Acetic Hydrolysis Research Articles

Green process for xylo-oligosaccharide production from acetic acid hydrolysis of sugarcane bagasse by an integrated membrane technology and activated carbon adsorption.

Xylooligosaccharides (XOS), consisting 2-6 xylose residues, are a new type of prebiotic and functional oligosaccharides, and can usually be produced from the xylan-riched lignocellulosic biomass by acetic acid (HAc) hydrolysis, while the waste HAc was a problem to the environment. In this study, the main aim was to recover and reuse the waste HAc in XOS production. First, it was found that a temperature of 190°C and a hydrolysis time of 60min were favorable for XOS production by HAc hydrolysis, and the by-products xylose and furfural were the main inhibitors, hindering the reuse of the waste HAc. Then, xylose can be successfully decreased below to its inhibition concentration (i.e., 0.05g/L) by a two-stage NF90 membrane process under 25°C. After diafiltering the NF90 retentate using a triploid volution of a HCl-solution of pH 2.37, the total HAc recovery rate reached 82.87%. Moreover, after the recovered HAc solution was further treated with 25g/L activated carbon under 25°C and pH regulator with glacial HAc to 2.37 wherein the furfural concentration was below 0.015g/L, the recovered HAc solution can be successfully reused in XOS production without affecting the XOS production. Thus, in the developed integrated process, it replaced 82.87% of the pristine HAc with the recovered HAc and simplified extraction process of XOS by HAc hydrolysis on an industrial scale.

Comparative analysis of biopolymer films derived from corn and potato starch with insights into morphological, structural and thermal properties

Starch biopolymer films were prepared using the solvent casting method involving acetic acid hydrolysis and glycerol plasticization. This process facilitated a more uniform distribution of plasticizers within the starch matrix, enhancing the films' flexibility. Fourier-transform infrared (FTIR) and Raman spectroscopy confirmed the formation of ester linkages and structural changes in the biopolymer films, attributed to glycerol integration. The optimal formulation comprised 6% starch, 6.8% acetic acid, and 6.8% glycerol. X-ray diffraction (XRD) analysis revealed a reduction in crystallinity of the starch during film formation, enhancing flexibility. Second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) microscopy indicated that potato starch films had higher crystallinity compared to corn starch films. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that potato starch films exhibited lower gelatinization temperatures and higher thermal stability compared to corn starch films. Functional characterization demonstrated that higher starch content decreased water solubility and water vapor transmission rate, while increasing starch content improved the film's structural integrity. The films were hydrophilic, with static water contact angles indicating moderate wettability. Degradation studies showed that the films were stable in neutral and basic conditions but degraded under acidic conditions over time. The results suggest that potato starch films, with optimized glycerol and acetic acid content, offer improved flexibility, thermal stability, and structural integrity compared to corn starch films. Their performance in various conditions highlights their potential for specific applications, particularly where moisture and environmental stability are critical.

Biorefinery of red seaweed Palmaria palmata for production of bio-based chemicals and biofuels

The seaweed Palmaria palmata was used as feedstock for production of chemical/fuel precursors (acetone, butanol, ethanol) and biogas. Palmaria palmata consists of xylan as major cell wall polysaccharide, as well as galactan and glucan. First, the biomass was subjected to acid hydrolysis at laboratory scale to solubilise fermentable sugars using acetic or hydrochloric acid as catalysts. Differences were observed in composition and amenability to hydrolysis of seaweeds from different harvests. Highest saccharification yields were obtained using HCl (pH 1.7, 120 °C, up to 80 % of xylose). Hydrolysates were fermented to acetone-butanol-ethanol by Clostridium beijerinckii reaching yields of 0.28 g products/g consumed sugars. The process by-products (solids after acetic acid hydrolysis and spent fermentation broth) were used as feedstocks for anaerobic digestion showing biogas yields between 310 and 650 L/kg dry organic material when mixed in different ratios with sugar beet pulp. Subsequently, the hydrolysis and fermentation processes were upscaled up to a 100-L pilot volume where nanofiltration was implemented to increase sugar concentration and remove salts. While high monomeric sugar yields were replicated during upscaling, fermentation inhibition was observed in the upscaled process. This paper shows Palmaria palmata to be a suitable feedstock for the co-production of bio-butanol and biogas and highlights process development needs to desalt and detoxify seaweed hydrolysates prior to fermentation.

Identification, Synthesis, and In Vitro Activities of Antimicrobial Peptide from African Catfish against the Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli.

The global surge in multi-drug resistant bacteria, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli has led to a growing need for new antibacterial compounds. Despite being promising, the potential of fish-derived antimicrobial peptides (AMPs) in combating ESBL-producing E. coli is largely unexplored. In this study, native African catfish antimicrobial peptides (NACAPs) were extracted from the skin mucus of farmed African catfish, Clarias gariepinus, using a combination of 10% acetic acid solvent hydrolysis, 5 kDa ultrafiltration, and C18 hydrophobic interaction chromatography. Peptides were then sequenced using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The identified peptides were screened for potential antibacterial activity using Random Forest and AdaBoost machine learning algorithms. The most promising peptide was chemically synthesized and evaluated in vitro for safety on rabbit red blood cells and activity against ESBL-producing E. coli (ATCC 35218) utilizing spot-on-lawn and broth dilution methods. Eight peptides ranging from 13 to 22 amino acids with molecular weights between 968.42 and 2434.11 Da were identified. Peptide NACAP-II was non-hemolytic to rabbit erythrocytes (p > 0.05) with a zone of inhibition (ZOI) of 22.7 ± 0.9 mm and a minimum inhibitory concentration (MIC) of 91.3 ± 1.2 μg/mL. The peptide is thus a candidate antibacterial compound with enormous potential applications in the pharmaceutical industry. However, further studies are still required to establish an upscale production strategy and optimize its activity and safety in vivo.

Development and Application of a High-Throughput Method for the Purification and Analysis of Surface Carbohydrates from Klebsiella pneumoniae.

Klebsiella pneumoniae (Kp) is a Gram-negative bacterium, and a leading cause of neonatal sepsis in low- and middle-income countries, often associated with anti-microbial resistance. Two types of polysaccharides are expressed on the Kp cell surface and have been proposed as key antigens for vaccine design: capsular polysaccharides (known as K-antigens, K-Ags) and O-antigens (O-Ags). Historically, Kp has been classified using capsule serotyping and although 186 distinct genotypes have been predicted so far based on sequence analysis, many structures are still unknown. In contrast, only 11 distinct OAg serotypes have been described. The characterization of emerging strains requires the development of a high-throughput purification method to obtain sufficient K- and O-Ag material to characterize the large collection of serotypes and gain insight on structural features and potential cross-reactivity that could allow vaccine simplification. Here, this was achieved by adapting our established method for the simple purification of O-Ags, using mild acetic acid hydrolysis performed directly on bacterial cells, followed by filtration and precipitation steps. The method was successfully applied to purify the surface carbohydrates from different Kp strains, thereby demonstrating the robustness and general applicability of the purification method developed. Further, antigen characterization showed that the purification method had no impact on the structural integrity of the polysaccharides and preserved labile substituents such as O-acetyl and pyruvyl groups. This method can be further optimized for scaling up and manufacturing to support the development of high-valency saccharide-based vaccines against Kp.

Pickering emulsions stabilized by starch nanocrystals prepared from various crystalline starches by ultrasonic assisted acetic acid: Stability and delivery of curcumin

Ultrasonic assisted acetic acid hydrolysis was applied to prepare starch nanocrystals (SNCs) from native starches with different crystalline structures (A, B, and C types). The structure properties, morphology, Pickering emulsion stability and curcumin deliver capacity of both SNCs and native starches were investigated and compared. Compared with native starches, SNCs showed smaller size and higher crystallinity. The size of SNCs varied with different crystalline types, with C-type starch exhibiting the smallest SNCs (107.4 nm), followed by A-type (113.8 nm), and B-type displaying the largest particle size (149.0 nm). SNCs-Pickering emulsion showed enhanced stability with smaller emulsion droplets, higher static stability, and denser oil/water interface. SNCs-Pickering emulsions displayed higher curcumin loading efficiency (53.53 %–61.41 %) compared with native starch-Pickering emulsions (13.93 %–19.73 %). During in vitro digestion, SNCs-Pickering emulsions proved to be more proficient in protecting and prolonging the biological activity of curcumin due to their smaller size and better interfacial properties. These findings demonstrated the potential of SNCs for application in Pickering emulsion and delivery of bioactive components.

Experimental and kinetic modeling study of acetic acid oxidation and hydrolysis in supercritical water

The oxidation and hydrolysis of 0.11–0.14 M acetic acid in supercritical water (SCW) have been investigated at temperatures of 773–873 K and a pressure of 25.0 MPa in a flow reactor. CO and CO2 were the main products at oxygen-rich conditions. For hydrolysis experiments, CH4 and CO2 were produced in nearly equal amounts while the yield of CO was negligibly small. A detailed chemical kinetic model was developed by revising the kinetic parameters of key elementary reactions. The model performance was evaluated by comparison to the present data as well as data from literature. The model predicted the kinetic behavior of acetic acid oxidation fairly well, despite of slight underprediction of CO and overprediction of CH4. It also reproduced satisfactorily the species concentrations during acetic acid hydrolysis at high temperatures. Based on the model, kinetic analyses were further conducted to identify important elementary steps and to infer reaction mechanisms.

Use of isoperibolic reaction calorimeter for the study of reaction kinetics of acetic anhydride hydrolysis reaction: Effect of acetic anhydride and water ratio

Use of isoperibolic reaction calorimeter for the study of reaction kinetics of acetic anhydride hydrolysis reaction: Effect of acetic anhydride and water ratio

Biological properties of macroporous cryostructurate based on extracellular matrix components

Objective: to study the biological properties of macroporous cryostructurate from multicomponent concentrated collagen-containing solution (MCCS) as a promising matrix for the formation of cell- and tissue-engineered constructs.Materials and methods. A macroporous spongy carrier was obtained by cryostructuring of collagencontaining extract, prepared by acetic acid hydrolysis of chicken connective tissue (BIOMIR Service, Russian Federation). N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide (Sigma-Aldrich, USA) was used to make the cryostructurate water insoluble. The micromorphology of the sponge surface was studied using scanning electron microscopy. The cytotoxicity of the carrier was evaluated by reaction of the mouse NIH 3T3 fibroblast cell culture using automated microscope IncuCyte ZOOM (EssenBioscience, USA). Biocompatibility of the macroporous carrier was studied on cultures of human adipose tissue-derived mesenchymal stromal cells (AD-MSC), human hepatocellular carcinoma cell line HepG2 and human umbilical vein endothelial cell line EA.hy926. The metabolic activity of cells was determined using PrestoBlue™ reagents (Invitrogen™, USA). Cell population development during long-term cultivation of the cell-engineered construct (CEC) was assessed by fluorescencelifetime imaging microscopy over the entire surface of the sample using a Leica Dmi8 inverted microscope with Leica Thunder software (Leica Microsystems, Germany).Results. Optical microscopy and scanning electron microscopy (SEM) showed the presence of pores of different sizes in the resulting biopolymer material: large pores with 237 ± 32 μm diameter, medium-sized pores with 169 ± 23 μm diameter, and small-sized pores with 70 ± 20 μm diameter; large and medium-sized pores were predominant. The studied media did not exhibit cytotoxicity. Cell adhesion and proliferation on the surface of the material and their penetration into the underlying layers during long-term cultivation were observed. The highest metabolic activity of the cells was observed for human AD-MSC on day 14, which corresponds to the normal dynamics of development of a population of cells of this type. The functional activity of HepG2 cells – albumin and urea production – was shown in the liver CEC model.Conclusion. The good adhesion and active proliferation that were shown for the three cell types indicate that the resulting biopolymer carrier is biocompatible, and that the spread of the cells into the inner volume of the sponge and active population of the sponge under prolonged culturing indicates that this material can be used to create cell- and tissue-engineered constructs.

Effect of Fiber’s Size on Acoustic Absorption of Abaca Fiber/Epoxy Resin Composites

This study develops an absorber containing abaca fiber (Musa Textiles) and epoxy resin as a binder. The ability to absorb sound energy is related to the pore’s size present in the absorber. One of the methods to create porosity is to vary the length of fiber, which is 1, 10 mm, 15 mm and 20 mm. Before the fiber is cut to be certain length, it is treated employing NaOH alkalization and acetic acid hydrolysis. The characterization carried out includes density, morphology and absorption coefficient measurement using impedance tubes. Moreover, the fibers are measured for the density, then continued to determine the porosity and air flow resistivity using the Konzeny-Carman equation. The air flow resistivity parameter is utilized to determine the absorption coefficient using Delany-Bazley model. The value of the absorption coefficient from experiments using impedance tubes and based on theoretical analysis shows a similar trend curve. The results show that the fiber with the length of 20 mm exhibits the highest sound absorption coefficient.

Synthesis of 2-(5-(2-Aminopropyl)-2-hydroxyphenyl)acetic Acid, a Metabolite of the Drug 5-APB

5-(2-Aminopropyl)benzofuran (5-APB), also known as “Benzo Fury,” is a novel psychoactive substance (NPS) belonging to a new class of synthetic phenethylamines. It acts by disrupting serotonergic circuits as a serotonin–norepinephrine–dopamine reuptake inhibitor and is classified as an entactogen, similar to MDMA and MDA. Despite its popularity among users, recent toxicity events have been associated with the consumption of 5-APB and other benzofurans, highlighting the need for a better understanding of their pharmacodynamics and toxicity. One way to achieve this is by developing the synthesis of 5-APB metabolites as biomarkers of exposure. In this study, we present a six-step synthesis for one of the 5-APB metabolites, 2-(5-(2-aminopropyl)-2-hydroxyphenyl)acetic acid (1), involving methylation, formylation, Aldol-type condensation, reduction, and hydrolysis reactions. The compound was obtained in an overall yield of 11%.

Development of an optimal bilayered back propagation neural network (BPNN) to identify thermal behaviors of reactions in isoperibolic semi-batch reactors

It is very important to identify the thermal behaviors of semi-batch reactors (SBRs) in isoperibolic operating mode. First, a default bilayered back propagation neural network (BPNN) is selected from multiple recognition algorithms to achieve this task, which is suitable for three kinds of reactions with arbitrary reaction orders: homogenous, kinetically−controlled, and diffusion−controlled liquid−liquid heterogeneous reactions. Then, it is further optimized by Bayesian regularization and genetic algorithm (GA). The result shows that the optimal bilayered BPNN undoubtedly has better recognition accuracy and generalization performance. It is found that the accuracy of the two test sets are 98.8% and 100%, respectively. Subsequently, a simple and user-friendly standalone desktop application program (app) is designed to easily use the developed optimal bilayered BPNN. Finally, a case of acetic anhydride hydrolysis reaction with acetic acid solvent is studied to prove the good validity of the bilayered BPNN and the great reliability of the standalone desktop app.

Acidic hydrolyzed xylo-oligosaccharides bioactivity on the antioxidant and immune activities of macrophage

Xylo-oligosaccharides (XOS) prepared by the acetic acid hydrolysis of corncob were adulterated with many impurities including pigments, salts, and monosaccharides. Monosaccharides, acids, and most of the pigment were removed by a combination of decolorization, bipolar membrane electrodialysis and catalysis by Gluconobacter oxydans. These steps retain 90% of XOS in the acidolysis slurry. In this study, the effects of purified-XOS (PXOS) and crude XOS (CXOS) on the antioxidant and immune activities of macrophage were compared to verify the bioactivity of acidic hydrolyzed XOS, mainly focusing on the benefits of the purification process. PXOS was more effective in increasing superoxide dismutase activity and reducing malondialdehyde content, and thus had more potent antioxidant activity. In addition, PXOS could more efficiently promote the secretion of tumor necrosis factor-α, interleukin-6, nitric oxide, and interleukin-1β by macrophage. All these data, suggest that the purification process contributed to improve the immunomodulatory activity of XOS from acidolysis slurry.

Identification of Kinetics and Autocatalytic Behavior in Acetic Anhydride Hydrolysis Reaction via Reaction Calorimetry

In the fine and pharmaceutical chemical industries, the operation of highly exothermic reactions with the autocatalytic feature needs great caution. Identification of the autocatalytic behavior for a given reaction is of signification importance. In this work, first, an autocatalytic mathematic model for the acetic anhydride hydrolysis reaction is established. Then, a series of experiments at an approximate mole ratio of acetic anhydride to water with the solvent of acetic acid are designed to study this reaction by reaction calorimetry. Third, the six isothermal experiments are used to fit the kinetic constants, and the fitting result is very good and reasonable when compared to the published literature. Besides, it is proven that this reaction also has an autocatalytic feature at an approximate mole ratio of acetic anhydride to water. Last, the determined kinetic constants are also verified by two experiments operating under isoperibolic conditions.

An integrated process using acetic acid hydrolysis and deep eutectic solvent pretreatment for xylooligosaccharides and monosaccharides production from wheat bran

Organic acid hydrolysis for xylooligosaccharides (XOS) production from lignocelluloses provides the benefits of simple operation, rapid reaction and high XOS yield. However, no literature reported the XOS production from wheat bran (WB) by organic acid hydrolysis. In this paper, acetic acid (AA) hydrolysis was employed to produce XOS from WB. After AA hydrolysis (5 %, v/v, 170 °C, 20 min) of 100 g/L WB, the concentrations of X2, X3, X4, X5 and X6 were 2.4, 5.0, 1.9, 1.9 and 1.4 g/L respectively and the total XOS yield was 62.9 %, which was the highest among the previous researches. The arabinose yield reached 76.1 %. Then, AA-hydrolyzed WB was delignified by deep eutectic solvent (DES) pretreatment and the resulting residue had the glucose and xylose yields of 83.8 % and 54.8 %, respectively. This work offers a productive method for the conversion of WB into XOS, arabinose and glucose by AA hydrolysis and DES pretreatment.

Comparison of runaway criteria for prediction of different thermal behaviors in the acetic anhydride hydrolysis reaction performing in batch or semi-batch reactors

In this paper various runaway criteria for batch reactors (BRs) and semi-batch reactors (SBRs) have been used and compared to study the boundaries of different thermal behaviors for the acetic anhydride hydrolysis reaction with the solvent of acetic acid carried out in BRs and SBRs. It is shown that the majority of criteria for BRs could give relatively precise results, but the remaining minority are less accurate due to they all have some specific assumptions. Besides, the simulated results indicated that all the criteria for SBRs could accurately identify the transition point from TR to QFS behaviors in spite of that they give slight different results of transition point corresponding to NI and TR behaviors. The results can give an effective instruction for selection and usage of runaway criteria, especially in terms of effectiveness and applicability, to easily identify thermal behaviors in chemical industry.

Lignin removal improves xylooligosaccharides production from poplar by acetic acid hydrolysis

Organic acid hydrolysis is a potential method for xylooligosaccharides (XOS) production from lignocelluloses. However, the effect of lignin content on XOS production using organic acid hydrolysis remains unclear. In this work, the effect of delignification on XOS production from poplar by acetic acid (AC) hydrolysis was investigated. Hydrogen peroxide-acetic acid (HPAC) pretreatment catalyzed by 0–200 mM H2SO4 (HPAC0–HPAC200) removed 21.6–86.5% of lignin in poplar. HPAC pretreatment increased the xylan accessibility to AC solution, thus increasing the xylan removal during AC hydrolysis. An appropriate delignification (61.7%) resulted in the highest XOS yield of 37.4% by AC hydrolysis, increased by 29.9% compared to the optimal XOS yield (28.8%) from raw poplar. After alkaline post-incubation, the glucose yield of poplar residue rose from 57.1% to 78.6%. This work developed a delignification process to efficiently improve XOS and monosaccharides production from poplar.

Thermokinetic analysis of the stability of acetic anhydride hydrolysis in isothermal calorimetry techniques

Thermokinetic analysis of the stability of acetic anhydride hydrolysis in isothermal calorimetry techniques

Effect of Dilute Acetic Acid Hydrolysis on Xylooligosaccharide Production and the Inhibitory Effect of Cellulolytic Enzyme Lignin from Poplar

Effect of Dilute Acetic Acid Hydrolysis on Xylooligosaccharide Production and the Inhibitory Effect of Cellulolytic Enzyme Lignin from Poplar

Xylooligosaccharides production by optimized autohydrolysis, sulfuric and acetic acid hydrolysis for minimum sugar degradation production

Xylooligosaccharides (XOS) acts as a prebiotic, a food component that is not digested but stimulates the growth of beneficial microorganisms present in the intestine, such as bifidobacteria and lactobacilli, improving the health of the host. This study obtained XOS by comparing optimized conditions for acid hydrolysis and autohydrolysis of sugarcane bagasse, showing that is possible to produce XOS with minimum degradation of sugras. The acid hydrolysis process varied the parameters applying a 23 factorial design using 1–3% (m/v) sulfuric or acetic acid; a temperature of 100–160 °C and a reaction time of 15–55 min. The autohydrolysis was performed by 22 factorial design using the same range of temperature and time. The acetic acid hydrolysis of the sugarcane bagasse resulted in the conversion of xylan into XOS of 18.41% (m/m) with 1% (m/v) acid at 100 °C for 15 min, with xylopentaose/xylohexaose predominance. The hydrolysis of sugarcane bagasse with sulfuric acid resulted in 90.13% (m/m) of XOS with 2% (m/v) of acid at 79.55 °C for 35 min, with xylobiose prevalence. Autohydrolysis of bagasse resulted in 13.67% (m/m) xylan conversion into XOS at 172.4 °C for 35 min, with xylotetraose prevalence. The degradation sugar products were low for the conditions studied, with 0.31%, 0.16%, and 0.01% (m/m) of furfural using sulfuric, acetic, and autohydrolysis, successively. The results demonstrated that XOS with different degrees of polymerization can be produced applying specific pretreatment conditions of autohydrolysis, sulfuric, and acetic acid, with the minimum content of sugar degradation.