Sodium Hydroxide Pretreatment Research Articles

Consolidated bioprocessing of lignocellulosic wastes in Northwest China for D-glucaric acid production by an artificial microbial consortium.

D-glucaric acid is a platform chemical of great importance and the consolidated bioprocessing (CBP) of lignocellulose by the microbial consortium of Trichoderma reesei C10 and Saccharomyces cerevisiae LGA-1C3S2 features prospects in biomanufacturing it. Here we compared some representative lignocelluloses in Northwest China including corn stover, wheat straw and switchgrass, and the leading pretreatments including steam explosion, subcritical water pretreatment, sodium hydroxide pretreatment, aqueous ammonia pretreatment, lime pretreatment, and diluted sulfuric acid pretreatment. It was found that sodium hydroxide pretreated switchgrass (SHPSG) was the best substrate for D-glucaric acid production, resulting in the highest D-glucaric acid titers, 11.69 ± 0.73g/L in shake flask and 15.71 ± 0.80g/L in 10L airlift fermenter, respectively. To the best of our knowledge, this is the highest D-glucaric acid production titer from lignocellulosic biomass. This work offers a paradigm of producing low-cost D-glucaric acid for low-carbon polyethylene 2,5-furandicarboxylate (PEF) and a reference on developing biorefinery in Northwest China.

The Effect of Irradiation Combined with Sodium Hydroxide Pretreatment on Component, Structure, Utilization Efficiency of Phragmites Australis

The Effect of Irradiation Combined with Sodium Hydroxide Pretreatment on Component, Structure, Utilization Efficiency of Phragmites Australis

Optimization Research of Sodium Hydroxide Pretreatment to Enhance the Thermal Properties of Straw–Mortar Composite Materials

Optimization Research of Sodium Hydroxide Pretreatment to Enhance the Thermal Properties of Straw–Mortar Composite Materials

The optimization of sodium hydroxide (NaOH) pre-treatment for reducing sugar production from rice husk using response surface methodology (RSM)

Lignocellulosic biomass is an abundant renewable resource which amounts to 1.3 billion tonnes per year and can be used in a variety of sustainable applications. It is primarily made up of tightly bound cellulose, hemicellulose, and lignin. However, hemicellulose dissolution and delignification pose significant challenges to the utilisation of reducing sugar. To solve this issue, alkaline pretreatment was utilised. The aim of lignocellulosic biomass pretreatment is to break down the complex structure of the biomass and provide better access to the components that can be converted into useful reducing sugar. Response Surface Methodology (RSM) was used to identify the optimal values for the factors influencing the pretreatment. The optimisation parameters were sodium hydroxide concentration (1 – 4 % w/v), pretreatment time (15 – 60 minutes), and solid loading (6 – 16% w/v). Rice husk, which was used as biomass, was hydrolysed enzymatically to produce reduced sugar. The optimum conditions for producing the highest reducing sugar of 15.18 mg/mL from rice husk were 1.67% w/v sodium hydroxide pretreatment, 59.44 minutes of pretreatment time, and 7.67% w/v solid loading. As a result, less alkaline reagents can be used with a longer pretreatment time, thus lowering the cost of pretreatment. Therefore, this shows that RSM was one of the best methods to replace the conventional technique for optimising the parameters of rice husk alkaline pretreatment for reducing sugar production.

Low-temperature and low-concentration sodium hydroxide pretreatment for enhanced enzyme hydrolysis rate from Quercus variabilis Blume

A surface response design was employed to develop a sodium hydroxide (NaOH) pretreatment method for Quercus variabilis Blume using low NaOH concentration at low temperature. Nevertheless, the persistent issues associated with alkaline pretreatment of lignocellulose, namely high-water consumption and wastewater generation, remain prevalent in this pretreatment process. To address these challenges, this study aimed to conduct enzymatic hydrolysis of NaOH-treated Q. variabilis Blume without the intermediary washing steps. The results revealed that, following pretreatment and solid-liquid separation, NaOH-treated Q. variabilis Blume could be directly subjected to cellulase-mediated hydrolysis with pH adjustment, eliminating the need for washing steps. The maximum enzymatic hydrolysis efficiency reached 95.9% under specific conditions (1.2% NaOH, 8.9 °C, 32.1 h). This approach offers a promising avenue to enhance the enzyme hydrolysis rate of NaOH-treated lignocellulose. Notably, the low-temperature and low-concentration NaOH treatment effectively removed a substantial portion of lignin and hemicelluloses, resulting in a higher crystallinity index of the cellulose-rich residue compared to substrates treated solely with steam explosion. The integration of direct pretreatment and alkaline treatment emerges as an environmentally friendly and economically viable method for producing glucose and high-purity lignin. The obtained lignin can be further transformed into high-value products within the biorefinery framework.

Improvement of biohydrogen production from rice straw hydrolysate by green-self-prepared nano-silica

Rice straw stands as a highly sustainable agricultural residue enriched in silica and carbohydrates. This study delves into the potential of rice straw, focusing on the impact of green-synthesized nano-silica particles on biohydrogen fermentation using Enterobacter aerogenes. Rice straw was subjected to three different leading pretreatments, i.e., organsolv, sulfuric acid, and sodium hydroxide, to decimate the lignocellulosic structure. In addition to these, sodium hydroxide was employed as a secondary pretreatment for the organosolv- and sulfuric acid-pretreated straw. Three distinct nano-silica particles were extracted from the liquor of alkali pretreatments and examined using XRD, XRF, FE-SEM, and DLS analysis. The solid fractions of pretreatment were enzymatically hydrolyzed and subjected to dark fermentation, achieving the maximum biohydrogen yield of 156.9 ± 2.0 mL per g total solids (TS) from the organosolv-sodium hydroxide pretreated straw. Further improvement of biohydrogen yield to 178.3 ± 4.2 mL per g TS was obtained by adding 200 ppm of nano-silica particles isolated from one-step sodium hydroxide pretreatment. Analyzing the metabolic products exhibited that nano-silica particles modified the metabolic pathway, leading to an increase in acetic acid production and a decrease in ethanol production. It was concluded that nano-silica particles isolated from untreated and treated rice straws have the potential to boost biohydrogen generation. However, the degree of improvement was dependent on the composition and structure of the nanoparticles.

Effect of alkaline and steam pre-treatment on saccharification of corn cob and production of cellullase from fungal consortium

Lignocellulosic biomass as fossil fuel alternative comes with its challenges such as its inherent stability and recalcitrance. The use of commercial cellulase in the removal of lignin comes with high cost. This research seeks to answer questions on how alkaline and steam pre-treatment improve cellulose/glucose liberation from lignocellulosic biomass (corn cobs) using a consortium of <i>pichia kudriavzevii</i> and <i>cyberlindnera fabianii.</i><br /> In the current study, the effectiveness of steam and sodium hydroxide (NaOH) pre-treatment for reducing corn cob structure was examined, and the pre-treated biomass afterwards was exposed to the hydrolyzing activity of a consortium enzyme cocktail that was custom-formulated. The results of an analysis of composition showed that while alkaline pre-treated corn cob (APC) had 1.2% lignin, 75.8% cellulose, and 10.9% hemicellulose, steam pre-treated corn cob (SPC) had 2.5% lignin, 67.2% cellulose, and 25% hemicellulose. Lignin was eliminated from the biomass of corn cobs using both steam and NaOH pre-treatment. The hydrolyzing effect of the holocellulolytic enzyme cocktail, prepared with two multifunctional enzymes, was applied to the alkaline and steam pre-treated samples. This hydrolyzed SPCs more effectively than APC feedstocks, revealing that steam was a more effective pre-treatment attaining a remarkable 8.33 U/mg endoglucanase, 5.56 U/mg exoglycanase and 8.97U/mg beta-glucosidase levels (event 1) and glucose peak concentration of 0.433 mol/mL at 48 hours (event 2); according to a thorough examination of cellulase capacity and glucose levels.<br /> Overall, the consortium enzyme cocktail effectively hydrolyzed agricultural feedstocks that had undergone alkaline pre-treatment, making it a desirable option for usage in the bioconversion procedure in the biorefinery sector. This study demonstrates an effective technique for turning agricultural waste (corn cob) into high-value products through effective and practical chemical pre-processing.

The Effect of Chemical Treated Spent Mushroom Substrate (SMS) on Lignocellulosic Content

A by-product of the mushroom industry, spent mushroom substrate (SMS) is primarily made of lignocellulosic agricultural waste. SMS contains cellulose (38–46.6%), lignin (25–34.5%), and hemicellulose (19–27.7%) and is nutrient-rich. The primary objectives of this study included the characterization of SMS, analysis of lignocellulosic content prior to and following pre-treatment, analysis of the effects of various NaOH concentrations with varying molarities (1.0 to 5.0 Molar), and analysis of surface morphology using a scanning electron microscope (SEM). The result that comparison between untreated and treated sample The result for untreated are contain high amount of lignin from 23.85% to 27.39% and for treated are amount reduce from 20.6% to 23.85%. The difference of NaOH concentration from 1.0 to 5.0 Molar, so the best pre-treatment is alkaline pre-treatment from 1.0 to 3.0 M are the best concentration to treat SMS sample from alkaline pre-treatment and proved sodium hydroxide pre-treatment as an effective method to reduce the hemicellulose and lignin contents. Images clearly showed how the pre-treatment could alter the biomass’s structural makeup and distort it, increasing the surface area that was open to enzymatic attack. The pre-treated SMS’s surface had numerous sporadic pores and cracks. The study’s findings demonstrated that SMS from the P. sajor-caju species has the potential to provide a new source of glucose for bioethanol production.

The feasibility of sodium hydroxide pretreatment of rice straw for solid substrate preparation to enhance laccase production by solid state fermentation

BackgroundCurrently, broad industrial application of laccases is commonly restricted by the high-cost related production. Solid state fermentation (SSF) using agricultural waste is an attractively economic strategy for laccase production, yet its efficiency is low. Pretreatment of cellulosic substrate might be a vital breakpoint to solve the problem in solid state fermentation (SSF). In this study, sodium hydroxide pretreatment was involved to prepare solid substrates from rice straw. Fermentability of solid substrates in terms of carbon resource supply, accessibility and water retention value, and their influence on performance of SSF were analyzed.ResultsThe results showed that sodium hydroxide pretreatment provided desirable solid substrates with higher enzymatic digestibility and optimal water retention value, which further facilitated the homogeneity of mycelium growth, laccase distribution and nutrition utilization during SSF. The pretreated rice straw (1 h) with diameter less than 0.085 cm gave the maximum laccase production of 2912.34 U/g, which was 7.72 times higher than the control.ConclusionHence, we proposed that enough balance between nutrition accessibility and structure support was a must for rational design and preparation of solid substrate. Additionally, sodium hydroxide pretreatment of lignocellulosic waste might be an ideal step to enhance the efficiency and lower the production cost in SSF.

Valorization of cannabis green waste to cellulose nanomaterials via phosphoric acid hydrolysis

The recent increases in Cannabis sativa (cannabis) production, both in industrial hemp and recreational varieties, has highlighted the need for low-impact and sustainable practices for this expanding industry. Green waste of cannabis, consisting of the vegetative components like plant stalks, offers an unexplored opportunity for valorization through biomass optimization. Like hemp, recreational cannabis varieties contain two high cellulose fiber types: bast fiber (phloem tissue) and hurd fiber (xylem tissue). Using hemp as a model for recreational cultivars, this study demonstrates the ability to isolate cellulose nanomaterials from both bast and hurd fiber through phosphoric acid hydrolysis. Scanning electron microscopy (EM) shows that sodium hydroxide treatment is required for removing all non-cellulose surface components from hurd fiber. Comparison of the two fiber types with transmission EM reveals phosphoric acid-hydrolyzed bast fibers produce cellulose nanocrystals (CNC), while hurd fibers are more prone to producing a mixture of cellulose nanocrystals and nanofibril-like particles (CNF) without chemical pretreatment. Adding hydrogen peroxide to the sodium hydroxide pretreatment decreased the variation in CNC sizes resulting from both bast and hurd. The findings of this study provide several avenues for valorization of green waste, while aiming to minimize the techno-economic impact of pretreatments.

Optimization of pretreatment in delignification of hyacinth biomass for ethanol production

Water hyacinth ( Eichhornia crassipes ) is one of the potential feedstocks for bioethanol production due to their higher cellulose content. It needs the optimization of pretreatment to remove lignin and release cellulose and hemicellulose from lignocellulosic complex. Pretreatment was done using sulfuric acid, sodium hydroxide, and calcium hypochlorite as soaking agents. Experiment was carried out at 121 °C for 15 minutes. Pretreatment with 1% sulfuric acid decreased lignin by 6.74%, 4.0% sodium hydroxide reduced lignin content by 11.23%, whereas pretreatment with 0.3% calcium hypochlorite removed lignin by 8.30% from original lignin content lignocellulosic substrate. Therefore, sodium hydroxide pretreatment showed highest efficacy in delignification processes, followed by calcium hypochlorite, and sulfuric acid pretreatments. Keywords: Lignin reduction; Lignocellulose; Pretreatment; Water hyacinth

The volatile organic compounds emission mechanism of pretreated bamboo during heat treatment

Heat treatment can be used to improve bamboo product quality. Pretreatment of the bamboo material can reduce the energy consumption of heat treatment. However, large quantities of volatile organic compounds (VOCs) are released during the bamboo heat treatment process, causing potential problems for the environment and human health. In this study, the effects of pretreatment with sodium hydroxide and zinc chloride solutions on VOCs emissions during heat treatment were investigated. We also explored chemical and structural changes of heat-treated bamboo. The VOCs released by untreated bamboo during heat treatment were mainly aldehydes, alcohols, alkanes, and esters. Alcohol and alkane contents decreased as treatment temperature increased, accompanying the emergence of more complex chemicals. Compared with untreated bamboo, sodium hydroxide pretreatment destroyed the hemicellulose structure, released stable VOCs under heat treatment, and did not produce acidic compounds; ether compounds increased significantly with increase in temperature. The catalysis of zinc chloride pretreatment degraded hemicellulose during heat treatment. The relative contents of aldehydes and esters released from zinc chloride pretreated bamboo during heat treatment increased significantly with temperature. Up to 69.76 % of aldehyde compounds were released at 160 °C, among which the relative proportion of furfural reached 37.23 %. These results may provide theoretical support for controlling VOCs emissions from different pretreated bamboo materials during heat treatment, which is also conducive to the subsequent recycling of VOCs.

Process Simulation and Life Cycle Assessment of Dilute Sodium Hydroxide Pretreatment of Wheat Straw

Process Simulation and Life Cycle Assessment of Dilute Sodium Hydroxide Pretreatment of Wheat Straw

Anaerobic digestion of waste activated sludge to produce volatile fatty acids and release nutrients using sodium citrate with sodium hydroxide pretreatment

AbstractThis study investigated the synergistic effect of sodium citrate (SC) and sodium hydroxide (NaOH) on the anaerobic digestion (AD) efficiency of waste activated sludge (WAS). Using the amount of SC as the control variable, changes in sludge cell cracking and AD performance under different pretreatment conditions was investigated. The optimum treatment conditions were a NaOH input of initial pH 10 and an SC concentration of 0.20 g/g total suspended solids. The pretreatment was monitored in 150 min. And the changes in soluble chemical oxygen demand (SCOD), soluble polysaccharide, soluble protein, volatile fatty acids (VFAs), PO43−‐P and NH4+‐N during the pretreatment stage and fermentation process were studied. Results show a significant disintegration effect on WAS under optimal pretreatment conditions, with the peak concentration of SCOD, soluble protein, and soluble polysaccharide being 2059.5, 114.86, and 190.97 mg/L, respectively, which means that large amounts of intracellular carbon sources were released. The production of VFAs included acetic acid, propionic acid, isobutyric acid, n‐butyric acid, isovaleric acid, and n‐valeric acid, with a peak concentration of 9555.89, 1779.12, 608.84, 805.7, 777.91, 184.86 mg·COD/L, respectively. The content of PO43‐P and NH4+‐N were great in fermentation liquid, 71.82 and 320.75 mg/L, respectively. These results indicate that the synergistic process improve VFAs production and contribute to nutrients reuse.

Biogas production by co-digestion of sodium hydroxide pretreated Napier grass and food waste for community sustainability

ABSTRACT Community agricultural waste-to-energy management, especially in developing countries, can respond to sustainable development goals by the United Nations. Co-digestion techniques for waste from phytomass in fields as Napier grass (NP) and debris from consumption in the community as food waste (FW) into biogas production by conventional anaerobic digestion technology contribute to sustainable energy communities. However, lignocellulose requires proper pretreatment of the material type. Therefore, low sodium hydroxide (NaOH) concentration for Napier grass pretreatment and varying the co-digestion ratio with food waste from the community under conventional batch conditions were optimized to be economically cost-effective with elementary technology. The results showed the highest methane yield at 0.285 m3/kg VSadded at the 4% concentration of sodium hydroxide pretreatment with significant content of FW added with biomass. The best conditions of co-substrates can increase methane yields by up to 3.54 times compared to a single substrate. The energy and cost estimation based on energy consumption and chemical input cost showed that co-digestion with NaOH pretreatment could achieve the net benefits by increasing the biogas production (242 US$/tonne TS). This study confirms the application of waste management in agricultural communities that can be used as fuel in households to increase biogas and economic value. The authors expect this work to be a successful case study for further results that lack government financial support and limitations of advanced technology for a sustainable community.

Steering the formation of cellobiose and oligosaccharides during enzymatic hydrolysis of asparagus fibre

The enzymatic conversion of cellulosic-rich waste streams of white asparagus into cellobiose and cello-oligosaccharides (COS) is proposed for producing a natural carrier agent. The enzyme cocktail ‘Celluclast’ was used to steer towards maximum conversion and minimum formation of monosaccharides to obtain an enzymatic hydrolysate with a high glass transition temperature (Tg). Different enzyme loadings and hydrolysis times were tested in combination with a sodium hydroxide pre-treatment of the asparagus fibre. A loading of 700 nkat/g substrate and 7 h of hydrolysis time resulted in the best yield/purity combination, namely a conversion of 36 g/100 g cellulose with 81% celllobiose/COS. The same hydrolysis conditions were tested in a larger bench-scale experiment (conversion of 45 g/100 g cellulose) and the soluble hydrolysates were concentrated and spray-dried. The high Tg (108 °C) of the spray-dried hydrolysates of asparagus fibre proves its potential usage as a carrier agent for spray drying.

Coupling of pretreatment and pyrolysis improving the production of levoglucosan from corncob

Influence of organic biphasic pretreatment on levoglucosan (LG) yield from biomass pyrolysis was investigated with dilute sulfuric acid and dilute sodium hydroxide pretreatment as comparison, simultaneously, the mechanism was explored in depth. It was found that with monophasic (water) conditions, dilute sulfuric acid and dilute sodium hydroxide pretreatment, the yield of LG was all increase largely (from untreated 28% to treated 60–85%) due to the removal of hemicellulose or lignin. Phenoxyethanol was introduced to construct a biphasic system, and it showed that acid biphasic pretreatment of corncob followed by pyrolysis at 450 °C increased the LG yield to 91% and limited the formation of by-products, especially acids, ketones, and esters. In addition, it can easily realize the efficient recovery of the removed hemicellulose (75%) and lignin (49%). The different LG yields implied that removing lignin is more effective in increasing LG than removing hemicellulose. These findings provide instruction for the highly selective production of anhydrous sugars from biomass waste.

Structural and Thermal Properties of Cellulose Microfiber Isolated from Typha Australis by Sequential Alkali-Oxidative Treatment

ABSTRACT This study aims to investigate the feasibility of cellulose microfibers extraction from a wetland plant (Typha australis) and to assess its suitability as a source of bio-micro fibers for green composites. The method was based on an alkali sodium hydroxide pretreatment and subsequently an environmentally friendly hydrogen peroxide bleaching process for extracting microfiber. Alkali treatments resulted in fiber separation from leaves by partially removing the hemicellulose and lignin and an oxidative treatment significantly enhanced the effective defibrillation. The effectiveness of this method was confirmed by using Fourier Transform Infrared Spectrophotometer (FTIR), X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and Thermogravimetric Analysis (TGA). FTIR analysis showed the removal of non-cellulosic materials from the fibers in sequential alkali-bleaching treatments and changes in the absorption of cellulose functional groups. The cellulose content in the fiber increased from 43% to 75% after chemical treatment. XRD analysis showed the increase in the crystallinity of chemically treated fibers from 28% to 63% due to the removal of amorphous components as hemicellulose and lignin. The SEM images confirmed the defibrillation of the Typha fibers with a rigid structure and without degradation after the sequential alkali-bleaching treatments.

Evaluation of pretreatment potential and hydrogen recovery from lignocellulosic biomass in an anoxic double-staged bioelectrochemical system

The possible impact of bio and electrochemical reactions during pretreatment of rice straw using solvents, sulphuric acid (SA), ammonia (AM), sodium hydroxide (NA), and distilled water (W) was investigated. The total volatile fatty acids (tVFAs) of 163.48 ± 10.49 mM in the electrochemical pre-treatment in the presence of sodium hydroxide (ENA) followed by sulfate-reducing bacteria (EBA) (140.88 ± 0.07 mM) indicating the involvement of electrolytic breakdown of lignocellulosic biomass. The hydrogen production of 0.224 ± 0.05 and 0.218 ± 0.10 mM/g of the substrate was found in the ENA and anoxic sodium hydroxide pre-treatment (CNA) respectively. There was no detectable gasification in SA and AM electrochemical pre-treatments. The major advantage of the electrochemical process is the formation of acetic acid at a lower temperature, whereas processes like autohydrolysis form it at high temperatures during stream explosion pretreatment. The hydrogen production of 1.26 mM/g was found from anoxic hydrolysate pretreated (ECP) rice straw. The SEM and FTIR analysis show distortion of outer layers of biomass in the electrochemical pretreatment (ECP) system, which improved its accessibility towards enzymes for value-added product recovery.

Lignin, sugar, and furan production of industrial hemp biomass via an integrated process

Traditional pretreatment of lignocellulosic biomass is often accompanied by washing and disposal of wastewater, which leads to overuse of water and loss of by-products. The objectives of this study were to validate the potential of an acid-base integrated process for simultaneous sugars, furans, and lignin production without washing and wastewater discarding. The difference in conversion performance among different biomass resources was also demonstrated. Parallel acetic acid (HOAc, pH = 2.25) and sodium hydroxide (NaOH, pH = 13.46) pretreatments followed by solid and liquid integration were applied to four genotypes of industrial hemp (Cannabis sativa L.) biomass that were harvested from two planting locations (Haysville and Manhattan, KS). Results showed that genotype, planting location, and their interaction had notable influences on biomass composition and its conversion to bioproducts but exhibited different trends. Glucan content of biomass from Haysville, ranging from 47.29 to 50.05%, were higher than those of 42.49–48.38 % from Manhattan with the lowest being Vega (Manhattan) and the highest being Hlukouskii (Haysville). Xylan and lignin contents in all the hemp genotypes were 11.70–13.88 % and 10.45–15.14 %, respectively. The integration process effectively rendered the pH of the integrated filtrate and slurry to approximately 4.80. The highest lignin recovery of 73.13 g/kg biomass was achieved by Rigel from Manhattan. Fourier transform infrared spectroscopy (FTIR) characterization showed that only lignin derived from Vega (Haysville) and Anka (Manhattan) was comparable to the commercial alkali lignin. Retaining monosaccharides (2.24–3.81 g/L) enhanced sugar concentrations (glucose: 40.40–45.71 g/L; xylose: 7.09–8.88 g/L) and conversion efficiencies (glucose: 71.19–77.71 %; xylose: 45.42–52.03 %). Besides, furans including 0.79–1.25 g/L of hydroxymethylfurfural (HMF) and 0.99–1.59 g/L of furfural coupling with 1.96–2.95 % and 10.00–14.65 % conversion efficiencies, respectively, were obtained in the final hydrolysate. Biomass from Haysville produced relatively higher glucose concentrations than those from Manhattan. Based on mass balance, the most productive genotype was Rigel. This study offers essential information to reduce water and chemical overconsumption and to understand the effects of genotype and planting location on biomass valorization.