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► The optimal water/cellulose molar ratio is 10/1. ► The optimal dissolution temperature and time are 120
°C and 0.5
h, respectively. ► The optimal reaction temperature and time are ...120
°C and 3
h, respectively. ► The maximum HMF and monosaccharides yield are 21% and 24.9%, respectively.
The effects of several critical factors including H
2O/cellulose molar ratios, dissolution temperatures (
T
dis), dissolution times (
t
dis), reaction temperatures (
T
rxn), reaction times (
t
rxn), and types of ionic liquids (IL) were investigated for cellulosic conversion. We optimized the reaction conditions as: H
2O/cellulose
=
10/1,
T
dis
=
120
°C,
t
dis
=
0.5
h,
T
rxn
=
120
°C,
t
rxn
=
3
h for 1-ethyl-3-methylimidazolium chloride (EMIMCl)-based system, and the maximum yield of 5-hydroxymethylfurfural (HMF) up to 21% could be achieved without adding extra catalysts. Another pyridinium-typed IL, EpyrCl, was also used in the cellulosic conversion, and the results showed a high selectivity toward monosaccharides. The information obtained in this study will benefit many biofuel-related applications.
A alimentação artificial tem por objetivo suprir a falta de alimentos (néctar e pólen), o xarope de açúcar é uma alternativa pra substituir a falta de néctar, sendo um alimento importante como fonte ...de energia para abelhas. Com isso teve por objetivo desse estudo analisar qual alimento mais adequado pra se fornecer as abelhas o xarope de açúcar ou xarope de açúcar invertido. Onde mostra, para obter o xarope de açúcar invertido a mistura deve se levar ao fogo e posteriormente é adicionado um ácido com função de se inverter a sacarose que é a constituição em básica de do açúcar em glicose e frutose, facilitando a metabolização pelas abelhas. Já o xarope de açúcar é um processo mais rápido onde a água com açúcar são agitados até total diluição do açúcar. O que preocupa com xarope de açúcar invertido é quando adicionado ácido na solução e deixando por mais tempo em fervura pode vir a forma o hidroximetilfurfural (HMF), um produto toxico para as abelhas, mas seguindo a recomendação da receita o alimento tem durabilidade por mais tempo. Em relação ao xarope de açúcar, após sua confecção o alimento deve ser fornecido no mesmo dia e dever ser consumida em um período máximo de 24 horas. Mas em comparação com os dois alimentos, ambos teve resultado satisfatório. Onde deixa em aberto um estudo mais detalhado comparando os dois tipos de alimentos.
Artificial feeding aims to supply the lack of food (nectar and pollen), sugar syrup is an alternative to replace the lack of nectar, being an important food as a source of energy for bees. With that, the objective of this study was to analyze which food is most suitable to provide the bees with sugar syrup or invert sugar syrup. Where it shows, to obtain the inverted sugar syrup, the mixture must be brought to the fire and then an acid is added with the function of inverting sucrose, which is the basic constitution of sugar into glucose and fructose, facilitating metabolization by the bees. Sugar syrup, on the other hand, is a faster process where the water with sugar is stirred until the sugar is completely diluted. The concern with invert sugar syrup is when acid is added to the solution and left to boil for a longer time, hydroxymethylfurfural (HMF) can form, a product that is toxic to bees, but following the recipe's recommendation, the food lasts longer time. With regard to sugar syrup, after its preparation, the food must be provided on the same day and must be consumed within a maximum period of 24 hours. But compared to the
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Zeolite-metal organic framework nanocomposite catalyst is developed for the synthesis of 2-((5-(hydroxymethyl)furan-2-yl)methylene)malononitrile from sucrose/fructose/glucose via ...one-pot cascade protocol. To accomplish this objective, zeolite Beta and Zr based metal- organic frameworks such as UiO-66 and UiO-66-NH2 are investigated for the independent steps, i.e. the conversion of sucrose to HMF and the Knoevenagel condensation of HMF and malononitrile. Beta zeolite exhibits the best activity in the sucrose to HMF conversion, whereas UiO-66-NH2 exhibits the best activity in the Knoevenagel condensation. Therefore, zeolite Beta and UiO-66-NH2 are integrated to develop a highly sustainable and efficient multi-functional catalyst for the conversion of sucrose to 2-((5-(hydroxymethyl)furan-2-yl)methylene)malononitrile via one-pot cascade reaction. The composite catalyst contains the optimum acidity and basicity for the cascade reaction. The presence of both the frameworks in the composite material is confirmed by using various physico-chemical characterization techniques. Further, the integration of both the active frameworks enhances the chemical stability and recyclability of the composite catalyst in the cascade reaction. This study demonstrates a unique approach to develop a synthesis strategy for the integration of inorganic zeolite and MOFs to achieve the desired activity, selectivity, and stability of the developed catalyst.
The present study intended to enhance the bioethanol production potential of wheat straw by reducing furfural and 5-hydroxymethylfurfural. The combination of 180 °C and 2% H2SO4 was optimized for ...pretreatment of wheat straw, which resulted significantly higher total soluble sugar. The maximum amount of furfural and HMF were observed when wheat straw pretreated at 180 to 220 °C, using 4% (v/v) dilute sulfuric acid. Amendment of pretreated acid hydrolysate using activated charcoal (5%, w/v) reduced up to 84.01% furfural and up to 76.42% HMF concentration in filtrate. The maximum ethanol yield of 5.29% (v/v) was obtained from charcoal amended acid hydrolysate, equivalent to 87.9% theoretical yield. Ethanol yield coefficient (Yps) was found to be 0.44 g ethanol g−1 sugar utilized. These results indicate that activated charcoal treated acid hydrolysate will be effective among the available technologies and could make lignocellulosic biomass-based ethanol production process economically viable by maximizing ethanol yield.
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•Wheat straw could be a potential feedstock for ethanol production.•Pretreatment at 180 °C temperature with 2% H2SO4 significantly raise sugar recovery.•Activated charcoal amended acid hydrolysate reduced furfural and HMF.•Ethanol yield (5.29% v/v) could make the process economically viable.
The dehydration of fructose is a crucial chemical process for synthesizing valuable chemicals and biofuels. This work explored an attractive strategy for harnessing lignocellulosic biomass through ...the catalytic conversion of fructose, yielding valuable 5–hydroxymethylfurfural (HMF) chemicals and biofuels. Sustainable and cost–effective methodologies for crafting catalysts via Laponite (Lap) modification to facilitate fructose transformation into HMF within a biphasic system comprising aqueous NaCl and tetrahydrofuran (THF) were examined. The phosphated Zr–grafted Si–enriched Lap (P/Zr–SiLap), as a solid acid catalyst, was synthesized through multiple straightforward steps involving mesoporous silica formation, Zr atom incorporation, and phosphation of pristine Lap. The P/Zr–SiLap catalyst proved to be a most promising catalyst, achieving an optimized HMF yield of 78.4% at 150 °C with a turnover frequency (TOF) for HMF production of 2.8 × 10−5 h−1. Evaluation of the P/Zr–SiLap demonstrated the catalyst's robust endurance, ensuring its high potential for efficient recyclability. The enhanced HMF yield (%) attributable to the P/Zr–SiLap catalyst was systematically correlated with its structure–activity relationship, which was elucidated through various advanced analytical techniques.
The phosphated Zr–Si Laponite effectively facilitated the conversion of fructose to HMF in a water–tetrahydrofuran biphasic system, demonstrating their potential as environmentally friendly catalysts. Display omitted
•Fructose dehydration is crucial for the synthesis of valuable chemicals and biofuels.•Appropriate acid sites were created by the incorporation of phosphate into Zr–Si Laponite.•Phosphated Zr–Si Laponite provides efficient 5-hydroxymethylfurfural yield from fructose.
•Pd–Au composition in alloys is crucial for FDCA formation.•Au and Pd–Au alloys are able to oxidize HMFCA to FDCA.•Cannizzaro reaction is involved in FDCA synthesis with some of the studied systems.
...This work deals with the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in water using supported Pd–Au nanoparticles. The active phase composition was shown to be crucial for FDCA formation. Indeed, both Au and Pd monometallic nanoparticles formed 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) under the studied conditions; however, with Pd nanoparticles HMFCA was not further transformed, while Au and bimetallic Pd–Au systems both catalysed its oxidation to FDCA.
The thermal treatment of Pd–Au catalysts considerably modified their catalytic activity, because Pd atoms migrated and concentrated onto the outer part of bimetallic nanoparticles. The resulting active phase morphology showed a different reaction path for FDCA formation compared to the untreated catalyst, with an important contribution of the Cannizzaro reaction. PVP-protected Pd–Au nanoparticles with different structures (either alloy or core-shell morphology) were synthesized and their reactivity tested in order to confirm the presence of different mechanisms for HMF oxidation, depending on whether the active phase preferentially exposes either Pd or Au atoms.
5-Hydroxymethylfurfural (HMF) is synthesized by the thermal decomposition of the sugars. Numerous types of food products are having a significant amount of HMF. Besides the thermal processing, other ...food processing methods (drying and dehydration, roasting, baking and storage of the product) are important factors for the synthesis of the HMF. HMF possesses different health effects including positive and negative health effects. Only few regulatory bodies have issued the guidelines and limits related to HMF. The present review has been planned to explore the HMF in terms of synthesis, occurrence, the effect of food processing, health effects and the safety guidelines.
•Green pepper extract presented high polyphenols content and antioxidant capacity.•Optimum extraction conditions were obtained by response surface methodology.•β-Cyclodextrin complexation protected ...functional natural compounds of green pepper.•Green pepper extract inhibited the production of hydroxymethylfurfural.•Antioxidant activity of green pepper extract correlated with anti-glycation effects.
Green pepper (Piper nigrum) presents high levels of functional compounds, with antioxidant and anti-glycation properties. Thus, the optimization of the β-cyclodextrin-based extraction of functional compounds from green pepper through Response Surface Methodology was performed. The optimum extraction conditions were assessed by optimizing total polyphenolic content (TPC) and antioxidant activity (DPPH• and FRAP methods). 15 mM for β-CD solution, 5 min of ultrasonication and 41 °C were the optimum extraction conditions, with the TPC of 24.9 mg GAE/mL and the anti-radical activities were 3.1 mg GAE/mL (DPPH• assay) and 0.45 mg GAE/mL (FRAP method). This natural extract obtained through eco-friendly techniques proved to be effective to reduce the formation of hydroxymethylfurfural, a glycation marker, at 70 and 80 °C. GPE presented higher TPC than black and white pepper. The relationship between the antioxidant and anti-glycation properties was confirmed and green pepper and can be proposed as a natural potential anti-glycation agent.
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