SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
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Item Restricted Photocatalytic Reforming of Lignocellulosic Feedstocks for H2 Production using TiO2-based Catalyst(The University of Manchester, 2024-06-26) Aljohani, Meshal; Fan, Xiaolei; Christopher, HardacreThe demand for energy has increased massively, mainly supplied by fossil fuels with significant carbon emissions. Hydrogen (H2) emerges as an efficient and clean energy carrier, having many promising characteristics (such as higher heating value and zero carbon emission after combustion) to replace fossil fuels. Solar-driven photocatalytic reforming (photoreforming, PR) of biomasses (such as cellulose and lignin) at ambient conditions presents a promising solution to produce renewable H2 due to the use of (i) biomass (widely abundant in nature, sustainable and theoretically carbon neutral) and (ii) solar energy (i.e., the sun as the largest energy resource driving the catalysis). Current PR processes mainly employ cellulose and bio-derived chemicals such as bioethanol. Comparatively, although it is very challenging, the direct use of lignin for H2 production via PR can be advantageous. This PhD thesis employed platinised TiO2 catalysts to study the PR of model aromatic compounds, purified and IonSolv-extracted lignin and cellulose, and raw biomass feedstocks to produce H2. While PR of aromatic compounds and lignin yields comparable and low levels of H2 production (4.8−6.6 μmol gcat−1 h−1) compared to cellulose (~62.8 μmol gcat−1 h−1) due to poisoning by intermediates, alternating between anaerobic and aerobic atmospheres resulting in a threefold enhancement in H2 production from the PR of lignin. In addition, Pt nanoparticles loaded on TiO2 using an in-situ photodeposition method enhanced the production of H2 significantly from the PR of lignin and aromatic substrates compared to ex-situ methods. The PR of isolated cellulose pulps from various bioenergy crops showed the highest H2 production, while derived lignin was the lowest. The variations in H2 production from bioenergy crops were found to be unrelated to the differing composition of cellulose, hemicellulose and lignin. The interaction strength of bioenergy crops with water, as observed by NMR relaxometry, was determined to influence H2 production, correlating with H2 production. In summary, this thesis investigates the challenges of lignin PR, proposes mitigation strategies, and identifies factors impacting the PR of lignocellulosic feedstocks for efficient H2 production.17 0Item Restricted The Influence of Iron and Lignin on Molecules of the Gastrointestinal Microbiome and Its Effect on the Conjugation of Carbapenem Resistance Plasmids(University of Birmingham, 2022-09) Alharbi, Abdullah; Buckner, MichelleThe gastrointestinal microbiome has acted a reservoir for antibiotic resistance genes by harbouring favourable conditions for the the conjugative transfer of resistance plasmids. Resistance against carbapenems, the last resort β-lactam antibiotics, has been on the rise and is mainly mediated by the spread of carbapenemase-encoding plasmids by Klebsiella pneumoniae. Dietary intake of iron and iron chelators can modulate the metabolic and microbial profile of the gastrointestinal microbiome. This project focused on investigating the influence that molecules produced by the gastrointestinal microbiome might have on the conjugation of carbapenem resistance plasmids in K. pneumoniae in reaction to iron and lignin supplementation. A fluorescence reporter system was used to determine the effect of iron and lignin co-supplementation to an ex-vivo colonic supernatant on the conjugation of an endemic carbapenemase-encoding plasmid called pKp-QIL. This was followed by plating-based conjugation assays which measured the frequency of conjugation of a plasmid from clinical isolate called pCPE16_3 in an iron and lignin co-supplemented ex-vivo colonic supernatant. This project has revealed that lignin has no effect on the conjugation of resistance plasmids in iron- available gastrointestinal microbiome.18 0Item Restricted Novel Lignin from Pine Wood Chips using Microwave-Assisted Organosolv Method(Saudi Digital Library, 2024-01-01) Aljuhani, Abdulhameed Hamed; Laybourn, AndreaThe microwave-assisted Organosolv method for lignin extraction from pine wood chips, conducted in temperatures between 165°C to 205°C, is thoroughly examined in this study. Critical insights emerge as the highest lignin yield, standing at 25.237%, is achieved at 205°C, while purity reaches its pinnacle at 88.3% when operating at 195°C. Moreover, an optimal residence time of 30 minutes was optimised to achieve maximum yields of 1.93% of lignin-rich material. Microwave technology demonstrates advantages such as rapid heating and environmental friendliness, underscoring the need for judicious temperature-energy balance. A robust lignin calibration curve has been established, facilitating the precise determination of lignin concentration, ultimately revealing a lignin content of 19.582% with an STD of ±2.3% in the initial pine wood chips. These insights could be used to promote the utilisation of lignocellulosic biomass sustainably, emphasising the significance of temperature management in practical applications.21 0Item Restricted Optimisation of biomass valorisation process(Saudi Digital Library, 2023-11-16) Saeedi, Asyel; Bagnato, GiuseppeThe project was presented through an external collaborator which is Biotech Services Limited. Mainly, the report aims to build a literature review to understand the existing lignin extraction processes and optimise them in accordance with the external collaborator’s requirements. Moreover, the main consideration in this biomass valorisation process is lignin. However, an investigation of biomass, lignin, and different feedstocks that can be used to extract lignin was made in this report. In addition to the different mechanical and chemical pre-treatment methods and their uses and effects on the extraction processes. With the aim of finding the optimum extraction process according to this project's requirements a thorough investigation of the current and latest extraction methods was done to gain the necessary information that will aid in the selection process. Moreover, a decision matrix technique was used with the aim of supporting the decision-making process, within the matrix many assessments were done to evaluate each process's safety and the impact they possess on the economy, environment, and community. Finally, based on the gathered information a complete analysis was performed to determine the best extraction method by comparing the results that each process achieved in each criterion of the decision matrix, with that and the fact that the criteria were based on stakeholder's requirements alongside the business needs, the optimum process out of the sixteen processes covered in this paper, and the one that was recommended to the client was the soda process which achieved the highest score of 49 in the decision matrix, followed by the DES and organosolv processes which scored 42 and 40 respectively. At last, came the kraft process which scored 34 in the decision matrix.15 0