PRISM :: Browsing by Author "Hu, Jinguang"

Browsing by Author "Hu, Jinguang"

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Open Access
3D Geomechanical Modeling of Shale Formations and its Application in Borehole Stabilization
(2021-06-09) Deng, Liyu; Chen, Zhangxing; Hu, Jinguang; Almao, Pedro R Pereira
The issue of borehole instability as seen in shale formation drilling is a major problem currently facing the industry. In recent years, deep exploration and more intensive development of hard and brittle shale gas reservoirs has shown that borehole instability is a widely occurring issue present in this type of strata. Because of the high frequency of catastrophic failures that accompany drilling in shale, this is an important technical problem to be solved. Furthermore, as a result of the recent shale gas revolution in North America, there has been a focus on integrated innovations and the development of multi-disciplinary fields and multiple technologies related to exploitation of this resource. As part of this ongoing multi-disciplinary approach, the advanced development concept known as geological engineering integration has been put forward. Rooted in the study of geodynamics and aimed at the problem of borehole instability in shale formations, this study explores and develops concepts related to geomechanics, including well location optimization, well trajectory optimization, pre-drilling formation pressure prediction and well wall stability prediction techniques. The meticulous modeling of 3D geomechanics is of great significance to the study of regional borehole stability in a shale formation. Therefore, a geomechanical modeling method for shale formations and its field application in Indonesia's Oilfield A is demonstrated in this thesis. As part of this modeling, a detailed study on the physical, chemical, and mechanical properties of shale in Oilfield A is carried out by laboratory mineral analysis, electron microscopy, cation exchange capacity and rock mechanics parameters. These experimental results form the cornerstone of the 3D geomechanical modeling of Indonesia's Oilfield A. Leveraging the Petrel software platform, the 3D geomechanical modeling method and principles of a shale formation are introduced in detail. Through a series of core tests, well logging data and seismic inversion data, the mechanical parameters of Oilfield A are described in depth, and the spatial distributions of important parameters such as 3D elastic modulus, 3D Poisson’s ratio and 3D pore pressure in this oilfield are established. 3D geomechanical models of heterogeneity, porosity and elastoplastic features are also established. Using the finite element method, the 3D stress distributions and 3D safe density windows of Oilfield A are also calculated. By establishing a 3D fine geomechanical model, various attributes are extracted along the borehole trajectory of well A-10, and a prediction of borehole stability is carried out. The drilling fluid density windows and well depth structure are also recommended, indicating the type and approximate depth of possible downhole complications. The numerical results of the minimum in-situ stress present in Indonesia's Oilfield A are calibrated by LOT (leaking of test) data. Importantly, the relative errors that exist between LOT data and the minimum in-situ stress are small, and the maximum relative error is only 0.02. The drilling period of well A-10 is 28 days. Compared with the average drilling period of 55 days in Oilfield A, the drilling period is shortened by 49 days as a result of the modeling studied. Importantly, no complex accidents occur in the drilling process. Through direct or indirect validations of all established 3D pore pressure, collapse pressure, rupture pressure, in situ-stress and other models, both a confident geomechanical model and a density window model are finally determined. The results show that the geomechanical model can accurately reflect the magnitude and heterogeneity of in-situ stress in a shale formation and can effectively solve the problem of regional borehole stability found in this formation.
Open Access
Application of Machine Learning in Methane Emissions Modelling
(2022-07) Luo, Ran; Gates, Ian; Hu, Jinguang; Chen, Nancy; Siegler, Hector; Wong, Ron; Idem, Raphael
Methane emissions reduction activities are vital for reducing greenhouse gas emissions in the oil and gas industry. The Alberta Energy Regulator (AER) has been collecting air quality data throughout the province since 1986. Although the AER data is available to the public, the analysis of this data has not been thorough. Furthermore, there are many papers on reported emissions, and as yet, it remains unclear how to use and analyze this time series data. Machine learning is a state-of-the-art and effective method to forecast and understand methane emissions from the oil and gas sectors. The research documented in this thesis examined the methane emissions data from multiple monitoring stations in time by building machine learning models for prediction performance comparison. The first study compared Autoregressive Integrated Moving Average (ARIMA), Fully Connected Neural Network (FC-NN), and Long Short-Term Memory (LSTM) neural networks regarding total hydrocarbon non-methane hydrocarbon in general. The second study expanded the research by adding climate variables to build LSTM models to learn deep feature relationships between temperature, wind speed and wind directions regarding the methane concentration data. The third study examines the prediction performance of Gated Recurrent Units, Stacked LSTM, LSTM and Bidirectional LSTM neural networks with different scales of data for training to compare forecasting performance. The analysis of the experiments reveals 1. The LSTM neural network model provides better predictive performance than the other methods. With respect to the data itself, the average methane concentrations measured at the majority of Alberta airshed stations are higher than the global methane average. In addition, the methane concentration data itself exhibits both increasing and decreasing trends depending on the station. 2. Extra ambient climate variables can improve the predictive performance of the LSTM model: temperature improves the predictive performance of the methane concentration more than that of wind speed and direction. 3. GRU performs better when trained with shorter datasets, while the Stacked LSTM and the LSTM slightly outperform GRU and BiLSTM when training with more historical data. Also, more training data does not necessarily mean a significantly better prediction model but more training time. The results provide insights for the use of Predictive Emissions Monitoring System (PEMS) for estimating methane concentration emission data.
Open Access
Assimilation of carbon and nitrogen by microbial mats from alkaline soda lakes
(2020-11-19) Liu, Yihua; Strous, Marc; Hubert, Casey R J; Tutolo, Benjamin M; Hu, Jinguang
Background:Soda lakes are extreme terrestrial ecosystems characterized by high pH, alkalinity, and sodium carbonate concentration. Despite the extreme environment, soda lakes host diverse microbial communities with high primary productivity, carried out by fast-growing phototrophic microbes such as cyanobacteria. In Goodenough Lake, a soda lake on the Cariboo Plateau in BC Canada, carbon isotope analysis indicated that the photosynthetic rate but not bicarbonate availability controlled carbon dioxide assimilation. However, the roles of individual cyanobacteria populations in carbon fixation remain unknown. Despite the rapid growth of microbial mat communities, common nitrogen sources, ammonium and nitrate, were detected only occasionally and in trace amounts in lake water. Mat communities may use alternative nitrogen sources like urea and dinitrogen gas as enzymes for urea assimilation and dinitrogen fixation were highly expressed.Objective:The objective is to measure carbon and nitrogen assimilation by microbial populations in mat communities.Approaches:Incubation of microbial mats from Goodenough Lake with heavy stable isotope labelled bicarbonate, and nitrogen sources, followed by isotope ratio mass spectrometry and proteomics.Results and conclusions:Over 90 different microbial populations were detected in microbial mat communities using proteomics. The sampled mat microbial communities were different from each other, even if samples were close together, but the most abundant populations were the same across samples. The two most abundant cyanobacterial populations exhibited different carbon fixation dynamics, and their abundance was negatively correlated, suggesting that they occupy different ecological niches. Among nitrogen sources, urea was consumed at the highest rate, followed by ammonia. The nitrate consumption rate was much lower, and the fixation of nitrogen was not detected. Urea was consumed mainly during the day. Rates for nitrate and ammonia consumption were similar during the day and the night.
Open Access
Band Gap Engineering of Zinc Cadmium Sulfide for Solar Driven Lignin Depolymerization
(2022-08) Goes Palma, Bruna; Hu, Jinguang; Kibria, Md Golam; Hill, Josephine Mary; Donald Gates, Ian
Biomass photorefinery for simultaneous production of value-added chemicals and sustainable hydrogen holds a promising perspective for achieving a negative carbon economy scenario. However, an insight into the light-driven lignin depolymerization approach is still lacking due to the highly complex structure and constitution. Lignin corresponds to 15-30% of biomass weight and is the major renewable source of aromatics in nature, and still, most of it is used as low-grade solid fuel. This work aimed to address this challenge by designing a series of Zn1-xCdxS solid solutions photocatalysts to study the depolymerization mechanism of lignin model compounds. Bandgap engineering strategy was used by changing the Zn/Cd ratio, which is a proven method to regulate the reaction pathway. Specifically, Zn0.5Cd0.5S (ZCS50) demonstrated the best substrate conversion to mono phenolic compounds achieving 27% conversion in 2 hours. It was also observed that different reaction pathways could occur depending on the photocatalyst's band structure, which directly affected product distribution. For instance, the application of Zn0.75Cd0.25S (ZCS25) led to the highest hydrogen yield, which is considered a side product with large importance for biorefineries, however it presented low overall depolymerization of lignin. Finally, the photocatalyst with better performance, ZCS50, was applied in the conversion of two different types of lignin to demonstrate its applicability. After 16h reaction, a wide range of monomeric aromatics were detected as products with simultaneous H2 production, but a low conversion was observed. Nevertheless, the present study could demonstrate excellent examples of biomass valorization by fine designing photocatalysts with room for future optimization.
Open Access
Biodegradable Cryogels for Adsorption and Electrochemical Oxidation of Organic Dyes
(2022-01-03) Abuhatab, Saqr S; Trifkovic, Milana; Hu, Jinguang; Kibria, MD G
The supply of clean water is becoming one of the greatest challenges of the 21st century. Therefore, sustainable and cost-effective measures must be developed and implemented to reduce water scarcity and prevent contamination of our water systems. This work aims to develop novel, environmentally-friendly 3D structured adsorbents for the removal of dissolved organic pollutants from wastewater. This was achieved by developing hydrophobic cryogels composed of TEMPO-oxidized cellulose nanofibers (TOCN) and electrochemically exfoliated graphene (EEG). TOCN/EEG cryogels were hydrophobized by incorporating oleic acid (OA) into the precursor gels. The cryogels were synthesized by mixing the components at 50 °C and 300 rpm for one hour, followed by freeze-drying the gels. The effect of OA loading, TOCN/EEG weight ratios (1:1 and 1:2), and initial solids content were systematically investigated through microstructural and rheological characterization of the precursor gels, and the morphology and adsorption capacity of the derived cryogels. The optimum OA loading for the hydrophobization of TOCN (HTOCN) was found to be 5 wt.%, at which the strongest gel was obtained. The initial solids content and EEG loadings in the precursor gel alter the morphology and adsorption capacity of the derived cryogels. The maximum adsorption uptake was increased by 180% for the 1:1 HTOCN/EEG weight ratio when the initial solids content in the precursor gels was increased from 1 wt.% to 4 wt.% compared to only 70% rise when the solids content was increased from 1.5 wt.% to 6 wt.% for the 1:2 HTOCN/EEG cryogels. The drop in the adsorption capacity enhancement of the 1:2 HTOOCN/EEG cryogels was attributed to the higher extent of EEG sheets aggregation at higher EEG contents. The electrochemical regeneration studies confirmed the ability to oxidize the methylene blue adsorbed onto the cryogels with minimal changes in the cryogels’ adsorption capacities after multiple regeneration cycles. The cryogel made of 1:1 HTOCN/EEG with 1 wt.% solids content gel was tested for 18 adsorption-electrochemical regeneration cycles with no observable mass loss and retained adsorption capacity confirming the feasibility of the proposed approach for developing adsorbents with long-term stability.
Open Access
Biomass and Municipal Solid Waste (MSW) Pyrolysis in a Bench-scale Drop Tube Reactor
(2023-05-30) He, Congxiao; Mahinpey, Nader; Hu, Jinguang; Siegler, Hector De la Hoz
Biomass pyrolysis has been recognized as a promising solution to address the challenges of energy demand and solid waste treatment in a renewable manner. However, the complexity of the process has limited the understanding of the link between theoretical modeling and engineering data, and commercial reactors are not yet available in the market. This thesis investigates the effect of biomass pyrolysis controlling parameters on a bench-scale drop tube reactor (DTR) and analyzes the behavior of a biomass-MSW mixture in TGA and DTR. The study aims to achieve three main objectives: (1) to modify the bench-scale DTR to enhance its efficiency, (2) to investigate the effects of temperature, carrier gas (N2) flow rate, and feedstock particle sizes on product yield and composition, and (3) to analyze the behavior of a biomass-MSW mixture in TGA and DTR reactions. To achieve these objectives, a series of experiments were conducted, and the products were analyzed for properties such as heating value, moisture, chemical composition, and yield. The results indicate that poor heat transfer limits the efficiency of the reaction, resulting in low liquid yields of 10-25%. The optimal reaction temperature is found to be around 500°C, as temperatures below this value result in unreacted biomass, while temperatures higher than 600°C led to gasification and the production of more syngas than bio-oil. An increase in nitrogen flowrate can improve heat transfer, but it also reduces the time for product condensation and collection. Smaller feedstock particles (<125 μms) are less affected by heat transfer issues, but they tend to agglomerate, which reduces bio-oil yield. The study also found that a temperature higher than 500°C is required to fully convert MSW mixtures. The study proposes several recommendations to address the heat transfer issue, including decreasing the reactor diameter, increasing the reactor length, and preheating the nitrogen flow to 400-500°C before it enters the reactor. Overall, the findings of this study have significant implications for the development of biomass pyrolysis technology and provide insights into the design and optimization of pyrolysis reactors for efficient and sustainable energy production and waste management.
Embargo
Biomass upgrading using enzyme-photocatalyst coupled catalytic systems (EPCS) based on NADH
(2023-04-04) Shirvani, Hamed; Hu, Jinguang; Donald Gates, Ian; Mahinpey, Nader
The development of sustainable methods to transform biomass into value-added products is crucial to realize the circular bioeconomy and mitigate the happening climate change. Photocatalysis and biocatalysis have emerged as two such methods in recent years. However, there are some significant obstacles for each one of them. Recently, inspired by the process of photosynthesis in nature, enzyme-photocatalyst-coupled systems (EPCSs) based on Nicotinamide adenine dinucleotide, reduced (NADH) has offered a new method that could potentially mitigate the drawbacks of each one of these methods and yield interesting synergy. In this study, we indicate the huge potential of zinc-blende (ZB) CdS as an outstanding catalyst for NADH regeneration in EPCSs with a rate of 13.1 mM/h, the highest reported in the literature, to the best of our knowledge. The catalyst shows decent stability for repeated cycles. In the second part, we report for the first time, the photoenzymatic reduction of levulinic acid, a major platform chemical derived from biomass. This serves as an example to expand the reaction spectrum of EPCSs based on NADH to enzymes and reactions beyond those that are frequently used. Almost 4 mM of levulinic acid could be reduced within 3 hours using the EPCS. During the course of this study, we also examined the importance of the sacrificial electron donor (SED) in the EPCSs, for the first time, and showed that our catalyst can accept various chemicals, especially glycerol, as SED. Besides, we report some unprecedented cross-inhibitory effects between SED and the enzyme which should be considered for future studies.
Open Access
Blending of Alberta Oilsands Asphaltene (AOA) with Polymers for Manufacturing of Carbon Fibres
(2024-01-24) Ge, Lin; Park, Simon; Cheng, Frank; Hu, Jinguang
Carbon fibres (CFs), characterized by a carbon content of 90 wt.% or above, derived from polymeric precursors, have garnered considerable interest since their discovery by Shindo in 1961. Their unique properties have led to widespread applications in sectors such as energy, aerospace, medical, and sports, where lightweight structures with excellent mechanical attributes are essential. Anticipated growth in demand for CFs over the next five years underscores the need for a substantial reduction in manufacturing costs. Currently, the main precursors for carbon fibre (CF) production are poly(acrylonitrile) (PAN), pitch, and cellulose. However, the substantial costs associated with these raw materials and production methods present significant challenges. Alberta oilsands asphaltene (AOA), the heaviest fraction of Alberta Oilsands Bitumen, stands out as a promising alternative precursor. It is estimated to be one to two orders of magnitude less expensive than PAN, and it possesses favorable attributes such as high carbon content, high aromaticity, and abundant reserves. Despite these economic advantages, the brittleness of AOA limits its processing capabilities, impeding the widespread utilization of CFs derived from AOA. Polymer blending proves to be an effective method for enhancing the physical and chemical properties of polymer materials. This process enhances the melt spinnability of polymers, resulting in improved manufacturing efficiency and enhanced mechanical performance. The effects of polymer blending on the spinnability of AOA, subsequent post-treatment processes, and the ultimate properties of carbon fibres remain poorly. Investigating the behaviors of AOA with and without polymer additives is crucial, as it can provide meaningful insights for the manufacturing of carbon fibres derived from AOA. The manufacturing process for CFs involves melting precursors and processing them into spun fibres, followed by post-treatment processes like stabilization, carbonization, and graphitization. Stabilization process accounts for the most cost and determine the properties of the final carbon fibre products. Better and more efficient stabilization processes account for better performance of carbon fibres. The conditions to stabilize and carbonize AOA fibres, behaviors, and mechanism of the post-treatment remain unclear. This research focuses on the potential of AOA as a CF precursor, emphasizing (1) preprocessing AOA feedstocks, (2) modifying AOA using polymer additives, (3) designing a melt spinning process for AOA fibres, and (4) employing conventional thermal treatment for post-treatment including stabilization and carbonization processes. Solvent preprocessing and strategic additive use aim to enhance the viscosity and spinnability of AOA. Polystyrene and poly(styrene-butadiene-styrene) are employed and compared as polymer additives for blending with asphaltene, with the anticipation of enhancing the performance of AOA. Melt spinning is proposed for preparing fibres tailored for various applications. Melt spinning system, including extruder, melt pump, and godets, are designed for processing asphaltene sample. Thermal post-treatment, including stabilization and carbonization processes, were performed for stabilizing and carbonizing AOA fibres with or without polymer additives.
Open Access
Cadmium Sulfide Based Catalysts for Photocatalytic Hydrogen Production and Lignin Photoconversion
(2023-12-13) Cheng, Xi; Hu, Jinguang; Shimizu, Kisa Hayashi, Shimizu; Du, Ke; Mahinpey, Nader
With the development of industrialization, the requirement for fossil fuels is becoming more and more huge, and as a consequence, the environment is degenerated by the combustion of fossil fuels such as coal and petroleum. There are two sources that are considered excellent candidates for solving this problem. One of them is hydrogen energy, green, pollution-free, renewable, and so on features that have attracted widespread attention. Another one, biomass, similar to fossil fuel in ingredients, is a widely distributed and renewable carbon-based substance. The usage of biomass has been proven to be an effective method to relieve the imbalance of the global carbon cycle and can even achieve a negative carbon economy scenario in the future. Among the composition of lignocellulosic biomass, the special structure makes lignin with bulk renewable aromatic groups possess the most potential for producing high-value chemicals. Achieving this promising conversion process with more moderate and green reaction conditions is a key point to propel the development of lignin conversion. Photocatalysis is a technology that realizes a series of catalytic reactions by directly using endless solar energy as a resource that has been recognized as a green and sustainable strategy. Therefore, applying photocatalysis to simultaneously achieve lignin conversion and hydrogen production will not only avoid harsh catalytic conditions but also achieve more efficient photoconversion of lignin. However, the high recombination rate between photogenerated electrons and holes, inefficient regulation of redox capacity, the photostability of photocatalysts, and the complex structure of lignin restrict the application of photocatalytic technology in lignin photo upgrading and hydrogen production by splitting water. Therefore, it is necessary to design photocatalytic materials with better performance to overcome the above problems to achieve more efficient hydrogen production and lignin photoconversion. In this work, cadmium sulfide (CdS) with good photo response ability and suitable bandgap position was selected as the base to study the photoconversion process of lignin and hydrogen evolution performance. The details are as follows: (1) A homojunction structured CdS with rich sulfur vacancies was successfully synthesized by the one-pot solvothermal method. Nanoparticle structured zinc blade phase CdS grew on nano prisms structured hexagonal wurtzite phase CdS. The perfect lattice matching between these two phases effectively guides the spatial separation of photogenerated electrons and holes. On the other hand, with the assistance of rich sulfur vacancies, the well-designed photocatalyst exhibited an unprecedented hydrogen production ability (835.8 μmol·g-1h-1) and value-added phenolic compounds were also generated by decomposing kraft lignin. (2) Using CdS as a base, nickel phosphide (Ni2P) was in-situ grown on the surface of CdS by high temperature phosphating strategy. The introduction of Ni2P created a synergistic effect between Ni2P and CdS, which not only improved the light response of CdS that enhanced photocarriers generation but also optimized the redistribution of photogenerated electrons, therefore, Ni2P/CdS exhibited a marvellous H2 evolution activity ca. 199.1 mmol·h-1·g-1 with lactic acid. Subsequently, replacing the substrates to lignin, cellulose, and hemicellulose, even the virgin biomass, significant amounts of hydrogen and value-added compounds are produced over Ni2P/CdS. In addition, density functional theory (DFT) calculation was also applied to reasonably reveal a possible catalytic pathway.
Open Access
Catalytic Conversion of Hydrocarbons to Valuable Chemicals and Methanotreating of Oxygenates to Fuel
(2023-05-02) Jarvis, Jack; Song, Hua; Chen, Zhangxing; Hu, Jinguang
The world is accelerating towards a gasoline fuel-free future and research focus is shifting towards alternative energy. The efficient use of remaining downstream fossil-fuel derived oil sources and effective treatment of renewable fuel sources has become imperative. Remaining fossil fuel sources like crude oil distillation and Fischer Tropsch products, which contain large amounts of n-paraffins, are no longer desirable as fuels because of their negative environmental impact. As such, they need to be valorized to valuable chemicals instead. This issue is addressed in this thesis by a thorough investigation of numerous hydrocarbons which can be found in such sources, including olefins, paraffins, and naphthenes. Their valorization to aromatics by heterogenous catalysis are investigated to provide a solution and use for remaining hydrocarbons derived from fossil fuels. Additionally, this thesis focuses on the treatment of bio-oils, a suitable fuel source replacement for fossil fuel-based fuels. Bio-oils can come from various sources, but they all have the same issue; they are high in oxygen content. This means energy density is low, acidity is high, and that the oil is thermochemically unstable. Hydrotreating is currently used to deoxygenate these feedstocks as it contributes to decarbonylation, decarboxylation, and saturation reactions. However, hydrogen is expensive, unavailable naturally, and environmentally unfriendly to synthesize as it is obtained predominantly from steam methane reforming. Direct use of methane for the deoxygenation of bio-oils (methanotreating) is investigated in this research. With carefully tailored catalysts, methane can be activated at low temperatures and pressures to provide hydrogen directly and contribute its carbon moiety to oxygen containing components in the product, highlighting the potential for methanotreating in the future of renewable fuels.
Open Access
Catalytic Heavy Crude Upgrading under Methane Environment
(2019-09-18) Chen, Shize; Song, Hua; Hu, Jinguang
As a rich and important resource in Canada, heavy oil has the disadvantage of being transportable by pipeline because of its high viscosity. It would be of great importance to upgrade the heavy oil for potential transportation and usages. Instead of the conventional hydrogen used in hydrocracking, this thesis focused on the heavy oil upgrading by methane. In this thesis, various catalysts have been developed for the upgrading. Detailed physical and chemical properties of several types of heavy oil and their upgraded products were well characterized such as viscosity, density, and total acid value, etc. A good performance and simple version of catalyst was optimized to be 1 wt% Ag-5 wt% Mo-10 wt% Ce/HZSM-5. After the upgrading, it was confirmed that the viscosity of some heavy oil could be considerably lowered to less than 300 cP to meet the requirements for pipeline transportation. In addition, a very difficult raw feed of oil mud was also included for the upgrading in this thesis, which proved this upgrading approach by using methane can be expanded to other heavy oil feeds. Furthermore, octylbenzene was used as a model compound to run the upgrading reaction to further understand the reaction mechanism. This thesis proved that our optimized catalyst could generally upgrade heavy oil at mild conditions together with methane instead of hydrogen. It showed potential industrial applications.
Open Access
Catalytic Light Crude Upgrading under Methane Environment
(2022-04-20) Li, Yimeng; Song, Hua; Du, Ke; Hu, Jinguang
The catalytic upgrading of light crudes is a very important aspect of the petrochemical industry. In recent years, the desulfurization of marine fuels and the deoxygenation of biofuels attract more attention due to the implementation of IMO 2020 sulfur emission regulation and the increased demand for renewable fuels. In this thesis, the catalytic desulfurization of marine gas oil and marine diesel oil, as well as the catalytic deoxygenation of vegetable oil are both conducted under a methane environment, and using various catalyst supports doped with several metal species. Besides, some control experiments are also conducted under a nitrogen environment while the other reaction conditions remain the same. This research aims at fine performances of reducing sulfur and oxygen content within the light oils and oil quality improvement while yielding coke at a low level through methane-assisted catalysis. Catalysts are screened to gauge those with the best performances. As a result, the methane-assisted desulfurization and deoxygenation techniques are proved to be feasible and achieve promising performances of sulfur or oxygen content removal. The participation of methane during the upgrading processes not only promotes the desulfurization and deoxygenation performances but also improves the quality of the product oils, and reduces coke yields.
Open Access
Characterization of heterogeneous fluid-fluid interfaces via microrheology
(2022-09) Roy, Teetas; Natale, Giovanniantonio; Harrison, Joe; Hu, Jinguang
Two-point microrheology was applied to a homogeneous (DPPC monolayers) and a heterogeneous (biofilms) interface of physiological relevance. For DPPC monolayers, both the longitudinal and transverse correlated motions showed a purely diffusional regime at different surface pressures. A good agreement between the single particle and two particle mean square displacements was observed. For biofilms of Pseudomonas aeruginosa at air-water interface, a transition from viscous to elastic regime was observed as the interface aged. The thermal cross-correlations of particles showed a strong scattering over the particle distances confirming the heterogeneity of the biofilms at air-water interface. This heterogeneity was also reflected in the mean square displacements where discrepancies are observed between results from one particle and two particle microrheology. Choosing one single particle as reference, a map of the spatial heterogeneity of biofilms was developed. The novel methodology provide insights into local micromechanics of complex interfaces that is not accessible with classical interfacial rheometry.
Open Access
Comparative study of acid- and alkali-catalyzed 1,4-butanediol pretreatment for co-production of fermentable sugars and value-added lignin compounds
(2023-03-28) Xie, Xinyu; Chen, Mingjun; Tong, Wenyao; Song, Kai; Wang, Jing; Wu, Shufang; Hu, Jinguang; Jin, Yongcan; Chu, Qiulu
Abstract Background Organosolv pretreatment is one of the most efficient methods for delignification and boosting biomass saccharification. As compared to typical ethanol organosolv pretreatments, 1,4-butanediol (BDO) organosolv pretreatment is a high-boiling-point solvent pretreatment, which can generate low pressure in the reactor during high temperature cooking that improves the operation safety. Although several studies showed that organosolv pretreatment can lead to effective delignification and enhancement in glucan hydrolysis, there has been no studies on acid- and alkali-catalyzed BDO pretreatment, as well as their comparison on promoting biomass saccharification and lignin utilization. Results It was shown that BDO organosolv pretreatment was more effective in removing lignin from poplar as compared with typical ethanol organosolv pretreatment under the same pretreatment conditions. HCl-BDO pretreatment with 40 mM acid loading led to 82.04% of original lignin removed from biomass, as compared to the lignin removal of 59.66% in HCl-Ethanol pretreatment. Besides, acid-catalyzed BDO pretreatment was more effective in improving the enzymatic digestibility of poplar than alkali-catalyzed BDO pretreatment. As a result, HCl-BDO with acid loading of 40 mM provided a good enzymatic digestibility of cellulose (91.16%) and the maximum sugar yield of 79.41% from original woody biomass. The linear correlations between physicochemical structure (e.g., fiber swelling, cellulose crystallinity, crystallite size, surface lignin coverage and cellulose accessibility) changes of BDO pretreated poplar and enzymatic hydrolysis were plotted to figure out the main factors that influenced biomass saccharification. Moreover, acid-catalyzed BDO pretreatment mainly brought about the phenolic hydroxyl (PhOH) groups formation in lignin structure, while alkali-catalyzed BDO pretreatment mostly led to the lower molecular weight of lignin. Conclusions Results indicated that the acid-catalyzed BDO organosolv pretreatment could significantly improve enzymatic digestibility of the highly recalcitrant woody biomass. The great enzymatic hydrolysis of glucan resulted from increased cellulose accessibility, which mostly associated with the higher degree of delignification and hemicellulose solubilization, as well as the more increase in fiber swelling. Besides, lignin was recovered from the organic solvent, which could be used as natural antioxidants. The formation of phenolic hydroxyl groups in lignin structure and the lower molecular weight of lignin contributed to its greater radical scavenging capacity.
Embargo
Controlling Nanoarchitecture of Biopolymer-based Flexible Electrolyte Membranes for Solid-state Lithium-ion and Sodium-ion Battery
(2024-08-29) Hassan, Md Mehadi; Lu, Qingye; Hu, Jinguang; Kibria, Golam
This thesis focuses on utilizing naturally abundant animal and plant-based biopolymers with diverse functionalities (e.g., chitosan (CH), cellulose acetate (CA), and polylactic acid (PLA)) for developing solid-state electrolyte (SSE) membranes and their applications in solid-state sodium-ion (ss-SIBs) and lithium-ion batteries (ss-LIBs). The nanoarchitecture of these membranes with porous morphology, is finely tuned and controlled using additive materials and facile fabrication techniques such as solution casting and electrospinning. In the first study, with a facile and cost-effective solution-casting technique, we fabricated a flexible, wearable, and thin film (~0.08 mm) solid polymer electrolyte membrane (SPEM) consisting of 2D-HGO, lithium bis(trifluromethanesulfonyl)imide (LiTFSI) salt, polyvinylpyrrolidone polymer binder, nano-SiO2, and CH biopolymer. In the composite SPEM, a unique arrangement of coherently aligned 2D porous HGO nanosheets was observed within the host CH polymer matrix, facilitating the creation of unique 3D-ion transfer pathways and exhibited impressive ionic conductivity of 2.76x10-3 Scm-1 at room temperature (RT= 23 °C). The second study utilized a distinct and versatile humidity-induced electrospinning method to fabricate porous fiber membranes composed of PLA biopolymer. The impact of porous morphology and the degree of alignment of the polymer fibers on the mechanical properties, surface roughness, wettability and ion conduction performance were evaluated using the electrospun membrane. In the third and fourth studies, a simple combination of electrospinning and solution casting was utilized to fabricate mechanically robust, flexible, free-standing, and thin-film CA and CH biopolymer-based randomly distributed electrospun composite electrolyte (ECE—third study) and aligned ECE (AECE—fourth study), respectively, where CA electrospinning fiber mat was casted by the CH and NaPF6 salt solution. RT Na+ conductivity of nano-porous AECE (4.12x10-4 Scm-1) demonstrated improved performance compared to that of randomly distributed nano-porous electrospun ECE (1.04x10-4 Scm-1). Further, RT specific discharge capacity of 98.1 mAhg-1 was attained at a 0.1 C rate, with a capacity retention of 93.4% over 120 charge-discharge cycles in the ECE-based hybrid full-cell assembly. Overall, the novel porous microstructure engineering strategies of nanocomposite SSE membranes, along with their comprehensive characterization and battery application findings, offer valuable insides for future designs of eco-friendly, flexible and wearable solid electrolytes for ss-LIBs and ss-SIBs.
Open Access
Correlating macroscopic rheological behaviour to microstructure of polymer flocculated Mature Fine Tailings (MFT)
(2021-01-28) Nagial, Rahul; Trifkovic, Milana; Hu, Jinguang; Yarranton, Harvey W
Northern Alberta holds over 178 million barrels of proven oil reserves in the form of oil sands. However, these deposits require extensive processing to extract the bitumen and result in generation of vast amount of tailings waste. The growing inventory of tailings represents a huge oil sands industry liability and an enormous environmental issue due to the associated GHG emissions and potential pollution of water bodies in their vicinity. Treatment of tailings with polymers (combined with other processes such as thin-lift drying, atmospheric fines drying) is one of the preferred methods for capturing the suspended solids and releasing the trapped water. However, the fundamental understanding of microstructure of the sludge formed after polymer treatment (i.e. flocculation) is still lacking. The microstructural information is vital for designing enhanced flocculation procedures. In this study, the microstructural and rheological parameters were utilized to understand the effect of processing conditions on the polymer flocculation of mature fine tailings (MFT). Laser scanning confocal microscope (LSCM) was used to capture 3-D images of sludge fabric and microstructural parameters (i.e. porosity and fractal dimension). Oscillatory amplitude sweep tests were performed to acquire rheological signature of the flocculated samples. The effect of overshearing as well as ionic strength of the polymer solution was investigated. It was shown that as the over-shearing time increased from 30 sec to 210 sec, the porosity of flocculated MFT increased from 18.77% to 31.26% and the fractal dimension decreased from ~2.903 to ~2.869. An explicit link between microstructural and rheological parameters was established, wherein bond breakage was quantified both at micro and macro scales. This information can be used to optimize energy input, increase water release and improve sediment strength in MFT flocculation procedures. Flocculation experiments done with process water showed that ionic strength of the process water utilized for polymer dissolution by itself does not change polymer configuration significantly (as compared to model process water) to change the strength of sludge appreciably. However, dilution of MFT resulted in lower sludge strength post flocculation, but these differences became negligible after aging the samples for 30 days due to consolidation effects.
Open Access
Development of a Cyanobacterial Biorefinery:Integration of Autofermentation and AnaerobicDigestion for Maximal Value Generation and Reduced Energy Inputs
(2023-01-25) Demirkaya, Cigdem; De la Hoz Siegler, Hector; Bassi, Amarjeet; Nowicki, Edwin; Mahinpey, Nader; Hu, Jinguang; De la Hoz Siegler, Hector
Cyanobacteria are ideal bio-factories for diverse biotechnological applications owing to their capacity to use solar energy and fix carbon dioxide into valuable bioactive compounds such as proteins and pigments. However, the economic viability of large-scale cyanobacteria cultivation is hindered by low volumetric productivity due to the slow mass transfer rate of CO2 into the culture media and significant CO2 losses. High pH (>10) and high alkalinity (>>10000 ?Eq L-1) can be used to improve CO2 delivery efficiency, as alkalinity enhances buffering capacity and improves CO2 mass transfer rates. Another important factor is the high cost associated with harvesting and energy intensive downstream processing methods. Thus, there is a need to develop integrated biorefinery strategies to maximize product recovery and value creation. To develop an economically viable cyanobacterial biorefinery, an alkaline cyanobacterial biomass production system was integrated with an autofermentation step, and a low temperature anaerobic digestion. Integration of these processes increase biomass productivity, trigger the release of valuable products, and enable multiple product recovery, nutrient recycling, and maximum energy production.Autofermentation was investigated as an energy-efficient and low-cost method to reduce pH to an optimal level (6.8–7.2) for the successful conversion of biomass to biogas and enable the production of hydrogen and organic acids simultaneously. High value-added products, hydrogen, and phycocyanin were also recovered from the process. Maximum total organic acid yield (60 % C mol/ C mol biomass) and hydrogen yield (326.1 ?mol/g AFDM) were obtained at the lowest biomass concentration after natural settling with no additional energy requirement.Three different inocula including digested manure, digested sewage sludge, and soda lake sediment were evaluated for energy efficient anaerobic digestion of cyanobacterial biomass at a low temperature (21 °C). Low temperature semi-continuous anaerobic digestion of fermented cyanobacterial biomass was carried successfully over 800 days with an average methane yield of 476 ml/ g VS by using soda lake sediment in duplicate 2 L digesters operating at 21 °C. Techno-economic assessment of the integrated process showed that phycocyanin is an important parameter for the economic value of this proposed alkaline cyanobacterial based biorefinery.
Open Access
Development of a Highly Efficient Amidoxime Functionalized Cellulose Adsorbent for Enhanced Separation of Vanadium using Acetate as a Complexing Agent
(2020-12-16) Bakuska, Derrick C. R.; Ponnurangam, Sathish; Roberts, Edward; Hill, Josephine; Hu, Jinguang
Vanadium is a strategic alloying metal that is used in high strength steel for varying applications, from high performance tools to earthquake resistant rebar. However, most vanadium is produced as a by-product of iron ore mining and this cannot meet increasing demand. Several new vanadium deposits, such as stone coal or carbonaceous shales, are suitable for low-cost hydrometallurgical extraction, which involves dissolving metal ions into solution for recovery. Currently, purifying vanadium ions from other dissolved metals is done with solvent extraction, which utilizes organic solvents and toxic extractants. In this work, a cellulose-based adsorbent material was developed that demonstrates high selectivity towards vanadium. Cellulose powder was functionalized with amidoxime functional groups via a simple two step heterogenous reaction, first adding nitrile groups to the surface followed by conversion to amidoxime. We developed a new hybrid approach for amidoxime functionalization on cellulose which uses fewer reagents under benign conditions, resulting in an adsorbent with high adsorption capacity for vanadium (70 mg g-1). Furthermore, by dissolving acetic acid as a complexing agent, the vanadium adsorption capacity of the adsorbent was found to increase by over a factor of 4, from 70 mg g-1 to 330 mg g-1. Additionally, the inclusion of acetate enhanced the selectivity towards vanadium over chromium, increasing from 2.0 ± 0.5 to 7.0 ± 0.2 at an acetate concentration of 0.5 M. When in competition with simple divalent metal ions such as copper or nickel, the adsorbent had a selectivity towards vanadium of more than 150, the lower bound of detectability. Following adsorption, vanadium was found to be easily recovered through elution with dilute sulfuric acid (0.5 M) which makes the adsorbent promising for future applications. The applicability of amidoxime functionalized cellulose was further demonstrated through the synthesis and utilization of functionalized cellulose beads. Using the insights gained from functionalizing cellulose fibers, cellulose beads were functionalized to yield a similar adsorption capacity per gram of cellulose while at the same time providing mechanical structure for use in an adsorption column. From adsorption column experiments, the kinetic performance was analyzed, and future optimizations were proposed.
Open Access
Development of a Redox Functional Nucleic Acid Integrated Electrochemical Biosensors for Wearable Applications
(2024-01-19) Janghorban, Mohammad; Pandey, Richa; Sanati Nezhad, Amir; Dalton, Colin; Hu, Jinguang
The corrugated nature of biosensor surfaces holds paramount significance in increasing their efficiency. This investigation scrutinizes the electrochemical performance of wrinkled and flat sensor surfaces. The textured surface is embedded with wrinkles about 1 μm in thickness and a wavelength of 32 μm. Testing the biosensors with a 1μM cortisol sample, the wrinkled electrode produced a fold change of 1.84±0.65 compared to the planar electrode, which produced a fold change of -0.11±0.07. Such observations underscore the heightened signal augmentation of the textured design. Additionally, specificity tests for the cortisol concatenated aptamer showed no false positive signal when tested with other interferent biomarkers. Initial trials utilizing cortisol mixed artificial sweat and DI samples demonstrated its performance in cortisol detection with an LOD of 59 nM in artificial sweat. The assay's reusability was tested through multiple incubations with a standard cortisol solution, indicating consistent performance over three cycles. Stability trials in artificial sweat revealed a stable initial response, maintaining stability for up to six hours before a notable decline after 72 hours. However, further experiments may be required to prepare the device for more practical applications. Attempts to regenerate the biosensor using UV light were unsuccessful, and further on-body and human sweat tests showed reduced effectiveness compared to laboratory conditions. While the initial development, optimization and testing of the biosensor achieved some successes, it also highlighted several areas requiring refinement, including but not limited to electrode design, standardization of testing procedures, and optimization of the heating process to enhance the functionality and reliability of the biosensor for its intended applications.
Open Access
Development of Bilayer Ionomer Coatings for Enhanced Carbon Dioxide Electrolysis Towards Multi-carbon Products
(2024-03-26) Rashid, Mohsina; Kibria, Md Golam; Ponnurangam, Sathish; Hu, Jinguang
In the realm of carbon neutrality, electrochemical CO2 reduction (eCO2R) stands as a pivotal technology for converting carbon dioxide into valuable multi-carbon (C2+) products, such as ethylene (C2H4) and ethanol (C2H5OH). Despite significant strides in achieving high Faradaic efficiency (FE) at industrial-scale current densities, persistent challenges like cathode flooding and (bi)carbonate salt accumulation in alkaline electrolytes continue to pose fundamental concerns. This study addresses these challenges by leveraging ion-conducting polymers (ionomers) to tailor the micro-environment mitigating cathode flooding and (bi)carbonate crossover and thus, enhance the local CO2 availability in eCO2R. Exploring the impact of cation and anion exchange ionomer layers, specifically Nafion and Sustainion XA-9, reveals that a cation infused ultra-thin bilayer configuration significantly reduces cathode flooding and salt accumulation by approximately 58%, outperforming commercial anion exchange membranes (AEM). Initially, a Single Layer Ionomer (SLI) using Sustainion XA-9 proves effective in mitigating cathode flooding due to the back convection of the thin hydrophobic cathode. Despite an impressive initial partial current density towards C2+ products (jC2+) of ~280 mA/cm2, challenges arise concerning (bi)carbonate formation and CO2 loss. Introducing an additional Nafion layer mitigates (bi)carbonate crossover, attributed to controlled OH- and K+ ion transport facilitated by the Nafion layer. However, the introduction of a Bilayer Ionomer (BLI) configuration results in lower C2+ selectivity due to insufficient OH- diffusion to establish the alkaline micro-environment essential for C2+ reaction pathways. Subsequently, incorporating cation infusion in this bilayer ionomer system (Cation Infused Bilayer Ionomer or CIBLI) proves beneficial, promoting C-C bond formation and creating a favorable micro-environment for selective C2+ product generation. The CIBLI system achieves a substantial high partial current density of approximately ~284 mA/cm2 towards C2+ products, maintaining stable eCO2R performance over 24 hours. The scalability of the directly deposited ultrathin CIBLI configuration offers a minimal conversion energy of 117 GJ/ton for C2+ products with an electrolyzer energy efficiency (EE) of 29% at 350 mA/cm2 current density. This one-step CO2 conversion process represents a promising advancement, emphasizing both efficiency and sustainability in carbon recycling technologies.