane waste, extraction, green chemistry, hyaluronic acid, sustainability

Giardia intestinalis is a protozoan parasite that causes waterborne diarrheal disease in animals and humans. It is an unusual eukaryote as it lacks the capacity for heme biosynthesis; nonetheless it encodes heme proteins, including three cytochrome b5 isotypes (gCYTB5s) of similar size. Homology modelling of their structures predicts increased heme pocket polarity compared to mammalian isotypes, which would favour the oxidized state

and lower their reduction potentials (E°'). This was confirmed by spectroelectrochemical experiments, which measured E°' of -171 mV, -140 mV and -157 mV for gCYTB5-I, II, III respectively, compared to +7 mV for bovine microsomal cytochrome b5. To explore the influence of heme pocket polarity in more detail, five gCYTB5-I mutants in which polar residues were replaced by nonpolar residues at one of three positions were investigated.

While these substitutions all increased the reduction potential, replacement of a conserved tyrosine residue at position-61 with phenylalanine had the most significant effect, raising E°' by 106 mV. This tyrosine residue occurs in all gCYTB5s and is likely the greatest contributor to their low reduction potentials. Finally, complementary substitutions were made into a bovine microsomal cytochrome b5 triple mutant to lower its reduction potential. These not only lowered the E°' by more than 140 mV but also weakened the interaction of heme with the protein. The lower reduction potentials of the gCYTB5s may indicate that these proteins have different roles from their more well-known mammalian counterparts.