Search Results (1,744)

Capsicum residue generated from industrial capsaicin extraction is rich in nutrients and represents a significant fraction of solid waste in the food processing industry. Despite its potential value, limited efforts have been devoted to its resource recovery, leading to considerable resource loss and environmental burdens. This study systematically evaluates the applicability of existing food waste recycling technologies for capsicum residue and assesses its valorization potential through comprehensive characterization. The results indicate that capsicum residue holds promise as a feedstock for pectin extraction and as a component in animal feed. Regarding anaerobic fermentation for acid production, the maximum volatile fatty acids (VFAs) yield and VFAs/SCOD ratio reached 462.09 mg·L⁻¹ and 3.16%, respectively, suggesting moderate potential for acidogenic conversion but limited suitability for methanogenesis. Fluorescence spectroscopy of dissolved organic matter revealed that microbial humic-like substances (C1) were the dominant fluorophore, accounting for 42.64% of the total fluorescence, followed by terrestrial humic-like (C2, 19.28%), fulvic-like (C3, 19.12%), and tryptophan-like (C4, 18.95%) components. The favorable C/N ratio of amino acids and humic substances supports the feasibility of composting. Additionally, trace levels of residual capsaicin may confer antibacterial benefits and enhance soil fertility, further supporting the potential of capsicum residue as a value-added resource. Full article

The total antioxidant capacity (TAC) of food products is a key parameter for assessing food quality and safety. In this work, iron-doped carbon dots (Fe-CDs) were successfully prepared using waste coffee grounds as a precursor with a satisfactory fluorescence quantum yield of 9.6%. The Fe-CDs exhibited exceptional peroxidase-like activity, which can oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to form blue oxTMB. Concurrently, oxTMB induced an inner filter effect, quenching the fluorescence of Fe-CDs. After being added to antioxidants such as glutathione, ascorbic acid, and L-cysteine, the generated reactive oxygen species (ROS) are consumed, thereby preventing the oxidation of TMB. The color of the mixed solution changed from dark to light blue, accompanied by the fluorescence recovery of Fe-CDs. Nevertheless, these three antioxidants possessed remarkable differences in ROS elimination capability, which resulted in different signal responses in absorption and fluorescence, and were successfully used for constructing the colorimetric/fluorescent dual-channel sensor array. Furthermore, the sensor array signals were processed using principal component analysis to achieve simultaneous detection of glutathione, ascorbic acid, and L-cysteine, and were able to effectively discriminate between mixtures and individual antioxidants. The constructed sensor array was successfully applied for the TAC detection in various foods (including vegetables, fruit, and beverages) and for the precise differentiation of antioxidants in milk samples. Overall, the prepared sensor array exhibited outstanding potential in detecting food quality. Full article

The massive production of municipal solid waste presents a significant global challenge for sustainable urban development and maintaining citizens’ quality of life, requiring effective management and disposal strategies. Waste-to-energy incineration technology has become increasingly important as a solution that simultaneously addresses the growing volumes of municipal solid waste and rising energy needs worldwide. This comprehensive review examines the research findings on the effectiveness of incineration as a waste-to-energy conversion method. The primary goal was to conduct a thorough systematic review assessing WtE incineration effectiveness across several key areas: energy recovery efficiency, waste volume reduction capabilities, environmental impact, and economic feasibility. A comprehensive literature search was conducted across ScienceDirect and additional pertinent databases, utilizing appropriate search terms in accordance with the PRISMA framework. A total of 431 studies were systematically identified, published between 2015 and 2025, and only 25 relevant studies were included in this review. Researchers collected data focusing on energy recovery percentages, volume reduction rates, emission reductions, and economic performance metrics. The findings revealed that every study included in the analysis showed positive results for WtE incineration across various performance measures. This research discovered the feasibility of generating electrical power from garbage through WtE incineration processes. The projected energy yields, ranging from gigawatt-hours to kilowatt-hours, were quantified for several nations, including Mexico (11,681.64 GWh), Cambodia (1625.81 GWh), Bangladesh (187.04 GWh), South Africa (6944 GWh), Iran (17,678 GWh), Nigeria (10,000 GWh), Indonesia (2487 MWh), Algeria (11.6 MWh), China (2316.52 MWh), Iraq (203.917 MWh), Uganda (774 kWh), and Pakistan (675 kWh). Energy recovery efficiency demonstrated a wide range from 30% to 92.75%, with waste volume reduction consistently reaching 90–95% levels, significantly prolonging landfill operational lifespans. From an environmental perspective, technology achieved greenhouse gas emission reductions ranging from 30% to 87%. This dual-purpose approach makes it an attractive, sustainable solution for both waste management and renewable energy production. By adopting this approach, cities can address waste and energy issues while boosting economic growth and job creation. However, it also involves substantial costs, technical difficulties, and environmental hazards that necessitate meticulous oversight. Full article

The increasing challenge of waste disposal and the growing demand for reliable renewable energy sources are particularly critical in developing countries. Waste-to-Energy technologies have emerged as a promising approach to harness the energy potential of waste in an economically viable and environmentally sustainable manner. This study provides a global overview of scientific developments and technological trends in Waste-to-Energy through a bibliometric analysis of 1869 documents retrieved from the Web of Science database, covering the period 2017–2021 and focusing on the field of bioenergy. Here, the term bioenergy is used in a broad sense, encompassing energy recovery from both biogenic waste (e.g., food waste, agricultural residues) and non-biogenic waste (e.g., plastics, synthetic polymers) under the Waste-to-Energy framework. The analysis revealed that developing countries prioritize specific technologies for energy recovery: anaerobic digestion for organic waste, incineration for non-biodegradable mixed waste, and pyrolysis and gasification for carbon-rich waste streams such as biomass and plastics. Landfilling is mentioned solely as a final disposal route for inert materials, not as an energy recovery pathway. Additionally, research highlights the potential benefits of synergistic combinations of raw materials in improving product quality and reducing pollution in Waste-to-Energy processes. This bibliometric and content-based review supports future research efforts by identifying key trends, influential contributions, and critical implementation challenges. The findings underscore the role of Waste-to-Energy technologies as valuable tools in sustainable waste management strategies, especially in regions where improving energy access and reducing environmental impact are pressing concerns. Full article

The use of preservatives such as diuron and isoproturon in the paint industry is essential to protect products against microbial attack. However, these compounds are subject to strict regulation due to the harmful effects they have on the environment and human health. Therefore, analytical strategies to control the production process at paint plants are fundamental to ensure suitable products. In the present work, a low-cost portable square-wave voltammetry device with commercial screen-printed electrodes was proposed to control the starting products and to determine isoproturon and diuron levels in manufactured paint products. Under the optimized conditions (electrolyte HClO₄ 0.18 M, nickel oxide-doped carbon electrodes, E_SW = 0.02 V, E_step = 0.0015 V, and ƒ = 15 Hz), the results indicated satisfactory analytical performance, with detection limits of 3.5 and 3.0 mg L⁻¹ for isoproturon and diuron, respectively, and precision lower than 7.5% for both biocides. The analytical strategy employed to achieve satisfactory selectivity involved taking advantage of the specific interaction of cysteine with 1,2-benzisothiazol-3(2H)-one (BIT) as a potential interferent in some commercial products and the use of matrix match calibration. A recovery study provided values in the range of 92–104% for accuracy validation. A sample pretreatment step was needed due to the paint composition, and a miniaturized method was proposed here. The novelty of this method lies in the use of a portable voltammetry device in real-world industrial applications to control the paint production process using a cost-effective, time-saving, sustainable, and green protocol. The HEXAGON tool is used for assessing greenness and sustainability. The choice of reagents like HClO₄ and the minimization of waste from the small volumes used align with the principles of using safer solvents, a key concern in green and sustainable chemistry. Full article

Rice is a staple food for global nutrition, and its processing generates large volumes of waste with a consequent environmental impact. The industry needs to improve its capacity to manage and treat this waste with more sustainable options than traditional management methods, thereby mitigating the environmental impact of the rice industry. Among the waste streams generated, rice bran represents a significant fraction that is largely underutilized. This study proposes a comprehensive approach to rice bran recovery, aiming to transform 100% of the waste into bio-based products through a three-stage biorefinery approach that combines chemical and biological operations. The process began with the ethanolic extraction of rice bran, which yielded 20.58% (w·w⁻¹) rice bran oil. This oil, evaluated through both in vitro and in vivo trials, has demonstrated effectiveness when combined with commercial edible coatings, reducing post-harvest damage in grapes and lemons by 15–20%. Following extraction, the remaining defatted rice bran, accounting for 79.42% (w·w⁻¹) of the initial material, was used as a carbon-rich substrate for microbial fermentation by Haloferax mediterranei. This step converts 28.75% (w·w⁻¹) of rice bran into microbial biomass and 12.75% (w·w⁻¹) into polyhydroxybutyrate-valerate. The undigested residual biomass, comprising 37.95% (w·w⁻¹) of the starting material, was further valorized through the purification of high-value products such as cellulose (13.08% (w·w⁻¹)), hemicellulose (14.58% (w·w⁻¹)), and lignin (10.29% (w·w⁻¹)). Overall, the biorefinery model recovers 100% of the initial waste and demonstrates, under laboratory conditions, the model’s ability to transform rice bran into six products of industrial interest, offering an option with the potential to effectively manage rice bran waste and help circularize the production model of an industry that traditionally operates under a linear production model. Full article

Heat exchangers are key components of advanced waste-heat recovery energy systems that operate on low-boiling working fluids. The efficiency and cost of power plants depend directly on their design characteristics. Increasing the heat-transfer surface area, on the one hand, reduces temperature differences and improves cycle efficiency, but on the other hand increases material consumption and equipment cost. For given fluid parameters and heat-exchanger duty, the required surface area is determined by the type of heat exchanger, the choice of device, the shape of the enhanced heating surface, and the methods of heat-transfer intensification. This paper provides a comprehensive analysis of the current state of heat exchangers for low-boiling working fluids and discusses their areas of application. A methodology has been developed for optimizing the main design characteristics of heat exchangers, including a search algorithm aimed at minimizing the total costs of equipment production and operation. Using this methodology, computational studies were carried out for advanced energy cycles with low-boiling working fluids (organic Rankine cycles, recompression supercritical CO₂ (s-CO₂) Brayton cycle). The relationships of weight, size, and cost parameters of heat exchangers for waste-heat recovery cycles using low-boiling fluids to exhaust-gas temperatures and external economic factors were obtained. Optimal channel geometric parameters and heat-exchanger design types were identified that ensure minimal material consumption and cost while delivering the required heat-transfer performance. Recommendations are formulated for selecting and designing heat exchangers for waste-heat recovery power plants using low-boiling working fluids, the implementation of which will improve their efficiency and reduce costs. Full article

With the rapid increase in solid waste generated worldwide, sustainable approaches for the recovery of resources considering environmental protection are required. As one of the emerging strategies in recent years, biochar has shown great potential due to its high carbon stabilization, adjustable porosity and tunability. This review focuses on the critical assessment of the available technologies for biochar upgrading, with a specific objective of biochar physicochemical functionality improvement and critical materials recovery in line with circular economy targets. We systematically review physicochemical activation methodologies, functionalizations and leaching approaches, accounting for their effects on surface area, porosity and functional group chemistry. Particular attention is paid to the dual functionality of upgraded biochar (i) as a catalyst support for thermochemical processes and (ii) as a medium for the recycling of essential nutrients (e.g., phosphorus, potassium, magnesium, calcium). It is evidenced that customized activation can further improve its adsorption and catalytic efficiency as well as promote near-total nutrition extraction. This review positions advanced biochar as an enabling multipurpose technology across sustainable material production, nutrient cycling and waste valorization in the circular bioeconomy. Full article

The limited availability of high-quality ore deposits and the environmental hazards of metallurgical wastes highlight the importance of developing resource-efficient metal recovery technologies. Zinc kiln slag (ZKS), also known as Waelz slag, a by-product material enriched in non-ferrous metals, was processed through oxidative HCl leaching with H₂O₂ as an oxidant. Thermodynamic simulation and laboratory experiments were applied to determine optimal leaching conditions to dissolve copper, zinc, and iron. Optimal leaching efficiency was achieved with consumptions of 0.8 g HCl and 0.1 g H₂O₂ per gram of ZKS, a liquid-to-solid (L/S) ratio of 5 mL/g, a temperature of 70 °C, and a duration of 180 min, which resulted in recoveries of 96.3% Cu, 93.6% Fe, and 76.8% Zn. The solid residue with 43.5 wt.% C is promising for reuse as a reductant material in pyrometallurgical processes. Copper and arsenic were separated from the leachate via cementation with iron powder, achieving recovery rates of 98.9% and 91.2%, respectively. A subsequent two-step iron precipitation produced ferric hydroxide with 52.2 wt.% Fe and low levels of impurities. As a result, the developed novel hydrochloric acid oxidative leaching and metal precipitation route for ZKS recycling provides an efficient and sustainable alternative to conventional treatment methods. Full article

The rapid advancement of technologies such as artificial intelligence, big data, and cloud computing has driven continuous expansion of global data centers, resulting in increasingly severe energy consumption and carbon emission challenges. According to projections by the International Energy Agency (IEA), the global electricity demand of data centers is expected to double by 2030. The construction of green data centers has emerged as a critical pathway for achieving carbon neutrality goals and facilitating energy structure transition. This paper presents a systematic review of the role of waste heat recovery technologies in data centers for achieving low-carbon development. Categorized by aspects of waste heat recovery technologies, power production and district heating, it focuses on assessing the applicability of heat collection technologies, such as heat pumps, thermal energy storage and absorption cooling, in different scenarios. This study examines multiple electricity generation pathways, specifically the Organic Rankine Cycle (ORC), Kalina Cycle (KC), and thermoelectric generators (TEG), with comprehensive analysis of their technical performance and economic viability. The study also assesses the feasibility and environmental advantages of using data center waste heat for district heating. This application, supported by heat pumps and thermal energy storage, could serve both residential and industrial areas. The study shows that waste heat recovery technologies can not only significantly reduce the Power Usage Effectiveness (PUE) of data centers, but also deliver substantial economic returns and emission reduction potential. In the future, the integration of green computing power with renewable energy will emerge as the cornerstone of sustainable data center development. Through intelligent energy management systems, cascaded energy utilization and regional energy synergy, data centers are poised to transition from traditional “energy-intensive facilities” to proactive “clean energy collaborators” within the smart grid ecosystem. Full article

The oil sector in Ecuador represents one of the largest national energy consumers, with significant contributions to greenhouse gas and thermal emissions due to reliance on diesel-based thermoelectric generation. This study assesses the feasibility of implementing waste heat recovery processes in upstream petroleum operations, aiming to improve energy efficiency and reduce the sector’s carbon footprint. Historical production and energy consumption data (2015–2020) from the main oil blocks (43-ITT, 57-Shushufindi, 57-Libertador, 58-Cuyabeno, 60-Sacha, and 61-Auca) were analyzed, alongside experimental parameters from thermoelectric equipment. Key energy indicators, including recoverable heat potential, energy intensity, and CO₂ emissions, were quantified to identify inefficiencies and opportunities for recovery. Results show that blocks with the highest crude production also exhibit the largest energy demand, with flue gas temperatures averaging 400 °C and an estimated recovery potential of up to 1.9 MWe through Rankine Cycle systems. Pre-feasibility analysis indicates a cost–benefit ratio of 1.03 under current conditions, which could reach 1.29 with higher load factors, while avoided emissions surpass 7000 tCO₂ annually. The findings highlight a strong correlation between energy intensity and CO₂ emissions, emphasizing the environmental relevance of recovery projects. Adoption of heat recovery technologies, coupled with regulatory incentives such as carbon pricing, offers a viable pathway to enhance energy efficiency, reduce operational costs, and strengthen sustainability in the Ecuadorian oil industry. Full article

Aqueous phase reforming has been posed as a promising technology for renewable hydrogen production in the framework of the transition to a sustainable energy economy. Since the use of chemical compounds as process feedstock has proven to be one of the major constraints to its potential scalability, several cost-free residual biomasses have been investigated as alternative substrates. This also allows for the recovery of residues, offsetting the significant costs of waste management through conventional treatment. In recent years, different wastes from the food processing industry such as brewery, fish canning, dairy industries, fruit juice extraction, and corn production wastewaters, have taken the attention of scientific community due to their composition, favorable to this process, and its high-water content. However, few and heterogeneous results can be found within the literature, suggesting that the research into this application is now at a stage of development which will require further investigation. Therefore, this work is focused on compiling and discussing the reported studies, aiming to present a critical reflection on the potential of aqueous phase reforming as a means for the valorization of this kind of residue. Full article

The rising amount of food industry waste has sparked interest in its valorization as a source of bioactive compounds. This study combines bibliometric analysis and a systematic review to map the scientific literature on the recovery of bioactive compounds from food byproducts, focusing on green extraction strategies and their alignment with the principles of the circular economy. A total of 176 documents, published between 2015 and 2025, were analyzed. The analysis shows significant growth after 2020 and highlights bioactive compounds, extraction, and the circular economy as the primary research themes. Italy, Spain, and Brazil emerged as the leading countries in scientific production. The systematic review covers green extraction techniques, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE), enzyme-assisted extraction (EAE), and natural deep eutectic solvent extraction (NADES). UAE- and NADES-based processes were the most frequently applied extraction techniques, mainly targeting phenolic compounds and flavonoids. Significant progress has been observed, particularly in the advancement of extraction technologies, in the recovery of key bioactive compounds, and in their industrial applications. These methods recover phenolics, flavonoids, anthocyanins, and other compounds with antioxidant, antimicrobial, and cardioprotective properties, which have potential applications in functional foods, nutraceuticals, pharmaceuticals, cosmetics, and biodegradable packaging. Nutraceuticals and functional foods represent the main application areas, followed by cosmetics and pharmaceuticals. Despite progress, challenges remain, including scalability, equipment costs, solvent recovery, and process standardization. The green extraction of bioactive compounds from food byproducts shows promise and can support the goals of the 2030 Agenda. Full article

Oil production generates approximately 250 million barrels of produced water (PW) daily, nearly three times the volume of oil, with salinity levels reaching up to 300,000 ppm. Improper management of this wastewater causes significant environmental degradation, including soil salinization and aquatic toxicity. To address these impacts, this study applies circular economy (CE) principles to PW management through flash vaporization and resource recovery. Implementing this approach enables 85–90% water recovery and reduces salinity to below 1000 ppm, allowing reuse for irrigation. Simultaneously, residual brine processed via evaporation ponds yields 15–25% potash (KCl) and 30–40% halite (NaCl), thereby transforming waste into valuable products. As a result, the integrated CE process can reduce wastewater disposal by 80%, cut greenhouse gas emissions by 25–30%, and lower treatment costs by 20–35%, while generating additional revenue of $150–300 per ton of recovered potash. These outcomes demonstrate that adopting CE strategies in PW management not only mitigates environmental degradation but also strengthens economic resilience and resource efficiency. The framework offers a scalable pathway for achieving the UN Sustainable Development Goals (SDG 6 and 12) and advancing sustainability within the oil and gas industry. Full article

Plastic pollution, driven by the durability and widespread use of polyolefins such as polypropylene (PP) and high-density polyethylene (HDPE), poses a formidable environmental challenge. To address this issue, we have developed an integrated multiscale framework that combines thermocatalytic experimentation, process-scale simulation, and molecular-level modeling to optimize the catalytic pyrolysis of PP and HDPE waste. Under the identified optimal conditions (300 °C, 10 wt % HMOR zeolite), liquid-oil yields of 60.8% for PP and 87.3% for HDPE were achieved, accompanied by high energy densities (44.2 MJ/kg, RON 97.5 for PP; 43.7 MJ/kg, RON 115.2 for HDPE). These values significantly surpass those typically reported for uncatalyzed pyrolysis, demonstrating the efficacy of HMOR in directing product selectivity toward valuable liquids. Above 400 °C, the process undergoes a pronounced shift toward gas generation, with gas fractions exceeding 50 wt % by 441 °C, underscoring the critical influence of temperature on product distribution. Gas-phase analysis revealed that PP-derived syngas contains primarily methane (20%) and ethylene (19.5%), whereas HDPE-derived gas features propylene (1.9%) and hydrogen (1.5%), highlighting intrinsic differences in bond-scission pathways governed by polymer architectures. Aspen Plus process simulations, calibrated against experimental data, reliably predict product distributions with deviations below 20%, offering a rapid, cost-effective tool for reactor design and scale-up. Complementary density functional theory (DFT) calculations elucidate the temperature-dependent energetics of C–C bond cleavage and radical formation, revealing that system entropy increases sharply at 500–550 °C, favoring the generation of both liquid and gaseous intermediates. By directly correlating catalyst acidity, molecular reaction mechanisms, and process-scale performance, this study fills a critical gap in plastic-waste valorization research. The resulting predictive platform enables rational design of catalysts and operating conditions for circular economy applications, paving the way for scalable, efficient recovery of fuels and chemicals from mixed polyolefin waste. Full article