Search

The exploration of sustainable lignocellulosic nanomaterials with unique properties and applicable functions is receiving growing interest. In this work, holocellulose nanofibrils (HCNFs) were prepared from moso bamboo using mild alkaline peroxide bleaching method (MAPB) followed by mechanical nanofibrillation. MAPB was proved to effectively remove lignin and retain hemicellulose. Meanwhile, partial allomorphic changes from cellulose I to cellulose II were revealed together with varying degrees of crystallinity. Thermogravimetric analysis (TGA) experiment showed an increasing thermal stability trend due to more allomorphic changes into anti-parallel cellulose II. Well-dispersed HCNFs suspensions were successfully prepared by homogenization and HCNFs films with high transparency and flexibility were fabricated. The films reached the maximum tensile strength of 55.8 MPa and tensile strain of 1.55 % along with a calculated toughness of 25 MJ/m3. Moreover, the prepared materials are biocompatible and completely non-toxic, which will theoretically support the application of HCNFs materials in fields of biology, medicine and food industry. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years, the biological activity of polysaccharides and their derivatives has been widely studied. However, in addition to the natural polysaccharides directly extracted from plants and animals, there are rich polysaccharides in the pulping waste liquor that have not been fully utilized. The extracted polysaccharide from eucalyptus Alkaline Peroxide Mechanical Pulping (APMP) waste liquor was used as a raw material. For the production of carboxymethyl polysaccharide, the effects of temperature (T), the amount of alkali (NaOH) and the amount of etherifying agent (ClCH 2 COOH) on the degree of substitution (DS) were investigated, the optimal preparation conditions are: reaction time 2 h, temperature 75 °C, and the molar ratio of polysaccharide, NaOH and ClCH2COOH is 1:1:2, the highest DS is 1.47; FT-IR, NMR and GPC were used to characterize the structure and Molecular weight, the results show that the polysaccharide of APMP waste liquor is rich in xylan, and it was proved that the carboxymethyl substitution was successful and the positions of the substituent group were determined. The characterization and biological activity research of xylan polysaccharide (XP) and carboxymethyl xylan polysaccharide (CMXP), such as antioxidation, moisture absorption/retention, bacteriostatic action and cytotoxicity were discussed. CMXP shows better effects compared with XP. [Display omitted] • The carboxymethylation of XP from APMP waste liquor is proposed • The positions of carboxymethyl substitution are on the C-2 and C-3 of the xylose • The CMXP has the better bioactivity than XP • The bioactivity of CMXP provide a promising application in biomedicine and cosmetics fields [ABSTRACT FROM AUTHOR]

An enzymatic method for the carbohydrate hydrolysis of different microalgae biomass cultivated in domestic (DWB) and pig manure (PMWB) wastewaters, at different storage conditions (fresh, freeze-dried and reconstituted), was evaluated. The DWB provided sugars yields between 40 and 63%, although low xylose yields (< 23.5%). Approximately 2% of this biomass was converted to byproducts as succinic, acetic and formic acids. For PMWB, a high fraction of the sugars (up to 87%) was extracted, but mainly converted into acetic, butyric and formic acids, which was attributed to the bacterial action. In addition, the performance of an alkaline-peroxide pretreatment, conducted for 1 h, 50 °C and H 2 O 2 concentrations from 1 to 7.5% (w/w), was essayed. The hydrolysis of pretreated microalgae supported a wide range of sugars extraction for DWB (55–90%), and 100% for PMWB. Nevertheless, a large fraction of these sugars (∼30% for DWB and 100% for PMWB) was transformed to byproducts. [ABSTRACT FROM AUTHOR]

Vineyard pruning residues were subjected to alkaline peroxide treatment for delignification. Experimental conditions maximizing lignin removal were determined by using Box–Behnken statistical experiment design. NaOH/Biomass, H 2 O 2 /Biomass and retention time were chosen as independent variables and percent lignin removal was the objective function. Experiments were done at constant Solid/Liquid ratio of 0.1 (w/w) and 135 °C. All parameters were found to have significant effect on lignin removal. Complete delignification was obtained in 120 min at a NaOH/Biomass ratio of 1.10 and a H 2 O 2 /Biomass ratio of 0.65. The solid residue consisted of 95% total carbohydrate indicating significant carbohydrate enrichment after complete delignification. [ABSTRACT FROM AUTHOR]

Abstract: The effect of alkaline peroxide bleaching on the total anionic groups (AGs) and surface AGs in aspen chemithermomechanical pulp (CTMP) fibers was investigated. Alkaline treatment, especially alkaline peroxide bleaching resulted in the formation of new AGs and surface AGs in the CTMP fibers. The carboxylic groups in uronic acid units, including 4-O-methylglucuronic acid, galacturonic acid, and glucuronic acid units were the main contributors to the AGs in the fibers. However, the oxidized lignin accounting for more than 30% of the total AGs in the bleached CTMP fibers, was the main origin of the new AGs formed during the peroxide bleaching. In addition, the new AGs were also formed by extensive deesterification of the residual esterified uronic acids in pectins and lignin-carbohydrate complexes (LCCs). Although some uronic acid units were dissolved in the process water, both the total AGs and surface AGs in the fibers increased after alkaline peroxide bleaching. [Copyright &y& Elsevier]

The effect of pretreatments by hydrothermolysis (180 °C; 15 min) and alkaline delignification (NaOH 5M; H 2 O 2 1%; 24 h) in citrus peel waste (CPW) was evaluated, as well as the effect on H 2 , organic acids and alcohols production, in addition to characterization of the microbial community involved in fermentation. Batch reactors at 37 °C were operated with 3 gTVS/L of CPW with allochthonous consortium (UASB reactor sludge; 2 gTVS/L) and autochthonous of CPW (1.5 gTVS/L) as inocula. H 2 production was higher in reactors with in natura CPW (13.31 mmol/L) compared to hydrothermolysis (8.19 mmol/L) and alkaline delignification (7.27 mmol/L). The acetogenic pathway was predominant in the in natura CPW (4,355 mg/L acetic acid). The most abundant genera in the in natura CPW and after hydrothermolysis were Clostridium (18.97 and 12.90%, respectively) and Ruminiclostridium (16.65 and 1.04%, respectively) commonly related to cellulolytic bacteria and/or H 2 production. Image 1 • CPW delignification was higher in hydrothermolysis than in alkaline pretreatment. • Lower limonene content in CPW after hydrothermolysis and alkaline delignification. • Effect of hydrothermolysis on the microbial community involved in CPW fermentation. • Clostridium as the most abundant genera evolved in CPW anaerobic digestion. • Acetic acid was the major organic acid obtained through CPW biodegradation. [ABSTRACT FROM AUTHOR]

The current study explores alkaline and alkaline peroxide pretreatments in order to achieve a method to improve saccharification of agricultural residues for ethanol production. The effects of reagent concentration and pretreatment time at 30 °C and atmospheric pressure on biomass dissolution after the pretreatment and enzymatic hydrolysis of the pretreated biomass were investigated. In fact, although all pretreatments tested improved enzymatic hydrolysis of native residues, the best results were not achieved for the highest biomass loss. The maximum conversions to reducing sugars in the hydrolysis stage of 77.5% and 92.6% were obtained for rice hulls and straw pretreated by alkaline peroxide (4%, 24 h) and alkaline (1%, 48 h) methods, respectively. For both pretreated residues, the reduction to more than half the recommended enzyme loading allowed obtaining more than 94% the reducing sugars attained with the recommended dose. [ABSTRACT FROM AUTHOR]

Highlights: [•] Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. [•] Xylose units in the main chain of xylans are substituted by arabinose at C2 and C3. [•] The arabinoxylans extracted with water at high temperature contained less arabinose. [•] The water-soluble arabinoxylans are more branched, acetylated and low-molar-mass. [•] Water-extracted hemicelluloses contain more lignin than alkaline peroxide extracted. [ABSTRACT FROM AUTHOR]

Abstract: The steam pre-treatment with low severity preserves valuable biomass components, and further delignification with alkaline peroxide could improve hydrolysis. A combination of low severity steam pretreatment and alkaline peroxide post-treatment of Lespedeza stalks was investigated. The post-treatment of steam-pretreated Lespedeza stalks with alkaline peroxide significantly increased the cellulose content and changed the structure of the cellulose-rich fractions. A glucose yield of 503.5mgg−1 raw material from enzyme hydrolysis was obtained when the steam-pretreated material (184°C for 4min) was post-treated with 2% hydrogen peroxide at 60°C for 24h with a substrate concentration of 3.3%. Its hydrolysis yield is 88.8%, which is higher than that of samples processed by steam pretreatment alone (63.7%). The samples obtained by post-treatment with alkaline peroxide were found to have a smoother surface and looser structure in scanning electron microscopy images. The isolated lignin preparations had a yield range from 10.9 to 14.7 (% dry matter). The lignin was characterized by thermogravimetric analysis/differential thermal analysis, Fourier transform infrared spectroscopy, and gel permeation chromatography. Alkaline peroxide treatment increased the thermal stability of lignin, and decreased the amounts of all functional groups. Depolymerization and repolymerization occurred during the alkaline peroxide treatment. [Copyright &y& Elsevier]

Abstract: Bamboo is an alternative feedstock for the production of fine chemicals, such as fuel ethanol and lactic acid, because bamboo has a large amount of sugars. An effective pretreatment method for enzyme saccharification is required for the efficient production of these materials. Enzyme saccharification (48h) using a 35atm and 5min steam exploded bamboo produced 426 and 488mg/(g initial dry sample) of glucose and reducing sugar, respectively. In addition, pretreatments using 20atm and 5min steam explosion or mechanical milling for 5min followed by 10wt.% sodium hydroxide treatment at 121°C for 60min were attempted in order to enhance the digestibility of the holocellulose component. Both of these pretreatment methods had a large positive effect on the production of sugars by subsequent enzymatic hydrolysis. In particular, the maximum value of glucose production was obtained by the 20atm steam explosion and 10wt.% sodium hydroxide treatment. This produced 456mg/(g initial dry sample) of glucose and 460mg/(g initial dry sample) of reducing sugar. In comparison, the mechanical milling and 10wt.% sodium hydroxide treatment produced 383 and 485mg/(g initial dry sample) of glucose and reducing sugar, respectively. From these results, it was concluded that the pretreatment with 20atm steam explosion and 10wt.% sodium hydroxide treatment was the most effective pretreatment method for the production of glucose from bamboo by enzyme saccharification. However, since this pretreatment method requires the severe conditions of both high pressure and temperature steam explosion and high concentration sodium hydroxide, an alkaline peroxide pretreatment without a steam explosion and high concentration sodium hydroxide was also attempted. A comparatively large amounts of glucose and reducing sugar production, i.e. 399 and 568mg/(g initial dry sample), respectively, were obtained in 1%(v/v) hydrogen peroxide and 1wt.% sodium hydroxide treatment at 90°C for 60min. Therefore, it was concluded that alkaline peroxide pretreatment is an effective and environmentally friendly method for the enzyme saccharification of bamboo. [Copyright &y& Elsevier]

Abstract: In these studies, alkaline peroxide pretreatment of wheat straw was investigated. Pretreated wheat straw was hydrolyzed using cellulolytic and xylanolytic enzymes, and the hydrolysate was used to produce butanol using Clostridium beijerinckii P260. The culture produced less than 2.59gL−1 acetone–butanol–ethanol (ABE) from alkaline peroxide wheat straw hydrolysate (APWSH) that had not been treated to reduce salt concentration (a neutralization product). However, fermentation was successful after inhibitors (salts) were removed from the hydrolysate by electrodialysis. A control glucose fermentation resulted in the production of 21.37gL−1 ABE, while salt removed APWSH resulted in the production of 22.17gL−1 ABE. In the two fermentations, reactor productivities were 0.30 and 0.55gL−1 h−1, respectively. A comparison of use of different substrates (corn fiber, wheat straw) and different pretreatment techniques (dilute sulfuric acid, alkaline peroxide) suggests that generation of inhibitors is substrate and pretreatment specific. [Copyright &y& Elsevier]

Abstract: The cellulose content of substrate is one of the most important factors for ethanol production from lignocellulose. To increase the cellulose content of substrate and ethanol yield in simultaneous saccharification and fermentation (SSF), a pretreatment method coupling steam explosion with alkaline peroxide for wheat straw was studied. After the complex pretreatment, the cellulose content in wheat straw increased from 31.5% to 67.2%. In the hydrolysate of wheat straw pretreated with the complex method and steam explosion, the glucose concentration was 110.9g/L and 67.8g/L, respectively. The optimal conditions for SSF were 40°C, 120h, cellulase loading 40FPU/(g wheat straw), yeast inoculum 10% (v/v) and substrate concentration 16.7% (w/v). Under the optimal conditions, the total ethanol concentration in SSF of wheat straw pretreated with steam explosion and alkaline peroxide reached 51.5g/L, and an overall yield of 81.1% was obtained. [Copyright &y& Elsevier]

[Display omitted] • A ball-mill assisted alkaline peroxide pretreatment process was developed. • 70% of XOS alone with high yield of fermentable sugars was achieved. • The pretreatment process was environmental-friendly. • The mechanism of enhanced enzymatic digestibility by BAP pretreatment was revealed. The aim of this work was to develop a feasible ball mill-assisted alkaline peroxide pretreatment followed by stepwise hydrolysis to improve the yield of xylo -oligosaccharides (XOS) and fermentable sugars. The hydrogen peroxide charge, ball-milling time, and solid-to-liquid ratio affected the compositions, particle sizes, morphology, and crystallinity of the corn stover, directly improving the following hydrolytic efficiency. The optimal pretreatment was with 0.45 g/g (H 2 O 2 : substrate) and 1:3 solid-to-liquid ratio (w/v) for 1.0 h ball-milling, resulting in 84.29% delignification. Physicochemical properties of the pretreated samples were characterized and their correlations to the enzymatic hydrolysis were revealed. Compared with one-step cellulase hydrolysis, the two-step xylanase-cellulase hydrolysis of the pretreated corn stover showed significant advance in preparing XOS, producing 69.65% (on the base of xylan content in pretreated sample) of XOS, along with 20.55% xylose, 68.94% glucose, and 21.15% gluco -oligosaccharides. The yield of XOS was 2–7 times higher than those in previous studies. [ABSTRACT FROM AUTHOR]

Abstract: Rice hulls used in this study contained 35.62±0.12% cellulose and 11.96±0.73% hemicellulose. Alkaline H2O2 pretreatment and enzymatic saccharification methods were evaluated for conversion of rice hull cellulose and hemicellulose to simple sugars. The yield of sugars from diluted alkaline peroxide pretreated (7.50% H2O2, v/v; pH 11.5; 35°C; 24h) rice hulls (15.0%, w/v) after enzymatic saccharification (45°C, pH 5.0, 72h) by three commercial enzyme preparations (cellulase, β-glucosidase, and xylanase) using 0.12ml of each enzyme preparation per g hulls was 428±12mg/g (90% yield). During the pretreatment, no measurable furfural and hydroxymethyl furfural were produced. The almost complete conversion (96%) of rice hulls to sugars was achieved by saccharifying the liquid and solid fractions separately after alkaline peroxide pretreatment. The concentration of ethanol from alkaline peroxide pretreated, enzyme saccharified rice hull (39g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35°C in 24h was 8.2±0.2g/l with a yield of 0.49g/g available sugars (0.21g/g hulls). The ethanol concentration was 8.0±0.2g/l with a yield of 0.20g/g hulls in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35°C in 48h. [Copyright &y& Elsevier]

Two-stage treatments of Caligonum monogoliacum and Tamarix spp. with acidic organosolv and alkaline peroxide were performed. Pre-treatment with ethanol–H2O (60/40, v/v) under acid catalyst (0.2 N HCl) at 70 °C for 4 h released 18.7 and 17.8% hemicelluloses from dewaxed C. monogoliacum and Tamarix spp., respectively, Sequential treatment with 2% H2O2 at pH 11.5 for 16 h at 45 °C solubilized 26.2 and 26.5% hemicelluloses from pre-treated C. monogoliacum and Tamarix spp., respectively. Cellulose predominated in the insoluble residues, accounting for 36.7–37.8% of dry materials. It was found that the two alkaline peroxide soluble hemicellulosic preparations contained a much higher amount of xylose (74.1–77.3%) but lower in glucose (7.4–18.6%), galactose (3.0–8.3%), rhamnose (2.3–2.9%), mannose (0.8–2.7%), and arabinose (1.3–1.4%) than those of the two acidic organosolv soluble hemicellulosic fractions in which xylose (31.8–50.8%), glucose (21.4–30.3%), galactose (7.6–24.1%), and rhamnose (5.7–10.1%) were the major sugar components. The content of uronic acids was slightly higher in the two alkaline peroxide soluble hemicellulosic preparations (7.5–8.3%) than the two acidic organosolv soluble hemicellulosic fractions (5.0–6.5%). Furthermore, the studies showed that the two alkaline peroxide soluble hemicellulosic preparations were more linear and acidic, and had a large molecular mass (M¯w, 27,220–31,410 g mol−1) than the two acidic organosolv soluble hemicellulosic fractions (M¯w, 13,820–18,380 g mol−1). Lignin content and its composition associated in the four isolated hemicelluloses were determined by alkaline nitrobenzene oxidation and monitored with HPLC. No significant differences in lignin content (5.94–9.82%) and its composition were found. Further comparative study of the four hemicellulosic preparations and two cellulosic fractions was carried by both degraded methods such as acid hydrolysis and thermal analysis and non-degradation techniques such as FT-IR and 13C-NMR spectroscopy. [Copyright &y& Elsevier]

Eight hemicellulosic fractions were obtained by sequential treatment of dewaxed barley straw with 0.1 M NaOH at 45 °C for 3 h, 0.25, 0.5, 1.0, 1.5, 2.0, and 3.0% H2O2 at 45 °C for 3 h at pH 11.5, and 10% KOH–1% Na2B4O7·10H2O at 28 °C for 15 h under continuous agitation. The yields of the fractions were 8.0, 3.1, 3.3, 3.3, 2.2, 2.0, 2.0, and 9.9%, respectively, of the initial amount of barley straw, corresponding to the dissolution of 21.6, 8.4, 8.9, 8.9, 5.9, 5.4, 5.4, and 26.7% of the original hemicelluloses. Meanwhile, the successive treatment also solubilized 29.1, 15.8, 14.6, 10.8, 4.5, 3.2, 2.7, and 3.7% of the original lignin, respectively. This sequential extraction together resulted in dissolution of 91.1% of the original hemicelluloses and 84.8% of the original lignin. The 0.1 M NaOH-soluble hemicellulosic fraction contained mainly xylose, glucose, and arabinose, 44.2, 15.7, and 15.2%, respectively, while the 10% KOH–1% Na2B4O7·10H2O-soluble fraction predominated in xylose, 75.0%. The six alkaline peroxide-soluble fractions were composed of 50.3–54.4% xylose, 14.7–16.9% arabinose, 6.8–10.7% glucose, 6.8–8.5% glucuronic acid or 4-O-methyl-d-glucuronic acid, 0.4–1.5% mannose, and 0.3–1.2% rhamnose. All the hemicellulosic fractions contained substantial amounts of glucuronoarabinoxylans and noticeable quantities of β-glucans. In comparison, the six hemicellulosic fractions, isolated with alkaline peroxide, had much higher molecular weights (56,890–63,810 g mol−1) than those of the two hemicellulosic preparations (28,000–29,080 g mol−1), isolated with alkali in the absence of hydrogen peroxide. The thermal stability of the hemicelluloses increased with an increment of their molar mass. [Copyright &y& Elsevier]

An efficient scheme was developed for the conversion of wheat straw (WS) into bioethanol, silica and lignin. WS was pre-extracted with 0.2 mol/L sodium hydroxide at 30 °C for 5 h to remove about 91% of initial silica. Subsequently, the alkaline-pretreated solids were subjected to alkaline hydrogen peroxide (AHP) pretreatment with 40 mg hydrogen peroxide (H 2 O 2 )/g biomass at 50 °C for 7 h to prepare highly digestible substrate. The results of enzymatic hydrolysis demonstrated that the sequential alkaline-AHP pretreated WS was efficiently hydrolyzed at 10% (w/v) solids loading using an enzyme dosage of 10 mg protein/g glucan. The total sugar conversion of 92.4% was achieved. Simultaneous saccharification and co-fermentation (SSCF) was applied to produce ethanol from the two-stage pretreated substrate using Saccharomyces cerevisiae SR8u strain. Ethanol with concentration of 31.1 g/L was produced. Through the proposed process, about 86.4% and 54.1% of the initial silica and lignin were recovered, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A two-stage pretreatment method was proposed and tested for deconstruction of recalcitrant Miscanthus. During a 1st pretreatment at 50°C, 1.0–4.0% alkaline peroxide solutions were used to partially remove hemicellulose and lignin. The remaining solids were subjected to a 2nd pretreatment at 121°C with electrolyzed water. Using 15 filter paper units of cellulase per gram cellulose, a digestibility of 95% was achieved by the two-stage method, which was higher than 81% obtained from a 1% H2SO4 pretreatment (200°C, 8min). A mass balance for the two-stage process showed that 63% hemicellulose and 64% lignin were removed from the Miscanthus samples after the 1st pretreatment. The Scanning Electron Microscopy images and Fourier Transform Infrared Spectroscopy spectra revealed that after the 1st pretreatment, crystalline cellulose fibers were partially exposed and the linkages between residual lignin and hemicellulose disappeared. After the 2nd pretreatment, cellulose fibers were completely exposed even with cracks developed. [Copyright &y& Elsevier]

Highlights: [•] Ethanol productivity was improved by a combined AP pretreatment and SSSF process. [•] 64.9% of lignin was removed by AP pretreatment. [•] Ethanol yield was significantly increased from 12.8% to 63.1%. [•] SSSF generated fewer inhibitors than SSF. [Copyright &y& Elsevier]

In this paper, the seven acid-insoluble lignin preparations from barley straw were first extracted with alkaline hydrogen peroxide in order to study how the delignification and degradation of the lignin is influenced by aqueous 1.5% H2O2 extractant to straw ratios. The results showed that treatment of dewaxed barley straw with 1.5% H2O2 at 45 °C for 14 h (pH 12.0) under the extractant to straw ratios of 10:1, 13:1, 15:1, 18:1, 20:1, 25:1, and 30:1 resulted in dissolution of 65.8%, 68.4%, 68.4%, 69.0%, 69.7%, 71.6%, and 72.3% of the original lignin and 78.7%, 79.8%, 82.3%, 83.4%, 84.8%, 85.3%, and 85.3% of the original hemicelluloses, respectively. The degraded seven lignin samples were analyzed with respect to their chemical compositions, content of chemically linked polysaccharides, molecular weights and structural changes. It was found that the alkaline peroxide treatment under the conditions given led to a noticeable increase in a amount of carboxyl groups due to the oxidation. The results from 13C-NMR analyses showed that the treatment was extremely effective for isolation of highly pure lignins from the straw, and the treatment under the conditions used did not affect the overall structure of lignin. The β-O-4 ether bond and β–β carbon–carbon linkage were found to be the major linkages between lignin units. Hydroxycinnamic acids, such as p-coumaric and ferulic acids, appeared to be strongly linked to lignin molecules, in which p-coumaric acid was found to be bonded to lignin by ester linkage, while ferulic acid was linked by its phenolic group via ether bond to lignin and also principally linked by its carboxyl group via ester bond to lignin and/or hemicelluloses. [Copyright &y& Elsevier]

The effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the methane produced by the anaerobic digestion of wheat straw (WS) and sugarcane bagasse (SCB) was studied, using whole slurry and solid fraction. All the pretreatments released formic and acetic acids and phenolic compounds, while 5-hydroxymetilfurfural (HMF) and furfural were generated only by acid pretreatment. A remarkable inhibition was found in most of the whole slurry experiments, except in thermal pretreatment which improved methane production compared to the raw materials (29% for WS and 11% for SCB). The alkaline pretreatment increased biodegradability (around 30%) and methane production rate of the solid fraction of both pretreated substrates. Methane production results were fitted using first order or modified Gompertz equations, or a novel model combining both equations. The model parameters provided information about substrate availability, controlling step and inhibitory effect of compounds generated by each pretreatment. [ABSTRACT FROM AUTHOR]

Olive tree biomass (OTB) can be used for producing second generation bioethanol. In this work, extracted OTB was subjected to fractionation using a sequential acid/alkaline oxidative pretreatment. In the first acid stage, the effects of sulfuric acid concentration and reaction times at 130 °C were investigated. Up to 71% solubilization of hemicellulosic sugars was achieved under optimized conditions (2.4% H 2 SO 4 , 84 min). In the second stage, the influence of hydrogen peroxide concentration and process time were evaluated at 80 °C. Approximately 80% delignification was achieved under the best operational conditions (7% H 2 O 2 , 90 min) within the experimental range studied. This pretreatment produced a substrate with 72% cellulose that was highly accessible to enzymatic attack, yielding 82 g glucose/100 g glucose in delignified OTB. Ethanol production from both hemicellulosic sugars solubilized in the acid pretreatment and glucose from enzymatic hydrolysis of delignified OTB yielded 15 g ethanol/100 g OTB. [ABSTRACT FROM AUTHOR]

Abstract: The enzymatic hydrolysis of sugarcane bagasse was investigated by treating a peroxide–alkaline bagasse with a pineapple stem juice, xylanase and cellulase. Pre-treatment procedures of sugarcane bagasse with alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 24 factorial designs, with pre-treatment time, temperature, magnesium sulfate and hydrogen peroxide concentration as factors. The responses evaluated were the yield of cellobiose and glucose released from pretreated bagasse after enzymatic hydrolysis. The results show that the highest enzymatic conversion was obtained for bagasse using 2% hydrogen peroxide at 60°C for 16h in the presence of 0.5% magnesium sulfate. Bagasse (5%) was treated with pineapple stem extract, which contains mixtures of protease and esterase, in combination with xylanase and cellulase. It was observed that the amount of glucose and cellobiose released from bagasse increased with the mixture of enzymes. It is believed that the enzymes present in pineapple extracts are capable of hydrolyze specific linkages that would facilitate the action of digesting plant cell walls enzymes. This increases the amount of glucose and other hexoses that are released during the enzymatic treatment and also reduces the amount of cellulase necessary in a typical hydrolysis. [ABSTRACT FROM AUTHOR]

To improve utilization of agricultural residues in biorefineries, the effects of alkaline peroxide (AP) pretreatment on thermal degradation and enzymatic digestibility of rice straw were investigated. A high-cellulose (>70%) pulp with a width of a few micrometers was obtained by rapid (10 min) treatment with AP, without prior heating or other treatment. Moreover, enzymatic hydrolysis of the pulp produced a high glucose yield (approximately 80%). Microfibril networks were exposed, and many nano-scale pores that are easily penetrated by cellulases were observed on the surface of the AP-treated sample. For enzymatic hydrolysis of the pulp, increasing the dosage of cellulases was more effective for improving the glucose yield than addition of a grinding treatment. This AP treatment has the potential for on-site application because it is simple, highly efficient, and can be performed in a short time. [ABSTRACT FROM AUTHOR]

Abstract: Oil palm empty fruit bunches (EFB) are a lignocellulosic by product generated by palm oil mills. Delignified EFB fiber is a potential source of inexpensive hemicellulose, a substrate that is easily hydrolyzed to sugars for use in diverse biotechnological processes. The conditions for maximized selective removal of lignin from EFB fiber via separate treatments with alkaline peroxide and peracetic acid, were established such that the loss of hemicellulose was kept to a minimum. The amount of a reagent used in delignification, the temperature and the length of treatment, were optimized using a combination of Box–Behnken experimental design and the response surface method. Treatments with peracetic acid always left behind more hemicellulose and removed more lignin compared with the treatments involving alkaline peroxide. Under the best conditions (20 cm3 peracetic acid per g EFB, 35 °C, reaction time of 9 h), hemicellulose, cellulose and acid insoluble lignin constituted (dry weight basis) nearly 36%, 47% and ∼16%, respectively, of the treated acetone-washed extractive-free EFB fiber. Approximately 53% of the lignin was removed, but nearly all the hemicellulose was retained. [Copyright &y& Elsevier]

Common reed was studied as raw material for sugar bioconversion. The low temperature alkaline, alkaline-peroxide and hydrotropic pretreatments were employed to overcome the recalcitrance of reed before enzymatic hydrolysis. After pretreatments, lignin was efficiently decreased from the fiber cell wall. Xylan was significantly reduced by hydrotropic pretreatment as well. The surface chemical compositions of reed before and after pretreatments were investigated by X-ray spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Reed had a high surface coverage by lignin. Hydrotropic pretreatment was outstanding to decrease the surface coverage by lignin and expose the polysaccharides to fiber surface. The surface lignin reduction was also supported by attenuated total reflectance (ATR)-FTIR results. Furthermore, the topochemical modification of the fiber wall by hydrotropic pretreatment could improve the fiber digestibility, and thus the maximum glucan and xylan yields with the cellulase dosage of 20 FPU/g raised to 93.1% and 25.5%, respectively. [ABSTRACT FROM AUTHOR]

Background: Clinical guidelines for denture care are available, but evidence for optimal nocturnal storage is scarce. The aim of the study was to compare the role of the overnight storage state on plaque growth and composition on acrylic removable dentures. Methods: In a parallel-group randomized controlled trial of 51 institutionalized participants, 3 denture overnight preservation methods were considered: (i) in water, (ii) dry or (iii) in waterwith added alkalineperoxide-based cleansing tablet. Biofilm samples weretaken on day 7 (developing biofilm - dBF) and day 14 (maturing biofilm - mBF) from a mechanically uncleaned, standardized region, situated distally to the second lower premolars. Total and individual levels of selected perio-pathogenicandcommensal species (n = 20), and of Candida albicans werecalculatedby PCR. Differences between storage conditions (water/dry/tablet) and between the samples (dBF/mBF) were assessed by means of unpaired and paired t-tests respectively, with α = 5%. Results: Overnight denture storage with cleansing tablet significantly decreased the total bacterial level of dBF and mBF up to 13.8%. Fn, Ec, Cs, Sc, Ao and Vp counts were particularly affected by tablet care. Significant lower amounts of Candida albicans for tablet storage compared to water preservation were recorded in dBF and mBF (-69.3 ± 3.8% and -75.9 ± 3.2% respectively). The mass and pathogenicity of dBF and mBF was equal, irrespective of the overnight storage intervention. Conclusions: The use of cleansing tablets for acrylic removable denture overnight storage reduces denture biofilm mass and pathogenicity compared to dry and water preservation, and may contribute to the overall systemic health. Clinical significance: Evidence-based clinical guidelines for overnight storage of removable acrylic dentures are lacking. The findings of this study indicate that alkaline peroxide-based cleansing tablets decrease bacterial and Candida levels in denture biofilms in case of poor oral hygiene. This provides evidence for a clinical guideline to minimize microbial load of dentures, thereby reducing associated systemic health risks. [ABSTRACT FROM AUTHOR]

Highlights: [•] Furfural residues were taken as substrate for bioethanol production. [•] Alkaline peroxide delignification simultaneously degraded lignin and carbohydrates. [•] The glucose content reached as high as 66.0% with 2% chemical dosage at 180°C. [•] 16.9g/L ethanol was finally obtained by simultaneous saccharification and fermentation. [ABSTRACT FROM AUTHOR]

Abstract: Alkaline peroxide pretreatment of rapeseed straw was evaluated for conversion of cellulose and hemicellulose to fermentable sugars. After pretreatment, a liquid phase called pretreatment liquid and a solid phase were separated by filtration. The neutralized pretreatment liquids were used in a co-fermentation process, with Saccharomyces cerevisiae and Pichia stipitis. The solid fraction was used for simultaneous saccharification and co-fermentation process in the same vessel. The effects of various operating variables were investigated. Pretreatment with 5% (v/v) H2O2 at 50°C for 1h was found to be the optimal pretreatment combination with respect to overall ethanol production. At this condition, 5.73g ethanol was obtained from pretreatment liquid and 14.07g ethanol was produced by co-fermentation of solid fraction with P. stipitis. Optimum delignification was observed when 0.5M MgSO4 was included in the pretreatment mixture, and it resulted in 0.92% increase in ethanol production efficiency. [Copyright &y& Elsevier]

Abstract: Olive tree wood, a renewable low-cost agricultural residue, was submitted to steam explosion pretreatment at 190, 210, 230 and 240°C for 5min. To improve enzymatic hydrolysis yields, the water-insoluble fiber was further delignified by an alkaline peroxide treatment. Enzymatic hydrolysis was performed using a commercial cellulolytic complex supplemented with β-glucosidase at 10% (w/v) pretreated material concentration. Delignification did enhance enzymatic hydrolysis yields of steam pretreated olive tree wood. Up to 80% of the lignin in the original wood was solubilized, leaving a cellulose-rich residue that led to a concentrated glucose solution (51.3g/l after 72h enzymatic hydrolysis in the best case). The maximum overall process yield, taking into account both sugars present in the liquid from steam pretreatment and glucose from the steamed, delignified and hydrolyzed solid was obtained at the lowest steam pretreatment temperature assayed. As a result, from 100g of raw material, 28.8g of sugars were recovered of 54.7g available (52.6%). [Copyright &y& Elsevier]

A new mechanism is proposed for the heterogeneous alkaline peroxide brightening reactions of mechanical pulps. The mechanism consists of four key kinetic steps: adsorption of hydrogen peroxide and hydroxide to the pulp fiber walls; chromophore-removing chemical reaction on the fiber wall; desorption of “light” organic products formed from the fiber wall; and oxidation chain reduction of the cleaved organic substances. The most important step here is the surface reaction, rather than reactions occurring in the liquid phase. In general, the removal of the cleaved organic substances from the fiber wall is not anticipated to occur completely during the brightening reaction operation stage. The failure of the “light” organic products to completely dissociate from the fiber wall is more pronounced at high consistencies and when agitation is weak. The pulp brightness is measured after washing the pulp and thus removing the “light” organic products. The overall brightness enhancement or chromophore-removal rate is thus limited by the reaction occurring on the fiber wall. A kinetic model has thus been developed based on the proposed mechanism. An apparent second-order reaction in terms of the chromophore concentration, first orders in terms of the adsorbed hydrogen peroxide and adsorbed hydroxyl concentrations are observed from the kinetic model. The derived kinetic model can explain the existing experimental data from various sources quite well. [Copyright &y& Elsevier]

Abstract: Although the moderate load (COD of 5000–10,000mg/L) and biodegradability of the APMP pulping effluent should allow biological treatment, toxic compounds in the effluent can interfere with this type of treatment. Studies were conducted to determine if treatment of the effluent with Aspergillus niger S13 was feasible. Under the optimized conditions (3% inoculum, pH 6, shaking at 160rpm, 60–72h, and 30°C), this fungus was able to remove about 97% of the methyl tertiary butyl ether (MTBE) extractives, and 60%, 77% and 43% of the chemical oxygen demand, turbidity and color even without a pre-flocculation step. These results are of practical interest in China because the APMP process has become popular, and efficient and cost-effective effluent treatment technologies are in high demand. [Copyright &y& Elsevier]

The multiple active site mechanistic model proposed earlier (Liu, Chem. Eng. Sci. 58 (2003) 2229) has been revisited and a simplistic “single active site” model has been developed. The effect of pulp consistency during brightening reaction has been examined based on the derived kinetic model. There are three competing factors affecting the brightening reaction arising from pulp consistency: effective chemical concentration in the brightening liquor, accessibility of chromophores to the active chemical agents, and frequency of the chromophore–chromophore contact. With the same brightening agent charges (on a dry pulp basis), increasing pulp consistency resulted in an increase in the effective brightening agent concentration in the brightening liquor and the brightening reaction rate increases as well as the final attainable brightness. Increase in pulp consistency under constant brightening agent concentration in liquor reduces brightening reaction rate and final attainable brightness due to the reduction of the accessibility of the brightening agents to the chromophore sites. Finally, increasing pulp consistency increases the frequency of chromophore contacts among different fibers and thus increases brightening reaction rate. Theoretical models are proposed for these effects and good agreement is found with existing experimental data. [Copyright &y& Elsevier]

• The high lignin content of bamboo is well known to make this abundant bioresource difficult to use for cellulosic ethanol. • This study examines and identifies an alkaline ethanol, peroxide pretreatment of bamboo that significantly decreases its recalcitrance. • The results are documented in enhanced sugar release, improved ethanol generation from fermentation and improved techno-economic evaluation. To overcome the typical delignification saturation point of alkaline peroxide pretreatment and further facilitate lignin removal, a novel modified alkaline hydrogen peroxide pretreatment (MAHP) was proposed by introducing ethanol into the reaction system. The dosages of H 2 O 2 , ethanol, and pretreatment temperature were optimized, and the results revealed that a maximum lignin removal as high as 79.25% could be achieved at only 100 °C, 3 wt% H 2 O 2 concentration and 1 wt% ethanol concentration. Meanwhile, 76.5% of glucan and 56.0% of xylan were preserved at this pretreatment condition. By overcoming the delignification saturation point, enzymatic hydrolysis efficiency was remarkably enhanced, achieving 96.76% and 97.38% of glucan and xylan conversion, respectively, which are 7.4 and 11.4 times as compared to that of the untreated bamboo. Furthermore, the simultaneous saccharification and fermentation (SSF) result indicated an identical ethanol yield of ~75% when elevating the SSF solid loading from 5% to 30%. Based on the sequential SSF and xylose fermentation results, about 5.6 tons of bamboo would be consumed to produce 1 ton of ethanol. Finally, the energy balance revealed that a positive balance of 1255.4 KJ could be generated via processing 1 kg bamboo. The results demonstrate that the MAHP is a promising high-efficiency pretreatment technology for bamboo due to the mild pretreatment severity and robust ethanol yield. [ABSTRACT FROM AUTHOR]

Rice husks surround rice grains, and are known to provide them with a protective lignocellulosic cover. This biomass has many potential uses, such as biofuel production. However, the high concentrations of lignin and silica limit its use, for example, they hinder fermentation reactions. In this study, both the delignification and silica removal from husks using a combination of hydrogen peroxide and sodium hydroxide has been investigated. Response surface methodology has been used to find the optimum conditions for maximizing lignin and silica removal, and solid yield. Three independent variables, namely, NaOH concentration, H 2 O 2 concentration and reaction temperature were studied by using Box-Behnken design. The first optimization focused on maximum removal of impurity, and was found at 8% NaOH, 1% H 2 O 2 and 20 °C. Under such conditions, 71.78% lignin removal, 88.47% silica removal and 50.89% solid yield were achieved. The second optimization emphasized the reduction of chemical costs, and was found at 5.29% NaOH, 1% H 2 O 2 and 20 °C; resulting in 59.85% lignin removal, 75.13% ash removal and 59.21% solid yield. Image 1 • Alkaline peroxide was used to extract lignin and silica from rice hulls. • The treatment temperature, NaOH concentration, and H 2 O 2 concentration were varied. • With RSM, the silica ash removal, lignin removal, and solid yield were optimized. • Nearly 51% solid yield was retained, with about 71% lignin and 88% silica removal. • Nearly 60% solid yield is possible, with about 60% lignin and 75% silica removal. [ABSTRACT FROM AUTHOR]

Olive stones (OS) constitute the main solid by-product of the olive oil industry, whose main application is direct burning. As an alternative, this work proposes an integrated multiproduct OS biorefinery, to produce furfural, lignin, antioxidants and sugars. A combination of pre-treatments, i.e. dilute acid pre-treatment followed by alkaline peroxide delignification, was assessed in order to improve on the previously limited results reported for the same raw materials. The operational conditions were optimised through experimental design and response surface methodology, to produce the highest recovery of sugars (xylose) from the liquid fraction plus glucose from the enzymatic hydrolysis (EH) of the pre-treated solids. This resulted in 70% and 41% recovery, respectively, while delignification yields reached 51% at 7% H 2 O 2 , increasing EH yields up to 70.3%. Phenolic compounds of potential interest were detected in the liquors, up to 25.3 mg gallic acid equivalent/g OS. Solubilised lignin was recovered by acid precipitation, with a yield of 76.3%, representing 11 g lignin/100 g OS, with a calorific value of 21,733 kJ/kg. 26.5 g/L of furfural was obtained from the xylose-rich hydrolysate with a yield of 45.7%. Consequently, OS can be considered to be a promising raw material for a multiproduct biorefinery. [ABSTRACT FROM AUTHOR]

• AHP with ethanol overcame the delignification saturation point at a mild temperature. • The proposed pretreatment maximized the enzymatic hydrolysis efficiency of bamboo. • The delignification methodology exhibited versatility for grass and hardwood. To overcome the delignification saturation point in traditional alkaline hydrogen peroxide pretreatment (AHP), a powerful modified AHP delignification methodology was established by introducing ethanol into the system. The pretreatment caused significant lignin removal of bamboo at elevated pretreatment temperature with the highest lignin removal reaching 80.0% at 100 °C, higher than that (74.9% lignin removal) in pretreatment without the ethanol assistance. In addition, a certain amount of carbohydrates was also solubilized during the process whose recovery was 83.3% (glucan) and 67.6% (hemicellulose), respectively. The pretreated solid exhibited excellent enzymatic digestibility, with hydrolysis yields of ~100% and 95.7% for glucan and xylan, respectively. Our studies further indicate that this delignification methodology is versatile for hardwood and herbaceous plants, but does not perform well on softwood. [ABSTRACT FROM AUTHOR]

So far, a large number of pretreatment methods have garnered significant attention aimed only at optimizing the reducing sugar and bioethanol yields. This study however, carried out pretreatment of sugarcane bagasse (SCB) using hydrothermal, organosolv, alkaline and alkaline peroxide pretreatment methods comparing their process performance. An evaluation of the energy consumption parameter during pretreatment showed lowest energy use (0.619 kWh/kg) during 5% alkaline peroxide pretreatment. The energy efficiency (0.162 kg bioethanol/kWh) was thus highest whereas the waste generation was lowest (38.895 kg waste/kg bioethanol) during alkaline peroxide pretreatment process. The solid biomass was utilized for enzymatic saccharification and bioethanol fermentation using SSF. Maximum enzyme efficiency and bioethanol yields achieved were 85.02% and 0.101 kg bioethanol/kg biomass respectively. Process performance evaluation can be projected to open up a new avenue for practical implementations of life cycle analysis (LCA) and techno-economic assessment aiding the circular bio-economy approach. [Display omitted] • Chemical pretreatment technologies investigated for process performance evaluation. • Energy efficiency and waste generation used to evaluate process performance. • 0.162 kg bioethanol/kWh- energy efficiency during alkaline peroxide pretreatment. • Also, lowest waste generation (38.895 kg waste/kg bioethanol) was recorded. • NaOH and H 2 O 2 at 5% (w/w) chemical concentration was most effective pretreatment. [ABSTRACT FROM AUTHOR]

This work describes the feasibility of using rice milling by-products as feedstock for bioethanol. Starch-rich residues (rice bran, broken, unripe and discolored rice) were individually fermented (20% w/v) through Consolidated Bioprocessing by two industrial engineered yeast secreting fungal amylases. Rice husk (20% w/v), mainly composed by lignocellulose, was pre-treated at 55 °C with alkaline peroxide, saccharified through optimized dosages of commercial enzymes (Cellic® CTec2) and fermented by the recombinant strains. Finally, a blend of all the rice by-products, formulated as a mixture (20% w/v) according to their proportions at milling plants, were co-processed to ethanol by optimized pre-treatment, saccharification and fermentation by amylolytic strains. Fermenting efficiency for each by-product was high (above 88% of the theoretical) and further confirmed on the blend of residues (nearly 52 g/L ethanol). These results demonstrated for the first time that the co-conversion of multiple waste streams is a promising option for second generation ethanol production. [ABSTRACT FROM AUTHOR]

The cellulose nanocrystals (CNCs) were produced from spruce wood using less hazardous and toxic reagents with understanding of influence of process parameters on CNCs properties. This study employed acetosolv pulping followed by alkaline-peroxide bleaching, eliminating highly reactive chemicals such as Na-chlorites and Na-sulfite for cellulose pulp extraction from spruce wood. Cellulose pulp yield of 41.5 ± 0.7 wt% of dry wood was obtained from pulping followed by bleaching treatment. Cellulose pulp was hydrolyzed with 59.0–65.0 wt% sulfuric acid followed by ultrasonic treatment to produce CNCs. CNCs yield of 8.0 ± 3.2 wt% of dry wood was obtained at 65 wt% acid concentration and yield of 25.1 ± 0.7 wt% at 62 wt% acid concentration. The optimization of acid hydrolysis and ultrasonic treatment resulted in CNCs with high aspect ratios (length/width) up to 48.1. It was demonstrated that higher acid concentration requires lower intensity of ultrasonic treatment for CNCs dispersion, and that higher intensity could enhance aspect ratio without impacting the crystallinity index. However, ultrasonic treatment for longer than 5 min led to destruction of the whisker morphology of CNCs. The extracted CNCs possess high crystallinity index of 80.8 ± 1.7 %, low residual hemicellulose (<2.0 %) and lignin (<0.7 %), and high-char content of 26.7 wt% from thermal degradation. [Display omitted] • S and Cl free pulping and bleaching processes were used for cellulose extraction. • Pure cellulose nanocrystals from spruce were obtained in high yield. • High aspect ratio of up to 48 and crystallinity index of 80.8 ± 1.7 % were achieved. • Ultrasonic treatment showed no negative impact on the crystallinity index of CNCs. [ABSTRACT FROM AUTHOR]

This study aimed to assess the efficacy of chemical agents in removing Candida albicans and Streptococcus mutans biofilm from invisible aligners. The samples were made of EX30 Invisalign trays, biofilm was cultured by standardized suspensions of C. albicans ATCC strain and S. mutans clinical strain on the sample. The treatments used were 0.5% sodium hypochlorite (NaClO) (20 minutes), 1% NaClO (10 minutes), chlorhexidine (5 minutes), peroxide (15 minutes), and orthophosphoric acid (15 seconds). The control group received phosphate-buffered saline for 10 minutes. The colony-forming units per milliliter of each microorganism were determined by serial dilutions seeded in plates with selective culture mediums for each one. Data were analyzed by the Kruskal-Wallis and Conover-Iman tests at an α of 0.05. For the C. albicans biofilm group, the control group had 9.7 Log10 of microorganism growth, and all treatment groups had statistically significant biofilm reduction, in which chlorhexidine presented the highest inhibition of 3 Log10, followed by alkaline peroxide and orthophosphoric acid both with 2.6 Log10, 1% NaClO (2.5 Log10), and 0.5% NaClO (2 Log10). As for S. mutans , the control group had 8.9 Log10 of growth, and a total microorganism inhibition was reached by chlorhexidine, 1% NaClO, and orthophosphoric acid, whereas alkaline peroxide inhibited growth to 7.9 Log10 and 0.5% NaClO 5.1 Log10. Within the limitations, chlorhexidine and orthophosphoric acid had greater efficacy in both biofilms. In addition, 1% NaClO and alkaline peroxide also had significant effects; therefore, their incorporation aligners disinfection protocols are valid. • Invisible aligners are susceptible to microorganism colonization. • Candida spp is considered part of the resident microbiota and opportunistic fungi. • The co-aggregation of C. albicans and S. mutans occurs via a cooperation mechanism. • Chlorhexidine and orthophosphoric acid were the substances with the best performance. • Alkaline peroxide and 1% sodium hypochlorite had statistically significant effects. [ABSTRACT FROM AUTHOR]

Abstract: Arabinoxylans (AXs) from spelt hull were extracted by three different alkaline methods and by two methods with several modalities and two organic acids. The first method enabled to extract 1.4% of the water-extractable AXs (WE-AXs) of the hull with molecular weight (MW) of 5400g/mol and arabinose to xylose (A/X) ratio of 0.55. The two successive extractions with 2% alkaline peroxide hydrogen at 60°C during 4h enabled to extract 20.4% of the water-unextractable AXs (WU-AXs) of the hull. Those fractions had MWs of 6800–7800g/mol and 227700–274600g/mol and A/X ratios of 0.32 and 0.45. The second method with 2% alkaline peroxide hydrogen at 50°C during 24h enabled to extract 25.4% of the hemicelluloses of the hull. The two AX populations had MW of 9200–11400g/mol and 256800–273200g/mol with an A/X ratio of 0.36. The third method with NaOH gave the highest yield, 41.9% after a 16h extraction. A/X ratios (0.18) and MWs (two populations of 9300–9500g/mol) were lower than those of the previous methods. Organic acids method offered insufficient yields and compounds of very low MW (1300–11300g/mol). Methods with alkaline peroxide hydrogen enabled to obtain high MWs and high A/X ratios with moderate yields while the NaOH method gave the highest yield efficiency with lower MWs and A/X ratios. Organic acids method did not bring any advantage neither on the yield nor on the MWs of the compounds. [Copyright &y& Elsevier]