Solid Residue Research Articles

Torrefaction Temperature Effects on Grindability of Wheat Straw Using TG-FTIR Analysis

Abstract Torrefaction used for pretreatment of biomass can enhance grindability along with significant reduction of energy consumption required for pulverization to aid in large-scale utilization of biomass energy. In this study, torrefaction experiments of wheat straw were conducted at different temperatures using an experimental furnace facility. The influence of torrefaction temperature on the grindability of resulting wheat straw was explored using a Hardgrove grindability index tester and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR). Increase in torrefaction temperature significantly enhanced the carbon content of wheat straw and decreased oxygen content to result in decreased O/C ratio from 0.66 to 0.39. The calorific value increased by 24% from 15.42 MJ/kg to 19.17 MJ/kg. Increase in torrefaction temperature from 220 °C to 269 °C increased the grindability index from 29 to 115. The grindability of wheat straw can be controlled to values similar to that of coal by tuning the torrefaction temperature. The main gas components released during torrefaction were H2O, CH4, CO2, and CO. Thermogravimetric data showed 29% solid residue from the raw wheat straw. Increase in torrefaction temperature increased the solid residue to 41%. Pyrolysis of wheat straw at different torrefaction temperatures can be grouped into three stages of dehydration, rapid pyrolysis, and carbonization. This study reveals effective large-scale utilization of torrefied wheat straw biomass having high heating value of the solid fuel after torrefaction pretreatment.

Evaluating the utilization of municipal solid waste incineration ash in enhancing ceramsite aerated concrete blocks

In an effort to forge a new pathway for the resourceful utilization of municipal solid waste (MSW) incineration ash, thereby transforming waste into treasure and detriment into benefit, this study investigates the impact of incineration ash on the fundamental properties of expanded clay aggregate aerated concrete blocks. Granular ash and powdered ash were separated from MSW incineration ash. These were then used as replacements for pottery sand and fly ash, respectively, in the production of ceramsite aerated concrete blocks. Replacement ratios were set at 0 %, 10 %, 20 %, 30 %, 40 %, and 50 % of the dry mass proportion. An experimental study was conducted on the product performance indicators of grade CA50.B07 ceramsite aerated concrete blocks at 28 days, including dry density, compressive strength, and thermal conductivity. Furthermore, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were employed to analyze the micro-material composition and pore structure. The results show that when the replacement rate of granular ash to sand is 20 %, and the replacement rate of powdered ash to fly ash is 10 %, the produced aerated concrete blocks exhibit optimal technical performance while meeting product quality standards. This successfully demonstrates the resource utilization potential of municipal solid waste incineration residues.

Microwave assisted treatment of carpentry waste wood flour with natural deep eutectic solvents for nanocellulose production and removal of organic pollutants.

Row carpentry waste wood flour, constituted of poplar (∼60%) and fir (∼30%) biomass, was subjected for the first time to microwave-assisted deep eutectic solvent (DES) treatment, with the purposes of solubilizing lignin and hemicellulose, leaving cellulose as solid residue, thus performing a biorefinery. Several acidic (choline chloride/oxalic acid; choline chloride/citric acid; betaine hydrochloride/oxalic acid) and alkaline (urea/choline chloride; glycerol/K2CO3) DESs were employed under the same reaction conditions. Since the highest extraction yield was obtained by using choline chloride/oxalic acid DES, the use of the latter was investigated by varying some parameters (temperature, manner of microwave irradiation, addition of water) aiming at increasing the solubilization yield, which in fact in some cases reached satisfying values (60%) under mild conditions. The solid residues (SRs) recovered after all treatments with all tested DESs were characterized by Thermogravimetric Analysis (TGA), Attenuated Total Reflectance-Fourier Tranform Infrared Spectroscopy, Solid-State NMR Spectroscopy, and titration of surface acid groups. All SRs were also ultrasonicated to produce cellulose nanoparticles which were in turn characterised by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. In addition, the solid residues recovered from acidic DESs were able to decontaminate water from organic pollutants, such as p-nitrophenol, by an adsorption process. Thus, the proposed DES treatment efficiently converted carpentry waste wood flour into a valuable biomaterial useful for environmental decontamination.

Turning Waste into Treasure: Utilizing Environment-Pollutant Graphite Tailings as Photocatalyst for Photocatalytic Building Materials

Graphite tailings, as solid waste residuals from graphite extraction and refinement, pose serious risks to the surrounding ecological environment and the safety of residents’ lives. However, it is desirable but challenging how to rationalize the utilization of graphite tailings and further to develop their functionality. Herein, we demonstrate a "turning waste into treasure" strategy: capitalizing on the characteristics of graphite tailings in visible light absorption and rich metal catalytic sites, graphite tailings are employed as photocatalysts and fine aggregates to manufacture photocatalytic building materials, achieving sustainable use. Tailings powder from Luobei, Heilongjiang Province is selected as the photocatalyst, we discover that it exhibits photocatalytic degradation capability for methylene blue (MB) in water under visible-light irradiation: the degradation rates reach 70% within one hour and near-complete degradation within two hours, accompanying good recyclability. Structural analysis reveals that the graphite tailings are enriched with Fe2O3 and TiO2. They are capable of forming type-II heterojunction that enable efficient charge separation and transfer processes, transmitting photogenerated electrons to the active catalytic site to accomplish the photocatalytic degradation of MB. Moreover, other tailings, such as those from Jixi, also achieve photocatalytic degradation of MB, and cement specimens made with graphite tailings also bespoke photocatalytic degradation performance. This work is to provide solutions for the reuse of graphite tailings in the field of functional building materials, and to explore the feasibility of transforming graphite tailings from industrial solid waste to photocatalytic building materials.

Exploring pyrolysis-based alternatives for the valorization of used diapers through a comprehensive understanding of all generated products

This study provides an in-depth evaluation of a pyrolysis process designed for the valorization of baby diaper waste from the rejected fraction of municipal solid waste treatment facilities. The diapers were separated, identified, and classified into distinct fractions/layers, each subjected to Thermogravimetric Analysis to determine the optimal temperature range for operation. This study identified that hydrogen and methane production is maximized at 575 °C. At this temperature, yields reach up to 7.4 mmol of hydrogen and 6.3 mmol of methane, with a total of 23 mmol of non-condensable gases per gram of diaper waste. The temperature of 525 °C optimized the production of lighter liquid fractions. This temperature yielded compounds with boiling points similar to heavy naphtha and comprised over 63 % of the liquid products. The solid residue resulting from pyrolysis was a partially amorphous carbonaceous material, with a maximum surface area of 9.7 m2/g achieved at 575 °C, which is considered low. The analysis is completed with a study of the degradation of the used diapers by TGA/MS-FTIR and the determination of the effective activation energy as a function of conversion. This study highlights the significant potential of pyrolysis technology for treating diaper waste, which generates several potentially usable or valuable products, including hydrogen, methane, light liquid compounds, and carbonaceous material.

Highly sensitive ultra-high-performance liquid chromatography coupled with tandem mass spectrometry method for the multiplex analysis of levosimendan and its metabolites OR-1855 and OR-1896 in human plasma

Levosimendan is a positive inotrope and vasodilator used in patients with acute and chronic decompensated heart failure. It is metabolized into OR-1855 (inactive metabolite), which is further acetylated into OR-1896 (active metabolite having a prolonged half-life, hence a sustained effect). Levosimendan represents a valuable alternative to traditional inotropes with broad clinical applications in critically ill patients with cardiogenic shock, advanced heart failure and post-cardiac surgery. However, while levosimendan demonstrates dose-dependent hemodynamic effects, its pharmacokinetics has not yet been investigated in adult critically ill patients, a vulnerable population characterized by complex and unstable conditions that may significantly alter drug disposition. Therefore, pharmacokinetics studies of levosimendan and metabolites in critically ill patients require a reliable and sensitive quantification method.We developed and validated a highly sensitive method using ultra-high-performance liquid-chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) for the quantification of levosimendan, OR-1855 and OR-1896 in human plasma. To achieve the required analytical sensitivity, plasma sample preparation included protein precipitation with acetonitrile, subsequent supernatant’s evaporation to dryness under nitrogen, and reconstitution of the solid residues with a solution of H2O:MeOH 4:1, followed by a 40 µL-aliquot injection into the LC column. Chromatographic separation of the three analytes was achieved in a 6-minute run in gradient mode, using an Acquity UPLC BEH C18 1.7µm, 2.1 ×150mm column. The method was extensively validated according to international bioanalytical assay guidelines, on a clinically relevant concentration range of 0.1 to 100ng/mL, for each analyte. Considering these very low concentrations, the assay showed excellent performances in terms of trueness (94.3-105.3%), repeatability (1.9-7.2%) and intermediate fidelity (2.3-9.7%).Of note, during our ex vivo studies on whole blood samples stability, acetylation of the metabolite OR-1855 into the active OR-1896 metabolite was observed in the presence of red blood cells.The UHPLC method is being applied for a prospective observational pharmacokinetics study of levosimendan in patients undergoing extracorporeal membrane oxygenation support. The benefit of levosimendan therapeutic drug monitoring in intensive care patients remains to be assessed.

Potencial de risco de incêndio das embalagens cartonadas como material de isolamento térmico

Abstract Long-life packaging is being used informally as an alternative to improve thermal insulation in single-family wooden houses. Its usage is backed by environmental concerns to reuse these solid residues as a radiant barrier for heat transmission. However, some published studies have only analyzed its thermal insulation efficiency, without considering the material performance in fire situations. Given this scenario, the objective of this research is to present the analysis and classification to a fire reaction of long-life packaging. In addition to the non-combustibility test, ignitability, radiant wall panel, optical smoke density and single burn item (SBI) tests were carried out. The results showed that the material is combustible and is classified as fire reaction class VI, according to the criteria for special materials. Thus, on the findings of this study, it can be concluded that long-life packaging should not be used as a lining for the internal surfaces of buildings.

Reductive Depolymerization of Lignin to Aromatic Compounds over Promoted Nickel Catalysts in Sub‐ and Supercritical Methanol

The use of γ‐Al2O3‐supported Ni catalysts promoted with either Cu or Fe was investigated for the reductive catalytic fractionation (RCF) of hybrid poplar in methanol at 200 and 250 °C. The effectiveness of lignin depolymerization was quantified in terms of the lignin oil production, the quantity and distribution of identifiable monomers present in the lignin oil, and the yield of residual solids. All of the Ni‐based catalysts tested provided improved yields of lignin oil and monomers, along with reduced char formation, relative to blank (sans catalyst) runs. The highest monomer yield of 51% was obtained at 250 °C over a 20 wt.% Ni‐5 wt.% Cu/Al2O3 catalyst, the improved performance obtained through Cu promotion being attributed to the ability of Cu to facilitate NiO reduction, resulting in an increased amount of Ni0 on the catalyst surface and, consequently, improved hydrogenation activity. The main monomers formed were propanol‐, propyl‐ and propenyl‐substituted guaiacol and syringol, the S/G ratio of the products corresponding closely to that in the native lignin.

Selective Leaching for the Recycling of Lithium, Iron, and Phosphorous from Lithium-Ion Battery Cathodes’ Production Scraps

The market for lithium iron phosphate (LFP) batteries is projected to grow in the near future. However, recycling methods targeting LFP batteries, especially production scraps, are still underdeveloped. This study investigated the extraction of iron phosphate and lithium from LFP production scraps using selective leaching, considering technical and economic aspects. Two leaching agents, sulfuric acid (0.25–0.5 M, 25 °C, 1 h, 50 g/L) and citric acid (0.25–0.5 M, 25 °C, 1 h, 70 g/L) were compared; hydrogen peroxide (3–6%vv.) was added to prevent iron and phosphorous solubilization. Sulfuric acid leached up to 98% of Li and recovered up to 98% of Fe and P in the solid residues. Citric acid leached 18–26% of Li and recovered 98% of Fe and P. Totally, 28% of Li was precipitated for sulfuric acid process, while recovery with citric acid did not produce enough precipitate for a characterization. Sulfur is the main impurity present in the precipitates. The total operative costs associated with reagents and energy consumption of the sulfuric acid route were below 3.00 €/kg. In conclusion, selective leaching provided a viable and economic method to recycle LFP production scraps, and it is worth further research to optimize Lithium recovery.

Atmospheric air pollution from the Ermakovskoe fluorite-beryllium deposit development waste

Relevance. Negative impact of waste from mining enterprises on the ecological state of the surrounding areas. Aim. To determine the migration ability of toxic chemical elements from waste storage sites of the Ermakovskoe beryllium deposit in the air. Object. Ermakovskoe fluorite-bertrandite-phenacite deposit and the surrounding area. Methods. Inductively coupled plasma mass spectrometry, laser diffraction, inductively coupled plasma atomic emission spectrometry. Results and conclusions. The paper introduces the experimental studies of surface atmospheric pollution by mining waste from the Ermakovskoe fluorite-bertrandite-phenakite deposit are presented using an installation for collecting aerosols above the sand surface. It was established that toxic components formed during the decomposition of residual sulfide mineralization and products of the interaction of acidic waters with rocks move from the sand thickness to the surface along with water vapor. The moisture condensed over the sand contains high contents of aluminum, iron, manganese, zinc, and phosphorus. These elements form a halo of air pollution over mining waste and are then dispersed by air currents into the surrounding area. In winter, due to wind dispersion of aerosols, the snow cover becomes contaminated over a vast area. Among the toxic elements found were beryllium, lead, cadmium, and molybdenum, which belong to the second hazard class. The solid residue of the snow cover contains a fine fraction of dust, the size of which is less than 10 microns. The halo of snow contamination with toxic chemical elements and dust extends several kilometers away from the disturbed lands.

The behaviour of scandium during crustal anatexis: Implications for the petrogenesis of Sc-enriched granitic magma

Scandium (Sc) is a compatible element in mafic silicate minerals, in particular amphibole, garnet and clinopyroxene, and is enriched in ultramafic rocks. Nevertheless, its concentration is also sufficiently high in some evolved granites and granite pegmatites to form minerals with essential Sc. In some granitic occurrences, Sc-bearing minerals occur in miarolitic cavities, indicating the importance of late- to post-magmatic fluids. In contrast, some granite pegmatites have thortveitite (Sc2Si2O7) and other Sc-rich minerals, including Sc-enriched garnet as part of evolved magmatic mineral assemblages. The maximum Sc concentration in garnet in thortveitite-bearing, Mesoproterozoic granite pegmatites of probable anatectic origin in South Norway is ca. 2000 ppm, corresponding to ca. 100 ppm in a coexisting silicate melt. As for any trace element, the behaviour of Sc during crustal anatexis is controlled by the amount of melt formed and the mineralogy of the solid residue. The melting process can be modelled from thermodynamical data on solids and melts for given protolith compositions, temperature and pressure. Simulations in a range of mafic/ultramafic to felsic systems show that mafic protoliths will form Sc-depleted anatectic melts, and correspondingly Sc-enriched solid residues under relevant pressure and temperature conditions (2-10 kbar, 700-800 °C). Limited enrichment in melt relative to protolith is only seen in granodioritic-tonalitic bulk compositions, reaching maximum concentrations of 30–60 ppm. The effect of fluorine during melting and subsequent fractionation is to lower the solidus temperature, depolymerise the silicate melt, and lower partition coefficients for Sc between mafic silicate minerals and felsic melt. Contamination with mafic material has only limited effect, as it will eventually sequester Sc into hybrid mafic silicate mineral assemblages and lead to reduction of the Sc concentration of the remaining melt fraction. Further increase of the Sc concentration requires fractional crystallisation of minerals with low KD, i.e. mainly feldspar minerals and quartz, which may be facilitated by selective, local contamination by quartz and feldspar from granitic country rocks.

Tuning the performances of smoke-light signaling agents by Zn-Mg alloys

In this study, the thermal behavior, combustion behavior, and smoke/light signal effects of smoke-light signaling agents were regulated using Zn-Mg alloys with different Mg contents (10 wt%, 20 wt%, 30 wt%, 50 wt%, 70 wt%) and particle sizes (100–200 mesh, 200–325 mesh, >325 mesh) under an oxygen balance of −20. The Zn-Mg alloy’s morphology and phase composition were characterized using SEM/EDS and XRD. The thermal performance was analyzed with TG/DSC, while the combustion process was recorded using high-speed camera and infrared thermal imaging. The visible light spectrophotometer and smoke chamber experiment tested the smoke and light effects. The results showed that increasing Mg content raised the combustion temperature to over 1400 °C, enhanced luminous intensity to over 5000 cd, reduced solid residue to under 6 %, and shortened combustion time from 7.9 s to 2.24 s. Smaller particle sizes also improved these effects. Alloys with higher Zn content produced denser smoke but had higher solid residue. This study demonstrates the potential for precise control over combustion and smoke-light effects by adjusting alloy composition and particle size, making Zn-Mg alloys promising candidates for future pyrotechnic formulations.

Anaerobic membrane bioreactor (AnMBR) with external ultrafiltration membrane for the treatment of sugar beet vinasse.

Vinasse, a by-product of ethanol production, is generated at significant rates. While rich in nutrients such as calcium, magnesium, and potassium, its high solids, organic matter, acidity, and sulfate content pose challenges when disposed directly on soil, necessitating treatment. Anaerobic digestion is a viable solution, reducing organic pollution while recovering energy in the form of biogas, aligning with the biorefinery concept. Traditionally, sludge bed reactors and anaerobic contact reactors are utilized for vinasse processing, with sludge granulation being vital for treatment success. However, challenges such as sludge wash-out due to recalcitrant compounds, high solids concentration in the influent, low pH, salinity, and temperature hinder granule formation. Anaerobic membrane bioreactors (AnMBR) offer an alternative, simplifying treatment by integrating intensified pre- and post-treatment units. Due to complete sludge retention, AnMBRs achieve high COD removal efficiencies, yielding a suspended solids-free and largely disinfected effluent. Therefore, AnMBRs show promise for vinasse treatment, eliminating the need for sludge granulation and producing nutrient-rich effluent with minimal residual organics and suspended solids. In this study, an AnMBR equipped with an inside-out external crossflow ultrafiltration membrane was proposed for the treatment of vinasse. The AnMBR reached a COD removal efficiency of 95% ± 2.6% and produced 0.3 CH4 L.g COD removed -1 working at organic loading rates of 8g COD. L-1 d-1 and membrane fluxes of 10 LMH. At organic loading rates of 10g COD. L-1 d-1 and fluxes of 12 and 14 LMH, the COD removal efficiency decreased to 77% ± 11% and 73% ± 7.9%, respectively. The AnMBR technology represents an innovation for wastewater treatment, however, more research using the cross-flow configuration and different types of effluents is needed. Literature studies that address the treatment of sugar beet or sugarcane vinasse using AnMBR are still scarce. This study explored the potentials of AnMBR technology for vinasse treatment and contributes to the dissemination of this technology, opening new possibilities for vinasse processing.

Salinization and salt expansion mechanism of soda residue soil at subgrade

The solid waste soda residue (SR) exhibits a high content of soluble salts, and the liquid phase soluble salts in soda residue soil (SRS) undergo phase transition crystallization during cooling process, leading to subgrade salt expansion and deformation damage. In order to explore the salt mechanisms of SRS, this paper systematically analyzes the impact of SR content on the salinization and salt expansion characteristics of SRS using soluble salt tests and salt expansion experiments. Combined with X-ray diffractometry (XRD) and low-temperature frost shrink tests, the study analyzed the salt expansion process of SRS. The results indicate that under different SR content, SRS is classified as chloride saline soil. The SRS is categorized into weak saline soil, moderate saline soil, strong saline soil, and over-saline soil with different soda residue dosage. During cooling from 20°C to −25°C, all SRS groups exhibit initial salt expansion followed by frost shrink deformation characteristics. As the SR content increases within the 0 % – 40 % range, the temperature range for severe salt expansion gradually decreases from 5°C to −15°C. At 25 % SR content, SRS exhibits the most severe salt expansion, while excessively high SR content inhibits the crystallization of sulfate salt phase transitions. The study identifies three stages in the salt expansion process of SRS: promotion stage, severe stage, and inhibition stage. The research findings provide valuable insights for the prevention of salt expansion in SRS and the widespread utilization of SR in road applications.

Oncom: A Nutritive Functional Fermented Food Made from Food Process Solid Residue

Food security is one of the critical issues in facing the world food crisis. Utilizing food processing residue waste to make nutritious and healthy functional foods should follow a double-merit approach in facing the world food crisis. Oncom, an overlooked traditional fermented product based on local wisdom, might be an example of potential sustainable food to overcome hunger and support the circular economy programme. This review attempts to portray the existence and role of oncom based on a systematic study of hundreds of reports from different angles, mainly focusing on its processing, the microbes involved, its sensory characteristics, nutritional benefits, and promising bioactivities. Oncom can be produced by various raw materials such as tofu dreg (okara), peanut press cake, and tapioca solid waste, involving various microbes, mainly Neurospora sp. or Rhizopus sp., and various processing steps. The products show promising nutritional values. In terms of sensory characteristics, oncom is sensory-friendly due to its umami dominance. Many bioactivity capacities have been reported, including antioxidants, lowering cholesterol effect, and cardiovascular disease prevention, although some findings are still only preliminary. Undoubtedly, oncom has the potential to be developed as a future functional food with standardized quality and reliable bioefficacy. This kind of solid fermented product, based on agricultural residue wastes, is worthy of further development worldwide with full scientific support to create more reliable functional foods with a modern touch to achieve zero hunger.

Gravimetric Characterization of Solid Waste in the Dump of the Municipality of Coari - Amazonas, Brazil

Objective: To estimate the gravimetric characterization of solid waste in the waste dump in the municipality of Coari, located in the state of Amazonas, in the region of the Middle Solimões, Brazil, and to evaluate the implications for sustainable management and management. Theoretical Reference: The main public policy bases related to solid waste treatment, from generation to final destination, were contextualized, as well as the scenarios regarding gravimetric composition, as well as the references to support a resolving horizon for materials of a recyclable nature. Method: This study addresses quantitative and qualitative analysis of the collected samples of solid waste destined to the landfill of the municipality of Coari - Amazonas, in accordance with the steps required by NBR 10.007/2004 and tabulation in Microsoft Excel. Results and conclusion: The results indicate that the majority is composed of organic material, followed by plastics and paper/cardboard, among other smaller fractions: glass, metals, wood, pointing to the need for the implementation of urgent recycling and composting practices, even if the municipality does not have an environmentally adequate destination. Implications of the research: In Brazil, even with the public policies already implanted, the great majority of the municipalities have not yet propitiated the extinction of their garbage dumps or have some irregular form as to the final destination of their solid residues. The gravimetric composition is one of the important tools for analyzing the composition of materials taken to the final destination, which is absent in many municipalities. Originality/value: Knowledge of the composition of the fractions of the solid waste generated is fundamental for guiding strategic actions and planning related to management and management, aligned with public policies that direct the practices of utilization from the generating source to the final destination, in order to avoid expansion or mitigate environmental impacts.

Valorization of White Lupin Straw Through Mild Dilute Acid Hydrothermal Treatment: A Sustainable Route for Monosaccharide and 5-Hydroxymethylfurfural Production

This study investigates the potential use of white lupine straw (WLS), an underutilized agricultural by-product, as a raw material to produce valuable biochemicals such as monosaccharides and 5-hydroxymethylfurfural (5-HMF) through hydrothermal pretreatment. The aim was to optimize mild reaction conditions to maximize the recovery of these products while minimizing degradation. The hydrothermal treatment of WLS in subcritical water with trace amounts of sulfuric acid was performed, followed by a two-step approach to evaluate the yields of hemicellulose and 5-HMF. The highest monosaccharide yield (163 g/kg) was achieved at temperatures between 174 and 181 °C and a holding time of 7–14 min, while the 5-HMF production was 139.9 g/kg at 199–203 °C and after 0.5–4.5 min. These results suggest that optimal 5-HMF production also increases the remaining solid residue. This study highlights the feasibility of WLS as a sustainable, low-cost biomass resource. It highlights the balance between temperature and time to maximize valuable product yields. The results contribute to advancing biorefinery processes by demonstrating that WLS can be effectively converted into bioethanol precursors and industrial chemicals, supporting circular bioeconomy principles and providing an environmentally friendly alternative to burning crop residues.

Comparison of biocrude production and characterization from Persian Gulf Sargassum angustifolium macroalgae, Chlorella vulgaris, and Spirulina sp. microalgae using hydrothermal liquefaction (HTL): Potential of solid residue for heavy metal adsorption.

Biocrude production using the hydrothermal liquefaction (HTL) process is a promising alternative energy source to conventional fossil fuels. Using algal feedstock types in this process has many advantages, such as not needing to dry a high moisture content, which consumes much energy. In this study, the feedstock types of Sargassum angustifolium macroalgae, Chlorella vulgaris, and Spirulina sp. microalgae affected the yield and property of the biocrude products were obtained at 350 °C, 18 MPa, 35 min residence time, and 8.7 wt% feedstock concentration. The biocrude yields from Sargassum angustifolium, Chlorella vulgaris, and Spirulina sp. were 26.15 wt%, 55.8 wt%, and 56.32 wt%, respectively. These values revealed that feedstock's carbon and nitrogen contents have the most effect on the biocrude yield, and increasing these elements increases the biocrude yields. Moreover, the properties of the produced biocrudes revealed that the main components were esters, organic acids, ketones, aldehydes, aromatic rings, amides, amines, alcohol, and phenol. The thermal gravimetric analysis (TGA) results of biocrudes showed the decomposition of more organic components at the 175-600 °C temperature range. Also, the simulated distillation of biocrudes showed that most biocrude components from Sargassum angustifolium and Chlorella vulgaris are the same as heavy naphtha, and the biocrude from Spirulina sp. is similar to kerosene. These results showed that the produced biocrude from Chlorella vulgaris has a higher yield and quality than other resources. The quality of the biocrude produced from Sargassum angustifolium is comparable to other biocrudes. Besides, the higher solid-phase yield produced from Sargassum angustifolium was used as a heavy metal biosorbent. The effect of adsorbent concentration and adsorption time on adsorption efficiency was investigated. Results showed that the maximum adsorption efficiency of Fe2+, Zn2+, and Mn2+ was 47.07 wt%, 48.93 wt%, and 42.47 wt%, respectively, at 2 g/L adsorbent concentration and 60 min adsorption time, and the structure destruction of the solid phase was carried out under the biosorption process.

Inhibition of Polycyclic Aromatic Hydrocarbons Formation During Supercritical Water Gasification of Sewage Sludge by H2O2 Combined with Catalyst

This work evaluated the alterations in the levels and types of polycyclic aromatic hydrocarbons (PAHs) within both liquid and solid products throughout the process of the catalytic supercritical water gasification of dewatered sewage sludge to examine the catalytic effect of various catalysts and the inhibit reaction pathways. The addition of Ni, NaOH, Na2CO3, H2O2, and KMnO4 reduced the concentrations of PAHs, with Ni and H2O2 showing the best performance. The concentrations of PAHs, especially higher-molecular-weight compounds in the residues, decreased sharply as the H2O2 amount increased. At a 10 wt% H2O2 addition, the levels of PAHs in the liquid and solid products were reduced by 91% and 88%, respectively. High-ring PAHs were not detected in the residues as the H2O2 amount increased to an 8 wt%. H2O2 addition evidently inhibits PAH formation by promoting the ring-opening reactions of initial aromatic compounds in raw sludge and inhibiting the polymerization of open-chain intermediate products. The addition of NaOH + H2O2 or Ni + H2O2 as combined catalysts significantly lowered PAH concentrations while increasing the H2 yield. The addition of 5 wt% Ni + H2O2 reduced PAH concentrations in the liquid and solid residues by 70% and 44%, respectively, while the H2 yield escalated from 0.13 mol/kg OM to 3.88 mol/kg OM. Possible mechanisms associated with the reaction pathways of these combined catalysts are proposed.

Recycling Li-Ion Batteries via the Re-Synthesis Route: Improving the Process Sustainability by Using Lithium Iron Phosphate (LFP) Scraps as Reducing Agents in the Leaching Operation

The development of hydrometallurgical recycling processes for lithium-ion batteries is challenged by the heterogeneity of the electrode powders recovered from end-of-life batteries via physical methods. These electrode materials, known as black mass, vary in composition, containing differing amounts of nickel, manganese, and cobalt (NMC), as well as other chemicals, such as lithium iron phosphate (LFP). This study presents the results of the hydrometallurgical treatment of mixed NMC and LFP black masses aimed at creating flexible recycling processes. This approach leverages the reducing power of LFP to optimize the leach liquor composition for re-synthesizing NMC precursors. In particular, the leaching conditions were optimized based on the LFP content in the solid feed to maximize the extraction of key metals (Ni, Mn, Co, and Li). The leaching solid residue, graphite, was treated and characterized as a secondary raw material for new anode preparation. Iron phosphate was recovered by increasing the pH of the leach liquor, and the NMC precursors were obtained via coprecipitation. This process achieved a recycling rate of 51%, based on the black mass input and the mass of recovered elements in the output products. Additionally, substituting LFP scraps as the reducing agent in place of H2O2 reduced the recycling process’s environmental impact by avoiding 1.7 tons of CO2-equivalent emissions per ton of NMC black mass.