Hydrogen Peroxide In Acetic Acid Research Articles

A novel cellulolytic/xylanolytic SbAA14 from Sordaria brevicollis with a branched chain preference and its synergistic effects with glycoside hydrolases on lignocellulose

In this study, the novel auxiliary activity (AA) family 14 lytic polysaccharide monooxygenase (LPMO) SbAA14 from Sordaria brevicollis was successfully characterized. It was active against heteroxylan, xyloglucan and cellulose in β-cellulose and released native oligosaccharides and corresponding C1- and/or C4-oxidized products. SbAA14 showed a branched chain preference, because partial removal of arabinosyl substituents from heteroxylan led to a decrease in activity. SbAA14 had synergistic effects with the debranching enzyme EpABF62C in an enzyme- and ascorbic acid-dependent manner. SbAA14 had synergistic effects with the GH10 endoxylanase EpXYN1, and the degree of synergy was greater with step-by-step addition than with simultaneous addition. SbAA14 could also synergize with Celluclast® 1.5 L on NaOH-pretreated wheat straw and on NaOH-pretreated and hydrogen peroxide-acetic acid (HPAC)-H2SO4-pretreated bamboo substrates. The greatest synergistic effect between SbAA14 and Celluclast® 1.5 L was observed for HPAC-H2SO4–200 mM pretreated bamboo, in which the degree of synergy reached approximately 1.61. The distinctive substrate preference of SbAA14 indicated that it is a novel AA14 LPMO that may act mainly on heteroxylan with numerous arabinosyl substituents between cellulose fibers rather than on recalcitrant xylan tightly associated with cellulose. These findings broaden the understanding of enigmatic AA14 LPMOs and provide new insights into the substrate specificities and biological functionalities of AA14 LPMOs in fungi.

Extraction and characterization of nanocellulose from cattail leaves: Morphological, microstructural and thermal properties

Hydrogen peroxide combined with acid treatment demonstrates its respective characteristics for the separation of lignocellulosic biomass. Herein, holocellulose was extracted from Cattail leaves (CL) by a two-step treatment with alkali and hydrogen peroxide-acetic acid (HPAA). Then carboxylated nanocellulose was hydrolyzed with a mixed organic/inorganic acid. The chemical composition of the holocellulose and the physicochemical properties of the separated carboxylated nanocellulose were comparable. Carboxyl groups were introduced on the nanocellulose as a result of the esterification process with citric acid (CA), which endows the nanocellulose with high thermal stability (315–318 °C) and good light transmission (>80 %). Furthermore, morphological analyses revealed that nanocellulose had a spider-web-like structure with diameter between 5 and 20 nm.

A Novel Quantitative Analysis Method for Lead Components in Waste Lead Paste

In this study, a method for determining the lead components in waste lead paste was proposed, using simulated and spent lead paste as research objects. To compare the effectiveness of different determining methods, we selected three methods for comparison and investigated the reasons for measurement deviation. The results indicate that the measurement deviation in the current method primarily stems from the following three factors: (1) Pb is soluble in an acetic acid solution under certain conditions; (2) Pb and PbO2 undergo redox reactions; and (3) hydrogen peroxide can undergo redox reactions with Pb. It is feasible to determine the lead content using the kinetic rules of Pb and PbO2 in the acetic acid-hydrogen peroxide system. The method of determination proposed in this paper is as follows. Firstly, lead dioxide is dissolved in hydrogen peroxide under acidic conditions. Subsequently, the concentration of lead dioxide is determined, and the quantity of hydrogen peroxide consumed is recorded. Then, a new sample is taken, and the lead oxide is dissolved in an acetic acid solution. The concentration of lead oxide is determined using the EDTA·2Na titration method. The residue of lead sulfate in the filtrate is dissolved in a sodium chloride solution, and its concentration is determined using the EDTA·2Na titration method. Based on the previously recorded volume of hydrogen peroxide, the remaining lead dioxide in the residue is dissolved in a mixture of acetic acid and hydrogen peroxide. The remaining lead dioxide is then removed from the new sample employing kinetic principles. Finally, the residual metallic lead in the sample is dissolved in a nitric acid solution, and its concentration is determined using the EDTA·2Na titration method.

Efficient production of high concentration monosaccharides and ethanol from poplar wood after delignification and deacetylation

Efficient enzymatic hydrolysis is required for the production of high concentration monosaccharides and ethanol. The lignin and acetyl group in poplar can limit the enzymatic hydrolysis. However, the effect of delignification combined with deacetylation on the saccharification of poplar for high concentration monosaccharides was not clear. Herein, hydrogen peroxide-acetic acid (HPAA) was used for delignification and sodium hydroxide was used for deacetylation to enhance the hydrolyzability of poplar. Delignification with 60% HPAA at 80 °C could remove 81.9% lignin. Acetyl group was completely removed with 0.5% NaOH at 60 °C. After the saccharification, 318.1 g/L monosaccharides were obtained with a poplar loading of 35% (w/v). After simultaneous saccharification and fermentation, 114.9 g/L bioethanol was gained from delignified and deacetylated poplar. Those results showed the highest monosaccharides and ethanol concentrations in reported research. This developed strategy with a relatively low temperature could effectively improve the production of high concentration monosaccharide and ethanol from poplar.

Synthesis and Characterization of Bamboo Employed Environmentally Friendly Cellulose Nanofibrils Reinforced Natural Rubber Composites with Uncompromised Mechanical Properties

In this study, high-purity cellulose nanofibrils (CNFs) were environmentally friendly extracted from natural bamboo. Physical, chemical, and mechanical treatments were comprehensively investigated, and then ensembled to effectively and efficiently remove lignin and hemicellulose with low energy from raw bamboo fibers, which combine microwave liquefaction, hydrogen peroxide-acetic acid delignification, alkaline treatment, and along with acid hydrolysis. This was able to allow for the extraction of CNFs. Compositional analysis, Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis were performed to investigate and confirm the successful removal of undesirable lignin and hemicellulose. The resultant cellulose fibers were then subjected to a mechanical treatment to obtain the cellulose nanofibrils. It was found that the obtained CNFs have an average diameter of 13 nm with a cellulose purity of 94.52%. Without any further surface modification, the incorporation of bamboo-based CNFs into natural rubber (NR) exhibits significant improvement in their mechanical properties including modulus (~66.67%), tensile strength (~120.83%), toughness (~139.34%), and elongation at break (~31.41%). Interestingly, there is no compromise between tensile strength and elongation at break for the nanocomposites. DMA results also showed that both storage and loss moduli were dramatically enhanced over those of neat NR in their glassy region, which is typically unusual. This study can show, if optimized for material extraction, the great promise to the potential use of natural materials to develop environmentally friendly composites with multi-functionality in a variety of real-world engineering structural applications.

Delignified wheat straw for production of xylo-oligosaccharides and monosaccharides using acetic acid/sodium acetate solution

The production of xylo-oligosaccharides (XOS) from lignocelluloses with conjugated acid-base system is highly efficient. However, XOS production from wheat straw with conjugated system of acetic acid/sodium acetate (HAc/NaAc) has not been reported. In addition, the impact of delignification of wheat straw for XOS production was not clear. In this study, the optimal conditions for HAc/NaAc hydrolysis were: 0.4 M, molar ratio 10:1, 170 °C, and 60 min. The yield of XOS could be rose to 50.2% after the HAc/NaAc hydrolysate was hydrolyzed using xylanase. After 70.3% of lignin in wheat straw was removed by hydrogen peroxide-acetic acid treatment, the XOS yield of delignified wheat straw using HAc/NaAc reached 54.7%. Finally, a glucose yield of 96.6% was gained by cellulase from wheat straw solid. This work suggested that HAc/NaAc hydrolysis could efficiently produce XOS from wheat straw and the delignification of wheat straw was conducive to XOS and monosaccharides production.

Efficient high solid loading enzymatic hydrolysis of hydrogen peroxide/acetic acid-pretreated bamboo for monosaccharides production

High solid loading enzymatic hydrolysis (HSLEH) produces high sugar concentrations with low water and energy inputs. Adequate information has been provided to confirm the excellent enzymatic digestibility of pretreated bamboo biomass with the solid content below 10%. However, the utilization of bamboo biomass for producing high-concentration sugars solution via HSLEH is rarely reported. In this work, hydrogen peroxide/acetic acid (HPAC) pretreatment removed 79% of lignin from bamboo and HPAC-pretreated bamboo was rich in glucan (55.3%) and xylan (20.4%). In the HSLEH of HPAC-pretreated bamboo, xylanase could increase glucose production by 9.4%. Alkaline incubation could increase the glucose production of HPAC-pretreated bamboo by 6.3% and saved 75% cellulase. The addition of Tween 80 (0.03 g/L) could further increase the glucose production of HPAC-pretreated bamboo by 14.1%. As a result, 204.9 g/L glucose and 60.2 g/L xylose, corresponding to glucose and xylose yields of 75.8% and 65.4% respectively, were obtained from the resulting bamboo solid via 400 g/L HSLEH with 10 FPU cellulase/g dry matter and 0.03 g/L Tween 80, which was the highest concentration compared with the previous literatures. This work developed an integrated process to produce very high-concentration sugars solution from bamboo residue via HSLEH.

The Novel Chiral 2(5H)-Furanone Sulfones Possessing Terpene Moiety: Synthesis and Biological Activity.

Over the past decades, 2(5H)-furanone derivatives have been extensively studied because of their promising ability to prevent the biofilm formation by various pathogenic bacteria. Here, we report the synthesis of a series of optically active sulfur-containing 2(5H)-furanone derivatives and characterize their biological activity. Novel thioethers were obtained by an interaction of stereochemically pure 5-(l)-menthyloxy- or 5-(l)-bornyloxy-2(5H)-furanones with aromatic thiols under basic conditions. Subsequent thioethers oxidation by an excess of hydrogen peroxide in acetic acid resulted in the formation of the corresponding chiral 2(5H)-furanone sulfones. The structure of synthesized compounds was confirmed by IR and NMR spectroscopy, HRMS, and single crystal X-ray diffraction. The leading compound, 26, possessing the sulfonyl group and l-borneol moiety, exhibited the prominent activity against Staphylococcus aureus and Bacillus subtilis with MICs of 8 μg/mL. Furthermore, at concentrations of 0.4-0.5 μg/mL, the sulfone 26 increased two-fold the efficacy of aminoglycosides gentamicin and amikacin against S. aureus. The treatment of the model-infected skin wound in the rat with a combination of gentamicin and sulfone 26 speeded up the bacterial decontamination and improved the healing of the wound. The presented results provide valuable new insights into the chemistry of 2(5H)-furanone derivatives and associated biological activities.

Effect of peracetic acid generation in hydrogen peroxide-acetic acid pretreatment on production of xylooligosaccharides from poplar by organic acid hydrolysis

Hydrogen peroxide-acetic acid (HPAA) compositions affect the peracetic acid generation and subsequent delignification of lignocellulosic materials. However, the effects of HPAA compositions on lignin removal and poplar hydrolyzability after HPAA pretreatment are not fully elucidated yet. In this work, different volume ratios of HP to AA were used to pretreat poplar, AA and lactic acid (LA) hydrolysis of delignified poplar to produce XOS was compared. Peracetic acid was mainly produced in 1 h of HPAA pretreatment. HPAA with HP to AA ratio of 8:2 (HP8AA2) generated 4.4% peracetic acid and removed 57.7% of lignin at 2 h. Furthermore, XOS production from HP8AA2-pretreated poplar by AA and LA hydrolysis was increased by 97.1% and 14.9% compared to those from raw poplar, respectively. After alkaline incubation, the glucose yield of HP8AA2-AA-pretreated poplar increased from 40.1% to 97.1%. The study results indicated that HP8AA2 was conducive to XOS and monosaccharides production from poplar..

Utilization of bamboo as biorefinery feedstock: Co-production of xylo-oligosaccharide with succinic acid and lactic acid

Herein, we investigated the possibility of co-producing xylo-oligosaccharides (XOSs) from bamboo, as value-added products, along with succinic and lactic acids, as platform chemicals. Xylan was extracted from bamboo using the alkali method under mild conditions. From xylan, XOSs were produced by partial enzymatic hydrolysis at a conversion rate of 83.9%, and all reaction conditions resulted in similar degrees of polymerization. Hydrogen peroxide-acetic acid (HPAC) pretreatment effectively removed lignin from NaOH-treated bamboo, and the enzymatic hydrolytic yield of NaOH and HPAC-treated bamboo was 84.3% of the theoretical yield. The production of succinic and lactic acids from the hydrolysate resulted in conversion rates of approximately 63.2% and 91.3% of the theoretical yield using Corynebacterium glutamicum Δldh and Actinobacillus succinogenes, respectively, under facultative anaerobic conditions. This study demonstrates that bamboo has a high potential to produce value-added products using a biorefinery process and is an alternative resource for compounds typically derived from petroleum.

Xylopentose production from crop residue employing xylanase enzyme

To produce xylo-oligosaccharides (XOS) from the agriculture waste, which included, green coconut and vegetable cocktail. The two pretreatment – hydrogen peroxide-acetic acid (HP-AC) and sodium hypochlorite-sodium hydroxide (SH-SH) – were used for this study. The optimal conditions for the pretreatment were 80 °C, 4.0 % NaClO, and 2 h, followed by 0.08 % NaOH, 55 °C, and 1 h. Further enzymatic hydrolysis of green coconut (GC) and vegetable cocktail (VC) were performed and found in case of GC, the best outcomes were observed. Different types of XOS were obtained from the treated biomass whereas a single type of XOS xylo-pentose was obtained in high quantity (96.44 % and 93.09 % from CG and VC respectively) with the production of other XOS < 2 %. This study presents a reasonably secure and economical method for turning secondary crop residue into XOS and fermentable sugars.

Two-step hydrogen peroxide-acetic acid and sodium hydroxide-urea pretreatment for saccharification of lignin-rich poplar

Pretreatment using high concentration (>60 %, v/v) of hydrogen peroxide-acetic acid (HPAA) exhibits highly selective and strong delignification capacity. However, the utilization of high concentrations of HPAA is costly and potentially explosive. Although low HPAA concentration is safer, it limits the improvement of the hydrolyzability of poplar. Herein, after the production of xylo-oligosaccharides from poplar by acetic acid (AC) hydrolysis, the obtained lignin-rich (35.6 %) poplar was pretreated with low concentration (10–20 %) of HPAA followed by sodium hydroxide-urea (SU) to enhance the hydrolyzability of AC-hydrolyzed poplar. Firstly, 37.0 % lignin and 93.2 % acetyl groups were removed from AC-hydrolyzed poplar via pretreatment using 10 % HPAA at 120 °C for 10 min. Then, SU pretreatment removed 35.2 % lignin of HPAA-pretreated poplar, which enhanced the glucose yield of the poplar from 21.4 % to 95.5 %. This HPAA-SU process saved 90 % HPAA loading and largely improved the hydrolyzability of lignin-rich poplar in a relatively short time. • The concentration of hydrogen peroxide-acetic acid (HPAA) in pretreatment was 10 %. • HPAA pretreatment removed 93.2 % acetyl group of acetic acid-hydrolyzed poplar. • Sodium hydroxide-urea treatment removed 35.2 % lignin in HPAA-treated poplar. • SU pretreatment enhanced glucose yield of HPAA-pretreated poplar to 95.5 %. • SU pretreatment saved 90 % HPAA dosage in HPAA pretreatment.

Mechanism of sulfur removal from coal by microwave assisted acetic acid-hydrogen peroxide system

The desulfurization effect of Ningxia Shuangma coal (SM) with an acetic acid-hydrogen peroxide system assisted by microwave, ultrasonic and ultraviolet light was compared. The results show that microwave-assisted desulfurization has the best effect. When the microwave power is 900W, the irradiation time is 5 min, and the volume ratio of acetic acid to hydrogen peroxide is 1:10, the desulfurization rate can reach 55.82%. Moreover, microwave-assisted desulfurization can effectively improve the removal effect of organic sulfur. XRD, XPS, SEM and other characterization showed that microwave assisted can effectively reduce the mineral content, expose more sulfur-containing groups, and improve the desulfurization effect. The desulfurization rate of three sulfur-containing compounds is: dibenzyl sulfide > diphenyl sulfoxide > benzothiophene. With the increase of intensity of the applied electric field, the C–S bond gets easier to fracture, the applied electric field can reduce the reaction energy barrier, is a benefit to the reaction.

Alkaline deacetylation-aided hydrogen peroxide-acetic acid pretreatment of bamboo residue to improve enzymatic saccharification and bioethanol production

Bamboo pretreatment with alkaline deacetylation-aided hydrogen peroxide-acetic acid (HPAC-NaOH) was investigated for producing high-value-added products. Comparing with HPAC pretreated D. sinicus, the post-treatment of alkaline deacetylation resulted in higher glucose yield of 91.3% and ethanol concentrations of 17.20 g/L, increased by about 20–27%. A strong negative correlation between the content of acetyl with cellulose accessibility and enzymatic hydrolysis yield was showed. The deacetylation of HPAC-DS contributed to the increase of cellulase adsorption capacities in substrates and the variations of hydrophilicity, cellulose crystallinity, and degree of polymerization, which can generate highly reactive cellulosic materials for enzymatic saccharification to produce bioethanol. The HPAC-NaOH pretreatment can provide a promising approach to improve the bioconversion of bamboo to biofuels, and has broad space for the biorefinery of bamboo in the south of China.

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.

Comparison of pH-controlled lactic acid hydrolysis and xylanase hydrolysis for xylo-oligosaccharides production from delignified poplar

Previously, lactic acid (LA) hydrolysis has been applied in xylo-oligosaccharides (XOS) production from poplar. However, the impact of the pH value of LA on the production of XOS was unclear. In this study, the delignified poplar was prepared by hydrogen peroxide-acetic acid pretreatment of poplar, and lignin removal reached 84.1%. LA with different pH values (2.0–5.0) was applied in XOS and monosaccharides production from delignified poplar, and the xylanase hydrolysis of delignified poplar for XOS production was used for comparison. Results demonstrated that a XOS yield of 18.5% was acquired from delignified poplar by xylanase hydrolysis. However, a high XOS yield of 44.1% was acquired from delignified poplar by LA hydrolysis at pH 2.5, an increase of 20.2% when compared with LA hydrolysis with original pH value (2.0). Xylanase hydrolysis of the LA hydrolysates increased the XOS yield by 38.3% and finally, a total XOS yield of 61.0% was obtained, which was the highest XOS yield from poplar in the previous reports. Additionally, a satisfied glucose yield of 89.4% was acquired from poplar residue by cellulase. This work confirmed the high efficiency of the combination of pH-controlled LA hydrolysis and xylanase hydrolysis in XOS production from poplar.

Highly selective delignification of poplar by hydrogen peroxide-ethyl acetate pretreatment at room temperature

Highly selective delignification of lignocellulose with green solvent at mild conditions is a challenge. Previously, hydrogen peroxide-acetic acid (HPAA) was used as a green solvent in pretreatment exhibits excellent selective delignification capacity at a low reaction temperature (<80 °C). However, the release of oxygen can increase the pressure of the hydrogen peroxide-acetic acid (HPAA) pretreatment system and the risk of explosion. To overcome this problem, a novel hydrogen peroxide-ethyl acetate (HPEA) pretreatment was developed to remove poplar lignin, aiming at improving the pretreatment safety and saccharification efficiency. After HPEA pretreatment at room temperature for three days, 97.2% of poplar lignin was removed and 92.1% of original carbohydrate was retained. The glucose and xylose yields of HPEA-pretreated poplar reached 90.6% and 81.5% by a cellulase loading of 5 FPU/g dry matter, respectively. Compared with HPAA pretreatment, HPEA pretreatment reduced more than 93% of pressure in pretreatment system and largely increased pretreatment safety. The results indicates that HPEA pretreatment exhibited stronger delignification capacity, high carbohydrate retention, high safety, and strong enhancement of digestibility of poplar. This work provides a safe pretreatment to selectively remove lignin at mild conditions for efficient saccharification of poplar.

Corrigendum: Experimental Investigation on the Cleaning Effect and Influence Rule of Hydrogen Peroxide–Acetic Acid on Lead–Bismuth Eutectic Alloy

Corrigendum: Experimental Investigation on the Cleaning Effect and Influence Rule of Hydrogen Peroxide–Acetic Acid on Lead–Bismuth Eutectic Alloy

Combined acetic acid and enzymatic hydrolysis for xylooligosaccharides and monosaccharides production from poplar

Efficient production of xylooligosaccharides (XOS) from lignocellulosic biomass without preliminary xylan isolation is challenging. Previously, organic acid has been used to produce XOS from lignocelluloses without xylan isolation. However, the knowledge about XOS production from the residual xylan in acid-hydrolyzed lignocelluloses is still unclear. In this study, acetic acid (AC) hydrolysis of poplar was used to produce XOS, then AC-hydrolyzed poplar was delignified by hydrogen peroxide-acetic acid (HPAC) solution. The AC-HPAC-pretreated poplar was sequentially hydrolyzed by xylanase and cellulase to produce XOS and monosaccharides. The results showed that the XOS yield of poplar after AC hydrolysis was 31.6% (based on the xylan in raw poplar). A high lignin removal (94.8%) of AC-hydrolyzed poplar was obtained by HPAC pretreatment. The highest XOS yield based on residual xylan in AC-HPAC-pretreated poplar by xylanase was 17.5%, and finally a total XOS yield of 36.5% based on xylan in raw poplar was achieved. The highest glucose yield was 88.0% with 20 FPU/g dry mass cellulase and 1.0 mg/mL Tween 80. Finally, 65.1 g of XOS was obtained from 1,000 g of poplar through this combined process including AC and xylanase hydrolysis, increased by 2.2 times compared with that from xylanase hydrolysis without AC hydrolysis. This work greatly improves the XOS production from poplar and provides a novel strategy to efficiently transform poplar carbohydrates into XOS and monosaccharides.

Effect of pretreatments on production of xylooligosaccharides and monosaccharides from corncob by a two-step hydrolysis

Xylan extraction by alkali is usually a prerequisite for traditional xylooligosaccharide (XOS) production from corncob. In this study, to avoid xylan isolation before XOS production, corncob was delignified by hydrogen peroxide-acetic acid (HPAA), followed by a two-step enzymatic hydrolysis for XOS and monosaccharide production. High lignin removal (55.5%–82.6%) was observed upon pretreatment with 75%–100% HPAA and using 50–100 mM H2SO4 as a catalyst. A high XOS yield of 27.8% was obtained from 75% HPAA-pretreated corncob with 75 mM H2SO4, and the xylose/XOS ratio was only 0.09, indicating that the purity of XOS was relatively high. The highest glucose yield (79.1%) was obtained from 100% HPAA-pretreated corncob with 50 mM H2SO4. Finally, 58.3 g of XOS, 186.9 g of glucose, and 56.4 g of xylose were obtained from 1 kg of corncob. This study provides a promising approach for XOS and monosaccharide production from corncob without xylan isolation.