Acid Pretreatment Research Articles

Waste to wealth: A novel low temperature eco-friendly lignocellulose pretreatment strategy for glucose production

Acid pretreatment is considered as one of the most promising pretreatment strategies. However, the operation temperature of acid pretreatment is commonly higher, and acid pretreatment is difficult to remove lignin. Herein, a novel pretreatment strategy (dilute sulfuric acid coupling K2S2O8 (DA-PDS) pretreatment) was proposed to remove lignin at lower temperature. The feasibility of DA-PDS pretreatment was predicted by means of density functional theory (DFT). Then, the optimal operation conditions of DA-PDS pretreatment were studied. Temperature was proved to be the most critical factor affecting the DA-PDS pretreatment. The optimal reaction conditions of DA-PDS pretreatment were 5 % DA and 6 % PDS at 80 °C for 2 h. The operation temperature was 40 °C lower than common acid pretreatment. On this condition, the cellulose content and enzymatic hydrolysis efficiency by DA-PDS pretreatment were about 59 % and 73 %, which were 11 % and 13 % higher than that of DA pretreatment, respectively. In addition, this study revealed the mechanism of DA-PDS pretreatment. DA not only accelerated radical generation rate, but also improved the contact probability between radical and lignin. Radicals generated by PDS destroyed the structure of lignin. This made DA more easily to remove hemicellulose. This work presented a novel and energy-saving strategy for lignocellulose pretreatment.

Fully upgrade bamboo biomass into three multifunctional products through biphasic γ-valerolactone and aqueous phosphoric acid pretreatment

In this manuscript, three components of lignocellulosic biomass were obtained by deconstructing bamboo with γ-valerolactone-H2O biphasic system, and the delignification rate of 80.92 % was achieved at 120 °C for 90 min. Lignin nanospheres with diameters ranging from 75 nm to 2 um could be customized by varying the self-assembly rate. Furthermore, the lignin nanospheres-poly(vinyl alcohol) film was prepared by cross-linking lignin nanospheres and poly(vinyl alcohol), which can obtain 90 % ultraviolet absorption capacity, while the light transmittance in non-ultraviolet band was almost unchanged. At the same time, due to the strong hydrogen formation between lignin nanospheres and poly(vinyl alcohol) bond network, the tensile properties of the composite film were also improved by 30 %. Besides, the high specific surface area of biomass-derived porous biochar (2056 m2/g) can be obtained after carbonization of solid residues at 850 °C for 2 h, which was almost 8 times the specific surface area of the direct biomass carbonization due to the removal of lignin and hemicellulose. biomass-derived porous biochar can be used as an adsorbent, with a CO2 capture capacity of 4.5 mmol g−1 at normal temperature (25 °C, 1 bar). The filtrate after the reaction contained a large amount of hemicellulose oligomers, which can be reacted with dichloromethane at 170 °C for 1 h to obtain the furfural yield of 74 %. In summary, the proposed biorefinery scheme achieves a full-component upgrade of lignocellulose and can be further applied in various downstream fields.

Visible Light Enhancement of Biocarbon Quantum-Dot-Decorated TiO2 for Naphthalene Removal.

In this study, carbon-quantum-dot (CQD)-decorated TiO2 was prepared using an ultrasonic doping method and applied in the photocatalytic degradation of naphthalene under sunlight irradiation. The CQDs were synthesized from a typical macroalgae via diluted sulfuric acid pretreatment and hydrothermal synthesis using an optimal design, i.e., 3 wt% and 200 °C, respectively. The CQD/TiO2 composite remarkably enhanced the photocatalytic activity. The degradation of naphthalene under a visible light environment indicated that there is a synergistic mechanism between the CQDs and TiO2, in which the generation of reactive oxygen species is significantly triggered; in addition, the N that originated from the macroalgae accelerated the photocatalytic efficiency. Kinetic analysis showed that the photocatalytic behavior of the CQD/TiO2 composite followed a pseudo-first-order equation. Consequently, our combined experimental approach not only provides a facile pretreatment process for bio-CQDs synthesis, but also delivers a suitable TiO2 photocatalyst for the visible environment along with critical insights into the development of harmful macroalgae resources.

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

Gallic acid pretreatment mitigates parathyroid ischemia–reperfusion injury through signaling pathway modulation

Thyroid surgery often results in ischemia–reperfusion injury (IRI) to the parathyroid glands, yet the mechanisms underlying this and how to ameliorate IRI remain incompletely explored. Our study identifies a polyphenolic herbal extract—gallic acid (GA)—with antioxidative properties against IRI. Through flow cytometry and CCK8 assays, we investigate the protective effects of GA pretreatment on a parathyroid IRI model and decode its potential mechanisms via RNA-seq and bioinformatics analysis. Results reveal increased apoptosis, pronounced G1 phase arrest, and significantly reduced cell proliferation in the hypoxia/reoxygenation group compared to the hypoxia group, which GA pretreatment mitigates. RNA-seq and bioinformatics analysis indicate GA’s modulation of various signaling pathways, including IL-17, AMPK, MAPK, transient receptor potential channels, cAMP, and Rap1. In summary, GA pretreatment demonstrates potential in protecting parathyroid cells from IRI by influencing various genes and signaling pathways. These findings offer a promising therapeutic strategy for hypoparathyroidism treatment.

Characterization of Cellulosic Pulps Isolated from Two Widespread Agricultural Wastes: Cotton and Sunflower Stalks.

Globally, huge amounts of cotton and sunflower stalks are generated annually. These wastes are being underutilized since they are mostly burned in the fields. So, in this work, we proposed a three-step method consisting of acid pre-treatment, alkaline hydrolysis, and bleaching for the extraction of cellulose pulps. These pulps were characterized to assess their morpho-structural and thermal properties. The design of experiments and response surface methodology were used for the optimization of the acid pre-treatment in order to achieve maximum removal of non-cellulosic compounds and obtain pulps enriched in cellulose. For cotton stalks, optimal conditions were identified as a reaction time of 190 min, a reaction temperature of 96.2 °C, and an acid (nitric acid) concentration of 6.3%. For sunflower stalks, the optimized time, temperature, and acid concentration were 130 min, 73.8 °C, and 8.7%, respectively. The pulps obtained after bleaching contained more than 90% cellulose. However, special care must be taken during the process, especially in the acid pre-treatment, as it causes the solubilization of a great amount of material. The characterization revealed that the extraction process led to cellulose pulps with around 69-70% crystallinity and thermal stability in the range of 340-350 °C, ready to be used for their conversion into derivatives for industrial applications.

Enhancing the valorization efficiency of Camellia oil extraction wastes through sequential green acid pretreatment and solid-state fermentation-based enzymatic hydrolysis

This study focuses on the underutilized Camellia oleifera oil extraction wastes, namely C. oleifera shell (COS) and cake (COC), which are often overlooked due to their high recalcitrance and antimicrobial properties. COS was found to be an ideal substrate for producing on-site enzymes through solid-state fermentation (SSF) that can be used for lignocellulosic biomass degradation. Additionally, pretreating COS with 2 % (w/v) oxalic acid greatly enhanced sugar production, achieving 9.22 and 5.24 times more sugar compared to room temperature and thermal pretreatment methods, respectively. The highest sugar of 28 g/L was achieved by utilizing a mixture of COS and COC. Enzymatic hydrolysis performance was evaluated through three routes. In the first two routes, the whole pretreated slurry was employed, except the pH was adjusted in route 2. In route 3, the pretreated hydrolysate was recovered, while the solid residue underwent further enzymatic hydrolysis. Ultimately, route 3 resulted in the highest sugar of 20.58 g/L, using SSF enzymes and oxalic acid pretreated solid residues of COS and COC mixture. This value is twice the performance achieved using a single substrate of COS. The fine-tuning strategy employed in route 3 led to (1) achieving high sugar recovery from pretreatment and enzymatic hydrolysis, (2) minimizing water and alkaline regulator consumption, and (3) optimizing resource utilization efficiency. The effectiveness of this approach was also attributed to the synergistic effect of oxalic acid pretreatment and the use of mixed substrate. The possible mechanisms underlying these processes were discussed, offering potential directions for future studies aimed at developing even more efficient approaches.

Investigation and characterization of changes in potato peels by thermochemical acidic pre-treatment for extraction of various compounds

Potato peel waste (PPW) is an underutilized substrate which is produced in huge amounts by food processing industries. Using PPW a feedstock for production of useful compounds can overcome the problem of waste management as well as cost-effective. In present study, potential of PPW was investigated using chemical and thermochemical treatment processes. Three independent variables i.e., PPW concentration, dilute sulphuric acid concentration and liberation time were selected to optimize the production of fermentable sugars (TS and RS) and phenolic compounds (TP). These three process variables were selected in the range of 5–15 g w/v substrate, 0.8–1.2 v/v acid conc. and 4–6 h. Whole treatment process was optimized by using box-behnken design (BBD) of response surface methodology (RSM). Highest yield of total and reducing sugars and total phenolic compounds obtained after chemical treatment was 188.00, 144.42 and 43.68 mg/gds, respectively. The maximum yield of fermentable sugars attained by acid plus steam treatment were 720.00 and 660.62 mg/gds of TS and RS, respectively w.r.t 5% substrate conc. in 0.8% acid with residence time of 6 h. Results recorded that acid assisted autoclaved treatment could be an effective process for PPW deconstruction. Characterization of substrate before and after treatment was checked by SEM and FTIR. Spectras and micrographs confirmed the topographical variations in treated substrate. The present study was aimed to utilize biowaste and to determine cost-effective conditions for degradation of PWW into value added compounds.

Gaussian process regression with levy flight optimization: Advanced AR66 adsorption studies

The coal fly ash (CFA), which is the residue generated by coal-fired power plants, was converted into a valuable zeolite material known as zeolite P (ZNa-P) through thermal and acid pretreatments followed by microwave radiation. Various analytical techniques were utilized to analyze the resulting zeolite, including X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, BET analysis, and zeta potential measurement. The efficiency of ZNa-P in eliminating anionic dyes from aqueous solutions was exhibited by successfully removing acid red dye 66 (AR66) from a solution composed of water. To optimize the removal process, Central Composite Design (CCD) was applied to investigate the impact of four main parameters: solution pH, initial dye concentration, adsorbent mass, and contact time. The generated CCD database was modeled using Gaussian process regression (GPR) with the Lévy flight distribution (LFD) optimization algorithm. The GPR model was then used to determine optimal conditions for maximum AR66 absorption (3405.3 mg/g), with a pH of 2, initial dye concentration of 1000 mg/L, adsorbent mass of 0.2 g/L, and contact time of 11 minutes. Furthermore, the GPR model exhibited significantly lower error (32.58 mg/g) in predicting the experimental values compared to the CCD model (204.92 mg/g), highlighting the efficiency and superiority of the GPR model in this study.

Remineralization of desalinated water: Duality roles of H2SO4 and CO2 injection during calco-carbonic equilibrium of osmosis water

In a desalination station, the remineralization step of osmosis water (OW) is essential to return to produced water its calco-carbonic equilibrium. For this, the use of calcite CaCO3 or lime Ca(OH)2 for water equilibrium in post-treatment processes needs the utilization of both CO2 and/or H2SO4 in osmosis water. For this reason, we describe here in detail, the effect of H2SO4 and CO2 on the remineralization process in a post-treatment desalination plant, especially with using hydrated lime Ca(OH)2 and calcite contactor (CaCO3)·In this paper, the different cases were discussed and investigated, by monitoring several indicator parameters such as pH, Ca2+ content, alkalinity, Langelier Index, etc. After the remineralization stage, we have shown that the efficiency of the remineralization process by CaCO3 or Ca(OH)2 depends on CO2 or H2SO4 content. Remineralization by CaCO3 (limestone) coupled with CO2 acidification is easy and more operator-friendly compared to the process using Ca(OH)2 (lime); it provides a clean environment for people working in the plant. In addition, the H2SO4 injection in the pretreatment stage followed by CaCO3 contact could lead to great results and correct calco-carbonic equilibrium. In the end, a comparative study of the investment cost in each process shows that the acidification of raw water with sulfuric acid (pretreatment) is the cheapest one, according to many studies. But on the other hand, the direct injection of CO2 is the easiest one to use for water balancing.

Multifunctional agricultural inputs based on biochar impregnated with algae residues extracts: Promoting effect on tomato growth

Macroalgae have been increasingly valorized in many applications due to their diverse biochemical composition and sustainable resource utilization. However, their residues are still undervalued even though they remain unexhausted and retain a broad spectrum of nutrients and molecules likely to be used in crop production as plant biostimulants and as soil amendment. In this study, macroalgae residues were recovered after an industrial extraction of agar and valorized through two pathways: 1) extraction of the remaining bioactive compounds using thermal, mechanical, physical, and biological processes, and 2) production of biochar using pyrolysis. After that, both outputs; extracts and biochar were combined to produce a multifunctional product “extract-impregnated biochar”, where the two components with different functionalities were co-integrated in the same formulation. Then, their effects were tested on tomato growth and nutrients content in the soil. Results indicated that the extracts obtained through enzymatic pyrolysis contained the highest protein content on (10.6 g/L), whereas the acidic attack provided the highest phosphorus content (1.24 g/L). The shoot and root biomass of tomato increased by 54 % and 100 %, respectively, with untreated biochar whereas it rose by 123–146 % and 200–450 % with extract-impregnated biochar. In addition, a slight improvement in soil total N and P was observed with both untreated and treated biochar applications when compared to the control. In general, the acidic and enzymatic pretreatments of algae residues appear to yield favorable results.

Queen bee acid pretreatment attenuates myocardial ischemia/reperfusion injury by enhancing autophagic flux

Queen bee acid (QBA), which is exclusively found in royal jelly, has anti-inflammatory, antihypercholesterolemic, and antiangiogenic effects. A recent study demonstrated that QBA enhances autophagic flux in the heart. Considering the significant role of autophagy in the development of myocardial ischemia/reperfusion (I/R) injury, we investigated the effect of pretreatment with QBA on myocardial damage. In an in vivo model, left coronary artery blockage for 30 min and reperfusion for 2 h were used to induce myocardial I/R. In an in vitro model, neonatal rat cardiomyocytes (NRCs) were exposed to 3 h of hypoxia and 3 h of reoxygenation (H/R). Our results showed that pretreatment with QBA increased the cell viability of cardiomyocytes exposed to H/R in a dose-dependent manner, and the best protective concentration of QBA was 100 μM. Next, we noted that QBA pretreatment (24h before H/R) enhanced autophagic flux and attenuated mitochondrial damage, cardiac oxidative stress and apoptosis in NRCs exposed to H/R injury, and these effects were weakened by cotreatment with the autophagy inhibitor bafilomycin A1 (Baf). In addition, similar results were observed when QBA (10 mg/kg) was injected intraperitoneally into I/R mice 30 min before ischemia. Compared to mice subjected to I/R alone, those treated with QBA had decreased myocardial infarct area and increased cardiac function, whereas, these effects were partly reversed by Baf. Notably, in NRCs exposed to H/R, tandem fluorescent mRFP-GFP-LC3 assays indicated increased autophagosome degradation due to the increase in autophagic flux upon QBA treatment, but coinjection of Baf blocked autophagic flux. In this investigation, no notable adverse effects of QBA were detected in either cellular or animal models. Our findings suggest that QBA pretreatment mitigates myocardial I/R injury by eliminating dysfunctional mitochondria and reducing reactive oxygen species via promoting autophagic flux.

Effect of Salt (NaCl) Stress on Germination in Clary Sage (Salvia sclarea) Subjected to Gibberellic Acid Pre-treatment

Effect of Salt (NaCl) Stress on Germination in Clary Sage (Salvia sclarea) Subjected to Gibberellic Acid Pre-treatment

Efficient and comprehensive utilization of sugarcane bagasse components through vanillic acid pretreatment

Lignocellulosic biomass, being a renewable carbon-based resource, holds paramount practical significance in terms of its comprehensive conversion and utilization for effectively substituting petroleum-based energy sources. Herein, we present a sustainable and environmental-friendly vanillic acid (VA) pretreatment approach for efficient and comprehensive utilization of sugarcane bagasse (SCB). The xylo-oligosaccharides (XOS)DP2-6 yield of 60.4 % (wt.% of xylan) was achieved under the conditions of 180 °C/15 min/6% VA (wt.% of SCB), while lignin condensation was simultaneously inhibited in this initial biorefinery stage. Subsequently, the enzymatic saccharification of the pretreatment residue was significantly enhanced due to the reduced cellulase adsorption of lignin. Lignin structural characterization demonstrated that VA could effectively incorporate to the lignin structure, resulting in the lignin exhibiting high preservation of β-O-4′ linkages (39.38/100 Ar), low molecular weight (2410 Da), abundant phenolic hydroxyl groups (3.70 mmol/g), and less degree of condensation (0.33). Importantly, the resulting less-condensed lignin (LCL) could effectively undergo melt-blending with poly(butylene adipate-co-terephthalate) (PBAT) owing to its low glass transition temperature, thereby facilitating the establishment of enhanced intermolecular interactions (π–π interaction and hydrogen bond) between LCL and PBAT. These interactions enhanced the plasticization of PBAT on LCL, and as a result, the prepared P/LCL30 composite film possessed excellent tensile properties without requiring lignin modification or additional additives. The study presents a straightforward and efficient biorefinery conversion strategy for lignocellulosic biomass, wherein hemicellulose was degraded into XOS, cellulose was enzymatically hydrolyzed to glucose, and the remaining lignin with lower condensation was utilized as a filler of PBAT composite film.

All-trans retinoic acid pretreatment of mesenchymal stem cells enhances the therapeutic effect on acute kidney injury.

A promising new therapy option for acute kidney injury (AKI) is mesenchymal stem cells (MSCs). However, there are several limitations to the use of MSCs, such as low rates of survival, limited homing capacity, and unclear differentiation. In search of better therapeutic strategies, we explored all-trans retinoic acid (ATRA) pretreatment of MSCs to observe whether it could improve the therapeutic efficacy of AKI. We established a renal ischemia/reperfusion injury model and treated mice with ATRA-pretreated MSCs via tail vein injection. We found that AKI mice treated with ATRA-MSCs significantly improved renal function compared with DMSO-MSCs treatment. RNA sequencing screened that hyaluronic acid (HA) production from MSCs promoted by ATRA. Further validation by chromatin immunoprecipitation experiments verified that retinoic acid receptor RARα/RXRγ was a potential transcription factor for hyaluronic acid synthase 2. Additionally, an in vitro hypoxia/reoxygenation model was established using human proximal tubular epithelial cells (HK-2). After co-culturing HK-2 cells with ATRA-pretreated MSCs, we observed that HA binds to cluster determinant 44 (CD44) and activates the PI3K/AKT pathway, which enhances the anti-inflammatory, anti-apoptotic, and proliferative repair effects of MSCs in AKI. Inhibition of the HA/CD44 axis effectively reverses the renal repair effect of ATRA-pretreated MSCs. Taken together, our study suggests that ATRA pretreatment promotes HA production by MSCs and activates the PI3K/AKT pathway in renal tubular epithelial cells, thereby enhancing the efficacy of MSCs against AKI.

Saccharification and structural changes in Areca catechu husk fiber

AbstractAreca nut husk (ANH) holds promise as a viable biomass source for xylose production. Xylose is a precursor for various biochemicals. However, the recalcitrant nature of ANH makes saccharification more complex. To address this, lime and acid pretreatments were carried out to enhance the susceptibility of biomass to saccharification. Before this, a compositional analysis was conducted to determine the initial constituents of the feedstock. Saccharification was conducted under the following conditions: 2% (wV−1) substrate loading, 100 rpm agitation, and 30 °C hydrolysis temperature for 12 h hydrolysis time at pH 4.5 to 5.0. However, parameters like xylanase enzyme loading were varied to enhance the saccharification of the ANH. The results demonstrated that acid‐treated husk (ATH), lime‐treated husk (LTH), and raw husk (RH) achieved the highest yield (gg−1) of reducing sugar, approximately 90, 83, and 15%, respectively, at an enzyme loading of 15.0 IUg−1. Various analytical techniques, including Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), zeta potential, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) were used to examine structural changes in the native, pretreated, and saccharified residues of ANH. The analysis revealed that a significant amount of partial crystalline and amorphous cellulose in the ANH biomass was hydrolyzed during the saccharification process. However, saccharification also led to the removal of amorphous substances, disruption of the crystalline structure, and conversion of crystalline regions into amorphous domains.

#2339 All-trans retinoic acid enhances the efficacy of mesenchymal stem cells in acute kidney injury

Abstract Background and Aims Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic strategy for acute kidney injury (AKI), but still suffer from the drawbacks of low survival rate, low homing rate, and uncertain differentiation. In search of better therapeutic strategies, we explored all-trans retinoic acid (ATRA) pretreatment of MSCs to observe whether it could improve the therapeutic efficacy on AKI. Method We established a renal ischemia/reperfusion (I/R) injury model induced by clamping of left renal artery for 30 minutes and contralateral nephrectomy. C57BL/6 mice were randomly divided into 4 groups: sham group, IRI group, MSCs group, and ATRA-MSCs group. MSCs or ATRA-pretreated MSCs were injected via tail vein. GFR was measured by transcutaneous monitoring the clearance of FITC-sinistrin. These mice were sacrificed 3 days after surgery, and the serum creatinine (SCr) and blood urea nitrogen (BUN) levels were measured. The renal pathological changes were examined by Periodic Acid-Schiff staining (PAS). The in vitro hypoxia/reoxygenation (H/R) model was established using human proximal tubular epithelial cells (HK-2 cells). Co-culturing HK-2 cells with MSCs or ATRA-pretreated MSCs. Western blot, quantitative real time-PCR (qRT-PCR), and immunohistochemistry were used to detect mRNA or protein expression. We performed RNA sequencing (RNA-seq) analysis in ATRA-pretreated MSCs. The content of hyaluronic acid (HA) in the supernatant of ATRA-pretreated MSCs culture was detected by ELISA. Hyaluronan synthase mRNA expression level in ATRA-pretreated MSCs assessed by qRT-PCR analysis. The HAS2 promoter-binding transcription factors were forecasted by the JASPAR Transcription Factor Binding Site database. Western blot was used to detect whether P13K/AKT pathway was activated by ATRA-pretreated MSCs. Whether this nephroprotective effect could be reversed were explored by silencing HAS2 or CD44 antibodies. Results The AKI mice showed a significant decrease in GFR and even complete loss of renal function. Administration of MSCs significantly increased GFR, and MSCs pretreated with ATRA further increased GFR. Mice injected with ATRA-pretreated MSCs had significantly lower levels of SCr, BUN and ATN scores compared with untreated MSCs. Western blot, quantitative real-time PCR (qRT-PCR), and immunohistochemistry showed that ATRA pretreated MSCs were more effective in reducing AKI inflammation and apoptosis and promoting proliferative repair than untreated MSCs. GO enrichment analysis demonstrated that the hyaluronan biosynthetic process may be a significantly expressed. HAS2 expression and HA content of MSCS were significantly increased after the addition of ATRA. Analysis for potential transcription factor binding sites revealed that the HAS2 promoter region has multiple potential binding sites for the retinoic acid receptor. Based on the predictions from the JASPAR database, the RXR-RAR heterodimer had the highest prediction score. We then performed ChIP analysis to experimentally verify the binding of RXR-RAR heterodimer transcription factor to HAS2 promoters. We further found that ATRA-pretreated MSCs activated the PI3K/AKT signaling pathway in AKI. As expected, we found that ATRA-pretreated MSCs anti-inflammatory, anti-apoptosis, and pro-proliferation effects were substantially reversed by silencing HAS2 or blocking CD44. Conclusion ATRA promotes HA secretion from MSCs and activates the PI3K/AKT pathway, which in turn enhances the therapeutic efficacy of MSCs on AKI.

Valorization of Afzelia bella oilseeds cake in bioethanol production using 1-butyl-3-methyl-imidazolium chloride ionic liquid and dilute sulfuric acid pretreatment

The use of renewable feedstocks and the variability of lignocellulosic feedstocks generating fermentable sugars also offer the advantages of the most abundant, sustainable and competitive non-food biomass. The aim of this study is to valorize the oilcake obtained from non-conventional Congolese Afzelia bella oilseeds, after extraction of the oil used in biodiesel production. The conversion of A. bella oilseeds cake into ethanol was carried out using the two methods of pretreatment (with the synthesized ionic liquid 1-butyl-3-methyl imidazolium chloride and dilute sulfuric acid), followed by hydrolysis with dilute sulfuric acid and fermentation by Saccharomyces cerevisiae. The lignocellulosic composition of the sample was 47.98% cellulose, 28.15% hemicellulose and 22.3% lignin. Pretreatment with 1-butyl-3-methyl-imidazolium chloride (ionic liquid) showed an increase in cellulose content of around 4.25% and hemicellulose content of around 7.7%, with simultaneous delignification of 12.25%. In contrast, with dilute sulfuric acid, the lignin and cellulose content of the sample fell to 3.88% and 1.88% respectively. Hemicellulose content, on the other hand, increased by only 3.58%. After dilute acid hydrolysis (5% H2SO4), the values for total reducing sugar, glucose and xylose were 66.06±1.34 mg.g-1; 36.25 ± 1.2 mg.g-1 and 29.71 ± 0.6 mg.g-1 respectively. The percentage conversion of sugars was 55.16 ± 0.5% for cellulose to glucose and 53.76 ± 0.75% for hemicellulose to xylose. The hydrolyzed product of the complex polysaccharide was then converted to ethanol using commercial yeast. Results showed an ethanol yield of around 10.3%, and Fourier Transform Infrared (FTIR) spectroscopy results confirmed bioethanol production. A. bella oilseeds cakes are therefore a potential source for ethanol production.

Production of sludge biochar by steam pyrolysis and acid treatment: Study of the activation mechanism and its impact on physicochemical properties

This study addresses the preparation of sludge biochar through a procedure that combines steam pyrolysis in a wide range of temperature (500–900 ºC) and acid treatment with HCl (performed before or after the pyrolysis). The acid washing after the pyrolysis maximizes BET surface area due to pore unblocking, thus making visible the pore structure generated. The drawback of the acid washing is the lower yield obtained (compared to the acid pretreatment), as well as the loss of the magnetic properties of sludge biochar. The acid pretreatment requires temperatures above 700 ºC to have a beneficial effect, due to the occurrence of additional reactions of the incorporated HCl with sludge constituents. The pretreatment results in materials with a high degree of microporosity. Among the reactions favoured, of interest is the development of magnetite in the whole temperature range. The activation protocol used in this study (especially the procedure that includes the acid pretreatment) is effective to generate biochar with magnetic properties through the transformation of the Fe introduced during the water treatment process, without adding a source of Fe. The presence of magnetite is an advantage for the reuse of sludge biochars in wastewater treatment.

Comparison of lactic and propionic acid hydrolysis for production of xylo-oligosaccharides and ethanol from polysaccharides in Toona sinensis branch

Xylan-type hemicellulose hydrolysis by an organic acid solution for the production of xylo-oligosaccharides (XOS) is efficient and eco-friendly, but the effects of different organic acids on XOS production from Toona sinensis branch (TB) biomass is limited. In this work, under the conditions of 170 °C for 60 min, 33.1 % and 38.7 % XOS yields were obtained from polysaccharides present in TB by 2 % lactic acid (LA) and 6 % propionic acid (PA), respectively. Then 77 % of the lignin was removed by hydrogen peroxide−acetic acid pretreatment system, and 39.5 % and 44.7 % XOS yield were obtained from polysaccharides in delignification TB by 2 % LA and 6 % PA, respectively. It was found that PA hydrolysis, especially from delignified TB, resulted in higher XOS yield and purity compared to LA hydrolysis. Moreover, the content of byproducts (xylose, hydroxymethyl-furfural and furfural) in PA hydrolysate was lower. Following the hydrolysis process, the simultaneous saccharification and fermentation of the TB solid residue achieved an ethanol yield of 71.5 %. This work proposed an integrated process to preferentially convert the TB hemicellulose into valuable XOS and then convert the cellulose into ethanol. This process had the advantages of eliminating the need for isolation and purification of xylan, and the potential to obtain multiple products from the same raw material.