DEVELOPMENT OF BIOPOLYMERS AND THEIR MODIFIED FORMS AS SUSTAINABLE SORBENT MATERIALS

The production of ethanol in the biofuels industry requires methods to remove water from mixtures to improve biofuel quality. To address the large energy footprint of conventional distillative separation of biofuels and water, new materials and methods are required to reduce GHG emissions and to develop more sustainable industrial processing. The overall goal of this research focuses on the sorption properties of biopolymers and their modified forms as adsorbents for fractionation of chemical mixtures such as water/ethanol in binary systems. The short term goals of this thesis are related to the synthesis, characterization, and evaluation of the sorption properties of biopolymers and their modified forms. Moreover, a long term goal relates to the development of biopolymer materials with tunable adsorptive properties for the fractionation of binary water-ethanol (W-E) mixtures. Biopolymers such as starch (linear and branched) and cellulose were modified with variable amounts of epichlorohydrin (EPI) as a cross-linker for the enhancement of physicochemical properties related to sorption processes. The characterization of materials included Thermogravimetry Analysis (TGA), Infrared spectroscopy (FT-IR) and NMR spectroscopy. These methods provided support that incorporation of incremental levels of cross-linker with the biopolymers resulted in variable structure and physicochemical properties related to sorption. This thesis describes four leading edge contributions related to the objectives of this study: i) The development of biopolymers and their modified forms for the controlled uptake of ethanol in binary W-E systems, ii) Evaluation of the adsorption properties using dye probes, nitrogen adsorption, and the use of quantitative NMR (qNMR) spectroscopy as a convenient and rapid analytical tool to quantify uptake of both water and ethanol content in binary solvent systems, iii) Evaluation of biomass and its biopolymer components for the fractionation of W-E mixtures, and iv) Evaluation of the role of solvent effects on the adsorption properties of biopolymers. Based on the results herein, the biopolymer adsorbents displayed preferential uptake of water over ethanol in binary W-E solutions. The adsorptive solvent uptake selectivity (Rselectivity; Qm(W)/Qm(E)) of water over ethanol for a given sorbent material requires an understanding of hydration phenomena, biopolymer structure, and textural properties of adsorbent materials. This thesis contributes to a molecular-level understanding of the solvent fractionation properties of biopolymers and their modified forms, along with the development of green strategies for biofuel separation. The isotherm modeling results show that the monolayer adsorption capacity (Qm) of ethanol and water by cellulose biopolymer materials along with its cross-linked forms cover a range (Qm= 1.13−2.44 g/g) of values. The parameters indicate heterogeneous adsorption behaviour, in agreement with the Sips exponential fitting parameter (ns ≠ 1). The Rselectivity values ((Qm(W)/Qm(E)) obtained at saturative conditions are variable (1.10 to 2.03) and further illustrate that cellulose materials display molecular selective solvent fractionation in binary W−E solutions. By comparison, the Qm values for starch and its cross-linked forms varied from 0.01 to 2.70 g·g−1 for water and ethanol in binary mixtures according to the Sips isotherm model. The Rselectivity (Qm (W)/Qm(E)) values of starch-EPI adsorbents for water (W) and ethanol (E) in the binary mixtures range from 3.8 to 80. As well, the isotherm results show that the monolayer adsorption capacity (Qm; g.g−1) of biomass such as miscanthus with water Qm (W) and ethanol Qm (E) fractions were determined by the best-fit Sips model isotherm parameters for raw Miscanthus (Qm (W) =8.93 and Qm (E) =4.15 g.g-1) and pretreated Miscanthus (Qm (W) =4.73 and Qm (E) =3.22, g.g-1). The fractionation properties of Miscanthus revealed variable Rselectivity (Qm(W)/ Qm(E)) values: raw Miscanthus (Rselectivity=3:1); pretreated Miscanthus (Rselectivity = 1.5:1), and lignin isolates (Rselectivity = 1: 5.4). The solvent interactions of biopolymers impact their biodegradability, recyclability and tunable physicochemical properties for various applications that employ composite materials, pharmaceutical delivery systems, paper production, fibers and biofuel production. Studies of the hydration properties of these materials were carried out that include dielectric absorption, Raman spectroscopy and Differential Scanning Calorimetry (DSC) to determine the structural and thermodynamic properties that reveal differences in biopolymer-solvent interactions that depend on the nature of the system

Antioxidants Classification and Applications in Lubricants

Oxidation is a chemical reaction that occurs in lubricants upon exposure to an oxidizing agent such as oxygen and can be catalyzed by copper and iron. Antioxidants are a group of chemicals that can be used in the formulation of lubricants to stop or reduce the rate of oxidation. Based on the mechanism of action, antioxidants are categorized as primary antioxidants (radical scavengers), secondary antioxidants (Peroxide decomposers), and metal deactivators (complex-forming or chelating agents). Selection of the antioxidants in a formulation is a critical decision that depends on the base oil, application and other ingredients in the formulations. Presence of some other ingredients in the product with antagonistic behavior may suppress the role of antioxidants; however, optimal application of antioxidants with synergistic behavior would increase the stabilization impact of the ingredients on the base oil

Suitability of bio-desiccants for energy wheels in HVAC applications

Government of the Saskatchewan (Ministry of Agriculture), Agricultural Development Fund: Project #20160266Peer ReviewedThis paper investigates the suitability of bio-desiccants for moisture recovery in energy wheels. Bio-desiccants are environment-friendly materials that have high water vapor adsorption capacities. The main contribution of this paper is that it reports the latent effectiveness of flax-fiber (bio-desiccant) coated energy wheels for a wide range of operating conditions and compares the effectiveness of the flax-fiber wheels with wheels that are coated with commercially available desiccants and other biomaterials. The moisture transfer performance of a flax-fiber coated exchanger is determined using a small-scale test facility and two different experimental methods: single step change tests and cyclic tests. The test results are used to verify the applicability of an effectiveness correlation from the literature. Using the energy wheel correlation and the sorption isotherms, the latent effectiveness of commercially available energy wheels coated with molecular sieve, ion exchange resin and silica gel desiccants are obtained and compared with that of bio-desiccants (flax fiber and starch particles). The highest latent effectiveness is obtained for silica gel followed by starch particles, ion exchange resin, flax-fiber and molecular sieve. The results from this study will be useful in research and development of bio-materials for energy recovery systems for building applications

Spectroscopic and Thermodynamic Study of Biopolymer Adsorption Phenomena in Heterogeneous Solid–Liquid Systems

Molecular selective adsorption processes at the solid surface of biopolymers in mixed solvent systems are poorly understood due to manifold interactions. However, the ability to achieve adsorptive fractionation of liquid mixtures is posited to relate to the role of specific solid–liquid interactions at the adsorbent interface. The hydration of solid biopolymers (amylose, amylopectin, cellulose) in binary aqueous systems is partly governed by the relative solvent binding affinities with the biopolymer surface sites, in accordance with the role of textural and surface chemical properties. While molecular models that account for the surface area and solvent effects provide reliable estimates of hydration energy and binding affinity parameters, spectroscopic and thermal methods offer a facile alternative experimental approach to account for detailed aspects of solvation phenomena at biopolymer interfaces that involve solid−liquid adsorption. In this report, thermal and spectroscopic methods were used to understand the interaction of starch- and cellulose-based materials in water–ethanol (W–E) binary mixtures. Batch adsorption studies in binary W–E mixtures reveal the selective solvent uptake properties by the biomaterials, in agreement with their solvent swelling in pure water or ethanol. The nature, stability of the bound water, and the thermodynamic properties of the biopolymers in variable hydration states were probed via differential scanning calorimetry and Raman spectroscopy. The trends in biopolymer–solvent interactions are corroborated by dye adsorption and scanning electron microscopy, indicating that biopolymer adsorption properties in W–E mixtures strongly depend on the surface area, pore structure, and accessibility of the polar surface groups of the biopolymer systems, in agreement with the solvent-selective uptake results reported herein

Nuclear Magnetic Resonance Investigation of the Fractionation of Water–Ethanol Mixtures with Cellulose and Its Cross-Linked Biopolymer Forms

Cellulose (CE) was cross-linked with epichlorohydrin (EPI) at variable compositions, and the fractionation properties were investigated in binary water–ethanol (W–E) solutions, including the pure solvent systems. The relative uptake of each solvent was measured using quantitative ¹H nuclear magnetic resonance (qNMR) spectroscopy. This study highlights the utility of qNMR as a rapid screening method for estimation of solvent selective fractionation in binary mixtures. The uptake properties of CE–EPI cross-linked polymers with ethanol and water were well-described using the Sips isotherm model. Modeling shows that the monolayer surface coverage (<i>Q</i>_m) of ethanol and water onto the polymer materials covers a range (1.13–2.44 g/g) of values with heterogeneous adsorption behavior, in agreement with the Sips exponential fitting parameter (<i>n</i>_s ≠ 1). The CE–EPI adsorbents display unique fractionation with water and ethanol from binary solutions, as evidenced by the relative selectivity (<i>R</i>_selectivity) value in binary W–E solvent systems. The <i>R</i>_selectivity [<i>Q</i>_m(W)/<i>Q</i>_m(E)] values at saturative conditions varied (from 1.10 to 2.03) and further illustrate that CE materials display molecular selective solvent fractionation in binary W–E solutions. This study provides a greater molecular level understanding for the adsorptive uptake properties of CE that are relevant to developing CE-based adsorbent technology for the fractionation of biofuels and related chemical separations

NMR Investigation of the Fractionation of Water–Ethanol Mixtures with Starch and Its Cross-Linked Forms

The development of low-cost materials and efficient methods for the fractionation of water and ethanol in binary mixtures is of great interest for food processing and biofuels production. Herein, we report a systematic study of a series of linear and branched starch-based biopolymers along with their modified forms via cross-linking with epichlorohydrin (EPI) at variable EPI composition. The fractionation properties of these adsorbent materials were studied in binary ethanol–water solutions and compared against those of neat solvents. ¹H NMR spectroscopy was used to assess the binary solvent composition for the study of isotherms for the respective solvent components. The monolayer adsorption capacity (<i>Q</i>_m) for starch and its cross-linked forms varied from 0.01 to 2.70 g·g^–1 for water and ethanol in binary mixtures according to the Sips isotherm model. The fractionation selectivity [<i>R</i>_selectivity; <i>Q</i>_m(W)/<i>Q</i>_m(E)] of starch-EPI adsorbents for water (W) and ethanol (E) in binary mixtures ranges from 3.8 to 80. At saturative conditions in binary W–E mixtures, the <i>R</i>_selectivity isotherm parameter reveals unique solvent-selective uptake that depends on the amylose versus amylopectin composition and the EPI content of these cross-linked materials. The unique water uptake properties of starch and its cross-linked forms illustrate the role of textural properties and relative hydrophobic character of the polymer network based on the selective adsorption properties. Starch and its modified forms represent a promising class of adsorbent materials and a sustainable technology for the adsorptive-based fractionation of W–E binary mixtures

Development of Novel Lipid-Based Formulations for Water-Soluble Vitamin C versus Fat-Soluble Vitamin D3

The aim of this study was to develop a facile and novel lipid-based formulation of vitamin C and vitamin D3. Liposomes loaded with vitamin C and D3 were characterized using transmission electron microscopy (TEM) and zeta potential measurements for evaluating morphology, particle size and physical stability. HPLC was employed to quantify the content of vitamin C and vitamin D3 in their liposomal forms. The UHPLC analysis of the lipid-based vitamin formulation is an easy and rapid method for the characterization as well as the quantification of all components. In addition, encapsulation efficiency, vitamin loading and stability analysis were performed by the UHPLC method, in order to evaluate the reliability of the optimized lipid-based formulation. The TEM results provided key support for the core type of liposome structure in the formulations, whereas the HPLC results indicated that the liposomal vitamin C and D3 systems were homogeneous, and did not undergo phase separation. Taken together, the results demonstrate that liposomal encapsulated vitamins (vitamin C and D3) possess a unilamellar vesicle morphology with uniform particle size, despite differences in the hydrophile&ndash;lipophile profiles of the vitamins. The highly efficient encapsulation properties of such liposomal constructs are proposed to contribute to enhanced vitamin bioavailability

Renewable Starch Carriers with Switchable Adsorption Properties

This Research Article describes a systematic study on the structure and sorption properties of Carnation-based starch-particles (SPs) by various techniques. Structural characterization of the SPs utilized spectroscopy (¹H NMR and FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The sorption properties of the SPs were characterized by solvent swelling and uptake isotherms with cationic adsorbates at equilibrium and kinetic conditions. The surface area (SA; ∼3–588 m²/g) of the SPs was estimated using nitrogen gas and dye adsorption isotherm methods, where the range in SA was related to solvent swelling effects on the textural properties. The SPs contain lipid constituents according to results obtained by ¹H NMR spectroscopy, DSC, and confocal laser microscopy (CLM) with iodine staining. The unique solvent swelling properties of the SPs reveal greater swelling in water over ethanol. SPs display preferential equilibrium uptake of methylene blue (MB; <i>Q</i>_m ≈ 716 mg/g) over cetylpyridinium bromide (CPB; <i>Q</i>_m ≈ 292 mg/g). The uptake of MB was reduced by an order of magnitude (<i>Q</i>_m ≈ 67 mg/g) when the SPs were doped with CPB, further revealing the role of competitive adsorption and similar binding modes for MB and CPB. The doping of SPs with CPB provide a facile approach for alteration of the surface functional properties such as the hydrophile–lipophile character, surface charge, and hydration properties of the SPs. Evidence of monolayer and multilayer adsorption of CPB onto SPs lead to switchable adsorption properties where such amphiphile surface patterning can be harnessed to yield materials with unique controlled-release properties for diverse chemical systems according to tunable surface charge using self-assembly

Vapor Adsorption Transient Test Facility for Dehumidification and Desorption Studies

The steady state performance testing of industrial-scale energy wheels requires large-scale and advanced instrumentation to analyze large volumes of data. In order to address the feasibility of laboratory-scale studies, experimental modelling and data simulation have been successfully performed by means of the transient and cyclic testing of a heat exchanger within an energy wheel setup in a parallel-flow air stream configuration. However, major challenges have been encountered in terms of predicting the effectiveness of a counter-flow energy wheel configuration in different operating conditions via the use of a transient test setup in a parallel-flow configuration. In the present study, we report the modification of a transient test facility intended to facilitate the more accurate simulation of a full-scale energy wheel operation in a small-scale test facility. A new test section was designed to: (1) enable tests in&nbsp;both counter-flow and parallel-flow configurations; (2) afford automated cyclic testing and achieve the reliable simulation of the energy wheels dehumidification/regeneration cycles;&nbsp;and (3) enhance the accuracy and reduce the uncertainty of the relative humidity (RH) measurements through utilization of the bag sampling method. The latter method is shown to yield greater accuracy with regard to the RH in non-isothermal operating conditions, as well as to reduce the data processing required for the estimation of latent effectiveness

Miscanthus Biomass for the Sustainable Fractionation of Ethanol–Water Mixtures

Miscanthus is a rich source of lignocellulosic biomass with low mineral content suitable for applications that range from biofuel production to value-added biomass-derived products including a sustainable biosorbent. Herein, Miscanthus and its modified forms were used for the fractionation of water (W) and ethanol (E) mixtures that were analyzed by an <i>in situ</i> analytical method, referred to as quantitative NMR (qNMR) spectroscopy. Miscanthus was pretreated by hydrolysis and subsequent grinding to yield materials with variable biopolymer content (cellulose and lignins) and particle size. The Miscanthus materials were evaluated as sorbents in binary water–ethanol (W-E) mixtures. The maximum biomass adsorption capacity (<i>Q</i>_m; g g^–1) with water (<i>Q</i>_m,W) and ethanol (<i>Q</i>_m,E) fractions were determined by the best-fit Sips model parameters listed in parentheses: raw Miscanthus biomass (<i>Q</i>_m,W = 8.93 and <i>Q</i>_m,E = 4.15) and pretreated Miscanthus biomass (<i>Q</i>_m,W = 4.73 and <i>Q</i>_m,E = 3.22, g g^–1). The fractionation properties of Miscanthus and its biopolymer constituents show molecular selectivity [<i>R</i>_selectivity = <i>Q</i>_m,W/<i>Q</i>_m,E] between W and E. The <i>R</i>_selectivity values are given in parentheses, as follows: untreated Miscanthus (3:1), pretreated Miscanthus (1.5:1), and lignins (1:5.4). The pretreated Miscanthus was prepared by acid and base hydrolysis for the removal of hemicellulose and lignins, respectively, leading to cellulose enrichment. The raw and pretreated Miscanthus have preferential water uptake properties that relate to the relative biopolymer composition. To test the reusability and regeneration of Miscanthus, the biosorbent was tested over four adsorption–desorption cycles. This work contributes to a greater understanding of chemical treatment effects on biomass adsorption properties and evaluation of the adsorptive contributions of biopolymer components for the fractionation of water–ethanol mixtures