Two-step Pretreatment Research Articles

Y and ZSM-5 Hierarchical Zeolites Prepared Using a Surfactant-Mediated Strategy: Effect of the Treatment Conditions.

Diffusional limitations associated with zeolite microporous systems can be overcome by developing hierarchical zeolites, i.e., materials with a micro- and mesoporous framework. In this work, Y and ZSM-5 zeolites were modified using a surfactant-mediated hydrothermal alkaline method, with NaOH and cetyltrimethylammonium bromide (CTAB). For Y zeolite, after a mild acidic pretreatment, the effect of the NaOH+CTAB treatment time was investigated. For ZSM-5 zeolite, different concentrations of the base and acid solutions were tested in the two-step pretreatment preceding the hydrothermal treatment. The properties of the materials were studied with different physical-chemical techniques. Hierarchical Y zeolites were characterized by 3.3-5 nm pores formed during the alkaline treatment through the structure reconstruction around the surfactant aggregates. The effectiveness of the NaOH+CTAB treatment was highly dependent on the duration. For intermediate treatment times (6-12 h), both smaller and larger mesopores were also obtained. Hierarchical ZSM-5 zeolites showed a disordered mesoporosity, mainly resulting from the pretreatment rather than from the subsequent hydrothermal treatment. High mesoporosity was obtained when the concentration of the pretreating base solution was sufficiently high and that of the acid one was not excessive. Hierarchical materials can be obtained for both zeolite structures, but the pretreatment and treatment conditions must be tailored to the starting zeolite and the desired type of mesoporosity.

Efficient enzymatic hydrolysis of active oxygen and solid alkali/dilute sulfuric acid-pretreated corn cob

This work proposed a two-step pretreatment method of cooking with active oxygen and solid alkali (CAOSA) followed by dilute sulfuric acid treatment (DA), to contribute enzymatic hydrolysis of corn cob. The first step, CAOSA pretreatment, removed 83.16 % of the lignin, while the second step, a milder pretreatment with DA further eliminated hemicellulose. After the two-step pretreatment, the cellulose content of the residue reached 66.74 %, and with a solid loading of 5 %, the glucose yield was remarkably high at 98.35 % with a concentration of 36.47 g/L. The optimal conditions of the process were determined as follows: DA with 1 % H2SO4 at a solid-to-liquid ratio of 1:10, a temperature of 110 ℃, and a pretreatment time of 60 min. To confirm the efficacy of the two-step pretreatment, we characterized the samples treated with different methods using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The developed method proposes an effective pretreatment and results in the complete enzymatic hydrolysis of corn cob.

A coupling strategy combined with acid-hydrothermal and novel DES pretreatment: Enhancing biomethane yield under solid-state anaerobic digestion and efficiently producing xylo-oligosaccharides and recovered lignin from poplar waste

Lignocellulose is an abundant renewable bio-macromolecular complex, which can be used to produce biomethane and other high-value products. The lignin, presents in lignocellulose is typically regarded as an inhibitor of anaerobic digestion. Therefore, it is crucial to develop a novel selective separation strategy to achieve efficient biomethane production and all-component utilization of biomass. Hence, a combination of two-step pretreatment and solid-state anaerobic digestion was employed to enhance the production of biomethane and to generate valuable chemicals from poplar waste. Optimal conditions (4 % acetic acid, 170 °C, and 40 min) resulted in 70.85 % xylan removal, yielding 50.28 % xylo-oligosaccharides. The effect of a strong acid 4-CSA-based novel three-constituent DES on delignification was investigated from 80 °C to 100 °C; the cellulose content of DES pretreated poplar increased from 64.11 % to 80.92 %, and the delignification rate increased from 49.0 % to 90.4 %. However, high delignification of the pretreated poplar (DES-100 and DES-110) led to a rapid accumulation of volatile organic acids during the hydrolysis and acidogenesis stages, resulting in methanogenesis inhibition. The highest biomethane yield of 208 L/kg VS was achieved with DES-80 (49.0 % delignification), representing a 148 % improvement compared over untreated poplar. This approach demonstrates the potential for comprehensive utilization of all components of biomass waste.

Highly Efficient Production of Cellulosic Ethanol from Poplar Using an Optimal C6/C5 Co-Fermentation Strain of Saccharomyces cerevisiae.

Cellulosic ethanol is the key technology to alleviate the pressure of energy supply and climate change. However, the ethanol production process, which is close to industrial production and has a high saccharification rate and ethanol yield, still needs to be developed. This study demonstrates the effective conversion of poplar wood waste into fuel-grade ethanol. By employing a two-step pretreatment using sodium chlorite (SC)-dilute sulfuric acid (DSA), the raw material achieved a sugar conversion rate exceeding 85% of the theoretical value. Under optimized conditions, brewing yeast co-utilizing C6/C5 enabled a yield of 35 g/L ethanol from 10% solid loading delignified poplar hydrolysate. We increased the solid loading to enhance the final ethanol concentration and optimized both the hydrolysis and fermentation stages. With 20% solid loading delignified poplar hydrolysate, the final ethanol concentration reached 60 g/L, a 71.4% increase from the 10% solid loading. Our work incorporates the pretreatment, enzymatic hydrolysis, and fermentation stages to establish a simple, crude poplar waste fuel ethanol process, expanding the range of feedstocks for second-generation fuel ethanol production.

A two-step approach of ozonation pre-oxidation and re-flocculation to regulate drinking water treatment sludge: Sludge reflux and enhanced coagulation

The characteristics of drinking water treatment sludge (DWTS) are important factors limiting the coagulation effect after sludge recycling. To enhance the coagulation performance of DWTS recycling, a two-step pretreatment strategy was employed, including ozonation pre-oxidation and the re-flocculation of polymeric aluminum chloride (PACl) and polyacrylamide (PAM). Ozonation pre-oxidation transformed insoluble organic matter into dissolved organic matter (DOM), reducing the organic content by 12.58% for UV254 and 8.94% for dissolved organic carbon (DOC) in the DWTS recycling process. Following re-flocculation with PACl and PAM, the size, zeta potential, and settling velocity of the ozonated sludge were further increased from 30.27 μm, −12.57 mV, and 2.06 mm/s to 187.6 μm, −3.49 mV, and 6.42 mm/s, respectively, which exhibited higher turbidity removal in DWTS recycling process. Following the two-step method, larger, denser, and more reversible flocs were observed during the recycling process, and the settling efficiency of the flocs was enhanced, which enabled achieving better water quality in a shorter duration. These findings provide innovative insights into drinking water plant optimization and sludge management.

A multi-variant approach to optimize process parameters of two-step pretreatment of high FFA Prosopis juliflora oil

<p>A feasible alternative fuel for diesel engines in recent days is biodiesel, which can be produced from both edible and inedible feedstock. When considering the economic and environmental aspects, there is a considerable academic interest among researchers in the transesterification of non-edible oils to yield valuable Biodiesel, as compared to biodiesel production from edible oils. Prosopis juliflora oil was extracted using the solvent extraction technique. By using a two-step acid esterification method, the FFA acid value was reduced less than 1%. The acid value underwent a two-step reduction, initially decreasing from 44 KOH/gm to 8.6 mg KOH/gm, and subsequently reaching 2.7 mg KOH/gm. The implementation of the above procedure can effectively mitigate significant problems in diesel engines when using high viscous non-edible oils. The primary objectives of this research were to maximize the biodiesel output and simultaneously minimize the acid value. Response Surface Methodology (RSM) was employed in the current investigation to optimize different parameters. D-optimal design technique in Response Surface Methodology (RSM), was used for analyzing the methanol/oil volume ratio (factor A), reaction temperature (factor B), and reaction time (factor C) as process variables. The focus of the analysis was on the percentage of acid value (Y).</p>

Ionic liquid and diluted sulfuric acid combinatorial pretreatment for efficient sugarcane bagasse conversion to L-lactic acid

An economical pretreatment method is needed to produce the L-lactic acid from renewable biomass. Six different combinatorial experiments including choline chloride [Ch][Cl], 1-ethyl-3-methylimidazolium chloride [Emim][Cl], and 1-butyl-3-methylimidazolium chloride [Bmim][Cl], diluted acid sulfuric acid (DSA), and two ionic liquids (ILs) were tested. Ionic liquid (ILs) step performed at 90, 110, and 130 °C. The cellulose content of sugarcane bagasse (SCB) increased from 42.1 % (raw material) to 74.6 % (combinatorial pretreatment with DSA and [Emim][Cl]) to 79.9 % (after water washing). Pretreated SCB was employed in enzymatic saccharification and L-lactic acid fermentation. Enzymatic hydrolysis resulted in the maximal levels of glucose titer (220.7 g/L) and yield (73.5 %). L-lactic acid concentration reached to 204.1 g/L when SCB fermented with Lactobacillus casei ATCC 334 at a 25 % w/w solid loading. The two-step pretreatment SCB underwent morphological changes, as evidenced by FTIR, XRD, and SEM analyses. High cellulose levels and high lactic acid highlight the advantages on energy efficiency of a two-step combined pretreatment procedure over a standard single-step pretreatment technique.

Development of a two-step pretreatment and UPLC-MS/MS-based method for simultaneous determination of acrylamide, 5-hydroxymethylfurfural, advanced glycation end products and heterocyclic amines in thermally processed foods

A two-step pretreatment and UPLC-MS/MS-based method was established to extract and determine 17 thermal processing hazards (TPHs) simultaneously. The first step was to extract acrylamide (AA), 5-hydroxymethylfurfural (HMF) and free heterocyclic amines (HAs). The bound HAs and advanced glycation end products (AGEs) were released by acid hydrolysis in the second step. A fairly good separation was achieved within 7 min. Almost all TPHs showed high correlation coefficients (R2 >0.999) in their respective linear ranges. The accuracy ranged from 98.13 to 100.96%. LODs and LOQs were in the range of 0.01–0.89 µg/L and 0.02–2.96 µg/L, respectively. The method was successfully applied to four representative food products, including high-starch, high-protein, high-fat and high-sugar foods, showing acceptable recoveries, intra-day and inter-day precisions. Moreover, PCA was performed to visualize the association between TPHs and food matrices. The developed method provided technical support for the formation and control researches of TPHs.

Integrated biorefinery of Mucor circinelloides biomass and sugarcane bagasse for application of high-value biopolymers

The replacement of expensive components in microbial growth media with pretreated lignocellulosic waste component to increase the product spectrum and add value to the bioproducts has been encouraged to achieve sustainable and feasible utilization of waste biomass as per the biorefinery approach. This study demonstrates an integrated biorefinery approach towards utilization of sugarcane bagasse and biomass of Mucor circinelloides ZSKP. A maximum reducing sugar recovery of 80.67 g/l was achieved after combining pretreatment with saccharification. A low temperature, glycerol, and ammonium phosphate pretreatment method was established, where glycerol pretreatment conditions were reduced from 250 to 150 °C and from 120 to 45 min. The ammonium phosphate-containing hydrolysate yielded 12.89 g/l of fungal biomass after fermentation to add to 20.8 g lignin from the delignification step. The biomass production was further improved to 17.69 g/l after supplementation with corn steep solids and mineral salts. The fermentation process also yielded 2.36 g/l chitosan and 4.9 g/l of lipids after extraction from the oleaginous fungus. The lignin infused glycerol plasticized chitosan biocomposite plastic had a 100% improvement in thermogravimetric properties with almost 50% more energy needed to increase the temperature of the material when compared to glycerol only plasticized biocomposite. The fungal chitosan showed antimicrobial properties and was effective as a preservative spray for fresh tomatoes and apples extending their shelf life to at least 14 and 18 days, respectively. This study therefore demonstrated that a novel two-step pretreatment process could be environmentally beneficial and yielded multiple products for biotechnological applications.

Two-Step Pretreatment of Lignocellulosic Biomass for High-Sugar Recovery from the Structural Plant Polymers Cellulose and Hemicellulose

Nitrogen explosive decompression pretreatment was tested on barley straw, aspen wood, and pine wood in a two-step pretreatment approach. The two-step approach aims to avoid the uncontrolled degradation of hemicellulose during pretreatment and to recover high sugar yields from hemicellulose and cellulose. Additionally, the pretreated biomass was filtered after each pretreatment step with a fine metal sieve so that fermentation and hydrolysis inhibitors were removed. A total sugar yield of 43 g per 100 g of dry biomass was achieved from barley straw and aspen wood. For pine wood, the total sugar yield was significantly lower, with 12 g per 100 g of dry biomass. Possible reasons for this low sugar yield are the adsorption and deactivation of cellulases on softwood hemicellulose and on repolymerized lignin after pretreatment.

Preparation of Alkali Activated Cementitious Material by Upgraded Fly Ash from MSW Incineration.

Utilization of municipal solid waste incineration fly ash (MSWI-FA) can avoid land occupation and environmental risks of landfill. In this paper, MSWI-FA was used to prepare alkali activated cementitious materials (AACMs) after two-step pretreatment. The ash calcination at 450 °C removed 93% of dioxins. The alkali washing with 0.2 g NaOH/g ash removed 89% of chlorine and retained almost 100% of calcium. The initial setting time of AACMs was too short to detect for 20% of MSWI-FA addition, and the prepared block had extensive cracks and expansion for CaClOH and CaSO4 inside. Alkaline washing pretreatment increased the initial setting time by longer than 3 min with 30% ash addition and eliminated the cracks and expansion. The significance of the factors for compressive strength followed the modulus of alkali activator > silica fume amount > alkaline washing MSWI fly ash (AW-MSWI-FA) amount. When the activator modulus was 1.2, 1.4 and 1.6, the blocks with 30% of AW-MSWI-FA had a compressive strength of up to 36.73, 32.61 and 16.06 MPa, meeting MU15 grade. The leaching test shows that these AACM blocks were not hazardous waste and almost no Zn, Cu, Cd, Pb, Ba, Ni, Be and Ag were released in the leaching solution.

Enhancement of sugar release from sugarcane bagasse through NaOH-catalyzed ethylene glycol pretreatment and water-soluble sulfonated lignin

In this work, five different NaOH-catalyzed ethylene glycol (EG) pretreatments together with water-soluble sulfonated lignin (SL) were used for enhancing sugarcane bagasse (SCB) enzymatic digestion. The results showed that the coupling of NaOH and EG into a one-pot pretreatment (10%NaOH/EG) was more beneficial to improve SCB enzymatic hydrolysis than that of single 10%NaOH or EG pretreatment, or the two-step pretreatment of NaOH and EG in different sequence (10%NaOH+EG and EG + 10%NaOH, respectively). The highest glucose yield of this work was 91.2 %, mainly released from the SCB that pretreated with 10%NaOH/EG at 130 °C for 60 min and 72 h enzymatic hydrolysis. The adding of SL into the enzymatic hydrolysis step could significantly lower the cellulase dosage and hydrolysis time from 20 FPU/g and 72 h to 10 FPU/g and 24 h, respectively, meanwhile keeping a high glucose yield of 90.4 %. The characterization of various pretreated or un-pretreated SCB confirmed that the improvement of hydrolysis efficiency of SCB after 10%NaOH/EG pretreatment was closely related to the removal of various components barriers in SCB and the fragmentation of pretreated solid. It can be concluded that the developed NaOH-catalyzed ethylene glycol pretreatment was an efficiency way to enhance the sugar release from SCB.

Facile synthesis of multi-layered nanostructured Ni/CeO2 catalyst plus in-situ pre-treatment for efficient dry reforming of methane

A multi-layered nanostructured Ni/CeO2 catalyst was synthesized through a facile one-pot hydrothermal reaction. The influence of catalyst pre-treatment was investigated as an efficient and easy strategy to improve its catalytic activity. The catalyst exhibited stable above 90% CO2 and 85% CH4 reactant conversions and high product H2/CO ratio (close to 0.95) for DRM at 700 °C for 24 h, with a two-step pre-treatment of the catalyst (H2 reduction followed by CO2 oxidation). This can be ascribed to the multi-layered structure of CeO2 support, enhancing of exposed metal-support interface between Ni and the CeO2 and formation of carbon and oxygen species on the catalyst surface, as indicated by characterizations of H2-TPR, XPS, XRD, FTIR and HAADF-STEM. The simple synthesis and pre-treatment method of such Ni/CeO2 catalyst with high DRM performance offers new opportunities for CeO2 application into DRM reaction as a promising support material.

Two-step pretreatment for improving enzymatic hydrolysis of spent coffee grounds

Spent coffee ground has attracted increasing attentions since it contains many useful components such as polysaccharides, protein, lipid and bioactive compounds. The aim of this research is to enhance the enzymatic hydrolysis to release important sugars in spent coffee ground using different pretreatment methods. Spent coffee grounds were pretreated by alkali pretreatment, organosolv pretreatment and the combined process. The pretreated material was hydrolyzed by different commercial enzymes including Cellulast, Pectinex, Ultraflomax and Viscozyme. Monosaccharides, total phenolic content and antioxidant activity in the hydrolysate were measured and evaluated. The use of Viscozyme achieved the highest reducing sugar yield and showed the significant difference from other enzymes. Alkali and organosolv pretreatment demonstrated to improve the production of sugars. The alkali pretreatment followed by organosolv treatment effectively removed lignin, resulting in only 14% lignin in the pretreated sample. The maximum reducing sugar concentration reached 6120 mg/L through two-step pretreatment and subsequent enzymatic hydrolysis, corresponding to a yield of 161 mg sugar/g substrate. The spent coffee ground hydrolysate contained 2917 mg/L mannose, 1633 mg/L glucose and 957 mg/L galactose. Phenolic compounds were observed to be released during the enzymatic hydrolysis, giving a total phenolic content of 174.4 mg GAE/L and the SCG hydrolysate also showed an antioxidant capacity equivalent to 263.2 mg/L ascorbic acid after 120 h hydrolysis. This study demonstrated a scalable two-step pretreatment process to obtain important sugars including mannose, glucose, and galactose along with phenolic compounds for further industrial uses.

Potential Techniques for Conversion of Lignocellulosic Biomass into Biofuels

Lignin has been found as a naturally available aromatic resource for biofuel production. Reduced reliance on fossil fuels and replacement with a green and environmentally friendly strategy are currently one of the most pressing challenges. There has been significant growth in energy consumption, necessitating the transition to an alternative energy source. The current renewable energy source has significant biofuel production potential. It is critical to discuss the process parameters for pinpointing lignin content as part of the technology development process. Biofuel production possesses various challenges that need to be addressed. In this research, we precisely discussed the numerous lignin conversion mechanisms that can boost the biofuel output. Catalytic deoxygenation is a fuel promotion process that decreases the oxygen content, which causes instability and corrosion. SiO2, ZrO2, CeO2, TiO2, and Al2O3 are used in catalytic deoxygenation to produce biofuel. The use of chosen Al2O3-TiO2 metal oxide catalysts is critical in biofuel production. To obtain hemicellulose levels, two-step pretreatments with alkali and acids are used. The constraints, challenges, industrial perspectives, and future outlooks for developing cost-effective, energy-efficient, and environmentally friendly procedures for the long-term valorization of lignocellulosic materials were examined in the conclusion.

Co-production of levulinic acid and lignin adsorbent from aspen wood with combination of liquid hot water and green-liquor pretreatments

Efficient lignocellulosic fractionation and conversion into platform chemicals provide a considerable opportunity for the industrial operation of a lignocellulosic biorefinery. However, single-step pretreatments are often insufficient to overcome biomass recalcitrance as the existence of insoluble lignin generally restricts component fractionation and conversion. This study performed a two-step pretreatment, consisting of sequential liquid hot water (LHW) and green-liquor (GL), for bioprocessing of aspen biomass into bioproducts such as glucose, levulinic acid (LA), and lignin adsorbent. The two-step pretreated glucan-rich solid displayed high cellulose accessibility, which is responsible for 94% of the glucose yield. The optimized LHW pretreatment (200 °C, 40 min) solubilized 91% of the hemicellulose, which together with monomeric sugars in the hydrolysate solution was straightly heated at 190 °C for 80 min and yielded 72.49% of LA in the presence of sulfuric acid as a catalyst. Moreover, GL post-treatment (Na2CO3+Na2SO3) solution maximized the delignification at 78% from LHW pretreated substrate. The isolated lignin possessed a remarkable ability for Cd2+ and Pb2+ uptake with maximized adsorption values of 250 mg/g and 228 mg/g, respectively. Finally, energy analyses showed that moderate lignocellulosic conversion could obtain an energy recovery of 85%, providing a sustainable pathway for biorefinery approaches.

A Combination Method of Liquid Hot Water and Phosphotungstic Acid Pretreatment for Improving the Enzymatic Saccharification Efficiency of Rice Straw

Chemical pretreatment can significantly improve the enzymatic hydrolysis efficiency of lignocellulosic biomass, thereby improving the yield of sugar materials for the production of cellulosic ethanol, but commonly used acid–base catalysts are difficult to recover and reuse. In this work, a combination method of liquid hot water (LHW) and phosphotungstic acid (PTA) pretreatment was performed to improve the saccharification efficiency of rice straw, and we attempted to evaluate the reuse effect of PTA catalysts. The rice straw was first treated with LHW at 180 °C for 90 min, and then treated with 20 mM PTA at 130 °C for 60 min. After pretreatment, the cellulose hydrolysis efficiency and glucose recovery of the rice straw increased by 201.85% and 164.25%, respectively. Glucose accounted for 96.8% of the total reducing sugar in the final enzymatic hydrolysate. After each PTA pretreatment, approximately 70.8–73.2% of the PTA catalyst could be recycled. Moreover, the catalytic activity of the PTA catalyst that had been used five times did not decrease. The improved enzymatic saccharification efficiency was attributed to the removal of 89.24% hemicellulose and 21.33% lignin from the lignocellulosic substrate. The two-step LHW-PTA pretreatment could pretreat biomass in the field of cellulosic ethanol production.

Profile analysis with reconstruction robustness for measurement data subject to outliers.

In the surface profile analysis, there are often a few observations that contain outliers. Due to the existence of outliers, the application of non-robust reconstruction algorithms for measurement data will become a huge problem because these methods are often sensitive to outliers and the approximation effectiveness will be greatly aggravated. In view of this, this paper presents a novel angle-based moving total least squares reconstruction method, to the best of our knowledge, that applies two-step pre-treatment to handle outliers. The first step is an abnormal point detection process that characterizes the geometric features of discrete points in the support domain through a new angle-based parameter constructed by total least square. Then, the point with the largest anomaly degree is removed, and a relevant weight function is defined to adjust the weights of the remaining points. After pre-treatment, the final estimates are calculated by weighted total least squares (WTLS) based on the compact weight function. The detection and removal of outliers are automatic, and there is no need to set a threshold value artificially, which effectively avoids the adverse impacts of human operation. Numerical simulations and experiments verify the applicability of the proposed algorithm as well as its accuracy and robustness.

Chemical and ultrastructural evolutions of corn stalk during sequential acid and alkaline hydrogen peroxide pretreatment

Two-step pretreatment, the sequential dilute acid pretreatment (DAP) and alkaline hydrogen peroxide pretreatment (AHP), is an efficient strategy to pretreat lignocellulose. Understanding the chemical and ultrastructural evolutions could improve the utilization of corn stalks. Advanced multiscale approach was integrated, to semi-quantitative elucidate the lignocellulose structural evolution. Implementing DAP followed by AHP offered greater accessibility to enzymes than the reverse order, with glucose yield reaching 57.1% under mild condition. DAP promoted lignin degradation in the following AHP, by partially solubilizing cell wall extracts from middle lamella, and relocating lignin to cell corner and lumen. This investigation can provide new insight into potential routes to further development of lignocellulose conversion.

Rapid screening of illegally added drugs in functional food using a miniature ion trap mass spectrometer

With the expansion of the functional food market, the qualification assessment of these products has become a major challenge, and efficient analytical tools are urgently needed. Here, a miniature mass spectrometer (MS) with self-aspiration capillary electrospray ionization (SACESI) source and ion trap analyzer was developed for rapid screening of various illegally added drugs in functional foods. No chromatographic separation was required, but a simplified two-step pretreatment method was developed to reduce the operational procedures and time consumption of the entire analysis. SACESI source uses capillary action to drive solution injection, which utilizes a simple structure and convenient operation to constitute a kind of disposable MS detection solution. To achieve accurate and automatic identification, an intelligent recognition algorithm with steps of spectrum preprocessing, characteristic peak matching, and support vector machine learning was constructed. The relative accuracy of rapid screening of 31 suspicious drugs in various samples is up to 99.78%. It achieves 100% correct identification for the 55 batches of actual samples captured by on-site inspection, which demonstrates the feasibility of the proposed analytical system and strategy in food safety applications.