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PublicationOptimization of enzymatic hydrolysis for acid pretreated date seeds into fermentable sugars(Elsevier, 2020)One of the issues in the Middle East is that tons of date palm fruit waste are discarded by the date processing industries daily. Open burning to dispose agricultural residues can create environmental problems. To mitigate this issue, it is desirable to evaluate the potentials of the date palm wastes, such as date seeds, to be converted into value-added products. Date seeds were found to contain 27.34% lignin, 20.63% cellulose and 13.49% hemicellulose which can be hydrolysed into fermentable sugars. In this project, acid hydrolysis at 70 °C coupled with enzymatic hydrolysis proved to be able to deteriorate the lignin and cellulose in date seeds based on the physical changes observed with FESEM. Response surface methodology was used to determine the optimum condition; 120 FPU/g of cellulase for 6 h, at 45 °C. Under this condition, the maximum concentration of reducing sugars obtained from enzymatic hydrolysis is 31 g/L, making a total of 0.3 g/g of fermentable sugar obtained when combined with acid hydrolysis, equivalent to 81% from the theoretical value. Validation of the model indicated that there was no variance between the predicted (32.5 g/L) and observed values (31 g/L). This is the first work done on optimization of dates seeds into fermentable sugar under mild conditions.
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PublicationSynthesis of bio-oil-phenol-formaldehyde resins under alkali conditions(University of Zagreb, 2020)In the present study, bio-oil produced from vacuum pyrolysis of woody biomass has been investigated as a source of chemical feedstock. Bio-based resins were produced using the bio- oil with phenol substitutions ranging from 10 to 30 wt%. The conventional GC/MS analysis was carried out for the evaluation of the chemical composition of bio-oil. TGA, DSC and FT-IR analyses were used in order to characterize the bio-oil-phenol-formaldehyde (BPF) resins. The bonding quality of wood samples bonded with the BPF resins was investigated under different pre-treatment conditions. The highest shear strength was observed for the control samples bonded with the laboratory PF resin. As the amount of bio-oil was increased up to 30 wt%, the shear strength of the samples decreased from 12.08 to 11.76 N/mm2. The bonding performance was not negatively affected by the combination of bio-oil under dry conditions. According to TS EN 12765 standard, the relevant performance requirements for bonded samples under dry conditions must be at least 10 N/mm2. Relating to the standard, all samples bonded with BPF resins obtained the requirements for durability class C1. Under wet conditions, the bonding performance was negatively affected by the addition of bio-oil. However, the BPF resins fulfilled the durability requirements for C1, C2, and C3 specified in EN 12765 (2002).
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PublicationComparison between commercial and synthesised nano flower-like rutile TiO₂ immobilised on green super adsorbent towards dye wastewater treatment(Elsevier, 2020)The combination of a semiconductor metal oxide with green low-cost adsorbent materials has prompted the emergence of new natural resources having higher efficiency for treating dye wastewater. This study investigated the characterisation and performance of synthesised nano flower-like rutile TiO₂ (F–TiO₂) via the facile hydrothermal method and sintered commercial TiO₂ (C–TiO₂). Both C–TiO₂ and F–TiO₂ were immobilised on green super adsorbent basil seed. The details of the structural properties were analysed by Rietveld refinement and the deconvolution method to verify the purity. The synthesised F–TiO₂ immobilised on basil seed (B–F–TiO₂) was found to have optimum physical and morphology properties. Kinetic and equilibrium studies illustrated that the adsorption behaviour of B–F–TiO₂ could be better described by pseudo-second-order kinetic (chemisorption). The maximum uptake capacity (49.47 mg g−1) with the highest removal of methylene blue (98.95%) was obtained at an equilibrium time of 180 min following photocatalysis and self-cleaning. A large antibacterial ring area (1.83 mm2) was also obtained from B–F–TiO₂. The removal of methylene blue dye for B–F–TiO₂ increased as the recycle times increased (3 times) due to the increase of the surface area exposed to methylene blue as the weight of B–F–TiO₂ immobilised on basil seed decreased. This demonstrates that B–F–TiO₂ provides better potential to apply as a multifunction green super adsorbent for dye wastewater treatment compared to B–C–TiO₂.
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PublicationMass transfer performance study for CO₂ absorption into non-precipitated Potassium Carbonate promoted with Glycine using packed absorption column(MDPI, 2020)The removal of carbon dioxide (CO₂) at offshore operation requires an absorption system with an environmentally friendly solvent that can operate at elevated pressure. Potassium carbonate promoted with glycine, PCGLY, is a green solvent that has potential for offshore applications. For high solvent concentrations at elevated pressure, the by-product of CO₂ absorption consists of precipitates that increase operational difficulty. Therefore, this study was done to assess the CO₂ absorption performance of non-precipitated PCGLY with concentration 15wt%PC+3wt%GLY, which is known to have comparable solubility performance with MDEA. A packed absorption column was used to identify the CO₂ removal efficiency, mass transfer coefficient in liquid film, klae, and overall volumetric mass transfer coefficient, KGav. A simplified rate-based model was used to determine klae and KGav based on the experimental data with a maximum MAE value, 0.057. The results showed that liquid flow rates and liquid temperature gives significant effects on the klae and KGav profile, whereas gas flow rate and operating pressure had little effect. The CO₂ removal efficiency of PCGLY was found to be 77%, which was only 2% lower than 1.2 kmol/m3 MDEA. KGav of PCGLY is comparable with MDEA. The absorption process using PCGLY shows potential in the CO₂ sweetening process at offshore.
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PublicationLa₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ powder: a simple microstructure modification strategy for enhanced cathode electrochemical performance(Springer, 2020)A simple strategy of producing well-dispersed La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ (LSCF) cathode nanopowders that utilizes a dispersing agent is presented. The cathode nanopowder was synthesized by employing a dispersing agent-assisted sol–gel method. Two types of dispersing agents were applied as the synthesizing aids in this study which are the activated carbon (AC) and ethylene glycol (EG). The synthesized cathode powder was systematically characterized by X-ray diffraction (XRD), thermogravimetric analyzer (TGA), field emission scanning electron microscopy (FESEM), and BET surface area analyzer. The electrochemical properties of the fabricated cell were evaluated using electrochemical impedance spectroscopy (EIS). TGA analysis shows that both dispersing agents decomposed below 600 °C. The XRD analysis demonstrates that the single-phase LSCF perovskite is attainable at the calcination temperature of 700 °C for 5 h. FESEM results are in accordance with the BET analysis in which application of the dispersing agents produced more dispersed cathode powders and larger surface area. The electrochemical performances of the LSCF cathode modified with the AC and EG are respectively in the average of six- and eightfolds higher as compared with the pristine LSCF. The dispersing reaction of AC and EG and their influences on the cathode microstructure and performance are also thoroughly discussed.