Search Results (646)

The rapidly growing concern over the hazardous impact of phthalates on the environment and public health has led to a critical need for alternative and environmentally friendly plastics. Plasticizers developed from natural materials represent one possible solution. This paper explores four types of renewable feedstocks (sorbitol/polyols, glycerin, cardanol from cashew nutshell liquid, and limonene from citrus peels) as sources for developing alternative plasticizer systems. Key areas explored include the type of feedstock utilized, the methods used for extracting or processing the feedstocks, the nature of the chemical modification processes (e.g., esterification, epoxidation, etherification, or reactive grafting) applied to generate the respective plasticizers, and the resultant physical and mechanical properties. The performance of each plasticizer system in polymers such as PVC, PLA, and polysaccharide-based bioplastics is evaluated, alongside the compatibility with biological tissues, toxicological properties, biodegradability, and chemical migration into food simulants. The feasibility of each family of plasticizers is also assessed from an economic perspective, including availability of the feedstocks, economies of scale associated with large-volume production, and competitive pricing relative to established petroleum-derived plasticizers. Overall, sorbitol/polyol and glycerin derivative families have reached a level of maturity that provides a good balance of processability, food-contact safety, and biodegradability. Cardanol-based systems provide an attractive option where aromatic functional groups and combined plasticization–stabilization effects are needed. Limonene-derived plasticizer systems appear promising for use in PLA, but their broader utility may be limited by volatility, strong odors, and susceptibility to oxidation. Common issues identified across all four families include chemical migration into food products, regulatory approval, and the need for detailed life-cycle assessments. Full article

The rational design of supported Lewis acid catalysts is frequently impeded by an incomplete understanding of how the support’s synthetic history governs its intrinsic acidity and catalytic efficacy. Herein, we elucidate the structure–property–performance relationship linking the aging dynamics of a boehmite precursor to the activity of the resultant chlorinated alumina (Al₂O₃–Cl) catalyst in n-butane isomerization. Using n-butane as the probe feedstock, we investigated how alumina supports with distinct physicochemical properties regulate the performance of Al₂O₃–Cl catalysts for n-butane isomerization. By systematically adjusting the aging parameters (stirring rate, temperature, and time), we reveal that the structural evolution of the alumina support transitions from initial particle aggregation to Ostwald ripening and surface reconstruction. A decisive structure–performance correlation is identified: precursor synthesis conditions govern both the population and accessibility of specific surface hydroxyls (notably Type II terminal OH groups), which act as anchoring sites for the generation of active Lewis acid centers upon chlorination. Optimal aging parameters (300 rpm, 90 °C, 6 h) promote the formation of a hierarchical pore architecture with a maximized density of accessible hydroxyls, thereby affording enhanced Lewis acidity and superior isomerization activity. This work provides a fundamental framework for tailoring solid acid catalysts by precisely engineering the precursor architecture. Full article

Indonesia, particularly Central Java, generates substantial amounts of agricultural biomass residues, including melinjo shells, tobacco stalks, and cacao shells, which remain underutilized for energy applications. This study addresses the limited scientific evidence on the fuel properties and environmental performance of these residues by systematically evaluating their suitability as briquette feedstocks. A factorial experimental design was applied using three biomass types and two binders (tapioca starch and clay). The produced briquettes were characterized for moisture content, ash content, volatile matter, and higher heating value according to the Indonesian National Standard (SNI 01-6235-2000), and their environmental performance was assessed using a Life Cycle Assessment (LCA) approach to estimate associated environmental costs. The results indicate that briquettes made from melinjo shells with tapioca starch binder exhibited the most favorable performance, achieving a moisture content of 7.01%, ash content of 13.58%, volatile matter of 47.15%, and a calorific value of 5453.43 cal g⁻¹. However, the ash and volatile matter contents exceeded the recommended limits for solid biofuels. These findings demonstrate that melinjo shells are a promising feedstock for briquette production due to their relatively high energy content, while further improvements in carbonization conditions and reductions in binder proportion are required to enhance fuel quality and environmental performance. Full article

Accelerated industrial development demands the search for efficient remediation technologies. Microbial fuel cells (MFCs) have the capacity to remediate organic matter-rich effluent by utilizing bacteria as biocatalysts capable of oxidizing organic material while simultaneously producing electricity. In this paper, a novel electrode is prepared through the carbonization of a tailored photopolymer with iron nanoparticles and carbon black (C-iNPCB) and its performance tested as an anode using dual chamber MFCs for the remediation of paper recycling plant effluent. Its efficiency is compared to a graphite rod (GR) and a carbon black-coated 3D-printed structure (3D-CB). The paper effluent containing chemical oxygen demand 5.0 g/L was used as feedstock in the MFCs. The GR anode (0.91 A/m²; 0.32 W/m²) and 3D-CB anode (0.88 A/m²; 0.30 W/m²) both achieved 56% COD removal, while the C-iNPCB-anode (5.71 A/m²; 3.75 W/m²) was the best performing, with over 80% COD removal. The photopolymerized doped anode exhibited superior performance in terms of both organic matter oxidation and conductivity, indicating higher effectiveness of this type of electrode in MFC technology. Full article

The energy utilization of residual woody biomass is a relevant strategy for the decentralized energy transition and local waste management in rural areas. The objective of this study was to characterize (physically, chemically, and energetically) five types of residual biomass: pine branches, huinumo (this material refers to the long, thin pine needles that, after drying and falling, form a layer on the forest floor), cherry branches and leaves, and grass waste generated in the community of San Francisco Pichátaro, Michoacán, Mexico, in order to evaluate its viability for the production of densified solid biofuels. A comprehensive analysis was conducted, including moisture content, higher heating value, proximate characterization, structural chemical analysis (using the Van Soest method), elemental CHONS analysis, ash microanalysis (by ICP-OES), and a multicriteria analysis with normalized energy and compositional indicators. The results showed that huinumo and cherry leaves were the most outstanding biomasses, presenting the highest heating values (20.7 MJ/kg) and low moisture and ash contents. Pine branches obtained the most balanced results, characterized by their equilibrium in fixed carbon and lignin, as well as their low potassium content. The multicriteria analysis showed that there is no absolute optimal biomass; however, it indicates that pine branches and huinumo are the most robust feedstocks for the production of briquettes or pellets. The results confirm the significant technical and environmental potential of local lignocellulosic residues for the production of solid biofuels and for contributing to sustainable energy solutions at the local scale. Full article

Magnetic biochar (MBC), a magnetically responsive soil amendment, has attracted considerable attention due to its efficient magnetic separation capability and strong potential for remediating heavy metal-contaminated soils. Despite extensive research, a comprehensive evaluation of its raw materials, synthesis routes, performance-influencing factors, removal mechanisms, and microbial interactions remains limited. This review systematically examines biomass feedstocks and magnetic precursors used in MBC production and critically evaluates preparation methods, including hydrothermal carbonization, co-precipitation, ball milling, microwave pyrolysis, and impregnation–pyrolysis. Key factors affecting heavy metal removal—such as metal speciation, pyrolysis temperature, soil properties, dosage, and feedstock type—are discussed in detail. The primary immobilization mechanisms, including redox reactions, surface and co-precipitation, ion exchange, functional group complexation, physical adsorption, π–π interactions, and electrostatic attraction, are comprehensively analyzed. Furthermore, the interactions between MBC, soil physicochemical parameters, and microbial communities are evaluated to assess ecotoxicological implications. Finally, we provide valuable recommendations for the future direction of magnetic biochar research to advance its application in heavy metal removal from soil. Full article

This work explores the influence of two preparation methods, solvent casting and melt mixing, on the structure–property relationships of poly-L-lactic acid (PLLA) composites reinforced with char derived from different waste feedstocks. Three types of char were produced by slow pyrolysis at 550 °C: olive pruning waste biochar (OC), tyre-derived char (TC), and a 1:1 hybrid co-pyrolyzed char (OTC). Each filler was incorporated into PLLA at 1 and 2 wt.% loadings, and the resulting composites were characterized through physicochemical, thermal, mechanical, and electrical analyses. Raman, FTIR, and SEM analyses revealed distinct structural characteristics for each char, with the hybrid OTC exhibiting the highest structural order due to synergistic interactions during co-pyrolysis. The preparation method affected filler dispersion. Solvent-cast films displayed micrometric agglomerates and interfacial voids, whereas melt mixing ensured a more homogeneous distribution. Thermal characterization showed that char addition did not significantly alter the crystallization or melting behavior of PLLA, although melt-mixed samples exhibited restricted chain mobility. Mechanical tests revealed opposing effects of filler loading depending on processing: in solvent-cast materials, stiffness increased while strength remained nearly unaffected, whereas melt-mixed composites exhibited reduced modulus and strength, attributed to the disruption of the denser amorphous structure generated during melt processing. Electrical resistivity depended on the preparation method. Solvent-cast composites remained insulating, while melt mixing, with OTC at 2 wt.%, led to a resistivity drop (down to 0.02 × 10¹⁵ Ω·cm from 20 × 10¹⁵ Ω·cm for unfilled PLLA), although all materials remained within the insulating regime. Overall, this work provides insight into the role of sustainable char fillers in improving the performance of PLLA composites and highlights the interplay between processing method and material properties. The developed PLLA/char composites are promising candidates for applications in flexible electronics, sensors, and antistatic components, as well as in lightweight structural materials and energy devices. Full article

This study quantitatively evaluates the effect of solid-phase pre-reduction of chromite concentrate on the energy efficiency and techno-economic performance of high-carbon ferrochrome (HC FeCr) smelting. Laboratory pre-reduction experiments were conducted at 1200–1400 °C using Shubarkol coal, metallurgical coke, and special coke as carbonaceous reducing agents. Structural and phase transformations were characterized by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). At 1200 °C, the degree of metallization remained low (<5%), whereas at 1400 °C it increased to 41.3% under laboratory conditions and up to 65% in pilot-scale tests due to the decomposition of the spinel matrix and the formation of metallic and carbide phases. The application of pre-reduced feedstock in a submerged arc furnace reduced specific electricity consumption by up to 33.5% compared with conventional smelting and increased chromium recovery to 89.71%. Industrial-scale extrapolation indicates the potential to decrease power consumption to approximately 3190 kWh/t of alloy. Techno-economic analysis demonstrates that the use of pre-reduced feedstock reduces the production cost by approximately 10–23%, depending on the type of carbonaceous reducing agent (Shubarkol coal, metallurgical coke, or special coke). Special coke provided the highest energy efficiency, whereas Shubarkol coal ensured the greatest direct economic benefit. The integrated microstructural, energetic, and economic assessment confirms the industrial applicability of the proposed pre-reduction approach. Full article

Olive pomace biochar, obtained through the pyrolysis of lignocellulosic biomass, has emerged as a sustainable and multifunctional additive for polymer composites. Its physicochemical properties, including porosity, surface area, and electrical conductivity, can be tailored by controlling feedstock type and pyrolysis conditions. Although mechanical reinforcement and thermal stability improvements are well documented, the influence of biochar on surface-related properties such as wettability and contact angle remains insufficiently explored for environmentally relevant composite systems. In this study, epoxy-based composites containing biochar synthesized at 750 °C were evaluated in terms of their water interaction behavior by monitoring the evaporation dynamics of ultra-pure water droplets (10 μL, 0.055 mS/cm conductivity) at eight time intervals between 20 and 580 s using high-resolution digital microscopy. Image enhancement and segmentation were performed prior to Discrete Cosine Transform (DCT) analysis to describe droplet geometry in the frequency domain. Time-dependent variations in the standard deviations of DCT coefficients were optimized using the Bat Algorithm, resulting in mathematical models capable of accurately representing droplet evolution and surface–fluid interactions. The primary novelty of this study lies in the development of a hybrid experimental–computational framework that integrates droplet-based wettability measurements with signal-domain analysis and metaheuristic optimization. Unlike conventional studies focusing solely on material characterization, this approach establishes quantitative relationships between surface behavior and numerical descriptors derived from DCT and the Bat Algorithm. The proposed methodology provides a data-driven tool for predicting wettability trends in biochar-reinforced composites and supports the development of moisture-resistant materials for coatings, packaging, and thermal insulation applications within the context of sustainable composite design. Full article

Microwave-assisted depolymerization (MD) of heterogeneous postconsumer plastics was carried out in a quarter-scale reactor to evaluate product composition and the influence of feedstock type on oil quantity and quality. Various waste streams, including: PS, PP, ABS materials, keyboard housings, textile plastics, PCBs, and mixed electronic components, were processed in 3–6 kg batches using magnetron powers up to 2 × 1.55 kW. All experiments yielded a condensed liquid fraction, with color intensity correlating with aromatic content. FTIR spectroscopy showed that all oils consisted of hydrocarbon matrices dominated by aliphatic C-H stretching bands (2956–2850 cm⁻¹). Aromatic contributions varied significantly: PS produced oils rich in aromatic OOP C-H bands (900–650 cm⁻¹), PP yielded predominantly aliphatic oils with minor aromatic features, and ABS or electronics materials produced mixed aliphatic–aromatic profiles. Textile oils additionally exhibited carbonyl and O-H bands, indicating oxygenated decomposition products. Fractional distillation separated the oils into low-boiling aliphatic (<250 °C) and heavier aromatic (250–350 °C) fractions. These results suggest that MD reliably converts diverse plastic wastes into hydrocarbon oils whose spectroscopic characteristics reflect both feedstock composition and thermal pathways intrinsic to microwave heating. Full article

Increasing global demand for animal-based protein has created a critical environmental management challenge regarding manure accumulation in intensive livestock production. Gasification offers a sustainable solution by converting organic residues into renewable synthetic gas (syngas) and carbon-rich biochar. This study systematically evaluated the performance of three major types of animal waste—dairy manure, poultry litter, and swine manure—against a lignocellulosic control (wood veneer waste) in a top-lit updraft (TLUD) gasifier. Three airflow rates (10, 15, and 20 L min⁻¹) were studied. The results indicated that increasing airflow significantly elevated the gasifier flame front temperatures, with poultry litter achieving the highest peak temperature (825.5 °C), followed by swine manure and dairy manure (753.7 and 727.0 °C, respectively) at 20 L min⁻¹ airflow. While dairy manure exhibited the fastest linear burning rate (25.7 mm/min), poultry litter demonstrated the highest mass consumption rate (32.8 g/min). Feedstock chemistry drove distinct reaction pathways in syngas composition. Poultry litter emerged as the superior feedstock for H₂ production, achieving a peak H₂ concentration of 10.78% at 20 L min⁻¹, which attributed to a synergistic combination of outstanding temperature, moisture content and catalytic alkali metals that promoted steam reforming and water–gas shift reactions. CO production was dominated by wood veneer (17.6%), which was driven by the dominance of elemental carbon and fixed solid (FS) content that favored partial oxidation and a Boudouard reaction. These findings suggest that while airflow regulates thermal kinetics, the specific energy profile of the produced syngas is fundamentally determined by the physiochemical properties of the biomass precursor. Full article

The growing demand for sustainable soil management strategies has intensified interest in hydrochar (HC), a waste-derived amendment produced via hydrothermal carbonization (HTC). This review synthesizes recent advances in HC production, characterization, and agri-environmental applications within a waste-to-resource framework. It covers studies conducted mainly over the last decade, encompassing a wide range of feedstocks, including agricultural residues, sewage sludge, animal manures, and food waste. HTC is typically performed at 130–280 °C under autogenous pressure (2–15 MPa), generating HCs with low intrinsic surface area (<50 m²g⁻¹) and oxygen-containing functional groups that govern nutrient dynamics and soil interactions. Reported application rates vary broadly between 10 and 60 t ha⁻¹, with most experiments conducted under greenhouse conditions. Positive effects on soil pH, cation exchange capacity, water retention, and phosphorus availability are frequently observed. However, plant responses vary according to the type of stimulation promoted by HC, as well as its processing conditions, application rates, and the soil characteristics in which it is applied. Advanced molecular-level analyses (e.g., FT-ICR-MS, GC-MS, and ¹³C-NMR) have provided mechanistic insights into carbon stability, nutrient release, and interaction with soil organic matter. Reusing HTC process water offers an additional pathway for nutrient recovery, although concerns about phytotoxic compounds remain. Despite promising short-term results, long-term field evaluations and standardized assessment protocols are still limited. This review integrates structural, functional and agri-environmental perspectives to identify critical knowledge gaps and guide the optimized and context specific use of hydrochar in sustainable agricultural systems. At the same time, it emphasizes its role in advancing carbon sequestration and in operationalizing resource-circular strategies, thereby underscoring its broader practical and strategic relevance. Full article

The world’s water resources are being deteriorated by the continuous discharge of various contaminants, highlighting the problem of dyes. Many industrial activities (dyeing, food, and medicines) depend on the use of synthetic dyes. Due to their strong color, toxicity, and carcinogenic properties, dye effluents are detrimental to human health and the environment and their treatment is mandatory before discharge. The manuscript intends to present a comprehensive summary of the advantages and drawbacks of using different treatments on the removal of dyes, mainly those based on adsorption. Emphasis is placed on the use of adsorbents from biomass or biomass waste, which are used in their original form or after conversion into biochar or activated carbon (AC). In this review, the use of biomass-based feedstocks to produce biochar and ACs and their application on the removal of various types of dyes from liquid effluents are compiled and critically discussed. This approach positions waste and sub products not as a problem, but as a valuable raw material for producing high value-added materials. The performance of different adsorbents, for the removal of cationic and anionic dyes, is discussed and related to the textural, physical and chemical characteristics of adsorbents and adsorption. It differs from the other revision manuscripts in that it elucidates to the readers the points to ponder before choosing an adsorbent for the removal of a specific dye, mainly for large-scale uses. Full article

In this study, a techno-economic and carbon footprint (GHG, CO₂-equivalent) analysis was conducted on two alternative biofuels, green diesel and bio-jet fuel, produced from renewable lipids. The focus of the work is the comparison of various lipid feedstocks, including waste cooking oil, and four types of vegetable oils: cardoon, soybean, palm, and sunflower. Process optimization and design were performed to minimize production costs by using the process simulation software Aspen Plus^®. Green diesel and bio-jet fuel were obtained via hydrodeoxygenation and hydroisomerization/hydrocracking, respectively. Sensitivity analyses confirmed consistent results across the tested vegetable oils. Hydrodeoxygenation achieved triglyceride molar conversions exceeding 97%, with overall mass yields into the diesel fraction surpassing 79%. Conversely, hydroisomerization/hydrocracking of green diesel resulted in over 90% conversion of n-paraffins and more than 50% overall mass yield. The economic analysis showed that the primary cost factor influencing the payback selling price of the biofuels is the price of the lipid feedstocks. Biofuels are economically viable only when lipid prices are below 1000 €/ton and hydrogen prices are below 3000 €/ton. An important aspect is also represented by the combined-cycle energy recovery system, which strongly affects the overall capital cost and increases internal power generation efficiency. The carbon footprint calculated over a cradle-to-grave boundary showed shows net GHG reductions versus the fossil reference fuels for all scenarios. Net avoided emissions range from 1.74 to 3.63 kgCO₂-eq/kg green diesel and from 0.80 to 3.70 kgCO₂-eq/kg bio-jet fuel across the investigated feedstocks, approximately 40–84% and 20–95% of the respective savings relative to the fossil reference fuels under the stated background and logistics assumptions. Results are expressed per kg of produced fuel as a functional unit, using literature-derived upstream emission factors for oil supply and background inputs (hydrogen, Italian grid electricity and transport). For the bio-jet configuration, co-product burdens were partitioned by mass; the Discussion section highlights the sensitivity of the GD vs. BJF comparison to co-product handling and allocation choices. In this context, the choice of feedstock is essential in establishing the resulting GHG intensity of the two biofuels. From both economic and climate change perspectives, waste cooking oil emerges as the most promising option, particularly given its classification as waste-derived feedstock in the system boundary, unlike the virgin oil sources. Full article

Reforming processes are key technologies for the production of hydrogen and synthesis gas from hydrocarbon feedstocks, with steam reforming and dry reforming being the most extensively studied routes. Steam reforming remains the dominant industrial process due to its high efficiency and economic viability; however, its associated CO₂ emissions raise environmental concerns, partially mitigated through an integration with carbon capture and storage technologies. Dry reforming has emerged as an attractive alternative, although it requires high operating temperatures and suffers from catalyst deactivation. Catalyst design is therefore critical for improving process efficiency and stability. Supported metal catalysts, particularly Ni-based systems, are widely employed, with the support material playing a decisive role in metal dispersion, resistance to sintering and coking, and reaction selectivity. Microporous and mesoporous silica-based materials, including zeolites and ordered mesoporous silicas, offer tunable structural and surface properties that enhance catalytic performance. The novelty of this work lies in its holistic approach to reforming catalysis, where the catalytic performance is not discussed solely in terms of active metals, but is systematically correlated with the surface properties, chemical composition, and structural features of silica-based supports. Moreover, this study expands the perspective to alternative and less-explored feedstocks. By considering multiple fuels and support types, the study provides new design guidelines for developing more efficient and sustainable reforming catalysts. Full article