Alkali Pretreatment Research Articles

Evaluating the combined influence of microwave-enhanced alkali pretreatment and copyrolysis on characteristics of biochars produced by thermal and microwave pyrolysis

Evaluating the combined influence of microwave-enhanced alkali pretreatment and copyrolysis on characteristics of biochars produced by thermal and microwave pyrolysis

Sustainable biofuels from corncobs: optimization of microwave pretreatment for enhanced fermentable sugar yield

Microwave-Assisted Alkali (MAA) pretreatment of corncob biomass was optimized for maximum fermentable sugar yield using dilute sulfuric acid hydrolysis. A Central Composite Design (CCD) investigated the effects of microwave power (450–9000 W), NaOH concentration (1.5 to 4.5% wt./v), and irradiation time (10–20 min) on lignin removal. The optimal MAA pretreatment conditions were found to be 691.73 W, 3.4% NaOH, and 15.5 min, resulting in the selective removal of 73.36% lignin with high retention of cellulose (71.69%) and hemicellulose (22.14%). Characterization techniques (FTIR, SEM, XRD, TGA) confirmed substantial changes in surface morphology, functional groups, crystallinity, and thermal stability of the pretreated corncobs. Dilute sulfuric acid hydrolysis (0.5–2.5%, 110130 °C, 3060 min) of the optimized sample yielded a maximum reducing sugar output of 537.42 mg/g, achieved at 0.534% H2SO4, 122.3 °C, for 58 min. Optimizing Microwave-Assisted Alkali pretreatment process for corncobs could boost biofuel production efficiency, sustainably utilize agricultural waste, and advance a more sustainable energy landscape.

Utilization of cotton stalk waste for sustainable isopropanol production via hydrolysis and coculture fermentation

The present investigation focused on isopropanol production from lignocellulosic cotton stalk biomass (CSB) using conventional pretreatment, enzymatic hydrolysis and fermentation methods. In comparison to alkaline (NaOH) pretreatment, dilute sulphuric acid (H2SO4) pretreatment showed higher cellulose exposure (448.5 mg/g). Further, ultrasono assisted acid and alkali pretreatment was performed for maximum exposure of cellulose and it was found 616.9 and 586.15 mg/g respectively. Chemical pretreated CSB was additionally exposed to independent enzymatic hydrolysis using commercial enzymes (Celluclast and Viscozymes) following Response Surface Methodology (RSM), which revealed a maximal production of glucose and xylose yield (544.6 mg/g and 41.8 mg/g). Pretreated and enzymatic hydrolyzed cotton stalk biomass at various conditions were analysed using SEM, FTIR, and XRD to determine the structural and functional changes. Further, a co-culture strategy was employed on pretreated and hydrolyzed CSB using two fermented yeast strains (Saccharomyces cerevisiae and Pichia pastoris) for isopropanol production. HR-MS analysis revealed that the maximum concentration of isopropanol (126.228 mM) was produced in 2:1 proportionate ratio of two fermented yeasts with 20 g/L of substrate loadings at 72 h of incubation time. These results indicate that the production of isopropanol (7.46 g/L) from CSB with different parametric conditions is an encouraging step and can be exploited further for various industrial applications.

Pre-treatment and its effect on the thermal conductivity of natural lignocellulosic rice straw stubble waste boards: Analysis vis a vis potential for the civil engineering applications

Once built, the residential or commercial building must maintain a temperature suitable for human comfort. Presently, according to an estimate, building energy consumption contributes about 40 % to global greenhouse gas (GHG) emissions. Thus, it is necessary to develop building materials that not only have low or zero carbon footprints during their production stage but also provide thermal insulation for buildings amidst variable climates. Among such materials, the use of straw waste boards can not only offer an opportunity to reduce the use of GHG-intensive materials but also provide excellent thermal insulation. The objective of the present work is to fabricate, characterize, and evaluate the thermal conductivity of composite boards made from rice (Oryza sativa) straw. The effect of water and alkali pre-treatment is also evaluated. Three different mass fractions (Mf) with 50 %, 60 %, and 70 % of straw by weight are considered, and three different matrix materials, viz., Polyethylene (PE), Polylactic acid (PLA), and epoxy resin, have been used. Among these, the epoxy matrix is found to be most suitable owing to its uniform dispersion, which leads to superior adhesion in the straw laminates. Subsequent morphological characterization techniques, such as energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), have been employed to evaluate the physicochemical structure changes of straw fibre and fibre boards. The microstructural characterization revealed that the alkali and water pre-treatment have a pronounced effect on the morphological properties of straw and composite boards. Thermal conductivity has been measured using the experimental setup based on the guarded hot plate method, and the lowest conductivity of heat is recorded in the order of 0.023 W/mK. The present research work attempts to demonstrate the development of a novel product using rice straw waste that can potentially replace/reduce the usage of EPS (Expanded Polystyrene) for building construction applications in the near future.

Enhancing detoxification of inhibitors in lignocellulosic pretreatment wastewater by bacterial Action: A pathway to improved biomass utilization

The process of preprocessing techniques such as acid and alkali pretreatment in lignocellulosic industry generates substantial solid residues and lignocellulosic pretreatment wastewater (LPW) containing glucose, xylose and toxic byproducts. In this study, furfural and vanillin were selected as model toxic byproducts. Kurthia huakuii as potential strain could tolerate to high concentrations of inhibitors. The results indicated that vanillin exhibited a higher inhibitory effect on K. huakuii (3.95 % inhibition rate at 1 g/L than furfural (0.45 %). However, 0.5 g/L vanillin promoted the bacterial growth (−2.35 % inhibition rate). Interestingly, the combination of furfural and vanillin exhibited antagonistic effects on bacterial growth (Q<0.85). Furfural and vanillin could be bio-transformed into less toxic molecules (furfuryl alcohol, furoic acid, vanillyl alcohol, and vanillic acid) by K. huakuii, and inhibitor degradation rate could be promoted by expression of antioxidant enzymes. This study provides important insights into how bacteria detoxify inhibitors in LPW, potentially enhancing resource utilization.

Thermostatic microwave-assisted pretreatment of corn stover at atmospheric pressure to enhance saccharification

A large amount of corn stover waste is produced from processing industries. In this study, the thermostatic microwave-assisted alkali pretreatment (TMAAP) of corn stover at atmospheric pressure was investigated to improve the utilization rate. The optimized conditions include pretreated time, NaOH concentration, temperature, initial power, and solid-liquid ratio. The pretreated corn stover samples for the enzymatic hydrolysis were studied on the crystallinity, surface microstructural changes, functional group changes and compositional analysis. The results showed cellulose recovery and lignin removal in the solid residue reached 87.39 % and 87.59 %, respectively when the corn stover was subjected for 45 min at a microwave reactor with an initial 600 W, 100 °C and 5 % NaOH. After TMAAP, the enzyme hydrolysis efficiency of the corn stove reached 85.40 %, which was higher than that of the untreated (59.96 %). The experiment can be carried out at atmospheric pressure without strict conditions. The techno-economic analysis predicts revenue of 22.82 USD by processing 100 kg of waste corn stover combined with enzyme cost analysis. To conclude, glucose (26.37 kg) and xylose (1.19 kg) were produced from corn stover (100 kg, 39.31 % glucan, 17.34 % xylan, 23.60 % lignin). The results can give insights into establishing an efficient alkali pretreatment of corn stove waste to produce glucose.

Co-pyrolysis of pretreated cotton stalk and low-density polyethylene: Evolved products and pyrolysis mechanism analysis

The preparation of bio-oil from cotton stalks and agricultural residue films using co-pyrolysis technology can achieve resource recovery and energy conversion, which has important research value and significance. In this study, cotton stalks were subjected to different chemical pretreatments using NaOH, HCl, and H2O solutions to understand their structural changes and pyrolysis characteristics. In addition, the lower H/C ratio of cotton stalks resulted in higher oxygen content in the pyrolysis oil, which limited its efficient and clean utilization. Therefore, the characteristics and pyrolysis kinetics of the pyrolysis products of pretreated cotton stalks and LDPE (low-density polyethylene) were studied. The results showed that the ash content of alkali pretreatment cotton stalks decreased by 1.24 %, and the dense structure of cotton stalks significantly relaxed. NaOH pretreatment effectively removed hemicellulose sugars and cracked them. During the co-pyrolysis process, when the ratio of NaOH-CS/LDPE was 50/50, the synergistic effect was more pronounced, and the oil yield increased by 2 % compared to the theoretical value. The oxygen content of CO and CO2 in the pyrolysis gas was higher than the theoretical value, at 10.4 % and 14.1 % respectively. The synergistic effect of bio-oil on hydrocarbons was the most significant, reaching 18.9 %. More hydrogen and less oxygen migrated into the co-pyrolysis oil, resulting in an increase in hydrocarbons and a decrease in oxygen-containing compounds, and improving the quality of bio-oil. Results from electron paramagnetic resonance (EPR) indicated that adding LDPE might raise the quantity of stable free radicals. The evolution mechanism of functional groups of NaOH-CS and LDPE co-pyrolysis behavior was analyzed by Fourier in-situ infrared spectrometry (FTIR), and it was found that C–O–C, C=O, and O–H decreased due to dehydroxylation, decarboxylation, decarbonylation, and demethoxy reactions with the increase of temperature, indicating that there was a synergistic effect between NaOH-CS and LDPE co-pyrolysis. The pyrolysis kinetics of NaOH-CS, LDPE and their blends were determined by the model-free method. The introduction of LDPE can reduce the activation energy of NaOH -CS pyrolysis alone, and the 3D diffusion (D3) model is suitable for their blends.

Upgraded cellulose and xylan digestions for synergistic enhancements of biomass enzymatic saccharification and bioethanol conversion using engineered Trichoderma reesei strains overproducing mushroom LeGH7 enzyme

Crop straws provide enormous lignocellulose resources transformable for sustainable biofuels and valuable bioproducts. However, lignocellulose recalcitrance basically restricts essential biomass enzymatic saccharification at large scale. In this study, the mushroom-derived cellobiohydrolase (LeGH7) was introduced into Trichoderma reesei (Rut-C30) to generate two desirable strains, namely GH7–5 and GH7–6. Compared to the Rut-C30 strain, both engineered strains exhibited significantly enhanced enzymatic activities, with β-glucosidases, endocellulases, cellobiohydrolases, and xylanase activities increasing by 113 %, 140 %, 241 %, and 196 %, respectively. By performing steam explosion and mild alkali pretreatments with mature straws of five bioenergy crops, diverse lignocellulose substrates were effectively digested by the crude enzymes secreted from the engineered strains, leading to the high-yield hexoses released for bioethanol production. Notably, the LeGH7 enzyme purified from engineered strain enabled to act as multiple cellulases and xylanase at higher activities, interpreting how synergistic enhancement of enzymatic saccharification was achieved for distinct lignocellulose substrates in major bioenergy crops. Therefore, this study has identified a novel enzyme that is active for simultaneous hydrolyses of cellulose and xylan, providing an applicable strategy for high biomass enzymatic saccharification and bioethanol conversion in bioenergy crops.

Effect of various aging conditions and treatment methods on thermal degradation of coffee waste/epoxy composites

In composites containing lignocellulosic fillers, the chemical composition of the filler mostly determines the heat resistance. Based on the rules of green chemistry, new bio-based composites were developed from the waste of industrial crop product coffee (CW), and their thermal stability in different aging environments was examined by thermogravimetric analysis (TGA). Alkali (NaOH), microwave (MW), ultrasound (US), and alkali pretreatment followed by microwave (NaOH+MW) were applied to modify the CW. The effect of various applied treatment methods and environmental conditions such as UV radiation, water sorption, seawater, and hydrothermally agings on the thermal properties of the composites was investigated. Fourier-transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy (FE-SEM) were used in the characterization of composites. Among the environmental factors tested, seawater and hydrothermal aging affected the thermal resistance of the composites the most, while NaOH+MW affected it most among the processing methods. Although the thermal stability of unaged and UV-exposed MW-CW composites was found to be the highest, it was more affected by aging in seawater, pure water, and hydrothermal environments. As a result, MW was found to be more effective among the treatment methods in terms of thermal properties under UV conditions, confirming that the adoption of environmentally friendly methods and surface modification of the filler can provide superior composites.

An eco-friendly wheat straw adsorbent functionalized with mercaptopropionyl for the removal of Cu(II) from aqueous solution

A novel absorbent called mercaptopropionyl wheat straw (MPWS) was prepared through alkali pretreatment and mercaptopropionyl modification for efficient removal of Cu(II) from aqueous solutions. Single factor experiments were conducted to investigate various parameters affecting the adsorption of Cu(II) with MPWS. Adsorption experiments including kinetics, isotherms, thermodynamics, as well as various characterization methods were employed to discuss the mechanism of Cu(II) uptake by MPWS in this study. The results showed that MPWS exhibited high removal capacity for Cu(II), achieving a maximum removal efficiency of 97.28 % under optimal conditions: oscillation rate at 150 rpm, temperature at 303 K, duration at 2 h, pH value at 6.0, and initial concentration of Cu(II) at 100 mg/L. The fitting results indicated that pseudo-second-order kinetic model better described the experimental data while Freundlich model provided a better fit for isothermal data. Thermodynamic calculations confirmed that the adsorptive process was spontaneous and endothermic. Characterization techniques such as FTIR spectroscopy SEM imaging, and EDS analysis confirmed chemisorption between Cu(II) ions and functional groups present on MPWS including sulfhydryl groups, amine groups, hydroxyl groups, and carboxyl groups. Overall, the main mechanisms governing Cu(II) uptake onto MPWS included coordination, ion exchange, electrostatic adsorption, and physical adsorption.

Effect of low-temperature thermal-alkali pre-treatment on waste activated sludge solubilisation

The study was aimed to examine the effects of alkaline and thermal-alkaline pre-treatment on sewage sludge solubilisation with different alkali and its doses ranging from 40 mg alkali/g TS to 120 mg alkali/g TS. Initially, the effect of alkali pre-treatment was monitored with four alkali at room temperature, to further enhance soluble chemical oxygen demand (sCOD) and reduce treatment time, thermal-alkaline pre-treatment was performed with varying temperature from 40 to 70 °C. To explore and optimise the effects of temperature, alkali, and alkali doses on COD solubilisation, response surface methodology was employed. Statistical analysis of the variance was conducted to identify the relationship between experimental data and the proposed model. The thermal-alkaline process was optimised for maximum COD solubilisation with optimal conditions achieved at 65.61 °C of 66.57 mg alkali /g TS for NaOH and 27 °C of 20 mg/g TS for KOH. The maximum COD solubilisation achieved at these optimised conditions for NaOH and KOH was 21.28 % and 16.13 %, respectively. The results demonstrated a significant improvement in protein and carbohydrate concentration and a 16–20 % reduction in sludge solid content after thermal-alkali pre-treatment.

Efficient preparation of anisotropic cellulose sponge from cotton stalks: An excellent material for separation applications

Water pollution and solid waste resource reuse demand immediate attention and research. Here, we present a method to create anisotropic cellulose sponges from cotton stalk waste. Using the inherent structure of cotton stalks, we selectively remove lignin and hemicellulose via acid and alkali pretreatment. This process yields cellulose sponges with a natural pore structure. Our findings demonstrate that these sponges retain the original pore configuration of cotton stalks, providing excellent connectivity and compressibility due to their unique anisotropic three-dimensional structure. Moreover, these sponges exhibit exceptional super-hydrophilic and underwater super-oleophobic properties, with underwater oil contact angles exceeding 150° for all tested oils. External pressure can reduce the pore size of the cellulose sponge, facilitating the gravity-driven separation and removal of dyes and emulsions. Remarkably, removal efficiencies for Methylene Blue (MB), Congo Red (CR), water-in-oil (w/o) emulsions, and oil-in-water (o/w) emulsions exceed 99 %, 97 %, 99 %, and 99 %, respectively, highlighting superior removal and recyclability. Further investigation into the mechanisms of dye and emulsion removal employs X-ray photoelectron spectroscopy (XPS) characterization and molecular dynamics (MD) simulation. These insights lay the groundwork for the efficient recycling and resource utilization of waste cotton stalks, offering promising applications in water purification.

Alkali Pretreatment and Analysis Of Biomass Content Of Narlisaray Population and Vezir Type Cannabis Plant

The cell wall of the hemp plant consists of cellulose, hemicellulose, and lignin cross-linked to these components. In such a structure, lignin is considered an undesirable byproduct in the production of textiles, paper, and biofuels from hemp. Therefore, the removal of lignin is essential for the industrial utilization of cellulose from hemp. In this study, lignin removal processes were conducted for the first time on the (native to Anatolia) Narlısaray population and the registered Vezir hemp. Alkaline (NaOH) treatment was preferred for pre-treatment due to its relatively low cost, lower energy requirements, and reduced risk factors. Structural changes before and after alkaline pre-treatment were compared using FT-IR spectra, SEM, and EDX analyses of the biomass. Examination of elemental trace values revealed that the O:C ratios of Narlısaray and Vezir fibers increased to 0.84 and 0.85, respectively. The increase in the O:C ratio indicated the removal of lignin, while the nearly identical ratios suggested that the lignin cross-linking energies in both local hemp fibers were almost the same. Additionally, SEM images provided clear information regarding the structural changes in Narlısaray and Vezir fibers before and after the lignin removal process.

Selective Extraction of Second-Generation Sugars by Sequential Acid and Alkali Pretreatment of Arundo donax for Xylitol and Ethanol Production by Candida tropicalis

Selective Extraction of Second-Generation Sugars by Sequential Acid and Alkali Pretreatment of Arundo donax for Xylitol and Ethanol Production by Candida tropicalis

Comparative Analysis of Various Seed Sludges for Biohydrogen Production from Alkaline Pretreated Rice Straw

The present work studied the effects of alkali pretreatment on the cellulosic biomass of rice straw. The improvement in the cellulose content and reduction in the lignin and hemicellulose percentage was observed with alkali pretreatment. Fourier transformation infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) analysis confirm the modification in the surface structure of alkali rice straw. Further, the study investigated the potential of different types of seed sludge as inoculum sources for dark fermentative biohydrogen production. In comparison to other sludge samples (beverage industry, food industry, and sewage treatment plant sludge), the mixed culture of sewage treatment plant sludge had the highest cumulative volume of biohydrogen (90.52 mL), as well as the highest hydrogen production yield (0.75 moleH2/mole) with the substrate utilization of 86.72%. The results provide information on the best sludge source for enhancing biohydrogen production in the dark fermentation method.

Nutrient Removal Efficiencies in a Bioretention Cell Using Pre-Treated Coconut By-Product as Carbon Source

Abstract In this research, the appropriateness of alkali pre-treatment on coconut by-products was managed by exposing coconut husk and shell to 2M NaOH. The powdered samples were analysed for morphology observation, Fourier Transform Infrared (FTIR), Particle Size Analyzer (PSA), and water quality tests. Weakening the hemicellulose structure resulted from subjecting the coconut shell to alkali pre-treatment shown in the morphology observation. Furthermore, the FTIR analysis exhibited the presence of O-H stretch in all pre-treated samples representing an indication for occurring the lignin breakdown, while an absence of the C=O functional group was shown in both additive samples after their subjection to alkali pre-treatment. In PSA analysis, the particles of all samples were found finer than the particle size distribution standards, in which the smallest D50 was obtained for the treated coconut shell (TCS), followed by untreated coconut shell (UCS), untreated coconut husk (UCH), and treated coconut husk (TCH). Among all the powdered samples (TCS, UCS, UCH, and TCH) analysed in this study, only TCH values met the ranges provided and recommended by the Urban Stormwater Management Manual for Malaysia (MSMA) and the Australian Department of Sustainability, Environment, Water, Population, and Communities (DSEWPC). Meanwhile, a poor removal rate for total suspended solids (TSS) was attained due to the contribution of TSS by the filter media which caused the TSS rates to surpass the inlet values. Additionally, the presence of a high concentration of total phosphorous (TP) in all the tested samples indicated their capabilities to provide PO43 in the bioretention cell, which is a vital nutrient for the plant’s growth. In contrast, Ammoniacal Nitrogen (AN) with a concentration rate as low as 4 mg/L was observed throughout the test periods which showed a significant reduction compared to the rate of AN at the inlet samples ranged between 5.2 and 11.4 mg/L. The findings indicated that coconut by-products, when subjected to an alkali pre-treatment process, are appropriate for incorporation as additives in bioretention filter media.

The Effect of Alkali Pretreatment and Different Parts of Sargassum polycystum Thallus on Alginic Acid Attributes

Alginic acid is an intermediate product in the alginate extraction process. In this study, alginic acid was generated from three separate sections of the thallus. The study aimed to define the influence of alkali solvents for pretreatment and the thallus parts from S. polycystum to produce alginate. Thus, this study identifies the proper utilization of seaweed as a source of alginate. The extraction procedure to obtain alginic acid was performed using Na2CO3 at a 2% concentration. The pretreatment improved the quality before extraction by soaking in KOH as a solvent. The statistical analysis was used to define significant differences in the pretreatment and thallus parts of the S. polycystum using ANOVA and the Tukey test as the post hoc. Alkali pretreatment and thallus sections substantially influence alginic acid yield, viscosity, and gel strength. Yield, ash content, moisture, pH, viscosity, whiteness degree, and gel strength of the best alginic acid chosen (pretreatment with KOH 0.90% from the basal section) were around 21.51 %, 10.34 %, 7.04 %, 2.54, 53.37 cP, 57.91 %, and 58.80 g/cm2, respectively. Except for the ash content parameter, the qualities of the alginic acid generated satisfied the standard. In conclusion, it is a better understanding of the alginate production from different thallus parts, making utilization more effective.

The DEP1 Mutation Improves Stem Lodging Resistance and Biomass Saccharification by Affecting Cell Wall Biosynthesis in Rice

BackgroundPlant cell walls have evolved precise plasticity in response to environmental stimuli. The plant heterotrimeric G protein complexes could sense and transmit extracellular signals to intracellular signaling systems, and activate a series of downstream responses. dep1 (Dense and Erect Panicles 1), the gain-of-function mutation of DEP1 encoding a G protein γ subunit, confers rice multiple improved agronomic traits. However, the effects of DEP1 on cell wall biosynthesis and wall-related agronomic traits remain largely unknown.ResultsIn this study, we showed that the DEP1 mutation affects cell wall biosynthesis, leading to improved lodging resistance and biomass saccharification. The DEP1 is ubiquitously expressed with a relatively higher expression level in tissues rich in cell walls. The CRISPR/Cas9 editing mutants of DEP1 (dep1-cs) displayed a significant enhancement in stem mechanical properties relative to the wild-type, leading to a substantial improvement in lodging resistance. Cell wall analyses showed that the DEP1 mutation increased the contents of cellulose, hemicelluloses, and pectin, and reduced lignin content and cellulose crystallinity (CrI). Additionally, the dep1-cs seedlings exhibited higher sensitivity to cellulose biosynthesis inhibitors, 2,6-Dichlorobenzonitrile (DCB) and isoxaben, compared with the wild-type, confirming the role of DEP1 in cellulose deposition. Moreover, the DEP1 mutation-mediated alterations of cell walls lead to increased enzymatic saccharification of biomass after the alkali pretreatment. Furthermore, the comparative transcriptome analysis revealed that the DEP1 mutation substantially altered expression of genes involved in carbohydrate metabolism, and cell wall biosynthesis.ConclusionsOur findings revealed the roles of DEP1 in cell wall biosynthesis, lodging resistance, and biomass saccharification in rice and suggested genetic modification of DEP1 as a potential strategy to develop energy rice varieties with high lodging resistance.

A novel additive promoting lignocellulose alkali pretreatment for its “two birds with one stone” role

Alkali pretreatment is one of the most commonly used pretreatment methods in lignocellulose bioprocessing. However, there are still some “pseudo-lignin” that hinder enzymatic hydrolysis and seriously affect the industrialization process of biorefining. Excellent pretreatment additives can effectively cover these shortages. However, most additives have disadvantages like high operating temperature, low effective utilization efficiency, or poor performance. To address this issue, we proposed a novel additive, dicyandiamide (DICY), by means of quantum chemical prediction, and verified its ability on assisting alkali to remove lignin by experiments. The results indicate that the lignin removal by KOH-DICY pretreatment is about 15% higher than KOH pretreatment, thereby increasing the enzymatic efficiency to 97%, while the reaction temperature was lower 20 ℃ than common alkali pretreatment. These are due to the “two birds with one stone” role of DICY on lignocellulose alkali-DICY pretreatment. DICY not only dissolves small amounts of lignin, but also assists alkali to remove lignin by reducing the diffusion resistance of KOH in lignin and blocking the generation of “pseudo-lignin”. Thus, DICY effectively improved the lignin removal and enzymatic hydrolysis efficiency of alkali pretreated lignocellulose, and performed better than urea. Moreover, the waste liquid pretreated by DICY combined with KOH has the potential on preparation of agricultural fertilizers. In summary, DICY is a new, environmentally friendly, and energy conservation additive for lign ocellulose alkali pretreatment

Alkali, thermal, or thermo-alkali pre-treatment to improve the anaerobic digestion of poly(lactic acid)?

Replacing petroleum-based plastics with biodegradable polymers is a major challenge for modern society especially for food packaging applications. To date, poly(lactic acid) represents 25 % of the total biodegradable plastics and it is estimated that, in the future, it could become the main contributor to the biodegradable plastics industry. Anaerobic digestion is an interesting way for the poly(lactic acid) end of life, even if its biodegradability is limited in mesophilic conditions. The aims of this study were to identify the best pre-treatment for maximizing the methane yield, minimizing the anaerobic digestion duration and limiting residual plastic fragments in the digestate. A systematic comparison was carried out between thermal, chemical, and thermo-chemical pre-treatment. Pre-treatment with 4 M KOH for 48 h at 35°C was effective in improving the mesophilic anaerobic digestion of the poly(lactic acid). Such pre-treatment allows obtaining 90 % of the theoretical methane potential, in 24 - 30 days. Importantly, such pre-treatment completely solubilized the poly(lactic acid), leaving no solid residues in the digestate. In addition, using KOH permits to avoid the sodication of the soil due to the digestate application as fertilizer.