Alkaline Hydrogen Peroxide Pretreatment Research Articles

EFFECT OF COMBINATION OF LIQUID HOT WATER SYSTEM AND HYDROGEN PEROXIDE PRETREATMENT ON ENZYMATIC SACCHARIFICATION OF CORN COB

Alkaline hydrogen peroxide pretreatment is an effectively enhance the increasing enzymatic digestibility of lignocellulosic biomass for conversion to fuels and chemicals in the biorefinery processes. In this study, effects of H2O2 on monomeric sugar in the liquid fraction during hydrogen peroxide pretreatment and sugar after enzymatic hydrolysis from corncobs were studied under varying reaction conditions. The temperature (30-120oC) and H2O2 concentration (2.5-10%) efficiently promoted sugar yield in the piqued fraction and improved enzymatic hydrolysis of pretreated solids. The optimal condition for H2O2 pretreatment of corncob (H2O2 concentration of 5% using 60 oC for 2 h) increased hemicellulose solubilization into the aqueous phase, resulting into the maximized pentose yield of 61.88% (xylose + arabinose) in the aqueous phase. H2O2 pretreatment under the optimal conditions at 60oC for 2 h, leading to the enhance glucose yield from enzymatic hydrolysis of the pretreated biomass using 10 FPU/g CelluclastTM (85.66 %) and small amount of formation of inhibitory by-products. Combined with glucose in the aqueous phase, this resulted in the maxima 95.61% glucose recovery from the native corncob. This was related to changes in crystallinity and surface area of the pretreated biomass. Scanning electron microscopy (SEM) showed disruption of the intact biomass structure resulting increasing enzyme’s accessibility to the cellulose microfibers which showed higher crystallinity index compared to the native biomass as shown by X-ray diffraction with a marked increase in surface area as revealed by BET measurement. The results provided efficiency of H2O2 pretreatment on increasing sugar recovery and an efficient approach for its processing in biorefinery industry.

Biohythane production from sugarcane bagasse and water hyacinth: A way towards promising green energy production

The present study embarks the concept of developing continuous biohythane (biohydrogen followed by biomethane) production from renewable energy sources. Combination of sugarcane bagasse and water hyacinth were used to reduce the use of costly chemicals for fermentation process. The lignin content of sugarcane bagasse was reduced using alkaline hydrogen peroxide pretreatment. The maximum lignin reduction of 89 ± 3% (w/w) was observed at 50 °C and 150 min pretreatment time. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy analysis were performed to confirm the lignin removal after pretreatment. Further, the influence of the hydraulic retention time on two stage biohythane production was studied by using combination of pretreated sugarcane bagasse and water hyacinth (1:2 ratio) (soluble COD, 30 ± 2 g/L) in continuous stirrer tank bioreactor. The suitable hydraulic retention time for biohydrogen and biomethane production were found to be 8 h and 10 d, respectively, which gave the maximum hydrogen and methane yield of 303 mL/g COD and 142 mL/g COD, respectively. The continuous biohythane production process increased the overall substrate conversion efficiency up to 86% with the maximum gaseous energy recovery of 8.97 kJ/g COD.

Impact of double alkaline peroxide pretreatment on enzymatic hydrolysis of palm fibre

A double pretreatment was developed to improve the efficiency of enzymatic hydrolysis and to increase the sugars production from palm fibre in batch and fed-batch systems. After alkaline peroxide pretreatment using NaOH-H2O2 solution, rigid structure of palm fibre was broken and partial of the hemicelluloses and lignin were removed. Compared with cellulase Accellerase® 1500, when using the conjunction of Accellerase® 1500 and Optimash BG, the conversion ratio increased from 35.9% to 45.0% and the reducing sugar yield increased from 245 mg/g substrate to 307 mg/g substrate. To further increase the hydrolysis efficiency, double pretreatment with NaOH-H2O2 solution was used to treat the hydrolysized residues. Then, the hydrolysis ratio reached 93% and reducing sugar yield was 752 mg/g substrate. Fed-batch enzymatic hydrolysis was carried out with 7% (w/v) solids loading and 0.3 mL/g substrate. Then, 7% solids were fed consecutively at 12 h, 24 h, 36 h and 48 h. After 144 h, the final concentration of reducing sugar reached 214.0 g/L and total biomass conversion ratio was 75.23%.

Insights into the improvement of alkaline hydrogen peroxide (AHP) pretreatment on the enzymatic hydrolysis of corn stover: Chemical and microstructural analyses

The alkaline hydrogen peroxide (AHP) pretreatment (0.5 g H2O2/g corn stover, 30 °C, 24 h) removed 91.53% of the initial lignin and 55.77% of the initial hemicellulose in corn stover and afforded a considerable glucose yield (88.34%) through enzymatic hydrolysis. A combination of chemical and microstructural analyses was used to illustrate the mechanism of the effect of AHP pretreatment on enzymatic hydrolysis. During pretreatment, H2O2-derived radicals effectively spread into and destroyed the cell wall of various parts (vascular bundle sheath, xylem vessels, tracheid, phloem, and parenchyma) of corn stover to remove most of the lignin, acetyl group, and partial hemicellulose. They destroyed the compact structure of the cellulose-hemicellulose-lignin network, increased the cellulase-accessible pore volume by 6 times, doubled the area of exposed cellulose, and decreased the unproductive adsorption of enzymes onto lignin. Combining all the effects, AHP pretreatment effectively improved the cellulose accessibility to enhance the subsequent enzymatic hydrolysis efficiency.

Integrated experimental and technoeconomic evaluation of two-stage Cu-catalyzed alkaline\u2013oxidative pretreatment of hybrid poplar

BackgroundWhen applied to recalcitrant lignocellulosic feedstocks, multi-stage pretreatments can provide more processing flexibility to optimize or balance process outcomes such as increasing delignification, preserving hemicellulose, and maximizing enzymatic hydrolysis yields. We previously reported that adding an alkaline pre-extraction step to a copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment process resulted in improved sugar yields, but the process still utilized relatively high chemical inputs (catalyst and H2O2) and enzyme loadings. We hypothesized that by increasing the temperature of the alkaline pre-extraction step in water or ethanol, we could reduce the inputs required during Cu-AHP pretreatment and enzymatic hydrolysis without significant loss in sugar yield. We also performed technoeconomic analysis to determine if ethanol or water was the more cost-effective solvent during alkaline pre-extraction and if the expense associated with increasing the temperature was economically justified.ResultsAfter Cu-AHP pretreatment of 120 °C NaOH-H2O pre-extracted and 120 °C NaOH-EtOH pre-extracted biomass, approximately 1.4-fold more total lignin was solubilized (78% and 74%, respectively) compared to the 30 °C NaOH-H2O pre-extraction (55%) carried out in a previous study. Consequently, increasing the temperature of the alkaline pre-extraction step to 120 °C in both ethanol and water allowed us to decrease bipyridine and H2O2 during Cu-AHP and enzymes during hydrolysis with only a small reduction in sugar yields compared to 30 °C alkaline pre-extraction. Technoeconomic analysis indicated that 120 °C NaOH-H2O pre-extraction has the lowest installed ($246 million) and raw material ($175 million) costs compared to the other process configurations.ConclusionsWe found that by increasing the temperature of the alkaline pre-extraction step, we could successfully lower the inputs for pretreatment and enzymatic hydrolysis. Based on sugar yields as well as capital, feedstock, and operating costs, 120 °C NaOH-H2O pre-extraction was superior to both 120 °C NaOH-EtOH and 30 °C NaOH-H2O pre-extraction.

Production of bioethanol and value added compounds from wheat straw through combined alkaline/alkaline-peroxide pretreatment

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 (H2O2)/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.

Valorization of Lignocellulosic Waste (Crotalaria juncea) Using Alkaline Peroxide Pretreatment under Different Process Conditions: An Optimization Study on Separation of Lignin, Cellulose, and Hemicellulose

ABSTRACTLignocellulose materials, essentially consisting of lignin, cellulose and hemicelluloses, are abundant sources of fermentable sugars. The bast fiber of Crotalaria juncea (Sunn hemp), a native cover crop of India, was used as feedstock for this study. The primary objective of this study was to add value to the waste C. juncea bast fiber. The same was achieved by pretreating the waste fiber using alkaline peroxide solution at various process conditions. The optimal process condition for alkaline peroxide pretreatment was identified for the fiber to pretreatment solution (S/S) ratio of 1/40 at 50°C for 5h with respect to all response variables (lignin removal, hemicellulose recovery, recovery of solid pretreated material, and crystallinity of lignocellulose). Three-way ANOVA results revealed that S/S ratio had no significant effect; whereas, both temperature and time, and the combination of parameters, exhibited significant effect on response variables. The characteristic peaks associated with lignin and cellulose demonstrated a higher amount of lignin removal and increased cellulose content with elevated treatment time. Autoclave assisted pretreatment proved to be inefficient due to removal of lower amount of lignin in addition to higher hemicellulose degradation. On the other hand, pretreatment using ultrasound was found to be most effective in removing lignin, liberating hemicelluloses along with diminition in cellulose crystallinity.

Engineered Lignin in Poplar Biomass Facilitates Cu-Catalyzed Alkaline-Oxidative Pretreatment

Both untransformed poplar and genetically modified “zip-lignin” poplar, in which additional ester bonds were introduced into the lignin backbone, were subjected to mild alkaline and copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment. Our hypothesis was that the lignin in zip-lignin poplar would be removed more easily than lignin in untransformed poplar during this alkaline pretreatment, resulting in higher sugar yields following enzymatic hydrolysis. We observed improved glucose and xylose hydrolysis yields for zip-lignin poplar compared to untransformed poplar following both alkaline-only pretreatment (56% glucose yield for untransformed poplar compared to 67% for zip-lignin poplar) and Cu-AHP pretreatment (77% glucose yield for untransformed poplar compared to 85% for zip-lignin poplar). Compositional analysis, glycome profiling, and microscopy all supported the notion that the ester linkages increase delignification and improve sugar yields. Essentially no differences were noted in the m...

Relating Nanoscale Accessibility within Plant Cell Walls to Improved Enzyme Hydrolysis Yields in Corn Stover Subjected to Diverse Pretreatments.

Simultaneous chemical modification and physical reorganization of plant cell walls via alkaline hydrogen peroxide or liquid hot water pretreatment can alter cell wall structural properties impacting nanoscale porosity. Nanoscale porosity was characterized using solute exclusion to assess accessible pore volumes, water retention value as a proxy for accessible water-cell walls surface area, and solute-induced cell wall swelling to measure cell wall rigidity. Key findings concluded that delignification by alkaline hydrogen peroxide pretreatment decreased cell wall rigidity and that the subsequent cell wall swelling resulted increased nanoscale porosity and improved enzyme binding and hydrolysis compared to limited swelling and increased accessible surface areas observed in liquid hot water pretreated biomass. The volume accessible to a 90 Å dextran probe within the cell wall was found to be correlated to both enzyme binding and glucose hydrolysis yields, indicating cell wall porosity is a key contributor to effective hydrolysis yields.

Ethanol production from bamboo using mild alkaline pre-extraction followed by alkaline hydrogen peroxide pretreatment

A sequential two-stage pretreatment process comprising alkaline pre-extraction and alkaline hydrogen peroxide pretreatment (AHP) was investigated to convert bamboo carbohydrates into bioethanol. The results showed that mild alkaline pre-extraction using 8% (w/w) sodium hydroxide (NaOH) at 100°C for 180min followed by AHP pretreatment with 4% (w/w) hydrogen peroxide (H2O2) was sufficient to generate a substrate that could be efficiently digested with low enzyme loadings. Moreover, alkali pre-extraction enabled the use of lower H2O2 charges in AHP treatment. Two-stage pretreatment followed by enzymatic hydrolysis with only 9FPU/g cellulose led to the recovery of 87% of the original sugars in the raw feedstock. The use of the pentose-hexose fermenting Saccharomyces cerevisiae SR8u strain enabled the utilization of 95.7% sugars in the hydrolysate to reach 4.6%w/v ethanol titer. The overall process also enabled the recovery of 62.9% lignin and 93.8% silica at high levels of purity.

Neural network modeling to support an experimental study of the delignification process of sugarcane bagasse after alkaline hydrogen peroxide pre-treatment

The present study examines the use of Artificial Neural Networks (ANN) as prediction and fault detection tools for the delignification process of sugarcane bagasse via hydrogen peroxide (H2O2). Experimental conditions varied from 25 to 45°C for temperature and from 1.5% to 7.5% (v/v) for H2O2 concentrations. Analytical results for the delignification were obtained by Fourier Transform Infrared (FT-IR) analysis and used for the ANN training and testing steps, allowing for the development of ANN models. The condition experimentally identified as the most suitable for the delignification process was of 25°C with 4.5% (v/v) H2O2, oxidizing 54% of total lignin. An ANN topology was selected for each proposed model, whose performance was evaluated by the correlation coefficient (R2) and error indices (MSE and SSE). The values obtained for R2 and the error indices indicated good agreements of the theoretical and actual data, of close to 1 and close to 0, respectively.

Alkaline hydrogen peroxide pretreatment of lignocellulosic biomass: status and perspectives

Lignocellulosic biomass is a renewable and abundant resource that is suitable for the production of bio-based materials such as biofuels and chemical products. However, owing to its complex chemical composition, it requires a process that enhances the release of sugars. Pretreatment is an essential stage in increasing the efficiency of enzymatic hydrolysis of lignocellulosic biomass. The most widely used pretreatment methods operate at high temperatures (160–290 °C) and pressures (0.69 to 4.9 MPa) and generate biological growth inhibitors such as furfural and hydroxymethylfurfural (HMF). Thus, there has been a growing need to adopt new approaches for an effective pretreatment that operates at ambient temperature and pressure and reduces the generation of inhibitors. Among these methods, alkaline hydrogen peroxide (AHP) is notable because it is effective for a wide range of lignocellulosic biomass concentrations, and can provide a high degree of enzymatic hydrolysis efficiency. However, few results have been discussed in the literature. Given this, the aim of this study was to investigate the use of alkaline hydrogen peroxide (AHP) as an oxidative pretreatment agent to improve the efficiency of enzymatic hydrolysis for different types of biomass and examine the key areas of the pretreatment. Finally, there is a discussion of the challenges facing a large-scale application of this method.

Alkaline Peroxide Delignification of Corn Stover

Selective biomass fractionation into carbohydrates and lignin is a key challenge in the conversion of lignocellulosic biomass to fuels and chemicals. In the present study, alkaline hydrogen peroxide (AHP) pretreatment was investigated to fractionate lignin from polysaccharides in corn stover (CS), with a particular emphasis on the fate of the lignin for subsequent valorization. The influence of peroxide loading on delignification during AHP pretreatment was examined over the range of 30–500 mg H2O2/g dry CS at 50 °C for 3 h. Mass balances were conducted on the solid and liquid fractions generated after pretreatment for each of the three primary components, lignin, hemicellulose, and cellulose. AHP pretreatment at 250 mg H2O2/g dry CS resulted in the pretreated solids with more than 80% delignification consequently enriching the carbohydrate fraction to >90%. Two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy of the AHP pretreated residue shows that, under high peroxide loadings (>250 mg H2O2...

Bioprocessing of tea oil fruit hull with acetic acid organosolv pretreatment in combination with alkaline H2O2

BackgroundAs a natural renewable biomass, the tea oil fruit hull (TOFH) mainly consists of lignocellulose, together with some bioactive substances. Our earlier work constructed a two-stage solvent-based process, including one aqueous ethanol organosolv extraction and an atmospheric glycerol organosolv (AGO) pretreatment, for bioprocessing of the TOFH into diverse bioproducts. However, the AGO pretreatment is not as selective as expected in removing the lignin from TOFH, resulting in the limited delignification and simultaneously high cellulose loss.ResultsIn this study, acetic acid organosolv (AAO) pretreatment was optimized with experimental design to fractionate the TOFH selectively. Alkaline hydrogen peroxide (AHP) pretreatment was used for further delignification. Results indicate that the AAO–AHP pretreatment had an extremely good selectivity at component fractionation, resulting in 92% delignification and 88% hemicellulose removal, with 87% cellulose retention. The pretreated substrate presented a remarkable enzymatic hydrolysis of 85% for 48 h at a low cellulase loading of 3 FPU/g dry mass. The hydrolyzability was correlated with the composition and structure of substrates by using scanning electron microscopy, confocal laser scanning microscopy, and X-ray diffraction.ConclusionThe mild AAO–AHP pretreatment is an environmentally benign and advantageous scheme for biorefinery of the agroforestry biomass into value-added bioproducts.

Short-time alkaline peroxide pretreatment for rapid pulping and efficient enzymatic hydrolysis of rice straw

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 (10min) 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.

Improving enzymatic saccharification of cassava stem using peroxide and microwave assisted pre-treatment techniques

The effectiveness of microwave assisted alkali (MAA) and alkaline hydrogen peroxide (AHP) pre-treatment methods in improving the enzymatic saccharification of cassava stem was investigated. Ground cassava stems were by MAA method by varying microwave power, NaOH concentration and pre-treatment time. AHP method was performed at various H2O2 concentrations, pre-treatment temperatures and times. The results showed that reducing sugar yield was higher from MAA pretreated stem when compared with AHP pre-treatment, which demonstrated that MAA pre-treatment was effective in releasing sugars. SEM studies on the pre-treated samples revealed extensive distortion of fibres in MAA pre-treated than AHP pre-treated samples, which showed pores and cracks in the fibrous structure. Spectral studies showed the change in the chemical structure of pre-treated samples. The work revealed that the studied pre-treatment methods were effective in improving the enzymatic saccharification of cassava stem.

Methane production enhancement from products of alkaline hydrogen peroxide pretreated sweet sorghum bagasse

Alkaline hydrogen peroxide (AHP) pretreatment was applied to improve methane production from sweet sorghum bagasse under mesophilic conditions.

The Effect of Alkaline Peroxide Pre-Treatment on Properties of Peanut Shell Powder Filled Recycled Polypropylene Composites

The Effect of Alkaline Peroxide Pre-Treatment on Properties of Peanut Shell Powder Filled Recycled Polypropylene Composites

Alkaline hydrogen peroxide (AHP) pretreatment of softwood: Enhanced enzymatic hydrolysability at low peroxide loadings

This study investigated the specific effects of hydrogen peroxide (H2O2), alkali and temperature on substrate hydrolysability during alkaline hydrogen peroxide (AHP) pretreatment of Douglas fir. We demonstrated that the presence of a small amount of hydrogen peroxide is essential for effective pretreatment of Douglas fir by alkali. However contradictory to previous finding from others, we found that increasing H2O2 did not directly correlate to enhanced substrate hydrolysability, whereas the alkali charge played a more dominant role. The paper illustrated a strategy to apply AHP for softwood pretreatment with low peroxide loadings and achieve high cellulose-to-glucose yield (up to 95%). It was also found that glucomannan gelation (physicochemical change) occurred during AHP pretreatment of softwood which presents a newly identified recalcitrance factor to substrate hydrolysability. The resulting glucomannan derived hydrogel-like material has a high affinity toward cellulases and can cause a non-productive binding effect.

Saccharification of microalgae biomass obtained from wastewater treatment by enzymatic hydrolysis. Effect of alkaline-peroxide pretreatment

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 1h, 50°C and H2O2 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.