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Item Bioinspired complex cellulose nanorod-architectures: A model for dual-responsive smart carriers(Elsevier, 2024-12-17) Heidari Nia, Marzieh ; Garzia, Livia; Jawhar, Wajih; Wilson, Lee; van de Ven, TheoThe synergy between nanomaterials as solid supports and supramolecular concepts has resulted in nanomaterials with hierarchical structure and enhanced functionality. Herein, we developed and investigated innovative supramolecular functionalities arising from the synergy between organic moieties and the preexisting nanoscale soft material backbones. Based on these complex molecular nano-architectures, a new nanorod carbohydrate polymer carrier was designed with bifunctional hairy nanocellulose (BHNC) to reveal dual-responsive advanced drug delivery (ADD). This carrier scavenges K+-ions within cancer cells, while simultaneously releasing doxorubicin, combining ion homeostasis disruption with targeted drug delivery. The BC ADD system resulted from cross-linking dibenzo-18-crown-6-ether (DB18C6) with BHNC particles. To enhance cellular internalization and facilitate tracking of uptake, the cellulose nanorod carrier was labeled with biotin and fluorescein isothiocyanate, referred to as BCFB. The BHNC serves as the backbone, while the immobilized DB18C6 moieties can capture doxorubicin via complex formation. The BCFB complex molecular nanorod carriers exhibit distinct ADD profiles with pH and K+-responsiveness. They were evaluated as biocompatible carriers for ADD in MDA-MB-231 breast cancer cells, including quantification of nanoparticle uptake and flow cytometry with KHOS cells. These cellulose-based carriers possess unique structure and properties with potential utility as phase transfer catalysts and as adsorbents for diverse waterborne contaminants.Item Aloe vera mucilage as a sustainable biopolymer flocculant for efficient arsenate anion removal from water(The Royal Society of Chemistry, 2024-07-24) Venegas-García, Deysi J.; Wilson, Lee; De la Cruz Guzmán , Paola MayelaIn recent years, utilization of biopolymers as natural coagulant–flocculant (CF) systems has become an area of interest, due to their sustainable nature (renewable, biodegradable, and non-toxic) and potential utility as alternative systems to replace synthetic flocculants. Herein, a biopolymer extracted from Aloe vera mucilage (AVM) was investigated for its arsenic(V) removal properties in a CF water treatment process. Structural characterization of AVM was supported by spectroscopy (FTIR, 13C solids NMR & XPS), TGA, rheology, and pHpzc. The arsenic(V) removal process was optimized by employing the Box–Behnken design under three main factors (coagulant, flocculant dosage and initial arsenic(V) concentration), which led to a reduction of the initial arsenic(V) concentration to levels below the Maximum Acceptable Concentration (MAC; 10 μg L−1). The kinetics and thermodynamics of arsenic(V) removal were analyzed with a one-pot in situ method, where the kinetic profiles followed a pseudo-first-order model. The thermodynamic parameters are characteristic of a spontaneous (entropy-driven) and endothermic physisorption removal process. Flocs isolated from the process were analyzed by XPS, where the results reveal that calcium and amide groups of AVM contribute to the arsenic(V) removal mechanism.Item Sustainable agro-waste pellets as granular slow-release fertilizer carrier systems for ammonium sulfate(Royal Society of Chemistry, 2024) Steiger, Bernd; Bui, Nam; Babalola, Bolanle; Wilson, LeeIn this study, several granular biocomposite carrier systems were prepared that contain biomaterials (chitosan, torrefied wheat straw and avian eggshells) as additive components at variable composition. The biocomposites were loaded with ammonium sulfate (AS) by two methods: (1) in situ addition of AS during pellet preparation, and (2) an adsorption method of AS after pellet preparation. Characterisation was carried out via spectroscopy (XRD, FT-IR) and complementary methods (TGA, acid stability). The pellet system (C1) by method (1) contained ca. 22 mg per g NH4+, whereas pellet systems by method (2) contained up to ca. 40 mg per g NH4+. The mol-ratio of NH4+ : SO42− varied from 2.18 (C1) to 2.72 (CW72), 2.97 (CW20), 2.64 (CW21) and 3.20 (CW22). Release studies in water showed that C1 pellets released almost 100% NH4+ within 3 h, while release varied from ca. 60% (CW72), ca. 40% (C20), 20% (C21) to 10% (CW22). By comparison, the systems prepared through method (2) showed a marginal increase of the release profiles up to 96 h. Granular AS carrier systems prepared by method (2) displayed greater mechanical stability and AS content versus the systems prepared by method (1). We demonstrated the ability to tailor the physico-chemical properties of such biocomposite carriers and highlight their promising potential as slow-release fertilizer systems.Item Valorization of Eggshell as Renewable Materials for Sustainable Biocomposite Adsorbents—An Overview(MDPI, 2024-10-08) Babalola, Bolanle; Wilson, LeeThe production and buildup of eggshell waste represents a challenge and an opportunity. The challenge is that uncontrolled disposal of generated eggshell waste relates to a sustainability concern for the environment. The opportunity relates to utilization of this biomass resource via recycling for waste valorization, cleaner production, and development of a circular economy. This review explores the development of eggshell powder (ESP) from eggshell waste and a coverage of various ESP composite sorbents with an emphasis on their potential utility as adsorbent materials for model pollutants in solid–liquid systems. An overview of literature since 2014 outlines the development of eggshell powder (ESP) and ESP composite adsorbents for solid–liquid adsorption processes. The isolation and treatment of ESP in its pristine or modified forms by various thermal or chemical treatments, along with the preparation of ESP biocomposites is described. An overview of the physico-chemical characterization of ESP and its biocomposites include an assessment of the adsorption properties with various model pollutants (cations, anions, and organic dyes). A coverage of equilibrium and kinetic adsorption isotherm models is provided, along with relevant thermodynamic parameters that govern the adsorption process for ESP-based adsorbents. This review reveals that ESP biocomposite adsorbents represent an emerging class of sustainable materials with tailored properties via modular synthetic strategies. This review will serve to encourage the recycling and utilization of eggshell biomass waste and its valorization as potential adsorbent systems. The impact of such ESP biosorbents cover a diverse range of adsorption-based applications from environmental remediation to slow-release fertilizer carrier systems in agricultural production.Item Stabilization of Oil-in-Water Pickering Emulsions by Surface-Functionalized Cellulose Hydrogel(Gels, 2024-10) Udoetok, Inimfon; Mohamed, Mohamed H.; Wilson, LeeAn amphiphilic cellulose (CLH) hydrogel was synthesized via grafting of quaternary ammonium groups onto cellulose. The structural properties of CLH were characterized via Fourier transform infrared (FTIR)/13C solid-state NMR spectroscopy, elemental (CHN) analysis, particle size distribution (PSD), thermogravimetric analysis (TGA), and wettability was assessed through contact angle measurements. Pickering emulsions of apolar oils in water were prepared using variable weights of the CLH hydrogel as the stabilizing agent, along with different methods of agitation (mechanical shaking and sonication). The characterization results for CLH provide support for the successful grafting of quaternary ammonium groups onto cellulose to produce hydrogels. Different methods of agitation of an oil/water mixture revealed the formation of an oil-in-water (O/W) Pickering emulsion that was stable to coalescence for over 14 days. The resulting emulsions showed variable droplet sizes and stability according to the dosage of CLH in the emulsion and the agitation method, where the emulsion droplet size is related to the particle size of CLH. The addition of methyl orange (MO), a probe to evaluate the phase partitioning of the dye, had minor effects on the emulsion droplet size, and the emulsion prepared with 0.8 wt.% of CLH and agitated via sonication exhibited the smallest droplet size and greatest stability. This study is anticipated to catalyze further research and the development of low-cost and sustainable biopolymer hydrogels as stabilizers for tunable Pickering emulsion. Grafted cellulose materials of this type represent versatile stabilizing agents for foods, agrochemicals, and pharmaceutical products and technologies.Item Hybrid Chitosan Biosorbents: Tunable Adsorption at Surface and Micropore Domains(Biomimetics, 2024-11) Udoetok, Inimfon; Mohamed, Mohamed H.; Wilson, LeeHerein, we report a study that provides new insight on the knowledge gaps that relate to the role of biopolymer structure and adsorption properties for chitosan adsorbents that are cross-linked with glutaraldehyde. The systematic modification of chitosan cross-linked with glutaraldehyde (CG) and its quaternized forms (QCG) was studied in relation to the reaction conditions: mole ratios of reactants and pH conditions. Complementary adsorbent characterization employed 13C NMR/FTIR spectroscopy, TGA and DSC, point-zero-charge (PZC), solvent swelling, and sorption studies using selected dye probes. The spectral and thermal techniques provide complementary evidence that affirm the key role of cross-linker content and quaternization on variation of the physicochemical properties of chitosan. The PZC results reveal a neutral surface charge for the modified materials between pH 6.0 to 6.3 ± 0.3, as compared with pH 8.7 ± 0.4 for pristine chitosan. Solvent swelling in water decreased with greater cross-linking, while the QCG materials had greater swelling over CG materials due to enhanced hydration. The adsorption results reveal variable dye uptake properties according to the cross-linker content. Similarly, surface versus micropore adsorption was demonstrated, according to the nature and ionization state of the dye for the modified adsorbents, where the CG and QCG materials had tunable sorption properties that exceeded that of unmodified chitosan. A key step in tuning the structure and surface chemical properties of cross-linked chitosan involves pH control during synthesis. The facile tunability of the physicochemical properties of the modified biopolymers reported herein means that they possess features of biomimetics that are relevant to advanced drug delivery, antimicrobial materials for wound healing, biosensors, and biosorbents for biomedical applications.Item Chemical activation of atom-precise Pd3 nanoclusters on γ-Al2O3 supports for transfer hydrogenation reactions(Royal Society of Chemistry, 2024-09-30) Singh, Siddhant; Wi, Dami; Salem, Kholoud E.; Higgins, DrewDeposition of atom-precise nanoclusters onto solid supports is a promising route to synthesize model heterogeneous catalysts. However, to enhance nanocluster-support interactions, activation of the nanoclusters by removal of surface ligands is necessary. Thermal treatment to remove surface ligands from supported metal nanoclusters can yield highly active heterogeneous catalysts, however, the high temperatures employed can lead to poor control over the final size and speciation of the nanoclusters. As an alternative to high-temperature thermal treatments, chemical activation of [Pd3(μ-Cl)(μ-PPh2)2(PPh3)3]+ (Pd3) nanoclusters on γ-Al2O3 supports under mild reaction conditions has been demonstrated in this work. Hydride-based reducing agents such as NaBH4, LiBH4, and LiAlH4 have been examined for the activation of the Pd3 nanoclusters. The structural evolution and speciation of the nanoclusters after activation have been monitored using a combination of XAS, XPS, STEM-EDX mapping, and solid-state NMR techniques. The results indicate that treatment with borohydride reducing agents successfully removed surface phosphine and chloride ligands, and the extent of size growth of the nanoclusters during activation is directly correlated with the amount of borohydride used. Borate side products remain on the γ-Al2O3 surface after activation; moreover, exposure to high amounts of NaBH4 resulted in the incorporation of B atoms inside the lattice of the activated Pd nanoclusters. LiAlH4 treatment, on the other hand, led to no significant size growth of the nanoclusters and resulted in a mixture of Pd single-atom sites and activated nanoclusters on the γ-Al2O3 surface. Finally, the catalytic potential of the activated nanoclusters has been tested in the transfer hydrogenation of trans-cinnamaldehyde, using sodium formate/formic acid as the hydrogen donor. The catalytic results showed that smaller Pd nanoclusters are much more selective for hydrogenating trans-cinnamaldehyde to hydrocinnamaldehyde, but overall have lower activity compared to larger Pd nanoparticles. Overall, this study showcases chemical activation routes as an alternative to traditional thermal activation routes for activating supported nanoclusters by offering improved speciation and size control.Item A Highly Sensitive Chitosan-Based SERS Sensor for the Trace Detection of a Model Cationic Dye(MDPI, 2024-08-28) Vafakish, Bahareh; Wilson, LeeThe rapid detection of contaminants in water resources is vital for safeguarding the environment, where the use of eco-friendly materials for water monitoring technologies has become increasingly prioritized. In this context, the role of biocomposites in the development of a SERS sensor is reported in this study. Grafted chitosan was employed as a matrix support for Ag nanoparticles (NPs) for the surface-enhanced Raman spectroscopy (SERS). Chitosan (CS) was decorated with thiol and carboxylic acid groups by incorporating S-acetyl mercaptosuccinic anhydride (SAMSA) to yield CS-SAMSA. Then, Ag NPs were immobilized onto the CS-SAMSA (Ag@CS-SAMSA) and characterized by spectral methods (IR, Raman, NIR, solid state 13C NMR with CP-MAS, XPS, and TEM). Ag@CS-SAMSA was evaluated as a substrate for SERS, where methylene blue (MB) was used as a model dye adsorbate. The Ag@CS-SAMSA sensor demonstrated a high sensitivity (with an enhancement factor ca. 108) and reusability over three cycles, with acceptable reproducibility and storage stability. The Raman imaging revealed a large SERS effect, whereas the MB detection varied from 1–100 μM. The limits of detection (LOD) and quantitation (LOQ) of the biocomposite sensor were characterized, revealing properties that rival current state-of-the-art systems. The dye adsorption profiles were studied via SERS by fitting the isotherm results with the Hill model to yield the ΔG°ads for the adsorption process. This research demonstrates a sustainable dual-function biocomposite with tailored adsorption and sensing properties suitable for potential utility in advanced water treatment technology and environmental monitoring applications.Item Cu(II) Ion Adsorption by Aniline Grafted Chitosan and Its Responsive Fluorescence Properties(MDPI, 2020-02-26) Vafakish, Bahareh; Wilson, LeeThe detection and removal of heavy metal species in aquatic environments is of continued interest to address ongoing efforts in water security. This study was focused on the preparation and characterization of aniline grafted chitosan (CS-Ac-An), and evaluation of its adsorption properties with Cu(II) under variable conditions. Materials characterization provides support for the grafting of aniline onto chitosan, where the kinetic and thermodynamic adsorption properties reveal a notably greater uptake (>20-fold) of Cu(II) relative to chitosan, where the adsorption capacity (Qm) of CS-Ac-An was 106.6 mg/g. Adsorbent regeneration was demonstrated over multiple adsorption-desorption cycles with good uptake efficiency. CS-Ac-An has a strong fluorescence emission that undergoes prominent quenching at part per billion levels in aqueous solution. The quenching process displays a linear response over variable Cu(II) concentration (0.05–5 mM) that affords reliable detection of low level Cu(II) levels by an in situ “turn-off” process. The tweezer-like chelation properties of CS-Ac-An with Cu(II) was characterized by complementary spectroscopic methods: IR, NMR, X-ray photoelectron (XPS), and scanning electron microscopy (SEM). The role of synergistic effects are inferred among two types of active adsorption sites: electron rich arene rings and amine groups of chitosan with Cu(II) species to afford a tweezer-like binding modality.Item Supramolecular Chemistry of Polymer-Based Molecular Tweezers: A Minireview(MDPI, 2024-09-14) Vafakish, Bahareh; Wilson, LeePolymer-based molecular tweezers have emerged as a prominent research area due to their enhanced ability to form host–guest complexes, driven by advancements in their design and synthesis. The impact of the spacer structure on the tweezers is predominant. They can be rigid, flexible, and stimuli-responsive. Herein, a new generation of molecular tweezers is introduced as polymer-based molecular tweezers. The integration of molecular tweezers onto biopolymers has significantly expanded their potential applications, making them promising candidates, especially in drug delivery, owing to their biocompatibility, adaptive structural features, and versatile interaction capabilities. The unique structure of polymer-based molecular tweezers, particularly when integrated with biopolymers, creates a unique nano-environment that enhances their interaction with guest molecules. This minireview focuses on the synthesis and applications of polymer-based molecular tweezers and examines how the incorporation of various spacers affects their binding affinity and specificity. These features highlight the advancement of these polymer-based systems, emphasizing their potential applications, particularly in drug delivery, water treatment technology, and future research opportunities.Item Surface-Modified Chitosan: An Adsorption Study of a “Tweezer-Like” Biopolymer with Fluorescein(MDPI, 2019-08-18) Vafakish, Bahareh; Wilson, LeeTweezer-like adsorbents with enhanced surface area were synthesized by grafting aniline onto the amine sites of a chitosan biopolymer scaffold. The chemical structure and textural properties of the adsorbents were characterized by thermogravimetric analysis (TGA) and spectral methods, including Fourier transform infrared (FT-IR), nuclear magnetic resonance (1H- and, 13C-NMR) and scanning electron microscopy (SEM). Equilibrium solvent swelling results for the adsorbent materials provided evidence of a more apolar biopolymer surface upon grafting. Equilibrium uptake studies with fluorescein at ambient pH in aqueous media reveal a high monolayer adsorption capacity (Qm) of 61.8 mg·g−1, according to the Langmuir isotherm model. The kinetic adsorption profiles are described by the pseudo-first order kinetic model. 1D NMR and 2D-NOESY NMR spectra were used to confirm the role of π-π interactions between the adsorbent and adsorbate. Surface modification of the adsorbent using monomeric and dimeric cationic surfactants with long hydrocarbon chains altered the hydrophile-lipophile balance (HLB) of the adsorbent surface, which resulted in attenuated uptake of fluorescein by the chitosan molecular tweezers. This research contributes to a first example of the uptake properties for a tweezer-like chitosan adsorbent and the key role of weak cooperative interactions in controlled adsorption of a model anionic dye.Item Flax fiber-chitosan biocomposites with tailored structure and switchable physicochemical properties(Elsevier, 2023-11-21) Mir, Mariam; Wilson, Lee D.A facile and sustainable synthesis of unique flax fiber composites (FFCs) is reported, where raw flax fiber (FFR) was immobilized with variable chitosan content. FFCs were structurally characterized via TGA, XRD, SEM analysis, and spectroscopy (IR, NMR, and Raman mapping). Physicochemical characterization of FFCs enabled estimation of the point-of-zero-charge (PZC), solvent swelling at variable pH. Dye adsorption with Rose Bengal (RB) and Methylene Blue (MB) afforded characterization of the surface chemistry of the materials. This contribution study is a first reported example that highlights the unique structure-property relationships of FFC materials and the role of electrostatic interactions between the pristine fiber substrate and chitosan. FFCs with incremental chitosan content display the following trends: (i) greater solvent swelling at variable pH (350 % for FFCs and ca. 100 % for FFR and commercial absorbents), (ii) two-fold enhanced adsorption of RB (FFC 0.5 to FFC 2.0) and (iii) 1.5-fold decreased adsorption of MB (FFC 2.0 to FFC 0.5). The unique “switchable” sorption properties of the FFCs toward solvent and dyes was revealed upon facile and noncovalent immobilization of chitosan onto FFR. The sustainable composites reported herein offer a potential adsorption-based technology suitable for filter-based applications in “smart textiles” to biomedical sorbents for wound healing.Item Chitosan Biocomposites with Variable Cross-Linking and Copper-Doping for Enhanced Phosphate Removal(MDPI, 2024-01-16) Udoetok, Inimfon A.; Karoyo, Abdalla H.; Mohamed, Mohamed H.; Wilson, Lee D.The fabrication of chitosan (CH) biocomposite beads with variable copper (Cu2+) ion doping was achieved with a glutaraldehyde cross-linker (CL) through three distinct methods: (1) formation of CH beads was followed by imbibition of Cu(II) ions (CH-b-Cu) without CL; (2) cross-linking of the CH beads, followed by imbibition of Cu(II) ions (CH-b-CL-Cu); and (3) cross-linking of pristine CH, followed by bead formation with Cu(II) imbibing onto the beads (CH-CL-b-Cu). The biocomposites (CH-b-Cu, CH-b-CL-Cu, and CH-CL-b-Cu) were characterized via spectroscopy (FTIR, 13C solid NMR, XPS), SEM, TGA, equilibrium solvent swelling methods, and phosphate adsorption isotherms. The results reveal variable cross-linking and Cu(II) doping of the CH beads, in accordance with the step-wise design strategy. CH-CL-b-Cu exhibited the greatest pillaring of chitosan fibrils with greater cross-linking, along with low Cu(II) loading, reduced solvent swelling, and attenuated uptake of phosphate dianions. Equilibrium and kinetic uptake results at pH 8.5 and 295 K reveal that the non-CL Cu-imbibed beads (CH-b-Cu) display the highest affinity for phosphate (Qm = 133 ± 45 mg/g), in agreement with the highest loading of Cu(II) and enhanced water swelling. Regeneration studies demonstrated the sustainability and cost-effectiveness of Cu-imbibed chitosan beads for controlled phosphate removal, whilst maintaining over 80% regenerability across several adsorption–desorption cycles. This study offers a facile synthetic approach for controlled Cu2+ ion doping onto chitosan-based beads, enabling tailored phosphate oxyanion uptake from aqueous media by employing a sustainable polysaccharide biocomposite adsorbent for water remediation by mitigation of eutrophication.Item Low adsorption affinity of athabasca oil sands naphthenic acid fraction compounds to a peat-mineral mixture(Elsevier, 2024-04-24) Meulen, Ian J. Vander; Steiger, Bernd G.K.; Asadi, Mohsen; Peru, Kerry M.; Degenhardt, Dani; McMartin, Dena W.; McPhedran, Kerry M.; Wilson, Lee D.; Headley, John V.Much of the toxicity in oil sands process-affected water in Athabasca oil sands tailings has been attributed to naphthenic acids (NAs) and associated naphthenic acid fraction compounds (NAFCs). Previous work has characterized the environmental behaviour and fate of these compounds, particularly in the context of constructed treatment wetlands. There is evidence that wetlands can attenuate NAFCs in natural and engineered contexts, but relative contributions of chemical, biotic, and physical adsorption with sequestration require deconvolution. In this work, the objective was to evaluate the extent to which prospective wetland substrate material may adsorb NAFCs using a peat-mineral mix (PMM) sourced from the Athabasca Oil Sands Region (AOSR). The PMM and NAFCs were first mixed and then equilibrated across a range of NAFC concentrations (5–500 mg/L) with moderate ionic strength and hardness (∼200 ppm combined Ca2+ and Mg2+) that approximate wetland water chemistry. Under these experimental conditions, low sorption of NAFCs to PMM was observed, where sorbed concentrations of NAFCs were approximately zero mg/kg at equilibrium. When NAFCs and PMM were mixed and equilibrated together at environmentally relevant concentrations, formula diversity increased more than could be explained by combining constituent spectra. The TOC present in this PMM was largely cellulose-derived, with low levels of thermally recalcitrant carbon (e.g., lignin, black carbon). The apparent enhancement of the concentration and diversity of components in PMM/NAFCs mixtures are likely related to aqueous solubility of some PMM-derived organic materials, as post-hoc combination of dissolved components from PMM and NAFCs cannot replicate enhanced complexity observed when the two components are agitated and equilibrated together.Item Eggshell incorporated agro-waste adsorbent pellets for sustainable orthophosphate capture from aqueous media(Royal Society of Chemistry, 2024-04-04) Steiger, Bernd G. K.; Bui, Nam T.; Babalola, Bolanle M.; Wilson, Lee D.In this study, granular adsorbents containing varying ratios of torrefied wheat straw (TWS), eggshells (ES), and chitosan (Chi) were prepared, which are referred to as ternary wheat straw composites (TWCs). The TWCs were assessed for mechanical stability during handling in aqueous media and their orthophosphate (Pi) adsorption properties were studied at equilibrium. The characterization of the TWCs employed spectroscopy (IR, solids 13C NMR, PXRD), TGA, and surface area/pore size analysis via N2 gas and dye (4-nitrophenol) adsorption. The BET surface area for the composites increased with greater ES/Chi content from 0.26 m2 g−1 for C72 (80% TWS content) to 2.2 m2 g−1 for C22 (20% TWS content; 40% each ES and Chi content). The Pi adsorption properties of selected TWC adsorbents were evaluated via the Langmuir, Freundlich, and Sips isotherms at variable pH (4.5, 8.5) and 295 K. The TWCs showed moderate Pi uptake (23–30 mg g−1) at pH 4.5 with a slight decrease (9–12 mg g−1) at pH 8.5 for elevated Pi concentrations. Environmentally relevant Pi concentrations (<5 mg L−1) revealed that TWCs with 20–80% TWS content observed similar uptake (ca. 1 mg g−1). This study demonstrates that sustainable composite adsorbents that contain TWS, Chi and ES were modified to yield mechanically stable systems with tailored orthophosphate adsorption properties, especially at low concentrations for neutral or slightly alkaline pH. The proof-of-concept for this adsorbent technology reveals the role of synergistic effects, along with its overall sustainability and scalability, according to a facile synthetic strategy that includes support based on a preliminary cost analysis for these granular adsorbents.Item Polylactic Acid Composites Reinforced with Eggshell/CaCO3 Filler Particles: A Review(MDPI, 2024-04-19) Homavand, Anahita; Cree, Duncan E.; Wilson, Lee DStatistics reveal that egg production has increased in recent decades. This growth suggests there is a global rise in available eggshell biomass due to the current underutilization of this bio-waste material. A number of different applications for waste eggshells (WEGs) are known, that include their use as an additive in human/animal food, soil amendment, cosmetics, catalyst, sorbent, and filler in polymer composites. In this article, worldwide egg production and leading countries are examined, in addition to a discussion of the various applications of eggshell biomass. Eggshells are a rich supplement of calcium carbonate; therefore, they can be added as a particulate filler to polymer composites. In turn, the addition of a lower-cost filler, such as eggshell or calcium carbonate, can reduce overall material fabrication costs. Polylactic acid (PLA) is currently a high-demand biopolymer, where the fabrication of PLA composites has gained increasing attention due to its eco-friendly properties. In this review, PLA composites that contain calcium carbonate or eggshells are emphasized, and the mechanical properties of the composites (e.g., tensile strength, flexural strength, tensile elastic modulus, flexural modulus, and elongation (%) at break) are investigated. The results from this review reveal that the addition of eggshell/calcium carbonate to PLA reduces the tensile and flexural strength of PLA composites, whereas an increase in the tensile and flexural modulus, and elongation (%) at break of composites are described herein.Item Hydrolyzed Forms of Cellulose and Its Metal Composites for Hydrogen Generation: An Experimental and Theoretical Investigation(MDPI, 2024-07-06) Faye, Omar; Udoetok, Inimfon A.; Szpunar, Jerzy A.; Wilson, Lee DThe quest for a smooth transition from fossil fuels to clean and sustainable energy has warranted studies on alternative energy materials. Herein, we report on an experimental and theoretical study focused on hydrogen generation through the hydrolysis of microcrystalline cellulose (MCC) treated in different media (deionized water, sodium hydroxide) and MCC functionalized with magnesium (MCC-Mg), titanium (MCC-Ti), and niobium (MCC-Nb). The XRD results reveal the decreased crystallinity of MCC due to ball milling along with the formation of metal oxide composites between MCC and various metals (magnesium, titanium, and niobium). Theoretical studies using NVT molecular dynamic simulations with the NH chain thermostat implemented in the Dmol3 provides further support to the experimental results reported herein. The results from the experimental and theoretical studies revealed that ball milling and composite formation with metal species enhanced the kinetics of the hydrolysis of MCC and, consequently, hydrogen generation, while the addition of NaOH and urea inhibited the hydrogen yield.Item Synthesis of Conjugated Polymers: Comparing the Indophenine Reaction with Traditional Methods(American Chemical Society, 2024-07-10) Berbigier, Jônatas Faleiro; Kelly, Timothy L.Conjugated polymers are an important class of materials whose development underpins many recent advances in organic electronics. Traditionally, these polymers have been synthesized by transition metal-catalyzed cross-couplings using organometallic reagents (e.g., Stille couplings). Although direct heteroarylation polymerization (DHAP) dispenses with the organometallic intermediates, DHAP is still a metal-catalyzed coupling, requiring both catalyst optimization and purification to remove trace metal contaminants. In contrast, a recent report from our group demonstrated that the indophenine reaction can be used as a metal-free method to prepare conjugated polymers; however, from this initial proof-of-concept study, it was not clear how it compared to other methods of conjugated polymer synthesis. Therefore, in this report, we synthesized the same polymer using three distinctly different approaches: Stille coupling, DHAP, and the indophenine reaction. This allows us to directly compare the three methodologies; we find that each offers distinct trade-offs in terms of atom economy, defects, and molecular weight.Item Effect of a Fluorinated Surfactant on Langmuir Monolayer Properties of Minimal-Linker Gemini Surfactants(Elsevier B.V., 2024-07-08) Singh, Srikant K.; Paige, Matthew F.A new class of carboxylic acid-terminated gemini surfactants which contain the smallest possible headgroup linker (a single bond) has recently been reported in the literature. In this current work, we have explored how Langmuir monolayers of two different alkyl tail chain length variants (n = 12, n = 16) of these surfactants, dubbed Cn-0-Cn, are impacted by mixing with a benchmark perfluorinated surfactant, perfluorotetradecanoic acid (PF). Pure PF and C16-0-C16 monolayers share similar general characteristics, yielding compact, incompressible, solid-like films at the air-water interface. In contrast, the shorter tail chain variant, C12-0-C12 forms expanded, compressible liquid-like films. While both tail chain variants formed mixed films with PF that were generally expanded in comparison with their pure components, and were also phase-separated, the extent of interactions between film components and the resulting micron-scale morphology of the mixed films were different for the two alkyl chain lengths. Overall, PF induces different packing behavior in both the systems and the observations are attributed to the difference in the dispersion forces originating from the tail chain length differences.Item Probing the Formation and Evolution of Pd Nanoparticles on the Surface of γ-Al2O3 using a Pd(II) Coordinating Polymer as a Precursor: An in-situ X-ray Scattering and Spectroscopy Study(American Chemical Society, 2024-06-26) Singh, Siddhant; Scott, Robert W.J.Due to the small size and very low metal loadings in heterogeneously supported nanoparticle catalysts, it is a characterization challenge to trace and control the formation and structural evolution of nanoparticles during their synthesis. In this report, we have probed the formation of alumina-supported Pd nanoparticles by thermal treatment of a 1:3 composite of a Pd(II) coordination polymer (Pd(II)-CP) and a γ-Al2O3 powder using in situ X-ray total scattering and X-ray absorption spectroscopy. By comparing the pyrolysis process of Pd(II)-CP in the absence and presence of γ-Al2O3, we found that the sintering of Pd nanoparticles by the coalescence of nucleation sites can be significantly reduced on γ-Al2O3 surfaces. The introduction of γ-Al2O3 provides far better control over the size, distribution, and speciation of the synthesized Pd nanoparticles. The results showed that the sintering of Pd nanoparticles does not occur on the surface of γ-Al2O3 until the Pd(II)-CP structure is fully collapsed at 400 °C, most likely because the organic framework of Pd(II)-CP provides spatially distinct sites for Pd nucleation. Moreover, the interface of the γ-Al2O3 surface and Pd(II)-CP protected the Pd nanoparticle nucleation sites from air oxidation up to 500 °C. Thereafter, a slow conversion of the Pd fcc phase to the PdO phase started taking place, which was facilitated by the formation of an amorphous PdOx phase as an intermediate.