Pretreatment Conditions Research Articles

Effects of Pretreatment Conditions and Branched Alkanes on Mo/MCM-41 Catalysts in Tandem Alkane Cross-metathesis for Non-hydrogen Polyolefin Recycling

Effects of Pretreatment Conditions and Branched Alkanes on Mo/MCM-41 Catalysts in Tandem Alkane Cross-metathesis for Non-hydrogen Polyolefin Recycling

Enhancing mesophilic methanogenesis in oleate-rich environments through optimized micro-aeration pretreatment.

Micro-aeration pretreatment has emerged as a promising technology for improving the performance of anaerobic bioreactors in the treatment of lipid-rich organic waste, particularly in mitigating the accumulation of long-chain fatty acids (LCFAs). Micro-aeration intensity is a critical factor in optimizing substrate hydrolysis and methanogenesis efficiency. In this study, optimal micro-aeration intensities for acetoclastic (30mL-air/g-COD) and overall methanogenesis (7.5 mL-air/g-COD) were initially determined using acetate and glucose as substrates, respectively. Subsequently, the addition of 0.5mM oleate (a typical LCFA) increased cumulative methane production by 22.1% when acetate was used as the substrate after 30mL-air/g-COD micro-aeration pretreatment. Conversely, it decreased cumulative methane production by 17.3% when glucose was used as the substrate after 7.5 mL-air/g-COD micro-aeration pretreatment. Additionally, the population of facultative hydrolysis microorganisms, such as the genus Pseudomonas, increased by 25.7% and 27.8% when acetate and glucose were used as substrates, respectively. Furthermore, the predominant methane-producing archaea, including the genus Methanosarcina, increased by 27.3% when acetate was used as the substrate, while the genus Methanosaeta decreased by 65.3% when glucose was used as the substrate. Collectively, these findings provide insights into the methanogenesis pathway under optimal micro-aeration pretreatment conditions, guiding future research in this field.

Effect of pretreatment temperature and atmosphere on the structure and adsorption properties of KOH-activated porous carbon for methylene blue removal

The synthesis and exploration of the properties of activated porous carbons – materials capable of capture of substances – increasingly attracts the attention of researchers nowadays. However, studies generally focus on absolute values of adsorption (or other) properties. Pretreatment of carbonaceous materials, whether at high or low temperatures, plays a key role in generating the precursor structure that is subsequently activated. Our research addresses a gap in the existing literature by exploring how pretreatment conditions influence the properties of activated carbon. For the first time, we show how both the pretreatment atmosphere (inert or air) and the temperature used affect the final structure and adsorption performance of polyacrylonitrile-based activated carbons. We found that as the pretreatment temperature increases, the specific surface area decreases, and the crystallite size grows. The sample without any pretreatment showed the largest surface area of 2298.3 m2/g and the best adsorption capacity for methylene blue, reaching 508.4 mg/g. However, it also possesses the lowest nitrogen content, affecting its suitability for certain applications. Additionally, pretreatment atmosphere influences surface characteristics, with inert pretreatment resulting in higher hydroxyl group concentration compared to air pretreatment. This difference in hydroxyl groups contributed to varied adsorption values, measuring 441.2 and 422.6 mg/g for the inert and air pretreated samples, respectively. This highlights the importance of both pretreatment temperature and atmosphere in tailoring the properties of activated carbons for diverse applications.

Synergistic Effect of Ultrasound and Osmotic Pretreatment on the Drying Kinetics and Antioxidant Properties of Satkara (Citrus macroptera): A Novel Preservation Strategy

This study aimed to investigate the effects of combined ultrasound and osmotic pretreatment conditions on the drying kinetics and antioxidant properties, such as total phenolic content (TPC), total flavonoid content (TFC), vitamin C content, and DPPH radical scavenging activity, of dried Citrus macroptera (Satkara) fruits. The fruit slices were immersed in 10% aqueous solutions of sucrose (S), glucose (G), and fructose (F) followed by an ultrasound treatment (40 kHz) for 10, 20, or 30 min. The samples were then dried in a convective oven at 50, 60, or 70 °C and 30% relative humidity with a constant air velocity of 3 m s−1. Four thin-layer kinetic models, namely Page, Newton, Henderson and Pabis, and Logarithmic, were evaluated. Among these, Page was found to be the most suitable model for predicting the drying kinetics. The pretreatment process accelerated the drying process significantly, reducing the drying time up to 6 h. Additionally, the pretreated samples exhibited improved retention of quality attributes, with vitamin C being best preserved in S solutions, TPC in both S and F solutions, TFC in F solutions, and DPPH in all three sugar solutions (S, F, and G). The application of ultrasound during osmotic treatment also had a positive impact on TPC and TFC retention, whereas it presented a negative effect on vitamin C when used for a prolonged duration and a negligible one on the antioxidant capacity. Overall, this study provides a new perspective on the drying kinetics of Satkara fruits, and their respective properties after drying, and being subjected to combined ultrasound and osmotic pretreatment. These findings will contribute to the development of effective and efficient drying methods suitable for industrial applications to produce dried Satkara products with a minimum quality degradation.

Adsorptive removal of aqueous MB molecules by spent lithium-ion battery cathode scrap

This study describes the application of cathode scrap obtained from spent lithium-ion batteries (LIBs) in the adsorptive removal of aqueous MB dye molecules. The physicochemical properties of the cathode scrap are thoroughly examined. High-resolution microscopic images display aggregation of small-sized particles in cathode scrap. Thermogravimetric analysis confirms the presence of stable metallic compounds (89% by weight) in cathode scrap above 600 °C. Surface charge analysis proves that negative surface charge of cathode scrap increases with the rising pH of the solution. The high negative surface charge facilitates adsorption of positively charged MB molecules onto negatively charged cathode scrap. The maximum quantity of MB adsorbed, as determined by the Langmuir model, is 80.42 mg/g at pH 12. Further, the material may be regenerated efficiently post-adsorption study without requiring any expensive solvent. Reusability studies demonstrate that the material maintains its activity even after five test cycles. The slight reduction in activity observed after each cycle may be attributed to the loss of some active sites into the solution during repeated use. The data clearly confirm that cathode scrap has the potential to remove various pollutants from wastewater with proper optimization of the pretreatment conditions.

Development of supported nickel-containing catalysts for methane tri-reforming: influence of pretreatment conditions

To improve the efficiency of catalysts for methane tri-reforming, the effect of pretreatment conditions of the Ce0.2Ni0.8O1.2/Al2O3 catalyst on its physicochemical and functional properties was studied. A set of methods (thermal analysis, low-temperature nitrogen adsorption, X-ray phase analysis, electron microscopy, temperature-programmed reduction with hydrogen) has established that varying the composition of the gaseous medium (oxidizing, inert, reducing) used during pretreatment at 800 °C allows one to adjust the textural, structural and redox characteristics of the catalyst and, as a consequence, its functional properties. It has been shown that in the series of compositions of the gas environment used in the pretreatment of the catalyst, oxidative → inert → reducing, an increase in the specific surface area and dispersion of the active component is observed, but a decrease in the resistance of the sample to reoxidation and coking. It has been established that the highest and most stable performance of the methane tri-reforming process (H2 yield – 86 % at CH4 conversion – 95 %) is provided by the catalyst after pretreatment in an inert environment due to the implementation of the optimal degree of metal-support interaction and an increase in the concentration of centers involved in CO2 activation.

Unraveling the Effects of Reducing and Oxidizing Pretreatments and Humidity on the Surface Chemistry of the Ru/CeO2 Catalyst during Propane Oxidation.

This work investigates the surface chemistry of the Ru/CeO2 catalyst under varying pretreatment conditions and during the oxidation of propane, focusing on both dry and humid environments. Our results show that the Ru/CeO2 catalyst calcined in O2 at 500 °C initiates propane oxidation at 200 °C, achieves high conversion rates above 400 °C, and demonstrates almost no change in activity in the presence of water vapor across the entire studied temperature range of 200-500 °C. Prereduction of the oxidized Ru/CeO2 catalyst in H2 significantly enhances its activity, though this enhancement diminishes at higher temperatures. Adding water to the reaction mixture boosts the low-temperature activity of the prereduced catalyst but decreases it at 300-400 °C. Several ex-situ analytical techniques in combination with the in-situ NAP-XPS analysis reveal that while exposed to oxygen, Ru nanoparticles on the ceria surface oxidize to form RuO2 below 200 °C and volatile RuO x (x > 2) at higher temperatures. The presence of water vapor in the reaction mixture leads to the transformation of RuO2 into ruthenium hydroxide at 200 °C, which, in turn, facilitates propane oxidation. At higher temperatures, the water does not have much influence on the oxidation state of Ru but slightly inhibits its evaporation from the surface. It is also demonstrated that Ru in the Ru/CeO2 catalyst exists predominantly in the Run+ (n > 4) oxidation states at typical VOC oxidation temperatures rather than the expected Ru4+ state.

Efficient Production of Fuel Ethanol via the Simultaneous Use of Distillery Stillage Biomass and Beet Molasses

The integrated production of ethanol fuel through the simultaneous use of various by-products and waste materials is an intriguing concept, as it maximizes the raw material potential while addressing the challenge of managing waste biomass from different technological processes. The efficient utilization of lignocellulosic waste depends on employing a pretreatment method that enhances the susceptibility of structural polysaccharides to hydrolysis. The aim of the study was to assess the possibility of the simultaneous use of corn stillage biomass and beet molasses as raw materials for the production of ethanol fuel. The research focused on optimizing the process conditions for the acid pretreatment of stillage biomass and the enzymatic hydrolysis of cellulose and evaluating the effectiveness of two fermentation strategies: SHF (Separate Hydrolysis and Fermentation) and SSF (Simultaneous Saccharification and Fermentation). The highest hydrolysis susceptibility was observed in biomass pretreated with 2% v/v H3PO4 for 30 min at 121 °C. The maximum glucose concentration of about 12 g/L (hydrolysis efficiency about 35.5%) was achieved even with the lowest enzyme dose, i.e., 7.5 FPU per gram of biomass. The yeast also showed high fermentation activity in media prepared from stillage biomass and molasses, producing about 50 g/L of ethanol regardless of the fermentation strategy used. The complete fermentation of carbohydrates assimilated by yeast confirmed the complementarity of the two raw materials used to prepare fermentation media, emphasizing the high potential of the proposed technological solution for ethanol fuel production.

Redefining the product portfolio of oilcane bagasse biorefinery: Recovering natural colorants, vegetative lipids and sugars.

Bioenergy crops have been known for their ability to produce biofuels and bioproducts. In this study, the product portfolio of recently developed transgenic sugarcane (oilcane) bagasse has been redefined for recovering natural pigments (anthocyanins), sugars, and vegetative lipids.The total anthocyanin content in oilcane bagasse has been estimated as 92.9±18.9µg/g of dried bagasse with cyanidin-3-glucoside (13.5±18.9µg per g of dried bagasse) as the most prominent anthocyanin present. More than 85% (w/w) of the total anthocyanins were recovered from oilcane bagasse at a pretreatment temperature of 150°C for 15min. These conditions for the hydrothermal pretreatment also led to a 2-fold increase in the glucose yield upon the enzymatic saccharification of the pretreated bagasse. Further, a 1.5-fold enrichment of the vegetative lipids was demonstrated in the pretreated residue.Re-defining green biorefineries with multiple high-value products in a zero-waste approach is the need of the hour for attaining sustainability.

Effect of pretreatment conditions on Fe-ZSM-5 properties and performance for Fischer–Tropsch synthesis

Our findings provide important insight into how pretreatment conditions on Fe-ZSM-5 affect iron particle size, phase, zeolite properties, and in turn, Fischer–Tropsch synthesis (FTS), guiding the selection of pretreatment conditions for Fe-ZSM-5.

Significantly improves the mechanical strength of aluminum alloy adhesive joint through electrochemical pretreatment in environmentally friendly medium

Adhesive bonding of aluminum alloys is extensively practiced to achieve optimum lightweight and reliable structures in the aerospace, automobile, and maritime industries. This paper represents the inaugural attempt to use neutral salt solutions as electrolytes for the electrochemical pretreatment of aluminum alloy bonding surfaces, with the aim of achieving high-performance bonding. The NaNO3 and NaCl solutions were selected carefully due to their non-toxic, easy to obtain, and inexpensive. Comprehensive experiments were conducted, and the specimen surfaces were characterized by advanced characterization methods before and after electrochemical treatment. The results demonstrated that the surface morphology of the treated aluminum alloy exhibited notable alterations, and the wettability, roughness, and chemical composition were effectively improved. Subsequently, aluminum alloy single lap joints were subjected to detailed examination in order to evaluate the effectiveness of the pretreatments on the bonding strength and fracture resistance. The results showed that under the condition of 5 A and 1 min, the specimen treated with NaCl solution demonstrated a notable enhancement in bonding performance, and its bonding strength increased by more than 200 % that of the untreated specimen joints. Moreover, this study integrates the characterization and experimental findings to provide a comprehensive analysis of the mechanisms underlying the deterioration or improvement of the bonding performances under different pretreatment conditions. This study demonstrates not only the extremely friendly characteristics to operators and environment, but also the technical advantages of low cost, high efficiency and good bonding performance.

Magnetic molecularly imprinted polymers coupled with UPLC-MS/MS for simultaneous detection of 19 steroid hormones in human plasma.

Steroid hormones constitute a group of hormones with molecular weights ranging from 200 to 400 daltons, characterized by their highly similar chemical structures. Each hormone within this group holds significant value for the diagnosis of various diseases. Accurate clinical measurement of the levels of each hormone is crucial for the diagnosis in clinical settings. Due to the wide variety and different properties of steroid hormones in organisms, sample pretreatment is the rate-limiting step for analysis and detection. In this paper, magnetic molecule-imprinting polymers (MMIPs) were prepared by surface imprinting on silicon coated magnetic spheres, and a detection method of MMIPs-combined with liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for 19 steroid hormones in plasma was developed and verified. Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy were used to confirm the formation of MMIPs materials, and the conditions of material synthesis and pretreatment of steroid hormones from plasma were optimized. The detection method was evaluated by using linearity, LOD and LOQ, precision, accuracy and matrix effect. The linearity of 19 steroid hormones was good, and the linear correlation coefficient was greater than 0.995. The coefficients of variation were 2.1-9.8 % and 1.1-9.7 % for intra-day and inter-day, respectively, and the recoveries were 83.6 %-118.2 % at low concentration, and the recoveries of medium and high concentrations were 94.6 %-113.8 % and 89.5 %-113.6 %, respectively. The coefficient of variation of Relative matrix effect of 19 steroid hormones measured in different batches of plasma was 2.1-5.4 % after isotope internal standard correction, which eliminated the influence of matrix effect.

Investigation on the Corrosion Behavior and Mechanical Properties of Nd-Fe-B Magnets Diffused by Electrophoretic Deposited TbF3

Grain boundary diffusion (GBD) technique was used for improving the magnetic properties of sintered Nd-Fe-B magnets by electrophoretic deposition (EPD) of TbF3 powders. In addition to the improvement of magnetic properties, the corrosion behavior and mechanical properties of diffused magnets were investigated. The results revealed that diffusing 0.8wt.% TbF3 induced a significant coercivity increment from 1091kA/m to 1926 kA/m, under optimal acid etching pretreatment, EPD and GBD conditions of 925°C/10h followed by 540°C/2h. Microstructural analyses showed that the core-shell structure formed by heavy rare earth substitution contributed to the coercivity enhancement. Diffused magnet exhibited an enhanced corrosion resistance ascribed to the existence of surface oxide layer and reduced interphase potential difference. The hardness of the magnet increased while the bending strength deteriorated after GBD using TbF3, due to the grain growth and the lattice diffusion of Tb during GBD. As a consequence, transgranular fracture and intergranular fracture were both observed from the diffused magnet, evidencing a more brittle behavior after diffusion.

Effect of pre-treatment conditions on the electrochemical performance of hard carbon derived from bio-waste.

Sodium-ion batteries (SIBs) offer several advantages over traditional lithium-ion batteries, including a more uniform sodium distribution, lower-cost materials, and safer transportation options. A promising development in SIBs is the use of hard carbons as anode materials due to their low insertion voltage and larger interlayer spacing, which improve sodium-ion insertion. Traditionally, hard carbons are made from costly carbon sources, but recent advancements have focussed on using abundant bio-waste, like coffee grounds. This approach reduces costs and helps manage global waste. This research investigates the electrochemical performance of bio-waste-derived hard carbons, which is significantly impacted by various pre-treatment methods. Techniques such as BET, XRD, TEM, and XPS are employed to examine the effects of pre-treatment variables, including washing solvents (organic, acidic, or distilled water), pre-oxidation temperatures, and post-heating processes. These factors influence the structural properties and purity of the hard carbon, impacting its effectiveness as an anode material in SIBs. A significant finding is a mesoporous hard carbon produced from coffee grounds that, after washing with distilled water, pre-oxidation at 150 °C, and thermal treatment at 1300 °C in argon, shows a 23% yield, a reversible capacity of 304 mA h g-1, and Initial coulombic efficiency of 78%. This study underscores the importance of pre-treatments in removing impurities and enhancing the material's sodium storage capabilities.

Unlocking the potential of vinegar residue: A novel biorefining strategy for amino acid-enriched xylooligosaccharides and humic-like acid.

In order to address the issue of low amino acid retention in the production of xylooligosaccharides (XOS) through hydrothermal pretreatment at high temperatures, a novel approach combining low temperature acid hydrolysis and enzymatic hydrolysis was employed. This innovative method not only allows for the production of amino acid-rich XOS, but also yields a valuable byproduct known as humic-like acid (HLA) from vinegar residue (VR). Under the optimal pretreatment conditions (89°C, 6h, 1.2% sulfuric acid), the yield of XOS was 19.88%. Furthermore, the hydrolyzate extracted from the acid pretreated VR had a content of 2.65g/L amino acids (corresponding to the retention rate of 82.0%), and the HLA yield of the sample was 10.51%. Comprehensive analyses, such as Fourier transform infrared spectroscopy, elemental analysis, total acidic functional group, and nuclear magnetic resonance were employed to examine the structure and composition of the produced HLA, indicating that it was similar to that of natural commercial humic acid (CHA) extracted from minerals. Through this innovative approach, the production of amino acid-rich XOS and HLA from VR offers a sustainable solution that not only addresses the issue of low amino acid retention but also maximizes the potential of VR as a valuable resource.

Efficient Separation of Poplar Lignin Using a New Carboxylic Acid-Based Deep Eutectic Solvents - Choline Chloride/Malonic Acid.

Separation of lignin by pretreatment is an important step in biomass refining. This study investigated how a novel dicarboxylic acid-based deep eutectic solvent (DES) - choline chloride (ChCl)/malonic acid (MA) - affected the process of separating lignin from poplar. At 140 °C for 3.0 h, with a ChCl: MA molar ratio of 1: 3.5, the ideal pretreatment conditions were met, and 91.8 % lignin was obtained. Even after five DES reuses, the consistent and effective separation efficiency of 77.9 % remains unchanged. The hydrolysate contained 92.4 % of the recovered lignin, with a purity of 94.6 %. Moreover, the regenerated lignin obtained through the new DES pretreatment exhibited a high phenolic hydroxyl content of 1.9 mmol g-1 and a low polydispersity index of 1.4. The results showed efficient and selective separation of lignin using the new binary carboxylic acid-based DES pretreatment was achieved. This research offers a novel approach to effectively separate wood fiber biomass and extract valuable lignin.

Optimized Ultrasound-Assisted Peracetic acid pretreatment approach for enhanced sugars and decreased inhibitors for bio-ethanol production from OPEFB

The Oil palm empty fruit bunch (OPEFB) constitutes the primary solid waste produced by the palm oil sector. This study aims to identify the best pretreatment conditions for increasing the sugars yield and lowering that of inhibitors in ultrasonic-treated OPEFB biomass using PAA. To study the individual and combined effects of pretreatment independent process variables, such as PAA concentration, sonication time, and temperature on the response variables glucose, xylose, arabinose, furfural, and HMF response surface approach, the central composite design (CCD) model was used. According to the findings from response surface analysis, the optimal conditions to obtain the highest sugar yield with the least amount of inhibitors were PAA concentration (10%), sonication time (120 min), and temperature (60ºC) for pretreatment, which produced 32.19, 15.83, and 5.92 g/L of glucose, xylose, and arabinose sugars, respectively, and about 1.86 and 3.2 g/L of furfural and HMF, respectively. The strong agreement observed between the experimental and predicted results. Detoxification with activated carbon, results in decreasing the inhibitory compounds in the hydrolysate. Subsequent fermentation studies demonstrated that hydrolysate with higher sugar content resulted in achieving a greater ethanol yield (67.5 g/L) than low ultrasonicated OPEFB (56.7 g/L).

Novel Ultrasonic Pretreatment for Improving Drying Performance and Physicochemical Properties of Licorice Slices During Radio Frequency Vacuum Drying.

To enhance the physicochemical quality, drying efficiency, and nutrient retention of dried Licorice products, this study investigated the effects of ultrasonic pretreatment on the radio frequency vacuum (RFV) drying characteristics, microstructure, and retention of natural active substances in Licorice slices. The ultrasonic time, power, and frequency were considered as experimental factors. The results showed that, compared with conventional RFV drying, ultrasonic pretreatment reduced the drying time of Licorice slices by 20-60 min. The Weibull model accurately described the moisture ratio changes under different pretreatment conditions (R2 > 0.9984, χ2 < 2.381 × 10-5). The optimal retention of polysaccharides, total phenols, total flavonoids, and antioxidants was achieved under pretreatment conditions of 30 min of ultrasonic time, 180 W of ultrasonic power, and 40 kHz of ultrasonic frequency. Furthermore, ultrasonic pretreatment preserved the internal cellular structure of Licorice slices, maintaining intact tissue cells and well-defined microchannels. However, a slight reduction in sample color was observed following ultrasound application. In conclusion, ultrasonic pretreatment significantly improved the RFV drying process for Licorice slices by enhancing drying efficiency, preserving active ingredients, and optimizing the physicochemical quality of the dried product. This study provides novel insights and methods for optimizing the drying process of Licorice, offering a foundation for further research and industrial applications.

Effect of Osmotic Dehydration Pretreatment on Melon (Cucumis Melo) Drying Time

Drying has been the most widely used method of dehydration since ancient times; however, its use generates high energy costs, due to the long duration of the process. On the other hand, the exposure of foods to high temperatures for long periods of time tends to considerably affect not only their organoleptic characteristics, but also their nutritional content. An alternative to these problems is osmotic dehydration, which allows generating a partial dehydration without deteriorating the food's properties. In this way, the food begins its drying process with a reduced moisture content, thus reducing the drying time, saving energy costs and avoiding exposing the food to heat for long periods of time. The methodology consisted of evaluating the osmotic dehydration process of melon at osmotic concentrations of 45 °Bx and 60 °Bx and immersion times of 120 and 180 minutes, to be subsequently dried at 50°C until reaching a minimum humidity of 15%. The osmotic dehydration tests demonstrated the significance (p &lt; 0.05) of the factors studied in water loss, weight loss and solids gain. Water losses between 48.393% and 68.204% were achieved, where drying time was reduced in a range between 23% and 46%. The treatment that generated the shortest drying time was the one that had as pretreatment conditions of 60°Bx and 180 minutes of immersion.

Production of 2,3-Butanediol From Ulva Pertusa Hydrolysate Using Hydrothermal Pretreatment Followed by Enzymatic Hydrolysis

This study aimed to evaluate the effectiveness of the marine macro-algae Ulva pertusa as a potential source of important chemicals, including 2,3-butanediol (2,3-BDO). This study examined how pretreatment conditions like liquid-to-solid ratio, reaction temperature, and reaction time influence the hydrolysis of U. pertusa biomass through hydrothermal pretreatment followed by enzymatic hydrolysis. Consequently, 23.44g/L (12.7% based on biomass weight) of reducing sugar was produced under hydrothermal pretreatment conditions (liquid-to-solid ratio of 6:1, reaction temperature of 165 °C, and reaction time of 15min), followed by enzymatic hydrolysis. During hydrothermal pretreatment, the sugar concentration peaked at 3.68g/L within the severity factor (SF) range of 3.5-4.4. During subsequent enzymatic hydrolysis, the sugar concentration remained stable until the SF reached 4.0. However, when SF exceeded 4.0, the sugar concentration rapidly decreased. The effectiveness of U. pertusa hydrolysate was evaluated via the fermentation of 2,3-BDO. Pantoea agglomerans successfully produced 2,3-BDO with a yield of 0.299g/g-sugar from U. pertusa hydrolysate. In summary, this study demonstrated the effectiveness of U. pertusa hydrolysate as a bioresource for producing biochemicals, including 2,3-BDO.