Search Results (2,095)

Aluminum–chromium slag (ACS), a by-product of aluminothermic reduction, which is used to produce metallic chromium and its alloys, contains toxic, carcinogenic hexavalent chromium (Cr(VI)). Therefore, improper ACS utilization may severely harm human health and the environment. This study analyzed the Cr(VI) contents, leaching characteristics, and surface concentrations in ACS and four industrially utilized products derived from it (fused alumina for refractories, ferrochromium, aluminum–chromium bricks, and high-chromium bricks). A risk assessment framework was established to evaluate their human health and environmental risks. Results showed 111 mg/kg Cr(VI) in the ACS, with its leaching concentration (7.8 mg/L) exceeding China’s hazardous waste standard. The Cr(VI) contents in the products were low (from <2 mg/kg to 16 mg/kg), and their maximum leaching concentration was below the detection limit (<0.004 mg/L). Furthermore, the four products were found to have acceptable levels of human health risk (<10⁻⁵ carcinogenic risk and <1 noncarcinogenic hazard quotient) under two risk assessment methods (particle-contact- and surface-contact-based methods). Additionally, the predicted concentration of leached Cr(VI) in groundwater (0.008 mg/L) was below the drinking water standard (0.05 mg/L). Cr(VI) limit standards for the products were then proposed based on the risk assessment (≤31 mg/kg content, ≤0.189 mg/m² surface concentration, and ≤0.259 mg/L leaching concentration). Overall, these results may provide a reference for the safe utilization and risk management of ACS and other solid wastes. Full article

Significant depletion of natural resources, coupled with increased environmental pollution resulting from the constant evolution of global industrialization, poses a considerable problem. Therefore, it is unsurprising that sustainable “green” chemistry and technology are gathering the worldwide scientific community, whose common goal is to find applicable solutions for the abovementioned problems. This paper combined the ultrasonic extraction method (a form of “green” technology) with natural deep eutectic solvents (NADESs, a type of “green” solvent) for the production of extracts from an industrial by-product (discarded waste wild apple dust). Waste wild apple dust was pretreated with different NADESs in order to explore the pretreatment benefits regarding ultrasonic extraction of bioactive compounds. Among all solvents used, aqueous propylene glycol was chosen as the best system, which, combined with Reline NADES pretreatment, provided the highest TPC and TFC values, together with the best antioxidant activities. UHPLC-DAD-MS analyses of extracts revealed the presence of natural organic acids, quercetin and kaempferol derivatives, tannins, and flavones. Following this procedure, valorization of agro-industrial apple herbal waste resulted in obtaining extracts with high potential for utilization in different industrial branches (food and pharmaceutical industries), contributing to both cleaner production and reduced environmental impact. Full article

Given that the stock of coal gangue is increasing annually, and especially considering the problem of resource utilization after the spontaneous combustion of coal gangue accumulations with large thickness, the post-spontaneous combustion of coal gangue (SC coal gangue) from Yangquan, Shanxi, was selected as a research object. After crushing and screening, SC coal gangue was used as a coarse and fine aggregate, and through concrete mix design and a trial mix of concrete and mix ratio adjustment, concrete of strength grade C20 was obtained. Through experiments, the strength, elastic modulus, frost resistance, carbonation depth and other performance indicators of the concrete were measured. Using the SC coal gangue concrete, a 20 mm thick SC coal gangue panel was designed and manufactured. Through experimental tests, the bearing capacity, hanging force, impact resistance, impermeability and other properties of the board met the requirements of the relevant standards for building wallboard. For the SC coal gangue panel composite rock wool, its heat transfer coefficient decreased by 34.0%, air sound insulation was $\ge 45 \mathrm{d}\mathrm{B}$, and the self-weight of the external wallboard was reduced by 37.5%, so the related performance was better than the requirements of the current standard. The research results have been successfully applied to an office building project in Shanxi, China. Using SC coal gangue to make the external wallboard of the building, the reduction and recycling of solid waste are realized. In addition, the production of wall panels has been industrialized, thereby improving the construction efficiency. Full article

A significant quantity of agro-industrial waste is generated globally across various agricultural sectors and food industries. Composed primarily of cellulose, hemicellulose, and lignin—known as lignocellulosic materials—this waste holds significant potential and can be repurposed as a nutrient-rich substrate for mushroom cultivation. Therefore, mushroom cultivation can be regarded as a promising biotechnological approach for the reduction and valorization of agro-industrial waste. This investigation is the first to explore the utilization of agro-industrial waste- and by-products for the cultivation of Epicoccum nigrum for the production of extracts with valuable biological activities. The logistic curve and autocatalytic growth models were applied to study the kinetics of the growth process on wheat bran, sunflower cake, wheat straw, pine sawdust, and steam-distilled lavender straw substrates. Through mathematical modeling, the optimal composition of a nutrient medium containing the selected substrates was determined and successfully validated in experimental conditions. Biologically active water extracts were obtained after solid-state cultivation with α-amylase and cellulase activity up to 10.6 ± 0.6 U/mL and 0.52 ± 0.03 U/g, respectively. The extracts exhibited antimicrobial activity against fungal strains from six different species, and the most susceptible was the phytopathogen Sclerotinia sclerotiorum, with a minimum inhibitory concentration of 0.156–0.313 mg/mL. Full article

Microbial electrosynthesis (MES) has emerged as a promising bio-electrochemical technology for sustainable CO₂ conversion into valuable organic compounds since it uses living electroactive microbes to directly convert CO₂ into value-added products. This review synthesizes advancements in MES from 2010 to 2025, focusing on the electrode materials, microbial communities, reactor engineering, performance trends, techno-economic evaluations, and future challenges, especially on the results reported between 2020 and 2025, thus highlighting that MES technology is now a technology to be reckoned with in the spectrum of biofuel technology production. While the current productivity and scalability of microbial electrochemical systems (MESs) remain limited compared to conventional CO₂ conversion technologies, MES offers distinct advantages, including process simplicity, as it operates under ambient conditions without the need for high pressures or temperatures; modularity, allowing reactors to be stacked or scaled incrementally to match varying throughput requirements; and seamless integration with circular economy strategies, enabling the direct valorization of waste streams, wastewater, or renewable electricity into valuable multi-carbon products. These features position MES as a promising platform for sustainable and adaptable CO₂ utilization, particularly in decentralized or resource-constrained settings. Recent innovations in electrode materials, such as conductive polymers and metal–organic frameworks, have enhanced electron transfer efficiency and microbial attachment, leading to improved MES performance. The development of diverse microbial consortia has expanded the range of products achievable through MES, with studies highlighting the importance of microbial interactions and metabolic pathways in product formation. Advancements in reactor design, including continuous-flow systems and membrane-less configurations, have addressed scalability issues, enhancing mass transfer and system stability. Performance metrics, such as the current densities and product yields, have improved due to exceptionally high product selectivity and surface-area-normalized production compared to abiotic systems, demonstrating the potential of MES for industrial applications. Techno-economic analyses indicate that while MES offers promising economic prospects, challenges related to cost-effective electrode materials and system integration remain. Future research should focus on optimizing microbial communities, developing advanced electrode materials, and designing scalable reactors to overcome the existing limitations. Addressing these challenges will be crucial for the commercialization of MES as a viable technology for sustainable chemical production. Microbial electrosynthesis (MES) offers a novel route to biofuels by directly converting CO₂ and renewable electricity into energy carriers, bypassing the costly biomass feedstocks required in conventional pathways. With advances in electrode materials, reactor engineering, and microbial performance, MES could achieve cost-competitive, carbon-neutral fuels, positioning it as a critical complement to future biofuel technologies. Full article

Traditional landfill disposal of muck uses a significant amount of land and pollutes the environment, while current solidification methods heavily depend on energy-intensive cement. This study introduces a novel approach for synergistically solidifying muck using cement, fly ash, and steel slag, aiming to utilize waste resources and achieve low-carbon disposal. Experimental optimization identified the optimal ratio (cement:fly ash:steel slag = 2:2:1). The findings indicate that cement is crucial for early strength, while industrial waste materials enhance long-term performance through continued reactions. At a total solidifying agent content of 4–6%, the material exhibits optimal mechanical properties and durability, with only a 4% strength loss after 12 dry–wet cycles. Microscopic analysis indicates that several gels and polymers with cementing properties are produced, collectively enhancing the material’s structure. Additionally, this material effectively immobilizes heavy metals, including chromium, lead, arsenic, and cadmium, with leaching concentrations that are well below safety thresholds. This approach provides a dependable and eco-friendly method for large-scale disposal of construction waste muck and industrial solid waste, offering significant potential for engineering applications. Further studies could investigate additional solid waste types and formulations suitable for high-moisture materials like sludge. Full article

Camellia oleifera Abel shell is an abundant lignocellulosic byproduct of the Chinese woody oil industry, which is currently underutilized. To achieve its high-value utilization, this study developed an innovative cascade process integrating ultrasound-assisted extraction and macroporous resin purification for the efficient preparation of purified polyphenols from the shell (P-CPCS). The major constituents were identified by quadrupole/Orbitrap high-resolution mass spectrometry (HPLC-Q-Exactive-MS: Biotech Pack Co., Ltd., Beijing, China) analysis. The optimized process significantly enhanced the polyphenol yield (40.05 ± 0.58 mg GAE/g dw) and purity (57.72%), surpassing conventional methods. P-CPCS exhibited exceptional multifunctional bioactivities, including potent antioxidant capacity (with low IC₅₀ values against DPPH, ABTS⁺·, and ·OH radicals), effective tyrosinase inhibition (whitening effect), and significant bacteriostatic effects against various pathogens. Furthermore, P-CPCS notably suppressed the LPS-induced inflammatory response in RAW264.7 macrophages by reducing NO overproduction. This work highlights a novel and efficient strategy for upcycling agricultural waste into a high-performance natural antioxidant, positioning P-CPCS as a promising ingredient for applications in functional foods, cosmetics, and biomaterial stabilization. Full article

Water contamination by heavy metals, particularly lead, derived from industrialization, climate change, and urbanization, represents a critical risk to human health and the environment. Several agricultural biomass residues have demonstrated efficacy as contaminant adsorbents. In this context, the study aimed to evaluate the potential of sugarcane tip (ST) waste biomass treated by hydrothermal carbonization (HTC) to produce hydrochar as an adsorbent material for Pb²⁺ in aqueous solutions. Samples were synthesized from the waste biomass at temperatures of 180 °C, 215 °C, and 250 °C, with a constant pressure of 6 MPa. Aqueous solutions of Pb²⁺ were prepared at concentrations of 10, 25, 50, 75, and 100 mg/L. Each solution was stirred at 1 g of hydrochar at 150 rpm, 25 °C, and pH 5 for 15 to 120 min. The solutions were filtered and stored at 4 °C for flame atomic absorption spectrophotometry analysis. In all cases, equilibrium was reached rapidly—within 15 min or less—as indicated by the stabilization of q_t values over time. At an initial concentration of 100 mg L⁻¹, the highest equilibrium uptake was observed for the hydrochar synthesized at ST HTC 180 °C (4.90 mg g⁻¹), followed by 4.58 mg g⁻¹ and 4.52 mg g⁻¹ for ST HTC 215 °C and ST HTC 250 °C, respectively. For the ST HTC 180 °C, the Sips model provided the best correlation with the experimental data, exhibiting a high maximum capacity (q_max = 240.8 mg g⁻¹; K_s = 0.007; n = 1.09; R² = 0.975), which reinforces the heterogeneous nature of the material’s surface. Hydrothermal synthesis increased the amount of acidic active sites in the ST HTC 180 °C material from 1.3950 to 3.8543 meq g⁻¹, which may influence the electrical charge of the Pb²⁺ adsorption process. HTC-treated sugarcane tip biomass represents a promising alternative for the synthesis of adsorbent materials, contributing to water remediation and promoting the circular economy by sustainably utilizing agricultural waste. Full article

Ti-bearing blast furnace slag (TBS), a byproduct of vanadium–titanium magnetite smelting, serves as an important secondary resource for titanium recovery. However, the complex mineralogical composition and finely dispersed nature of titanium in TBS present significant challenges for efficient extraction. This review systematically examines four major titanium extraction routes: hydrometallurgical leaching, pyrometallurgical smelting, molten salt electrolysis, and selective precipitation, focusing on their limitations and recent improvements. For instance, conventional acid leaching suffers from acid mist release, a colloidal formation that hinders titanium recovery, and waste acid pollution. The adoption of concentrated sulfuric acid roasting activation effectively suppresses acid mist emission and prevents colloidal generation. Pyrometallurgical approaches are hampered by high energy consumption and substantial carbon emissions, which can be alleviated through the use of gaseous reductants to enhance reaction efficiency and reduce environmental impact. Molten electrolysis faces issues such as polarization and undesirable dendritic deposition; these are mitigated by employing liquid metal cathodes integrated with vacuum distillation to achieve high-purity titanium products. Selective precipitation struggles with strict crystallization conditions and low separation efficiency, though advanced techniques like supergravity separation show improved extraction performance. We propose an integrated technical strategy termed “Online conditioning driven by waste heat-mineral phase reconstruction-directional crystallization-optimized liberation.” This approach utilizes the inherent waste heat of slag combined with electromagnetic stirring to enhance homogeneity and promote efficient titanium recovery, offering a sustainable and scalable solution for industrial TBS treatment. Full article

Poor solubility and bioavailability have limited the application of fucoxanthin and functional food processing. In order to encapsulate fucoxanthin in delivery systems, cellulose nanofibril-stabilized emulsion gels (CNFs) derived from industrial brown seaweed residue were developed to enhance fucoxanthin delivery. Cellulose nanofibrils (CNFs) were isolated using high-pressure homogenization at 105 MPa through 5, 10, and 15 cycles (denoted as C5, C10, and C15) and yielding reduced crystallinity down to 52.91 ± 2.13% (C15). The minimum particle size of the present CNFs is approximately 37 nm (C15). Moreover, single-factor and orthogonal experiments optimized the stability of the present emulsion. A 17.5 mg/mL CNFs 50% oil phase with coconut oil, 0.5 mg/mL fucoxanthin, and homogenization for 60 s were identified to be the optimal conditions for such emulsion gel. The present emulsions demonstrated a high storage stability at 4 °C versus 25 °C, which maintained minimal phase separation over 8 days. The release kinetics showed significant dependencies with fucoxanthin release increasing to 9.22 ± 0.62% at pH 8.0, 9.52 ± 0.58% under 1000 mM NaCl, and 8.25 ± 0.62% at 100 °C. In addition, the CNFs effectively preserved the antioxidant activity of the fucoxanthin under different pH values, salinities, and temperatures. The results establish seaweed-derived CNFs as effective stabilizers for fucoxanthin encapsulation, enhancing stability while preserving functionality against food-processing stresses. To our knowledge, no prior research has been reported on a fucoxanthin delivery system utilizing an emulsion gel stabilized by cellulose nanofibrils (CNFs). Such emulsions might provide a sustainable strategy for valorizing seaweed waste and advance functional food applications of marine bioactives. Full article

The aim of the study was to evaluate the feasibility of using exhaust gases as a CO₂ source in the cultivation of Tetraselmis subcordiformis microalgae for biomass and hydrogen production. It was shown that the growth rate of T. subcordiformis biomass and its biochemical composition depended on the CO₂ source. The highest growth rate of 286 ± 15 mgVS/L-d and a final biomass concentration of 2710 ± 180 mgVS/L were achieved in the variant where exhaust gases from a coal and biomass supplementary combustion plant were the CO₂ source (V2). The highest CO₂ reduction efficiency of 90.3 ± 3.2% was achieved in the case where waste gases from biogas combustion were the CO₂ source (V1). In V2, the highest CO₂ utilization efficiency was achieved (CO₂UE = 46.7 ± 2.4%). Analyzing the biomass composition confirmed differences in total carbon content (TC) and polysaccharide fraction. The highest H₂ production efficiency and rate, which were 70.9 ± 2.7 mL/gVS and 2.27 ± 0.08 mL/gVS·h, respectively, were obtained in V2. The results obtained indicate the possibility of integrating fuel combustion processes with the cultivation of T. subcordiformis and photobiological H₂ production, which is a promising solution in the context of climate neutrality and the implementation of circular economy postulates. This approach demonstrates a sustainable strategy for linking industrial CO₂ emissions with the production of renewable biohydrogen and thus contributes to climate protection and the promotion of circular economy concepts. Full article

As a solid waste generated during the desulfurization process of coal-fired power plants, the output of desulfurization dross is increasing year by year. If not properly treated, it may occupy land and potentially pollute the environment. This article reviews the physicochemical properties of desulfurization dross and the progress in its resource utilization. It specifically focuses on the application potential of semi-dry desulfurization dross, emphasizing how its comprehensive resource utilization can reduce environmental pollution and generate considerable economic benefits for related industries. It should be noted, however, that the leaching of heavy metals and the strong alkalinity of desulfurization dross may pose environmental risks such as soil and groundwater contamination. Current research still requires further improvement in the systematic assessment and management strategies of these risks. This review highlights the need to optimize pretreatment technologies for stabilizing desulfurization dross and enhance environmental risk management, to facilitate its large-scale and high-value utilization. This article also looks toward the research directions for semi-dry calcium-based desulfurization dross in the future, aiming to provide a reference for the sustainable development and environmental protection of semi-dry desulfurization dross. Full article

Due to its high content of lignocellulose, cotton stalk is difficult to degrade naturally and utilize effectively, so it is often regarded as waste. In this study, the effects of Pleurotus ostreatus XH005, Lactiplantibacillus plantarum LP-2, and cellulase enzyme on the cotton stalk substrate under aerobic solid-state fermentation (SSF) conditions were investigated, and the metabolites were analyzed to identify potential functional compounds in the cotton-stalk-fermented feed. Preliminary optimization results obtained through single-factor experiments were as follows: fermentation time 14 days, XH005 inoculum size 8.00% (v/m), material-to-water ratio 1:0.50 (v/m), LP-2 inoculum size 2.00% (v/m), and cellulase addition 0.60% (m/m). Based on these single-factor experimental results, XH005 inoculum size, LP-2 inoculum size, material-to-water ratio, and cellulase addition were selected as independent variables. Through response surface methodology (RSM) optimization experiments, 29 experimental groups were designed. Subsequently, based on Box–Behnken analysis of variance (ANOVA) of lignin and cellulose content, along with contour and response surface plots, the optimal aerobic solid-state fermentation parameters were determined as follows: fermentation time 14 days, XH005 inoculum: 7.00% (v/m), material-to-water ratio: 1:0.55 (v/m), LP-2 inoculum: 2.00% (v/m), and cellulase enzyme addition: 0.65% (m/m). Results showed that compared with the control group (CK), the optimized group exhibited a 27.65% increase in lignin degradation rate and a 47.14% increase in cellulose degradation rate. Crude protein (CP) content increased significantly, while crude fiber (CF), detergent fiber and mycotoxin contents decreased significantly. Non-targeted metabolic analysis indicated that adding cellulase and inoculating Pleurotus ostreatus XH005 and Lactiplantibacillus plantarum LP-2 in aerobic SSF of cotton straw feed produced functionally active substances such as kaempferol (C343), carvone (C709) and trilobatin (C604). Therefore, this study demonstrates that microbial-enzyme co-action SSF significantly enhances the nutritional composition of cotton stalk hydrolysate. Furthermore, this hydrolysate is suitable for the production of functional compounds, endowing the fermented feed with health-promoting properties and enhancing the utilization of cotton processing byproducts in the feed industry. Full article

An integrated approach to waste management is based on efficient and safe methods for waste prevention, recycling, and safe waste treatment. In accordance with these principles, in this study, non-hazardous aluminosilicate waste (dust and sand) was used in the solidification/stabilization (S/S) treatment of hazardous waste (coating, emulsion, and sludge) from the automotive industry. Also, the oily component of the waste was valorized and investigated for energy recovery through co-incineration. The two S/S processes were proposed and their sustainability was assessed by utilizing all types of waste generated in the same plant, obtaining stabilized material suitable for safe disposal and oil phases for further valorization, and by techno-economic analysis. The efficiency of the S/S processes was evaluated by measuring unconfined compressive strength, hydraulic conductivity, density, and the EN 12457-4 standard leaching test of S/S products, along with XRD, SEM-EDS, and TG-DTG analyses. The possibility of using the oil phase was assessed based on its calorific value. The techno-economic assessment compared the investments, operating costs, and potential savings of both treatment scenarios. The results show that an integrated approach enables safe waste immobilization and resource recovery, contributing to environmental protection and economic benefits. Full article

The research problem was to determine the possibility of aqueous mineral carbonation using fly ash from lignite fluidized bed combustion. Both direct and indirect routes were used. The innovative nature of the research consisted of conducting experiments at atmospheric pressure and ambient temperature (20 °C). The synthetic gas mixture with composition analogical to the flue gas (nitrogen and up to 16 vol.% of carbon dioxide) was used. The experiments proved that almost all CO₂ from the gas was chemically bound at pH > 12. The sequestration capacity of studied fly ash is about 55–76 g CO₂ per 1 kg of ash in the case of the indirect method, and 80–95 g CO₂ per 1 kg of ash for the direct route. These values are similar to those presented in the literature, but unlike most publications, they were obtained under ambient conditions, which can significantly reduce the costs of the process. Full article