Conversion Yield Research Articles

Studies of polyol production by the yeast Yarrowia lipolytica growing on crude glycerol under stressful conditions

Crude glycerol, the principal by-product of biodiesel production process, was employed as substrate by three wild-type Yarrowia lipolytica strains (ACA-YC 5030, LMBF 20 and NRRL Y-323). Stressful conditions (low pH value = 2.0 ± 0.3, low incubation temperature T = 20 ± 1 °C, non-aseptic conditions) were employed. Interesting production of yeast biomass and polyols (viz. erythritol, mannitol and arabitol) was noted at pH = 2.0 ± 0.3 and T = 20 ± 1 °C. Strains failed to produce significant quantities of cellular lipid, while variable quantities of intra-cellular polysaccharides were produced. Fermentations under previously pasteurized media supported significant biomass and polyols production for most of the tested strains, while only one strain (NRRL Y-323), managed to produce polyols at media that were not previously thermally treated at all. The production of mannitol was favored at low initial glycerol (Glol0) concentrations, whereas higher Glol0 quantities favored the biosynthesis of erythritol. For the strain NRRL Y-323, highly aerated / agitated bioreactor trials showed different physiological profiles as compared to the respective flask experiments. Finally, in flask experiments with the strain NRRL Y-323 at high Glol0 amounts (≈140 g/L) at low medium pH (=2.0 ± 0.3), a significant production of polyols (=84.2 g/L) with the corresponding remarkable conversion yield on glycerol consumed = 62 % w/w was achieved. Practical applicationRenewable and biodegradable fuels, such as biodiesel, are safer and environmentally friendlier than the conventional petroleum diesel. Glycerol is a cost-effective substrate obtained as the main side-product from biodiesel production process and is currently being employed in the realm of Industrial Microbiology and Biotechnology to produce metabolic products with added value. Current research focuses on using glycerol as a starting substrate for biotechnological conversions aiming at producing, amongst other compounds, polyols, microbial biomass, citric acid, etc. from selected strains of the Generally Recognized Αs Safe (GRAS) yeast Yarrowia lipolytica. In the current investigation therefore, we examined the capacity of new wild-type non-extensively studied strains of this yeast to grow and assimilate this inexpensive substrate. Specifically, we have performed the acclimatization of the mentioned strains to stressful environments (i.e., low pH, low incubation temperature, non-aseptic conditions, etc.) and remarkable quantities of the added-value compounds (polyols, yeast mass, citric acid) were produced.

Propylene Production via Oxidative Dehydrogenation of Propane with Carbon Dioxide over Composite MxOy-TiO2 Catalysts.

The CO2-assisted oxidative dehydrogenation of propane (ODP) was investigated over titania based composite metal oxides, 10% MxOy-TiO2 (M: Zr, Ce, Ca, Cr, Ga). It was found that the surface basicity of composite metal oxides was significantly higher than that of bare TiO2 and varied in a manner which depended strongly on the nature of the MxOy modifier. The addition of metal oxides on the TiO2 surface resulted in a significant improvement of catalytic performance induced by a synergetic interaction between MxOy and TiO2 support. Propane conversion and propylene yield were strongly influenced by the nature of the metal oxide additive and were found to be superior for the Cr2O3-TiO2 and Ga2O3-TiO2 catalysts characterized by moderate basicity. The reducibility of the latter catalysts was significantly increased, contributing to the improved catalytic performance. This was also the case for the surface acidity of Ga2O3-TiO2 which was found to be higher compared with Cr2O3-TiO2 and TiO2. A general trend was observed whereby catalytic performance increased significantly with decreasing the primary crystallite size of TiO2. DRIFTS studies conducted under reaction conditions showed that the adsorption/activation of CO2 was favored on the surface of composite metal oxides. This may be induced by the improved surface basicity observed with the MxOy addition on the TiO2 surface. The Ga2O3 containing sample exhibited sufficient stability for about 30 h on stream, indicating that it is suitable for the production of propylene through ODP with CO2 reaction.

Enhanced microalgal hydrogen production subsisting on visible light TiO2 nanotubes photocatalyst pre-treated palm kernel expeller

The present study investigated the application of photocatalytic process using TiO2 nanotubes (NTs) photocatalyst as an effective pre-treatment method for palm kernel expeller (PKE) in increasing its biodegradability to enhance the microalgal hydrogen production via dark fermentation. A series of TiO2 NTs photocatalysts were synthesized via employing electrochemical anodization of Ti foil at various voltages each in different types of electrolytes (choline chloride-ethylene glycol (ChCl-EG), choline chloride-urea (ChCl-U), choline chloride-glycerol (ChCl-Gly)). Increasing trend of average NTs diameters at 26.14 ± 1.30, 73.01 ± 1.94 and 122.00 ± 13.32 nm was observed for 25, 30 and 35 V in synthesizing TiO2 NTs using suitable ChCl-EG electrolyte, respectively. The high 35 V had resulted in noticeable pore ruptures within this TiO2 NTs photocatalyst. The PKE pre-treated by TiO2 NTs photocatalyst anodized at optimum 30 V in ChCl-EG electrolyte had demonstrated the highest releases of biochemical oxygen demand (BOD5) and soluble chemical oxygen demand (SCOD) concentrations at 594 and 607 mg/L, respectively. Moreover, the microalgal efficiency of BOD5 conversion and hydrogen yield were also consistently maintained from third cycle of TiO2 NTs photocatalyst's reutilizations, signifying the stability of TiO2 NTs photocatalyst.

Experimental studies on renewable hydrogen production by steam reforming of glycerol over zirconia promoted on Ni/Al2O3 catalyst

Abstract The impact of ZrO2 as a catalytic promoter for nickel-based alumina supported catalysts has been studied for the hydrogen synthesis via glycerol steam reforming. Hydrogen is a promising contender of clean fuel and has a key significance in the quest of an environment-preservation, low emission and more sustainable energy approach. Glycerol is a by-product produced during production of biodiesel by trans-esterification of vegetable oils. The higher hydrogen content in glycerol makes it the potential renewable feedstock for hydrogen production. Steam reforming process is the best method available which is highest in energy efficiency and most importantly most economical. The production of catalysts was based on the wet impregnation and co-precipitation methods. The majority of the bulk and surface properties of different synthesized catalysts were considered and determined by several characterization techniques like X-ray diffraction technique, BET surface area and scanning electron microscopy. The performance of catalyst is based on glycerol conversion and hydrogen yield obtained from the steam reforming process taking place in the fixed bed catalytic reactor. The effect of different operating conditions like contact time, temperature, metal loading, and steam to glycerol ratio were investigated to produce maximum hydrogen and glycerol conversion. The results show that the incorporation of promoter 2 % ZrO2 improved the activity of Ni/Al2O3 catalysts significantly resulting 96 % glycerol conversion, 84 % hydrogen production and greater stability at contact time = 15 kg cat s/mol, temperature = 800 °C, steam to glycerol ratio = 9:1 mol/mol, and pressure = 1 atm.

Enhanced generation of hydrogen through hydrolysis of biochar-coupled magnesium: Analysis of the performance of biochar-support and the effect of metallic coating on biochar

Hydrolysis is regarded as a safe, efficient and adorable approach to generate hydrogen (H2) from magnesium (Mg) or Mg-based materials. In this work, biochar (BC) and ferric oxide (Fe2O3) coated biochar (magnetic biochar: MBC) were synthesized and applied along with Mg as catalysts for an enhanced H2 generation. The Mg-Xwt%Y (X = 1.0, 3.0, 5.0, 10.0, 15.0 and Y = BC, MBC) composites were prepared via ball milling and employed to investigate their hydrolysis performance through kinetics in seawater. Among employed dosages, 10.0 wt% contents exhibited the best hydrolysis performance. Mg-10.0 wt%BC and Mg-10.0 wt%MBC composites after 1 h ball milling generated 820.03 and 828.02 mL/g (conversion yields of 89.03% and 89.99%) H2 in 40 and 10 min, respectively. Further, 10.0 wt% of BC and MBC decreased the hydrolysis kinetic energy of Mg from 63.9 to 41.07 and 17.16 kJ/mol, respectively. MBC has better catalytic effects for Mg hydrolysis compared with those by BC could be due to relatively more functional groups, providing more channels for water molecules to interact with Mg resulting in subsequent enhanced hydrolysis. Hence, MBC increased the reactivity and galvanic corrosion of Mg as well as prevented the formation of passive layer of magnesium hydroxide (Mg(OH)2) on fresh surface of Mg. The performance of MBC-supported Mg in hydrolysis process is anticipated to be essential for the creation of environmentally-friendly portable H2 generators, the use of clean generation of H2 energy and the reduction of environmentally adverse emissions.

Attapulgite-based MCM-41 zeolite supported Ni-Nb catalysts for hydrogen production by acetic acid steam reforming

Acetic acid steam reforming (AASR) was generally considered as one of the promising technologies for hydrogen production. In this work, the L-lysine-assisted attapulgite-based MCM-41 zeolite (LAMZ) was successfully synthesized by using attapulgite-derived silicon source and the LAMZ-supported Ni-Nb (xNi-yNb/LAMZ) catalysts were prepared via conventional impregnation method. The effects of LAMZ and Nb content on regulating the microstructures and properties of Ni-based catalysts were investigated by various characterizations. Results revealed that the addition of L-lysine could contribute to forming more void structures and increasing specific surface area of LAMZ support, which was beneficial for promoting the dispersion of active sites and enhancing the metal-support interaction. Additionally, Nb optimized the reduction of Ni, increased the concentration of surface-active Ni species, improved the strength of surface Lewis acid and promoted the formation of Ni-NbOx interfaces. Amongst, 5Ni-1Nb/LAMZ exhibited the highest surface Ni0 sites and Ni-NbOx interfaces, which further induces the generation of VO generation and the flow of lattice oxygen. Therefore, the 5Ni-1Nb/LAMZ catalyst presented the highest acetic acid conversion (82.1 %) and hydrogen yield (69.9 %) at reaction conditions of reaction temperature = 750 °C, S/C = 3, WHSV = 19.96 h−1, furthermore, it almost no any inactivation during 55 h of AASR. Additionally, the characterization results of spent catalysts confirmed that 5Ni-Nb/LAMZ possess high coke resistance and anti-sinter capability.

Revolutionizing carbon chemistry: Solar-powered C(sp3)-N bond activation and CO2 transformation via newly designed SBE-Y cutting-edge dynamic photocatalyst.

A solvent-free sulfur-bridge-eosin-Y (SBE-Y) polymeric framework photocatalyst was prepared for the first time through an insitu thermal polymerization route using elemental sulfur (S8) as a bridge. The addition of a sulfur bridge to the polymeric framework structure resulted in an allowance of the harvesting range of eosin-Y (E-Y) for solar light. This shows that a wider range of solar light can be used by the bridge material's photocatalytic reactions. In this context, supercharged solar spectrum: enhancing light absorption and hole oxidation with sulfur bridges. This suggests that the excited electrons and holes through solar light can contribute to oxidation-reduction reactions more potently. As a result, the photocatalyst-enzyme attached artificial photosynthesis system developed using SBE-Y as a photocatalyst performs exceptionally well, resulting in high 1,4-NADH regeneration (86.81%), followed by its utilization in the exclusive production of formic acid (210.01 μmol) from CO2 and synthesis of fine chemicals with 99.9% conversion yields. The creation of more effective photocatalytic materials for environmental clean-up and other applications that depend on the solar light-driven absorption spectrum of inorganic and organic molecules could be one of the practical ramifications of this research.

Screening Bacterial Strains Capable of Producing 2,3-Butanediol: Process Optimization and High Diol Production by Klebsiella oxytoca FMCC-197

In the present investigation, the potential of various newly isolated strains which belong to the Enterobacteriaceae family to produce 2,3-butanediol (BDO), an important bio-based compound, was studied. The most interesting strain, namely Klebsiella oxytoca FMCC-197, was selected for further investigation. Commercial (raw) sucrose or molasses, which are important agro-industrial surpluses, were employed as carbon sources for most of the trials performed. Different fermentation parameters (viz. incubation te4mperature, utilization of different carbon sources, substrate inhibition, aeration) were tested to optimize the process. Fermentations under non-aseptic conditions were also conducted to investigate the potential of growth of the strain K. oxytoca FMCC-197 to surpass the growth of other microorganisms in the culture medium and produce BDO. Besides BDO production, in trials in which molasses was employed as the sole carbon source, significant color removal was observed simultaneously with the production of microbial metabolites. The very high BDO concentration ≈115 g L−1 was reported in approximately 64 h during a fed-batch bioreactor experiment, using sucrose and molasses as carbon sources at 30 °C, reaching a conversion yield (YBDO) of 0.40 g g−1 and a productivity rate (PBDO) of 1.80 g L−1 h−1, while similar results were also obtained at 37 °C. The strain demonstrated remarkable results in non-previously sterilized media, as it produced 58.0 g L−1 in 62 h during a fed-batch bioreactor experiment, while the potential to decolorize molasses-based substrates over 40% was also recorded. From the results obtained it is shown that this wild-type strain can be used in large-scale microbial BDO production using various raw materials as fermentative substrates. The wastewater derived after BDO fermentation by K. oxytoca FMCC-197 can be disposed relatively safely into the environment.

An In situ Proton Filter Covalent Organic Framework Catalyst for Highly Efficient Aqueous Electrochemical Ammonia Production

AbstractThe electrocatalytic nitrogen reduction reaction (NRR) driven by renewable electricity provides a green synthesis route for ammonia (NH3) production under ambient conditions but suffers from a low conversion yield and poor Faradaic efficiency (F.E.) because of strong competition from hydrogen evolution reaction (HER) and the poor solubility of N2 in aqueous systems. Herein, an in situ proton filter covalent organic framework catalyst (Ru‐Tta‐Dfp) is reported with inherent Ruthenium (Ru) sites where the framework controls reactant diffusion by suppressing proton supply and enhancing N2 flux, causing highly selective and efficient catalysis. The smart catalyst design results in a remarkable ammonia production yield rate of 2.03 mg h−1 mgcat−1 with an excellent F.E. of ≈52.9%. The findings are further endorsed with the help of molecular dynamics simulations and control COF systems without in situ proton filter feasibility. The results point to a paradigm shift in engineering high‐performance NRR electrocatalysts for more feasible green NH3 production.

Biodiesel Production by Biocatalysis using Lipids Extracted from Microalgae Oil of Chlorella vulgaris and Aurantiochytrium sp.

Microalgae are lipid-rich microscopic eukaryotic algae that can be used aiming for more sustainable biodiesel production by employing environmentally sound processes. The present work evaluates biodiesel production using a biocatalyst and two microalgae species as oil feedstock (Chlorella vulgaris and Aurantiochytrium sp.). Lipid extraction was performed using different techniques, namely, Soxhlet extractions (8 h — both species) with different solvents (hexane; hexane:ethanol (1:1 v/v); and chloroform) and room temperature hexane extraction (72 h — Aurantiochytrium sp.). Transesterification occurred for 24 h (150 rpm), using 30 % lipase loading. The results showed that high extraction temperatures cause microalgae oil degradation, focused on unsaturated fatty acids, leading to a lower biodiesel conversion yield. Using Aurantiochytrium sp. oil, it was possible to obtain around 55 %wt. of biodiesel conversion yield using oil extracted at room temperature (6:1 methanol:oil molar ratio), whereas for the oil extracted in the Soxhlet apparatus, the biodiesel conversion yield was around 30 %wt.. The low lipid content (1.0 %wt.) and biodiesel conversion yield (up to 25 %wt.) obtained using C. vulgaris show that the biomass used in the current study has low potential for biodiesel production. However, enzymatic biodiesel production from microalgae represents a promising avenue for sustainable energy generation, offering a renewable and environmentally responsible solution to the world’s energy needs. For that purpose, further studies, such as the optimisation of the extraction and transesterification of Aurantiochytrium sp. oil, should be carried out.

Attapulgite-based titanosilicate zeolite-supported Ni catalyst for hydrogen production from catalytic steam reforming of toluene

Catalytic steam reforming for hydrogen production was a viable tar removal technology. The key issue of catalytic steam reforming of toluene (tar model) for hydrogen production (CSRT) was the devise and development of advantageous catalysts. In this work, attapulgite-based titanosilicate zeolite (ATS) supported Ni-based catalysts was prepared and applied into CSRT. In addition, compared with the attapulgite (ATP), attapulgite-derived silicon source (HTP) and commercial TiO2, the effects of four different supports over the catalytic performance of Ni-based catalysts for CSRT were further investigated. The structural characteristics of the prepared catalysts were revealed by various characterization methods. Amongst, N/ATS appeared the highest toluene conversion (90.71%) and H2 yield (63.57%) during 4 h of CSRT reaction, which mainly attributed to its highest surface Ni0 molar ratio. Additionally, N/ATS revealed unique resistance to carbon deposition under harsh reaction conditions. This was mainly due to the synthesized ATS had larger BET and the highest hierarchical factor (HF) of pore structure which better promoted mass and heat transfer and its unique nanocluster assembled lamellar structure better anchoring the Ni metal and inhibited sintering, while its superior dispersion of weak acidic sites resulted in less carbon deposits. This work provided a probability for the preparation of economical attapulgite-based heteroatom zeolite to support Ni for hydrogen production via steam reforming of biomass-based oxygenates.

One-pot synthesis of acrylic acid from glycerol over SBA-15 supported heteropoly acid catalysts: Influence of mesoporosity and acidity

Heteropoly acids (HPAs) of the Keggin type exhibit substantial Brønsted acidity and are commonly utilized as acid catalysts, particularly in acrylic acid synthesis via glycerol oxydehydration. The primary goal of this research is to comprehensively assess the morphological and physicochemical properties of SBA-15 supported HPAs (H4SiW12O40.xH2O, H3PW12O40.xH2O, and H3PMo12O40.xH2O). The synthesized catalysts were characterized via physisorption analysis, XRD, SEM, FT-IR, NH3-TPD, and H2-TPR. Furthermore, the catalyst's catalytic activity in acrylic acid synthesis via single-step liquid phase glycerol oxydehydration was evaluated by correlating its characteristics with glycerol conversion and acrylic acid yields. The PW/SBA-15 catalyst exhibited the best performance, with the highest acrylic acid yield reaching 17.5% at 87.8% glycerol conversion. Given that the partial oxidation of acrolein to acrylic acid necessitates an optimal level of redox properties, the superior performance of PW/SBA-15 was characterized by high acid sites and moderate oxidative capabilities.

Enhanced lactide yield in catalytic conversion of L-lactic acid from passivation of external acidic sites on aluminosilicate Beta zeolites by coating siliceous Beta zeolite

The development of efficient Beta zeolite for conversion of L-lactic acid (L-LA) to L,L-lactide (L-LT) is in urgent need but still remains challenging. Herein, we reported an enhancement of the L-LT yield by passivation of external acidic sites on aluminosilicate Beta zeolites by coating pure silica Beta (Al-Beta@Si-Beta). The passivation of external acidic sites was strongly evidenced by in situ 2,4,6-tritertbutylpyridine (TTBP) adsorption FT-IR spectra, where the external acidic sites of Al-Beta@Si-Beta were effectively covered. In the tests for conversion of L-LA to L-LT, the Al-Beta@Si-Beta exhibited much higher L-LT yield than commercial microporous Beta zeolite, which is reasonably attributed to that the passivation of external acidic sites of the Beta zeolite significantly decreases molecular weight of the reaction intermediates, favoring for reduction of coke formation. Furthermore, this strategy is extended to passivate mesoporous Beta zeolite (Al-Beta-meso@Si-Beta). As expected, the Al-Beta-meso@Si-Beta displayed higher L-LT yield than the Al-Beta@Si-Beta because the presence of mesoporosity in the zeolite catalyst is favorable for mass transfer in the conversion of L-LA to L-LT. The strategy for coating pure siliceous zeolite might offer a new opportunity to develop highly efficient zeolite catalysts for the production of L-LT in the future.

Influence of Rh addition to transition metal-based catalysts in the oxidative steam reforming of acetic acid

In this work, the Rh-promotion to transition metal (Ni and Co) CeO2-supported catalysts has been studied for the first time on the acetic acid oxidative steam reforming. Characterization of the prepared catalysts confirmed the promoting effect of rhodium addition, allowing lower crystallite size which increases the number of available active sites to reactants, along with higher reducibility as evidenced by temperature-programmed reduction (H2-TPR). The influence of the reaction temperature on the acetic acid conversion and hydrogen yield was assessed. Co-based catalysts achieved better catalytic performance than Ni-based samples, almost complete acetic acid conversion, and hydrogen yields were close to the equilibrium values at temperatures over 500 ºC. On the other hand, tests at higher weight-hour space velocity evidenced the superior activity of Co-Rh/CeO2 sample. This sample showed good stability with almost complete acetic acid conversion after 25 h time-on-stream, decreasing only the hydrogen yield by 7% after the first 8 h along with a slight increase in the acetone yield of about 6%. This suggests that after the acetic acid ketonization, acetone steam reforming advanced to a lesser extent on the reaction mechanism because of long-term slight catalyst deactivation.

Enhanced catalytic performance for methane dehydro‐aromatization on Mo/HMCM‐49 prepared with citric acid

AbstractA simple citric acid (CA)‐ammonium molybdate co‐impregnation method was applied to prepare the Mo‐based MCM‐49 catalyst to ameliorate the dispersion of metallic Mo for methane dehydro‐aromatization reaction (MDA). The newly prepared catalyst has higher crystallinity and maintains the original morphology of zeolite, which proves that the addition of citric acid will not destroy the basic structure of the catalyst. Based on H2‐TPR, UV‐vis, NH3‐TPD and XPS characterization results, it can be corroborated that the introduction of citric acid changes the coordination state of Mo element. Brønsted acid sites can stabilize the monomeric Mo oxide species by increasing MoOx migration into the MCM‐49 zeolite pores channel after calcination, which may affect the distribution of active sites MoCx and thus improve MDA catalytic activity. The experimental results show that the Mo‐based MCM‐49 catalyst with nCA : nMo ratios of 1.0 has higher methane conversion (14.5 %) and aromatics yield (9.8 %). The combination of XPS, TG and Raman tests of the spent catalyst confirms that the newly synthesized catalysts produce less carbon deposition, thus improving the catalytic durability during the MDA reaction.

Effectiveness of viterna supplements in feed to speed growth and minimize feed conversion rate in Batak fish seeds (Neolissochilus thienemanni)

Batak fish (Neolissochilus thienemanni) is a type of fish endemic to North Sumatra which is categorized as endangered by the IUCN (International Union for Conservation of Natural) (IUCN, 2017). This fish is a type of fish that has quite high economic value but its growth rate is relatively slow. One way to stimulate the growth of this fish is to increase the nutrition of the feed by using viterna supplements. Viterna is a supplement derived from various natural ingredients which is useful for increasing the nutritional content of feed, increasing appetite, increasing endurance, stimulating digestive enzymes and accelerating fish growth. The aim of this research was to determine the effect of adding viterna supplements to feed on the specific growth rate (SGR) and Feed Conversion Ratio (FCR) of Batak fish fry. This research was conducted from July to August 2022 at the P2MKP Ampibi Padang Lancat Center, South Tapanuli Regency. Viterna supplements are given with 4 different treatments, namely P0 (Control), P1 (10 ml/kg), P2 (15 ml/kg), P3 (20 ml/kg). Fish were fed ad-satiation with a frequency of 3 times/day. The research was carried out for 50 days with sample data taken every 10 days. The results of the research showed that the highest specific growth rate of Batak fish seeds was in the P3 treatment at 0.65%. The lowest feed conversion yield (FCR) of Batak fish seeds obtained during the research was in the P3 treatment at 2.33.Keywords: Batak Fish, FCR; SGR; Viterna.

Two-step physico-biological production of xylooligosaccharides from sugarcane leaves

The production of xylooligosaccharides (XOS) from sugarcane leaves (SCL) presents high potential to the nutraceutical industries as SCL are cheap and readily available. In this study, a two-step process using hydrothermal pretreatments and enzymatic hydrolysis are developed and optimized for XOS production to obtain high conversion yield and product specificity. Two operation methods for hydrothermal pretreatments, parr reactor, and microwave reactor were compared to extract xylan from SCL. Two hemicellulose enzymes, hemicellulase Amano and xylanase (X2753) were then tested for enzymatic hydrolysis of extracted xylan to XOS. Conditions with high conversion yield after pretreatments were found at 180 °C for 30 min (parr reactor) and 800 W for 8 min (microwave reactor): producing 4.95 mg/mL (22.11 %w/v) and 3.49 mg/mL (15.61 %w/v) XOS respectively. Subjection of derived liquor from hydrothermal pretreatment to enzymatic hydrolysis produced a maximum of 9.42 mg/mL (41.87 %w/v) and 7.81 mg/mL (34.71 %w/v) of XOS for hemicellulase Amano and xylanase (X2753) respectively. The hemicellulase resulted in XOS with degree of polymerization (DP) of 2–5 for the various pretreatment conditions whereas xylanase yielded XOS of DP 2 to 4. However, a negative effect on enzymatic hydrolysis was observed for microwave-assisted pretreated samples. This study revealed that combination of physico-biological methods on SCL could result in high XOS yield with distinct degree of polymerization.

Application of olive mill waste-based biochar for improving wheat response to salt stress

The production of olive mill solid waste (OMSW) raises concerns due to its toxicity and negative environmental impact. However, by utilizing pyrolysis, OMSW can be converted into biochar, a carbon-rich material that detoxifies the waste and preserves its nutrient content. The OMSW-based biochar possesses alkaline properties (pH 9.6), low electrical conductivity (EC), high cation exchange capacity (CEC), a porous surface morphology, various surface functional groups, and high mineral content. This study assessed the influence of two concentrations (5% and 10%) of OMSW-based biochar on wheat plants' growth biomarkers and physiological characteristics subjected to salt stress conditions (150 mM NaCl). Findings of the study revealed that salt stress had deleterious effects on various parameters, including shoot height, fresh and dry weights of shoots and roots, relative water content (RWC%), membrane stability index (MSI%), photosynthetic pigments, and photosynthetic parameters such as the coefficient of the effective quantum yield of photochemical energy conversion of PSII (ØPSII), photochemical quenching (qP), and photochemical efficiency of PSII (Fo, Fm, Fv/Fo, and Fv/Fm). Furthermore, the levels of lipid peroxidation (MDA), hydrogen peroxide (H2O2), superoxide dismutase (SOD), and peroxidase (POD) activities significantly increased in stressed plants. On the other hand, applying both concentrations of OMSW-based biochar effectively improved the overall performance of wheat plants, irrespective of the presence of salinity. OMSW-based biochar is a promising strategy for promoting wheat growth in salt-stressed soil by improving various growth parameters and mitigating plant oxidative stress.

Catalytic evaluation of Pd-promoted Ni-Co/Al2O3 catalyst for glycerol dry reforming: Assessing hydrogen-rich syngas production, kinetics and mechanisms

The Pd-promoted Ni-Co bimetallic catalysts were prepared using ultrasonic-assisted impregnation, and their performance was subsequently assessed in a fixed-bed reactor. The catalyst's performance was evaluated in glycerol dry reforming (GDR) over a range of temperatures, from 873 K to 1173 K and reactant partial pressures ranging from 10 kPa to 40 kPa. The results indicated that as the temperature was raised from 873 K to 1073 K, there was a noticeable rise in both reactant conversion and product yield. However, beyond 1173 K, catalytic performance declined due to glycerol thermal cracking and sintering of the support at high temperatures, resulting in increased carbon formation. The presence of excessive CO2 was found to suppress glycerol adsorption on the catalyst surface, causing a decline in catalytic activity with a CO2 partial pressure of more than 20 kPa, regardless of reaction temperature. Additionally, excess CO2 were found to enhance the side reaction, particularly reverse water-gas shift (RWGS) that related to produce intermediate H2O. Similarly, the glycerol partial pressure was found to impact catalytic performance, with a decrease in performance beyond 20 kPa due to competing reactants between glycerol and CO2. According to the Langmuir-Hinshelwood kinetic mechanism, a dual molecular adsorption site for glycerol and CO2 was appropriate for this GDR reaction, with an associated activation energy of 47.3 kJ mol−1. The GDR reaction was identified as a kinetically controlled process due to its high activation energy, more than 25 kJ mol−1. The plausible mechanism of GDR over Pd-Ni-Co/Al2O3 occurred through the dissociative-type of adsorption of on active metallic sites of the catalysts for both reactant (glycerol and CO2). This was further facilitated by the bifunctional mechanisms based on H2 generated from dissociative adsorption involving both catalyst's basic sites and metallic active sites. This was ascribed to the highly dispersed and strong interaction between metal-support in Pd-promoted Ni-Co bimetallic catalysts.

Production and purification of xylooligossaccharides from sugarcane bagasse and antioxidant potential assessment for functional ingredient application in the food industry

Xylooligosaccharides (XOS) are a type of prebiotic non-digestible carbohydrate obtained from lignocellulosic biomass through the enzymatic hydrolysis of hemicellulose; a raw material that is generated as a by-product of activity in the agro-industrial sector. As the most representative of lignocellulosic materials, sugarcane bagasse (SB) is a source for XOS production. Owing to the high impurity XOS content produced by direct enzymatic hydrolysis of xylan extracted from SB, subsequent refining steps (clarification and purification) are essential for food-related applications. This study aimed to investigate the XOS production process using enzymatic hydrolysis of xylan. Additionally, a refining step using active carbon during the XOS process was also applied; and the evaluation of the impacts the process may have on XOS antioxidant activity for potential application in food products. Xylan extraction was evaluated with potassium hydroxide (KOH) in the concentration range of 5–18 %, achieving a xylan extraction efficiency (E) up to 85 %, under hydrothermal conditions, and using 12 % hydroxide concentration for 45 min. The enzymatic hydrolysis reaction was performed by applying an endo-1,4-xylanase (NS50030-Novozymes®) cocktail, and 4.5 g/L of substrate with prebiotic fractions (xylobiose and xylotriose) as the major products, with a conversion yield of 260.82 g XOS/Kg xylan. The desorption was systematically investigated after evaluating of the ethanol elution concentration, and achieved up to 45 % of XOS recuperation in the translucent solution from 40 % ethanol eluate (v/v); demonstrating a high potential for use as a functional ingredient in food applications.