Search

Biogas has improved due to technological advancements, environmental awareness, policy support, and research innovation, making it a more cost-effective and environmentally friendly renewable energy source. The Generalized Linear Model (GLM) was employed to examine the relationship between purchased and generated energy from 2007 to 2023. Metrics such as deviance, log likelihood, and dispersion phi were examined to assess model fit. The Mann–Kendall test was utilized to detect trends in energy datasets. Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) reduction was significant, exceeding 97% from 2014 to 2023. However, treated sewage displayed limited susceptibility to biological degradation, with COD to BOD5 ratios increasing from 2.28 to 6.59 for raw sewage and from 2.33 to 7.05 for treated sewage by 2023. Additionally, the efficiency of sewage purification processes was calculated, and multivariate regression analysis was conducted on gas composition data. Principal Coordinate Ordination (PCO) and k-means clustering were used for dimensionality reduction and biogas component clustering, respectively. This research showed that biogas from the waste water treatment process can be used, particularly in methane production. Technological advancements have made biogas production more efficient, enhancing energy generation within a circular economy framework. [ABSTRACT FROM AUTHOR]

In recent years, the implementation of CO2 capture systems has increased. To reduce the costs and the footprint of the processes, different industrial wastes are successfully proposed for CO2 capture, such as gypsum from desulfurization units. This gypsum undergoes an aqueous carbonation process for CO2 capture, producing an added-value solid material that can be valorized. In this work, panels have been manufactured with a replacement of (5 and 20%) commercial gypsum and all the compositions kept the water/solid ratio constant (0.45). The density, surface hardness, resistance to compression, bending, and fire resistance of 2 cm thick panels have been determined. The addition of the waste after the CO2 capture diminishes the density and mechanical strength. However, it fulfills the requirements of the different European regulations and diminishes 56% of the thermal conductivity when 20%wt of waste is used. Although the CO2 waste is decomposed endothermically at 650 °C, the fire resistance decreases by 18% when 20%wt. is added, which allows us to establish that these wastes can be used in fire-resistant panels. An environmental life cycle assessment was conducted by analyzing a recycling case in Spain. The results indicate that the material with CO2 capture waste offers no environmental advantage over gypsum unless the production plant is located within 200 km of the waste source, with transportation being the key factor. [ABSTRACT FROM AUTHOR]

Since CO2 is an important component of gas emissions, its removal from gas streams is of the utmost importance to fulfill various environmental requirements. The technologies used to accomplish this removal are based mainly on absorption, as well as adsorption and membrane processing. Among the materials used in the above separation processes, materials in nano forms offer a potential alternative to other commonly used macromaterials. The present work reviews the most recent publications (2023) about CO2 capture using different nanomaterials, and whilst most of these publications were dedicated to investigating the above, several presented data on the separation of CO2 from other gases, namely nitrogen and methane. Furthermore, a number of publications investigated the recyclability of nanomaterials under continuous use, and just three of the references were about computational modeling; all others were experimental papers, and only one reference used a real industrial gas. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass represents the most abundant renewable carbon source on earth and is already used for energy and biofuel production. The pivotal step in the conversion process involving lignocellulosic biomass is pretreatment, which aims to disrupt the lignocellulose matrix. For effective pretreatment, a comprehensive understanding of the intricate structure of lignocellulose and its compositional properties during component disintegration and subsequent conversion is essential. The presence of lignin-carbohydrate complexes and covalent interactions between them within the lignocellulosic matrix confers a distinctively labile nature to hemicellulose. Meanwhile, the recalcitrant characteristics of lignin pose challenges in the fractionation process, particularly during delignification. Delignification is a critical step that directly impacts the purity of lignin and facilitates the breakdown of bonds involving lignin and lignin-carbohydrate complexes surrounding cellulose. This article discusses a two-step fractionation approach for efficient lignin extraction, providing viable paths for lignin-based valorization described in the literature. This approach allows for the creation of individual process streams for each component, tailored to extract their corresponding compounds. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment between 150 °C and 230 °C is widely used in wood processing, from the steam treatment of timber for better dimensional stability and durability to the pretreatment for enzymatic saccharification and chemical pulping. Understanding the ultrastructural changes of wood cell walls through hydrothermal treatments is crucial for controlling and optimizing these hydrothermal treatment-based processes. Here, we studied the ultrastructure of wood cell walls of 24 hardwood species using simultaneous small- and wide-angle X-ray scattering measurements before and after the hydrothermal treatment at 200 °C. Most hardwoods show similar equatorial scattering features, representing the structure in the cross-section of the cell walls. In a water-saturated native state, there is a prominent correlation peak between 0.1 and 0.2 Å−1 and a second peak between 0.2 and 0.4 Å−1. The hydrothermal treatment above 160 ˚C drastically altered the structure at this nanometric scale: the two native correlation peaks disappeared, coincident with a buildup of a correlation peak in the 0.03–0.04 Å−1 range. The hydrothermal treatment likely removed the cell wall matrix component between the microfibrils through autohydrolysis and phase separation, leading to the collapse of microfibrils with each other in the normal wood. In cellulose-rich cell walls, such as the G-layer in tension wood, cellulose microfibrils are already collated in the native state. [ABSTRACT FROM AUTHOR]

The delignification of birch chips during kraft pulping was investigated, targeting both the impregnation and cooking steps. Wood chips were impregnated using white liquor, white liquor + NaCl, water or NaCl aqueous solution. Then, the chips were cooked in batch autoclaves applying the same constant composition cooking conditions for all samples. Pulp and two fractions of black liquor (bulk liquor and centrifuged liquor representing the liquor inside the wood chips and fibers) were collected after different pulping times and analyzed for lignin and carbohydrate content. The dissolved wood components were precipitated from selected samples and characterized with respect to composition, molecular weight distribution and structural motifs. Cooking chemicals in the impregnation liquors led to faster delignification and xylan removal during cooking. Higher contents of lignin and xylan were measured in the lumen than in the bulk. The concentration profiles also showed accumulation of dissolved material in the lumen over time, suggesting significant mass transport limitation from lumen to bulk. Further analysis revealed higher fragmentation/degradation of dissolved material with increasing pulping time and in the bulk when compared to the lumen liquor, as demonstrated by the lower molecular weights and the changes in chemical shifts in the NMR spectra. [ABSTRACT FROM AUTHOR]

Huge amounts of manganese-rich solid residues are yearly produced worldwide by industrial electrolysis, calling for advanced methods of recycling in the context of the circular economy. Here, we review manganese recycling with focus on ore reserves, electrolytic production, residue stockpiling and environmental impact, reducing the amount of residue and improving metal separation, and recycling the residues. Diposal techniques include dry disposal, wet disposal and fire roasting disposal. Residues can be recycled in buildings, functional materials and fertilizers. [ABSTRACT FROM AUTHOR]

This work evaluated the hydrodynamic properties of heparin hydrolysed at temperatures ranging from 40 °C to 80 °C in buffered acid and alkaline environments. The correlation between hydrodynamic parameters led to the conclusion that polymer conformational changes appeared to be minimal until chain depolymerisation, initiated at pH 1 and 80 °C. However, the synergy of conformational changes, even if minimal, and sulphate loss observed at pH 1, pH 3 and pH 12 (various temperatures) resulted in a loss of the antifactor Xa activity. Therefore, the 'contribution' of conformational changes should be added to the generally recognized effect of desulphation towards the activity of heparin. This is of significance as the processing of medical heparin is complex, and requires adjustment of several physical and chemical factors, including pH and temperature. [ABSTRACT FROM AUTHOR]

In this study, partial least square (PLS), a multivariable analysis, was used to simultaneously quantitatively evaluate the effects of variables related to three pretreatments (alkaline, hot water and acid) and the biomass properties of poplar, salix and corncob. The results showed that biomass type was the most important variable influencing enzymolysis reducing sugar yield (ERSY). The biomass compositions affected the ERSY more than the pretreatment conditions, among which hemicellulose and lignin played vital roles. The alkaline pretreatment had a more positive effect on the ERSY than the acid and hot water pretreatments, in which alkaline content had more influence than temperature. This work provides a deeper understanding of the material properties and the pretreatment conditions in different complex systems before enzymolysis, which might be a guidance to future study. [ABSTRACT FROM AUTHOR]

Autohydrolysis is vastly used in industry to extract hemicellulose from lignocellulosic biomass. Despite their potential end-use applications, lignocelluloses cannot be completely extracted from hydrolysate as they may deposit on the equipment during the hydrolysis process. This study tends to investigate the physicochemical properties and adsorption behavior of the components of hydrolysates produced via the autohydrolysis process. In this work, the autohydrolysis of softwood was conducted under different conditions to produce hydrolysates with different lignin and hemicellulose contents. The results provided evidence for the aggregation of lignocelluloses under acidic conditions in hydrolysates. The hydrolysate with a higher concentration of lignin and hemicelluloses (sample 2) had a larger hydrodynamic size (98.5 nm), and the size decreased to 4 nm in the presence of 40 mM KCl. In the salty system, maintaining the hydrolysate unagitated for 4 h increased the hydrodynamic size of the hydrolysate components to 12 nm. Furthermore, the deposition of lignocelluloses on stainless steel surface was studied using Quartz crystal microbalance in hydrogen chloride and acetic acid buffer solutions. The results confirmed that sample 2 possessed a higher affinity for adsorption 3400 × 10−8 kg/m2 than sample 1 did (1290 × 10−8 kg/m2) on the stainless-steel surface. The image analysis indirectly confirmed the formation of agglomerates in hydrolysate and their deposition on the stainless-steel surface. The reversibility of lignocellulose deposition depicts the weak interaction between the dissolved lignocelluloses and stainless-steel surfaces. [ABSTRACT FROM AUTHOR]

Alkaline delignification of wood tissue is the core of the global pulping technology and the most prominent large-scale separation of the main wood components. This work aims at improved understanding of the interplay between the topochemistry of alkaline pulping and the associated morphological changes. Morphology and chemical structure of partially soda-delignified wood chips were studied combining X-ray tomography (XRT), X-ray diffraction analysis and compositional characterization (lignin and carbohydrate content). The XRT studies of wet samples (providing 3D structural information without interfering drying effects), allowed observation of the cell wall separation as an increasing amount of lignin was removed with the increasing pulping time. Comparison between the microstructure of the surface and the central parts of the treated chips showed a more delignified microstructure at the surface, which highlights the dependence of the delignification process on the mass transport (hydroxide ions and lignin fragments) through the wood tissue. The crystallite size of cellulose increased in the <200> crystal planes during the early stage of pulping while there was little effect on the <110> plane. [ABSTRACT FROM AUTHOR]

Autohydrolysis-based pretreatments enable extraction of hemicellulose from wood tissue prior to the paper pulp cooking processes enabling their further use as platform chemicals and in material applications. In this study, hot water extraction of birch meal was conducted in a small flow-through system. The combination of high surface area of the milled material with increased driving force induced by constant flow of freshwater, together with fast evacuation of extract, enabled a detailed study of the dissolution process. Based on the findings, deeper insight into acidification and autohydrolysis progress was obtained. [ABSTRACT FROM AUTHOR]

Background: Sixty five percent of procyanidins in grape seeds is polymeric procyanidins (PPC), and they could not be assimilated directly by human. To enhance procyanidin assimilation, steam explosion treatment (SE) was used to facilitate the preparation of oligomeric procyanidins (OPC) from grape seeds. Results: The results indicate that SE treatment made grape seeds loose and porous, and decreased the mean degree of polymerization (mDP) of procyanidins. The procyanidins content and total phenolic content (TPC) were decreased with the increase of SE severity, while the amount of catechin (CA), epicatechin (EC) and epicatechin-3-O-gallate (ECG) were increased, resulting in significant increase of antioxidant activity. Conclusions: Although SE treatment could depolymerize PPC and produce CA/EC/ECG with high yield, it caused the yield loss of total procyanidins. SE treatment is a potential effective method to prepare procyanidins with low degree of polymerization and high antioxidant activity. However, it still needs to study further how to balance the yield of total procyanidins and catechin monomers (CA/EC/ECG). [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Biorefinery processes utilize carbohydrates from biomass in order to produce biochemical and biomaterials. Lignin as the byproduct after biorefinery needs to be studied for applications. This study evaluated how hot water pretreatment, a typical biorefinery process, will impact on the heavy metal adsorption capacity of lignin. RESULTS: Paulownia elongata acid insoluble lignin was tested for its heavy metal adsorption capacities for Pb(II), Cu(II) and Cd(II). Hot water pretreatment was conducted on the lignin with both water and dilute acetic acid solution. Samples with both increased and decreased adsorption capacity were observed after the pretreatment, while samples with long duration of pretreatment encountered a substantial loss in the adsorption ability. Depolymerization and condensation lignin reaction schemes under acidic environment were summarized and applied to explain the capacity changes. NMR analysis was performed to quantify the functional groups in the lignin samples. Changes in the amount of functional groups were found in the samples after pretreatment. CONCLUSION: Hot water pretreatment can either increase or decrease the adsorption capacity of lignin depending on the treatment duration. Lignin byproducts after treatment under acidic and high temperature environments with long duration is no longer suggested for use as a heavy metal adsorbent. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background: Lignocellulose biomass is known as a recalcitrant material towards enzymatic hydrolysis, increasing the process cost in biorefinery. In nature, filamentous fungi naturally degrade lignocellulose, using an arsenal of hydrolytic and oxidative enzymes. Assessment of enzyme hydrolysis efficiency generally relies on the yield of glucose for a given biomass. To better understand the markers governing recalcitrance to enzymatic degradation, there is a need to enlarge the set of parameters followed during deconstruction. Results: Industrially-pretreated biomass feedstocks from wheat straw, miscanthus and poplar were sequentially hydrolysed following two steps. First, standard secretome from Trichoderma reesei was used to maximize cellulose hydrolysis, producing three recalcitrant lignin-enriched solid substrates. Then fungal secretomes from three basidiomycete saprotrophs (Laetisaria arvalis, Artolenzites elegans and Trametes ljubarskyi) displaying various hydrolytic and oxidative enzymatic profiles were applied to these recalcitrant substrates, and compared to the T. reesei secretome. As a result, most of the glucose was released after the first hydrolysis step. After the second hydrolysis step, half of the remaining glucose amount was released. Overall, glucose yield after the two sequential hydrolyses was more dependent on the biomass source than on the fungal secretomes enzymatic profile. Solid residues obtained after the two hydrolysis steps were characterized using complementary methodologies. Correlation analysis of several physico-chemical parameters showed that released glucose yield was negatively correlated with lignin content and cellulose crystallinity while positively correlated with xylose content and water sorption. Water sorption appears as a pivotal marker of the recalcitrance as it reflects chemical and structural properties of lignocellulosic biomass. Conclusions: Fungal secretomes applied to highly recalcitrant biomass samples can further extend the release of the remaining glucose. The glucose yield can be correlated to chemical and physical markers, which appear to be independent from the biomass type and secretome. Overall, correlations between these markers reveal how nano-scale properties (polymer content and organization) influence macro-scale properties (particle size and water sorption). Further systematic assessment of these markers during enzymatic degradation will foster the development of novel cocktails to unlock the degradation of lignocellulose biomass. [ABSTRACT FROM AUTHOR]