Search Results (2,144)

Alkali-activated cementitious materials (AACMs) are recognized as promising green building materials and a viable alternative to traditional cement due to their low carbon footprint, high durability, and superior mechanical properties. These materials primarily utilize industrial by-products such as coal gangue, steel slag, and gasification slag. The alkali activation process offers an environmentally friendly pathway for the construction industry. To address the need for the large-scale utilization of bulk solid wastes, this study established a ternary solid waste synergy system comprising coal gangue, steel slag, and gasification slag. The preparation and performance optimization of AACMs based on this system were investigated. An optimal mix proportion was identified through orthogonal experiments, and the influence of various factors on the mechanical properties at different curing ages was analyzed. The results indicate that the fluidity of all AACMs meets the requirements for general backfilling applications. Among the alkali activators, Na₂SO₄ had the smallest effect on fluidity. Under single-activator conditions, sodium silicate (water glass) and sodium hydroxide exerted a greater influence on strength development compared to anhydrous sodium sulfate. For the composite activator system, the significance of parameters affecting compressive strength followed the order: silicate modulus > alkali activator content. The maximum 28-day unconfined compressive strength reached 7.653 MPa with a mix proportion of 55% coal gangue, 45% steel slag, and 5% gasification slag, as well as a silicate modulus of 1.2 and a water glass content of 8%. This represents increases of 540.95% and 299.25% compared to the non-activated group and single-activator groups, respectively. Microstructural analysis revealed that the enhanced integrity and strength of AACMs are attributed to pore-filling by hydration products, predominantly C–S–H and C–A–S–H gels. This study successfully developed high-performance AACMs based on a coal gangue–steel slag–gasification slag ternary system, elucidating the critical regulatory role of silicate modulus in composite activators and the underlying microstructural strengthening mechanisms. The findings provide a theoretical foundation and technical support for the high-value, large-scale utilization of bulk industrial solid wastes in building materials. Full article

Mycelium-based composites (MBCs) are gaining attention as sustainable alternatives to conventional materials because they are grown biologically rather than produced through resource-intensive extraction and processing. This study evaluates MBCs for non-load-bearing wall panels and environmentally responsible substitutes for traditional building materials. A reproducible manufacturing process is presented, and heat-pressed panels are characterised for physical, mechanical, and chemical performance. Novelty lies in species-driven evaluation using rice-husk waste as the sole lignocellulosic substrate and a Queensland-native Amauroderma species. Five fungal species, Trametes hirsuta, Ganoderma sp., Amauroderma sp., Pycnoporus coccineus and Trametes versicolor, were cultivated on rice husks and compared under identical processing conditions. Statistical analysis showed species selection significantly influenced tensile strength, whereas flexural and compressive performance showed no significant interspecies differences. Panels achieved tensile, compressive, and flexural strengths up to approximately 0.47, 0.35, and 1.35 MPa, respectively, with Amauroderma exhibiting the highest stiffness and compressive performance. Composites from four of the five species showed low moisture sensitivity and favourable thermal behaviour relative to previously reported mycelium materials. These results demonstrate that fungal species selection is a key design lever and supports rice-husk-derived MBCs as sustainable insulation and non-load-bearing construction materials. 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

The recycling of technical textile waste represents a major challenge due to the complex and multilayered structure of these materials. Firefighter protective clothing, mainly composed of high-performance aramid fibers combined with polymeric membranes and auxiliary textile components, is commonly landfilled or incinerated at the end of its service life, resulting in a significant environmental impact. This work utilized recycled aramid-rich textile waste obtained from end-of-life firefighter protective clothing as reinforcement for polyamide 6 to develop high-performance thermoplastic composites within a circular economy framework. Composites containing 15, 30, 45, and 60 wt.% of recycled textile waste were manufactured by melt compounding followed by injection molding. In addition, a selected formulation containing 30 wt.% reinforcement was compatibilized using an amino-functional silane to improve interfacial adhesion. The materials were systematically characterized in terms of tensile properties, thermal behavior, thermomechanical performance, water uptake, flammability, colorimetric properties, and fracture morphology by field emission scanning electron microscopy. The results revealed a pronounced increase in stiffness and thermomechanical stability, with tensile strength increasing from approximately 65 MPa for neat PA6 up to 78 MPa at 30 wt.% reinforcement, and elastic modulus exceeding 5000 MPa at high reinforcement contents. An optimal balance between mechanical performance and ductility was achieved at 30 wt.% reinforcement, while higher contents enabled a substantial extension of the service temperature range, with HDT values increasing from 55 °C for neat PA6 up to 173 °C for highly reinforced systems. FESEM analysis confirmed improved interfacial adhesion in silane-compatibilized systems, explaining the enhanced mechanical and thermomechanical behavior. Furthermore, the incorporation of recycled aramid-rich textile waste led to a significant improvement in flame retardancy, enabling UL-94 V-0 classification at 30 wt.% reinforcement and above, without the use of additional flame-retardant additives, enabling UL-94 V-0 classification without additional flame-retardant additives. Overall, this study demonstrates the technical feasibility and high added-value potential of valorizing firefighter protective clothing waste into advanced PA6-based composites with enhanced mechanical, thermal, and fire-resistant properties, providing a sustainable route for the valorization of high-performance textile waste. Full article

Foam concrete and fiber-reinforced foam concrete are promising building materials for sustainable and energy-efficient construction. Improving the environmental performance of cellular composites through the use of industrial waste and additives based on them is highly relevant. This study intends to create a novel complex nanomodifying additive (CNA) from industrial waste and nanomaterials, alongside new eco-friendly foam concrete (FC) and fiber-reinforced foam concrete (FFC) mixes incorporating CNA and polypropylene fiber (PF). Experimental studies yielded the optimal CNA formulation and described a method for its preparation. The test results indicate that FC’s properties are enhanced by CNA. The properties were best in the FC that was modified with 10% CNA. The FC control composition was surpassed by a 25.5% increase in compressive strength and a 23.1% increase in flexural strength, with a 9.5% reduction in thermal conductivity. Dispersed PF reinforcement also positively impacts the properties of FFCs with CNA, and the combined modification of 10% CNA and 1.2% PF provides maximum increases in compressive and flexural strength, amounting to 43.1% and 102.2%, respectively, and a 16.9% reduction in thermal conductivity. A microstructural analysis of the cellular composites confirms the feasibility of the tested formulation solutions. The FFCs, when modified by CNA and PF, display a homogeneous cellular structure, and the interpore zones contain multiple clusters of calcium silicate hydrate. Using CNA in the production of FC and FFCs will reduce cement consumption and improve their environmental friendliness. Full article

Hydrothermal carbonization (HTC) of agricultural waste is a promising waste management technique. However, the use of different raw materials may produce hydrochars with varying efficiencies, both in yield and application, and environmental impacts, due to differences in composition and required processing conditions. To understand the influence of biomass type and acid-assisted HTC conditions, this study used sugarcane and agave bagasse to produce functionalized hydrochars and evaluated them for the removal of Reactive Orange 84; an azo dye used in the textile industry. Material characterization was performed using FT-IR, TGA, BET, and XRD analyses. In addition, a life cycle assessment was conducted to evaluate environmental impacts associated with hydrochars produced using H₂SO₄ at concentrations of 0.2 and 0.5 M. TGA and XRD results indicate that agave bagasse hydrochars (HBA) retain more crystalline lignocellulosic structures, whereas sugarcane bagasse hydrochars (HBS) exhibit predominantly amorphous structures after HTC. FT-IR analysis confirmed the presence of –SO₃H functional groups; however, HBA samples showed greater availability of these groups with increasing acid concentration. Adsorption experiments and LCA results demonstrated that the most favorable treatment, in terms of emission reduction and dye removal, was agave bagasse functionalized with 0.5 M H₂SO₄, achieving 75.7% mass yield and 94.5% dye removal. Full article

Waste-to-energy technology plays a crucial role in advancing the circular economy framework, a strategy that contributes to achieving the United Nations Sustainable Development Goals on responsible consumption and production, as well as the provision of affordable and clean energy. Hydrothermal co-liquefaction has emerged as a promising technology for addressing waste material challenges by converting them into valuable biofuels. This review focuses on biomass feedstock classification and provides an overview of hydrothermal co-liquefaction for sustainable waste management and improved energy production. Moreover, the article provides details on integrating other waste treatment methods with hydrothermal liquefaction to promote the circular economy. Research publications from 2015 to 2025 were obtained from Web of Science and Scopus to identify research trends and output across countries and map out future research directions. The retrieved data from Web of Science was analysed for mapping research, keyword occurrence, and network analysis using VOSviewer software. The study highlighted that waste treatment techniques not only mitigate environmental pollution but also provide a sustainable pathway for energy production and contribute to global carbon neutrality. The review shows that biocrude yield varies with blending ratio because of differences in the biochemical composition of feedstocks, which affect reaction pathways and lead to synergistic or antagonistic interactions during co-processing. Therefore, careful selection of biomass feedstock is essential to achieve optimal results. Full article

This study investigates the development of a composite material based on agricultural plant waste from Kazakhstan, utilizing a multicomponent binder incorporated with rice husk ash. The implementation of low-clinker binders enables the full utilization of ash dumps from the Kyzylorda thermal power plant (TPP) and rice husk residues from local rice-processing enterprises. Physical and chemical analysis of the ash–cement stone revealed a reduction in portlandite content compared to control samples. Phase composition analysis indicated the presence of hydroaluminate C₄AH₁₃ and a reduction in calcite, suggesting accelerated crystallization of calcium silicate hydrates. The formation of crystalline phases and intergrowth structures is assumed to contribute to the strengthening of the gel-like matrix. Experimental optimization of the ash–cement binder with rice husk ash yielded compressive strengths ranging from 3.03 to 4.10 MPa at densities of 790–900 kg/m³, depending on the type of organic filler. These results confirm the feasibility of using locally sourced agricultural waste for the production of heat-insulating and structurally stable composite materials. Full article

To investigate the influence of working fluid composition on the thermo-hydraulic performance of plate heat exchangers (PHEs) under single-phase sensible heat transfer conditions, a three-dimensional steady-state numerical model was developed for a transverse corrugated channel with a chevron angle of 60°. The governing equations were solved using the finite volume method implemented in ANSYS Fluent, in conjunction with the standard k–ε turbulence model. The analysis considered pure refrigerants R134a and R245fa, as well as their mixtures with mass ratios of 0.2, 0.5, and 0.8, with thermophysical properties assumed to be temperature-independent constants. The results indicate that as the mass fraction of R134a decreases from 1.0 to 0, the heat transfer coefficient (h) decreases from 1025 to 815 W/(m²·K), primarily attributed to the combined effects of reduced thermal conductivity and increased viscosity. Among the investigated cases, the R134a/R245fa mixture with a mass ratio of 0.8 provides the most favorable performance trade-off, exhibiting a heat transfer coefficient only 3.0% lower than that of pure R134a while achieving a 12.5% reduction in flow resistance compared with pure R245fa. Furthermore, the heat transfer coefficient is found to be weakly affected by heat flux in the range of 8000–20,000 W/m²; in contrast, increasing the mass flow rate from 0.001 to 0.005 kg/s enhances heat transfer coefficient by 65.1%, accompanied by a significant increase in pressure drop. Comparisons with established single-phase correlations for corrugated channels show average deviations of 6.5% for the Nusselt number and 3.8% for the friction factor. The present study provides useful guidance for working fluid selection and operational optimization of PHEs in applications dominated by sensible heat transfer, such as specific stages of heat pump cycles and medium-temperature waste heat recovery. Full article

Micro- and nano-plastic pollution caused by the mismanagement of plastics waste is a significant problem worldwide, causing severe impacts in aquatic and terrestrial environments. The purpose of this study was to evaluate the adsorption capacity of a thermally stable and superhydrophobic bio-substrate to remove microplastic particles (MPPs) from aqueous systems. In this work, the adsorption efficiency of cattail fluff towards MPPs from pristine PP, PVC, PA6, LDPE, HDPE, and their blend was evaluated. The effect of temperature (30 °C, 40 °C, and 50 °C) and two binding environments (distilled water and industrial wastewater) on adsorption was determined. Non-linear regressions of seven adsorption isotherm models including Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R), Redlich–Peterson (R–P), Toth, and Sips were applied to fit the experimental data. Error function analysis confirmed that the D–R adsorption isotherm model offers the best fit of the experimental data. The results show that the bio-substrate is very effective in adsorbing MPPs from aqueous systems with adsorption capacities of q_e = 3597 mg/g and q_e = 2807 mg/g in distilled water and synthetic industrial water, respectively. The composition of the MPPs determines the effect of temperature and binding environment on the adsorption performance of the bio-substrate. Physisorption dynamics for the MPP/bio-substrate system are also provided and discussed. Overall, the hydrophobic bio-substrate is highly effective in removing MPPs from aqueous systems, with the added advantages of low cost, sustainability, and scalability for practical applications. Full article

The growing production of lithium-ion batteries is leading to an increase in waste, which contains elements considered critical in industry, like cobalt, manganese and nickel. Urban mining offers an opportunity to recover these elements and reintroduce them into the value chain. This study aimed to detect and recover metals of interest present in discarded lithium-ion batteries and determine the influence of flotation operating parameters on the recovery of the detected elements through an experimental design. The batteries subjected to the flotation experiments were obtained from various types of common disused mobile devices. They were dismantled by separating the copper sheets from the anode and the aluminum sheets from the cathode, to be subjected to a comminution process and elemental composition analysis using X-ray fluorescence. Only the cathode components were subjected to flotation. The flotation process was carried out by controlling the level of agitation and aeration and the flotation time using an automated flotation cell. The experiments were configured in a 2³ experimental design. Average recoveries of approximately 67% for cobalt, 64% for manganese, and 63% for nickel were achieved at a pH of 12.5 and a pulp density of 3.33 g/L using MIBC as the sole reagent. Statistical analysis at a 95% confidence level identified agitation, aeration, and flotation time both individually and in combination as significant factors. Linear models were developed to predict metal recovery, showing good agreement with experimental data (errors < 10%; standard deviation < 3%). Full article

Waste from the wind power and textile industries poses major environmental challenges. While the textile industry is a significant global contributor to waste, producing around 92 million tons of waste annually, and greenhouse gas emissions, wind power, although one of the cleanest energy sources during operation, still generates waste and associated CO₂ emissions, particularly associated with the end-of-life decommissioning of turbine blades. This waste can be reused, combined with bio-based binders, to reduce the construction sector’s long-term environmental impact. The present work identifies research trends and gaps in the use of these waste materials, either individually or combined, for the development of thermal and acoustic insulation solutions for the construction sector, by means of a combined bibliometric and content analysis of Scopus and Web of Science documents from 2014 to 2025. The study focuses on bibliometric indicators and reports on physical properties (thermal conductivity, density, mechanical strength, and acoustic performance) of the resulting composites, including those produced with bio-binders. Additionally, a qualitative review of life cycle assessment studies indicates that bio-based and waste-derived insulation materials can significantly reduce environmental impacts compared with conventional mineral or petrochemical insulators. Results reveal growing scientific interest in this subject, highlighting an annual publication growth of 5.09%. They emphasize the performance of natural textile fibers in thermal and acoustic insulation, the mechanical capacity of synthetic fibers, and the semi-structural potential of fiberglass composites. Meanwhile, bio-binders improve the upcycling of textile waste; however, they reveal a significant research gap in the integration of wind turbine blade waste into insulation composites. No indexed studies were found that simultaneously combine textile waste, blade-derived fibers, and bio-based binders in a single insulation system, despite projected cumulative blade waste of 43 million tons by 2050. These findings advocate hybrid innovations and standardized assessments to drive circular economy and low-carbon building solutions. Full article

Bioplastics are in focus for the development of sustainable materials due to the depletion of fossil resources, generation of solid waste and global climate change. Considering this, the current research is devoted to the valorization of beachcast red seaweed F. lumbricalis for the development of thermoplastically processable bioplastics. The composites have been developed from beachcast red seaweed-derived furcellaran (FUR) and potato-derived thermoplastic starch (TPS) by using an ultrasound-assisted technique. Three different FUR concentrations (10, 30 and 50 wt.%) in relation to potato starch were examined for their thermoplastic processability. Fourier infrared spectroscopy (FTIR) was used to reveal the structural changes in the developed TPS/FUR composites depending on FUR content as well as thermal pre-treatment. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile mechanical tests were performed to assess the performance of the developed TPS/FUR composites. It was demonstrated that the ultrasound-assisted manufacturing route allowed TPS/FUR composites with an improved spectrum of properties to be obtained. The highest mechanical stress at break (almost three times higher than for neat TPS) was observed for the TPS + 50 wt.% FUR composite, which also possessed decreased deformability (only ca 10%), reduced thermal resistance at processing temperatures (150 °C) and high shear sensitivity. Thus, the TPS + 30 wt.% FUR and especially the TPS + 10 wt.% FUR composites were recognized as more suitable for thermoplastic processing and the development of TPS-based composites with improved exploitation properties. Full article

Alkali-activated solid waste-based geopolymer represents a novel form of inorganic cementitious material, which is one of the key research directions in the building materials field to achieve the targets of carbon peak and carbon neutrality. Therefore, taking solid waste materials as raw materials to prepare the alkali-activated solid waste-based geopolymers with better mechanical properties is of significant importance for expanding the utilization channels of industrial solid waste materials in Hebei Province. In this study, three solid waste materials, slag, iron tailings sand and coal gangue powder, were used as the precursors of geopolymer, and solid sodium silicate was used as the activator to prepare the solid waste-based geopolymer. Response surface methodology was adopted to design the composition of the geopolymer, and the dosages of slag, Na₂O and coal gangue powder were taken as design variables, and the compressive strength of the geopolymer at 7 days and 28 days were taken as response variables. The results show that it is feasible to optimize the composition of solid sodium silicate-activated solid waste-based geopolymer (SSG) by using response surface methodology. The error value of the SSG-mortar compressive strength prediction model is below 2.0%. The slag contents exhibit a positive correlation with the compressive strength of SSG-mortar, but the coal gangue powder contents and Na₂O contents have a negative correlation. The optimized compositions of SSG-mortar are 20% iron tailings sand, 26% coal gangue powder, 54% slag, and 6.41% Na₂O (regulated by 6.23% solid sodium silicate and 6.23% solid NaOH granules), and the corresponding compressive strengths of SSG-mortar at 7 days and 28 days are 37.1 MPa and 44.9 MPa, respectively. In addition, dry shrinkage tests, wet–dry cycling tests, freeze–thaw cycling tests, salt corrosion tests, SEM analysis and XRD analysis were conducted on the SSG-mortar with the optimal composition to evaluate its shrinkage behavior, freeze–thaw resistance, salt corrosion resistance and microstructural strengthening mechanisms. The results show that SSG-mortar has relatively good frost resistance and salt erosion resistance. The mass loss rate value and compressive strength loss rate value of SSG-mortar are 1.67% and 18.7%, respectively, after 100 freeze–thaw cycles. Furthermore, the corrosion resistance coefficient value of SSG-mortar is greater than 92%, and the mass loss rate value is lower than 2.4%. The SEM and XRD test results display that, in an alkaline environment, the interwoven consolidation of hydrated gels (including C-S-H gel, C-A-S-H gel, C-(N)-A-S-H gel and N-A-S-H gel) and the filling effect of solid wastes jointly achieve an improvement in the properties of SSG-mortar. Full article

Water contamination by synthetic dyes such as malachite green (MG) remains a significant environmental and public health challenge due to their high toxicity, chemical stability, and resistance to biodegradation. In this study, a CaO-CuFe₂O₄ composite was synthesized through a sustainable route using eggshells and orange peel as agro-industrial waste precursors. Comprehensive structural, spectroscopic and microscopic analyses confirmed the coexistence of a predominant CaO-based phase with spinel CuFe₂O₄, together with nanometric features, satisfactory elemental dispersion and practical magnetic recoverability. Under the experimental conditions employed, the composite exhibited high adsorption performance towards MG, reaching an equilibrium capacity of 2288.4 mg g⁻¹ and 99.98% decolorization within 60 min. The kinetics were better described by the pseudo-second-order model, while the equilibrium behavior was more satisfactorily fitted by the Langmuir isotherm than by the Freundlich model. Thermodynamic analysis indicated that the adsorption process was favorable over the temperature range studied and became more pronounced at higher temperature. The results suggest that the adsorption behavior arises from the combined influence of surface chemistry, calcium-derived basic sites, ferrite-associated metal centers and interfacial accessibility, rather than from surface area alone. In addition, the material could be readily separated from aqueous solution using an external magnetic field, highlighting its practical post-treatment recoverability. Overall, this work demonstrates a viable waste valorization strategy for the development of a magnetically recoverable CaO-CuFe₂O₄ adsorbent for cationic dye removal. Beyond the specific case of MG, the study underscores the potential of agro-waste-derived hybrid oxides as application-relevant materials for water remediation. Full article