Acetic Acid Pretreatment Research Articles

A combination of acetic acid and deep eutectic solvent pretreatment on poplar for coproduction of bioethanol, bio-oil and energy recovery

This work proposed an acetic acid (AC) pre-hydrolysis and a deep eutectic solvent (DES) post-delignification strategy for efficient fractionation of hemicellulose and lignin from lignocellulosic biomass, providing an easily hydrolyzed cellulose, which could be effectively converted to ethanol through semi-simultaneous saccharification and fermentation (SSSF) process. Results showed that, 11.20 kg xylo-oligosaccharides (XOSs), 19.91 kg ethanol and 25.89 kg lignin could be produced from lignocellulosic biorefinery based on the AC-DES pretreatment of 100 kg poplar. In addition, the lignin recovered from DES showed the potential as feedstock for production of hydrocarbon enriched bio-oil by pyrolysis. Higher heating values (HHV) of 27.19 MJ/kg and 31.56 MJ/kg for oil were measured, after pyrolysis of DES lignin and DES lignin/low-density polyethylene (LDPE) with ratio of 7:3, respectively. Finally, mass balance and energy analysis revealed that, lignocellulosic biorefinery based on AC-DES combined pretreatment to co-produce XOSs, bioerthanol and DES lignin could achieve an energy recovery of 78 %.

Electrochemical Oxidation of Glyphosate Using Graphite Rod Electrodes: Impact of Acetic Acid Pretreatment on Degradation Efficiency

The uncontrolled use of herbicides such as glyphosate (GLY) (N-phosphonomethylglycine) in agricultural production has resulted in its presence in water bodies and in negative impacts on the environment and public health. On the frame of understanding the interaction between GLY and graphite rod surfaces, this contribution relies on the study of electrochemical responses of different GLY concentrations by cyclic voltammetry under both open and closed-circuit conditions. Furthermore, the effect of the electrodes’ electrochemical pretreatment with acetic acid on the double-layer capacitance and the subsequent surface functionalization of the graphite rod materials were evaluated. The increment in GLY concentration showed a decrease in the electrochemical oxidation response associated with the adsorption of the contaminant on the surface of the graphite rod electrode and the concomitant blockage of the active sites. Electrochemical pretreatment of the electrodes with acetic acid and GLY concentration play crucial roles in electric double-layer formation due to their ability to interact with both positive and negative electrical charges. By means of optical microscope observations and Fourier Transform Infrared Spectroscopy analysis, it was possible to detect the formation of oxygenated functional groups on the electrode surfaces after the electrochemical pretreatment. Through a 23 factorial design analysis in repetition, the factors significant in the degradation of GLY were identified. The high degradation of GLY with the pretreated electrodes can be attributed to the preferential adsorption of the zwitterionic molecule at the interface, which allowed great direct oxidation of the contaminant on the anode’s surface.

PH-controlled acetic acid pretreatment for coproduction of low degree of polymerization xylo-oligosaccharides and glucose from corncobs

Acetic acid (HAc) pretreatment has been widely used for the production of xylo-oligosaccharides (XOS), requiring harsh reaction conditions because XOS are intermediates during the xylan degradation process. This complexity makes the pretreatment process difficult to regulate. In this study, a pH-controlled HAc pretreatment using sodium hydroxide (NaOH) was proposed to enhance the yield of XOS and to reduce its degree of polymerization (DP) from corncobs (CC). By employing this method (0.3 M-2.7), 49.7 % of XOS with DP 2–6 was obtained, alongside a notable increase in the fraction of XOS with DP 2–4 (10.1 g/L). This performance significantly surpassed that of the HAc alone (0.3 M). Moreover, the glucose yield from CC via pH-controlled HAc pretreatment was as high as 93.1 % after 72-h enzymatic hydrolysis. These results suggested that the pH-controlled HAc pretreatment could be a promising strategy for the coproduction of low-DP XOS and fermentable sugars.

Effective pretreatment of microwave combined with acetic acid soaking on oil absorption and quality of fried potato chips.

This study applied a combined pretreatment method involving microwave and acetic acid (AA) soaking to monitor oil absorption of fried potato chips based on texture and microstructure characteristics. Results demonstrated that medium-low microwave combined with 4 h of AA soaking significantly improved the texture profile of potato chips, and reduced oil content by approximately 53.25%. Higher microwave intensity led to greater surface roughness of samples, whereas AA soaking for 1-4 h effectively reduced surface roughness. The decrease in Fm and Nwr, along with the increase in Fwr and Wc with prolonged AA soaking time for 1-4 h indicated that medium-low microwave intensity combined with AA pretreatment enhanced hardness and brittleness of samples. Microscopic examination of cell structure revealed that this combined pretreatment facilitated pectin gelation between the cell walls of potato chips, resulting in a more intact cell structure with fewer gaps. Additionally, the color of pretreated potato chips became brighter. The combination of medium-low microwave intensity and AA soaking pretreatment resulted in a decrease in the oil content and improved the texture profile of fried potato chips. This study provides new strategies and insights for producing low-fat potato chips based on low-cost pretreatment. © 2024 Society of Chemical Industry.

Impact of Pretreatment With Acid and Ultrasound on the Production and Characteristics of Goat Skin Gelatin

Goat skin is a potential raw material source for gelatin production using acid-ultrasound pretreatment. The objective of this study was to investigate the use of ultrasound in combination with acid pretreatment for the preparation of goat skin gelatin. Gelatin was extracted from goat skin using different pretreatments: acetic acid (T1), acetic acid followed by ultrasound (20 kHz and 750 W) (T2), and without pretreatment (T0). The results showed that the combination of acetic acid and ultrasound pretreatment significantly impacted the quality of the resulting gelatin. The study results showed an increase in yield (9.24 to 25.48%), hydroxyproline content (102.07 to 231.31 mg/g), gel strength (4.76 to 197.62 g), viscosity (6.80 to 48.00 cP), melting point (32.47 to 35.85 oC), EAI (18.24 to 23.58 m2/g), and ESI (24.90 to 62.63 min). However, there was a decrease in pH, the value of color L*, and turbidity. The SDS-PAGE patterns showed differences in molecular weight distribution due to variations in pretreatment. All gelatin samples exhibited α1 and α2 chains as the predominant components. Interestingly, the ultrasound effect highlighted the β-chain more boldly compared to other pretreatments. FTIR spectroscopy analysis shows changes in molecular interactions due to acetic acid pretreatment followed by ultrasound, which results in shifts in the Amide A, Amide B, Amide I, Amide II, and Amide III groups. Ultrasonic treatment caused more dense and disturbed structures in the sample. Therefore, the combination of acetic acid and ultrasound pretreatment yielded the superior properties of goat skin gelatin.

Evaluation of Organic Acids and Ultrasound as Pretreatment in Convective Drying Kinetics and Quality Parameters of Pumpkin.

There is a growing interest in the food industry in new drying technologies that reduce the time required for dehydration, combined with low energy consumption, low environmental impact, and maintenance of the overall quality of the product. This work investigated convective drying of pumpkin with and without ultrasound-organic (citric or acetic) acid pretreatment for different durations (10, 20, and 30 min). Drying was carried out at 60 °C, and the Wang and Singh model had the best fit for the experimental data. Samples pretreated for 30 min had the shortest drying times. Water diffusivities ranged from 6.68 × 10-8 m2/s to 7.31 × 10-8 m2/s, with the pretreated samples presenting the highest values. The dried pumpkin water activity values were below 0.60. Regarding color parameters, there was a slight increase in luminosity, a slight reduction in a*, and a significant increase in b*. Drying resulted in the loss of ascorbic acid and phenolic compounds, but the samples pretreated with citric acid showed better retention. There was also a reduction in the total carotenoid content, but samples pretreated with acetic acid for 10 and 20 min showed the best retention.

Effect of calcium chloride blanching combined with acetic acid soaking pretreatment on oil absorption of fried potato chips

This study investigated the effect of calcium chloride (CaCl2) combined with acetic acid (AA) pretreatment on the oil absorption of potato chips and explored the possible mechanisms influencing oil absorption. Results indicated that compared with hot water blanching, the combination of 0.3% CaCl2 blanching and AA soaking for 2–8 h pretreatment was found to reduce oil content by 10.52%–12.68% and significantly improve the crispness and color of fried potato chips. Microstructural and textural analyses revealed that the main reason for the reduction in oil content was the promotion of pectin gelation in the cell wall by CaCl2 and AA. However, it was observed that prolonged AA soaking time and high-concentration CaCl2 blanching led to an increase in total oil content and decrease in brittleness. Based on the results of surface roughness and moisture content analyses, it was suggested that the CaCl2 and AA pretreatments affected surface roughness and moisture content, thereby increasing oil absorption and reducing brittleness during frying.

Sacral Magnetic Neuromodulation with Intermittent Theta Burst Waveform Enhances Overactive Bladder: In Vivo Study

BackgroundThe current treatment options for overactive bladder (OAB) continue to pose challenges for refractory cases and may involve invasive procedures. To assess the potential benefit of non-invasive repetitive peripheral magnetic stimulation (rPMS) on sacral roots using intermittent theta burst stimulation (iTBS) as treatment option for OAB. The study involved a total of 33 rats, which were divided into three different experimental phases. Materials and methodsTo induce bladder overactivity rats were pretreated with a continuous transvesical infusion of 0.5% acetic acid (AA). During bladder infusion, the intravesical pressure was recorded using cystometrography (CMG) to investigate the effects of AA pretreatment and the therapeutic intervention of acute sacral rPMS using iTBS. ResultsPre-application of rPMS with iTBS at a 100% intensity significantly extended the mean first voiding time (Tv) in normal healthy rats to 132%. Acute rPMS iTBS at a 100% intensity resulted in a significant increase of the inter-contraction interval (ICI) to 121%. An AA model was established with continuous saline infusion after 0.5% AA treatment and resulted in significant reductions of Tv to 42% and ICI to 56% of the corresponding control values. Subsequently, rPMS iTBS at a 100% intensity on the sacral nerve effectively inhibited AA-induced bladder overactivity and significantly increased the ICI to 167%∼222%. No significant changes in maximum bladder pressure (Pmax) were found. ConclusionsSacral nerve rPMS with iTBS demonstrated the ability to suppress AA-induced bladder overactivity. This promising modality could be developed as an alternative approach to enhance bladder continence in OAB syndrome patients.

Comparison of lactic and propionic acid hydrolysis for production of xylo-oligosaccharides and ethanol from polysaccharides in Toona sinensis branch

Xylan-type hemicellulose hydrolysis by an organic acid solution for the production of xylo-oligosaccharides (XOS) is efficient and eco-friendly, but the effects of different organic acids on XOS production from Toona sinensis branch (TB) biomass is limited. In this work, under the conditions of 170 °C for 60 min, 33.1 % and 38.7 % XOS yields were obtained from polysaccharides present in TB by 2 % lactic acid (LA) and 6 % propionic acid (PA), respectively. Then 77 % of the lignin was removed by hydrogen peroxide−acetic acid pretreatment system, and 39.5 % and 44.7 % XOS yield were obtained from polysaccharides in delignification TB by 2 % LA and 6 % PA, respectively. It was found that PA hydrolysis, especially from delignified TB, resulted in higher XOS yield and purity compared to LA hydrolysis. Moreover, the content of byproducts (xylose, hydroxymethyl-furfural and furfural) in PA hydrolysate was lower. Following the hydrolysis process, the simultaneous saccharification and fermentation of the TB solid residue achieved an ethanol yield of 71.5 %. This work proposed an integrated process to preferentially convert the TB hemicellulose into valuable XOS and then convert the cellulose into ethanol. This process had the advantages of eliminating the need for isolation and purification of xylan, and the potential to obtain multiple products from the same raw material.

Enhancing biogas production from empty fruit bunch through acetic acid pretreatment: process optimization and synergistic effects

Enhancing biogas production from empty fruit bunch through acetic acid pretreatment: process optimization and synergistic effects

Full utilization of poplar sawdust with chemical-mechanical pretreatment for coproduction of xylooligosaccharides, fermentable sugars and porous carbon materials

In recent decades, one of the major challenges of biorefinery is the full utilization of lignocellulosic components for coproduction of value-added materials. In this context, we proposed an integrated process of acetic acid (AC) pretreatment, Papir Forsknings Institutet (PFI) refining and enzymatic hydrolysis to coproduce xylooligosaccharides, fermentable sugars and lignin-based porous carbon materials. Results showed AC pretreatment (170 ºC, 60 min, 5 w/v % acetic acid and 5% 2-naphthol addition based on dry mass of biomass) resulted in maximum xylooligosaccharids (XOS) yield of 51.08%. The integrated process of AC pretreatment assisted by 2-naphthol-7-sulfonate addition and PFI post-refining led to cellulose hydrolysis yield of 98.20% and lignin-based porous carbon materials with methylene blue adsorption capacity of up to 749.17 mg/g. Moreover, it was found lignin repolymerization inhibitors (i.e. 2-naphthol, 2-naphthol-7-sulfonate) in acid pretreatment helped increase the specific surface area of substrate and decrease surface lignin coverage, which enhanced cellulose accessibility to cellulase enzymes. Moreover, they enhanced lignin detaching during enzymatic hydrolysis, which reduced cellulase aggregation and promoted the ease of cellulose hydrolysis. Results demonstrated an efficient pretreatment strategy to maximize coproduction of xylooligosaccharids, fermentable sugars and lignin materials from lignocellulosic biomass for full utilization.

Extracellular vesicles separated from goat milk by differential centrifugation coupled with sodium citrate pretreatments

Satisfactory separation of milk-derived extracellular vesicles (MEVs) is important for the downstream analysis of the functions and properties of MEVs. However, the presence of abundant proteins in milk hindered the separation of MEVs. In this study, three pretreatment methods, including sodium citrate (SC), acetic acid (AA), and high-speed centrifugation, were adopted to separate MEVs from goat milk while minimizing the impact of protein. The MEVs were then characterized by nanoparticle tracking, transmission electron microscopy and western blotting experiments. The results indicated that pretreatments with AA and SC greatly decreased the impact of casein, but AA pretreatment damaged the surface structure of MEVs. Additionally, the differential centrifugation process resulted in a slight loss of MEVs. Overall, MEVs with small size and high purity can be obtained under 125 k × g centrifugation combined with SC pretreatment, which suggests a promising method for separation of MEVs from goat milk.

Influence of Acetic Acid Pretreatment and its Residue on Bioethanol and Biogas Production from Water Hyacinth

Water hyacinth, an invasive species in natural water habitats, poses ecological challenges but also holds promise as a biofuel resource due to its abundant biomass. To optimize sugar yield for biofuel production, this study focuses on pretreating water hyacinth with acetic acid (AC) using Response Surface Methodology (RSM). Comparing AC, hydrochloric acid (HA), and untreated samples, AC-pretreated samples yielded the highest sugar content at 28.26 g/100 g of biomass, nearly 1.97 times higher than that of untreated samples. Additionally, AC-pretreated samples produced the maximum biogas (2573 mL) after 45 days of anaerobic digestion, while HA pretreatment yielded the highest ethanol production (9.32 g/L) within 48 h. The structural changes in the pretreated and untreated water hyacinth samples were compared using FTIR analysis, and the results showed that the pretreatment approaches exposed more cellulose to hydrolysis. Furthermore, the study investigated the impact of post-washing following acid pretreatment of water hyacinth and discovered that AC residues had no adverse effects, suggesting that the post-washing phase was unnecessary for ethanol production. These findings demonstrate that AC pretreatment can effectively enhance hydrolysis and biofuel production and that eliminating post-washing may reduce wastewater generated during the pretreatment process.

Integrated acetic acid and deep eutectic solvent pretreatment on poplar for co-production of xylo-oligosaccharides, fermentable sugars and lignin antioxidants/adsorbents

Efficient fractionation of lignocellulosic biomass in usable forms of hemicellulose, cellulose and lignin is very important for the sustainable lignocellulosic biorefinery. Herein, poplar sawdust was pretreated with an integrated process composed of acetic acid pre-hydrolysis (170 °C, 60 min) for xylo-oligosaccharides (XOS) production and mild deep eutectic solvent (90–130 °C, 60 min) post-delignification for recovering lignin fractions, resulting in easily hydrolyzed cellulose fraction. Results showed that, after integrated pretreatment and enzymatic hydrolysis, 51 % of xylan and 92 % of glucan in raw biomass could be converted to XOS (DP 2–6) and glucose, respectively, while 71 % of the original lignin could be recovered in DES solvent. The resulting XOS were proven to ensure the growth of probiotics, Bifidobacterium adolescentis. Besides, the lignin macromolecules recovered from DES solvent showed high-purity (around 95 %), low-molecular weight (Mw around 2000), small particle size (270–170 nm) and high-PhOH (3.08 mmol/g) content, which were likely relevant to the excellent antioxidant activity (RSI = 15.16) and adsorbent activity (Pb(II) 461.89 mg/g lignin). Finally, mass balance and energy analysis revealed that the integrated pretreatment could be used as a promising approach for the production of bio-based chemicals and materials from woody biomass.

High-performance poplar-polyethylene laminates based on microwave-assisted acetic acid pretreatment process with potential application in construction

High-performance poplar-polyethylene laminates based on microwave-assisted acetic acid pretreatment process with potential application in construction

Novel dual-action vanillic acid pretreatment for efficient hemicellulose separation with simultaneous inhibition of lignin condensation

Aromatic acids play a selective role in the separation of hemicellulose. Phenolic acids have demonstrated an inhibitory effect on lignin condensation. In the current study, vanillic acid (VA), which combines the characteristics of aromatic and phenolic acids, is used to separate eucalyptus. The efficient and selective separation of hemicellulose is achieved simultaneously at 170 °C, 8.0% VA concentration, and 80 min. The separation yield of xylose increased from 78.80% to 88.59% compared to acetic acid (AA) pretreatment. The separation yield of lignin decreased from 19.32% to 11.19%. In particular, the β-O-4 content of lignin increased by 5.78% after pretreatment. The results indicate that VA, as a “carbon positive ion scavenger”, it preferentially reacts with the carbon-positive ion intermediate of lignin. Surprisingly, the inhibition of lignin condensation is achieved. This study provides a new starting point for the development of an efficient and sustainable commercial technology by organic acid pretreatment.

Improving the Cellulose Enzymatic Digestibility of Sugarcane Bagasse by Atmospheric Acetic Acid Pretreatment and Peracetic Acid Post-Treatment.

Pretreatment of sugarcane bagasse (SCB) by aqueous acetic acid (AA), with the addition of sulfuric acid (SA) as a catalyst under mild condition (<110 °C), was investigated. A response surface methodology (central composite design) was employed to study the effects of temperature, AA concentration, time, and SA concentration, as well as their interactive effects, on several response variables. Kinetic modeling was further investigated for AA pretreatment using both Saeman's model and the Potential Degree of Reaction (PDR) model. It was found that Saeman's model showed a great deviation from the experimental results, while the PDR model fitted the experimental data very well, with determination coefficients of 0.95-0.99. However, poor enzymatic digestibility of the AA-pretreated substrates was observed, mainly due to the relatively low degree of delignification and acetylation of cellulose. Post-treatment of the pretreated cellulosic solid well improved the cellulose digestibly by further selectively removing 50-60% of the residual linin and acetyl group. The enzymatic polysaccharide conversion increased from <30% for AA-pretreatment to about 70% for PAA post-treatment.

Renewable deep eutectic solvents pretreatment improved the efficiency of anaerobic digestion by lignin extraction from willow

Lignin extraction from lignocellulosic biomass can enhance its bioconversion efficiency, whilst the recovered lignin can provide added economic value. This study comprehensively investigated the impacts of short-chain carboxylic acid-based deep eutectic solvents (DESs) pretreatments on lignin extraction from willow and assessed subsequent biomethane production through anaerobic digestion. Process parameters (including the DESs type, molar ratios of DESs components, temperature and reaction time) in the DESs pretreatments of willow for lignin extraction were optimized using the central composite surface response methodology. Results showed that lactic acid-based DES pretreatment outperformed acetic acid and propionic acid-based DES pretreatments in terms of lignin removal efficiency and methane production. Under the optimal conditions (choline chloride:lactic acid with a molar ratio of 1:10 at 160 °C for 15 min) lactic acid-based DES pretreatment retained over 94% of the glucan content in the raw willow whilst achieved the highest lignin removal of 80%. The recovered lignin showed a purity of above 81%. Compared with the biomethane production of 89.9 mL/g total solid from raw willow, the biomethane production significantly increased by 36.3% after the lactic acid-based DES pretreatment. The optimal condition reduced the digestion time from 22 to 10 days. The overall energy conversion efficiency of 62.7% demonstrated that lactic acid-based DES pretreatment of lignocellulose could be a promising method to co-produce renewable gaseous fuels and lignin in a sustainable approach.

Rapid and mild fractionation of hemicellulose through recyclable mandelic acid pretreatment

The development of organic acid pretreatments from biological sources is essential to facilitate the progress of green and sustainable chemistry. In this study, the effectiveness of mandelic acid pretreatment (MAP) was analyzed for eucalyptus hemicellulose separation. 83.66% of xylose was separated under optimal conditions (temperature: 150 °C; concentration: 6.0 wt%; time: 80 min). The hemicellulose separation selectivity is higher than acetic acid pretreatment (AAP). The stable and effective separation efficiency (56.55%) is observed even after six reuses of the hydrolysate. Higher thermal stability, larger crystallinity index and optimized surface element distribution in the samples were demonstrated by MAP. Lignin condensation is effectively inhibited through MAP, as determined from the structural of different lignin. In particular, the demethoxylation of lignin by MA was found. These results open up a new way to construct a novel organic acid pretreatment for separating hemicellulose with high efficiency.

Extraction and characterization of gelatin derived from acetic acid-treated black soldier fly larvae

Gelatin is a low-cost and widely used soluble protein compound derived from collagen. Black soldier fly (Hermetia illucens) larvae (BSFL) are a potential alternative source of gelatin due to their high nutritional value. This study investigated the effect of acetic acid pretreatment concentration, time, and centrifugation speed on the yield of BSFL gelatin and characterized its physicochemical properties. BSFL gelatin extracted with 0.05 mol/L acetic acid for 3 h and centrifuged at 3000 × g (BSFL3) had the highest yield of 1.085%±0.2%. The BSFL3 gelatin had lower protein content and amino acids than commercial porcine gelatin, specifically proline and hydroxyproline. It also had a high melting temperature of 135.12±1.04 °C, viscosity of 1.69±0.05 mPa·s, and rough microstructure with low foaming properties. The BSFL gelatin is high in K (680/01 mg/kg) and contains less Na, Mg, Ca, and P. Field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) revealed that BSFL3 gelatin has high potassium content. The results suggest that BSFL gelatin can be used as a novel techno-functional ingredient in the food industry.