Search Results (448)

Consolidated Bioprocessing (CBP) is a promising technology that integrates enzyme production, biomass hydrolysis, and sugars fermentation. However, CBP is underexplored from a process engineering point of view. Considering that cell recycling can increase process economic viability and that the selection of a bioreactor is a key factor to ensure process effectiveness, this study demonstrates the feasibility of recycling cells during sugarcane bagasse CBP by using magnetic immobilized enzyme producer yeast and a low shear stress vortex flow bioreactor. In the first step, Ca-alginate immobilized strains achieved good productivities (0.48 g/L/h) and 5.7 g/L of ethanol in only 12 h, but cell recovery was hindered by residual solids. To overcome this limitation, magnetic particles were incorporated into the spheres, allowing for rapid post-fermentation, maintaining ethanol production and productivity (6.1 g/L and 0.51 g/L/h). Three repeated batches were successful performed (producing an average of 5.5 g/L of ethanol, 0.46 g/L/h) with complete cell recovery from the remaining solid after biomass hydrolysis, maintaining high cell viability and bead integrity, highlighting the robustness of the immobilization strategy and the suitability of the bioreactor for the process. The successful cell recovery accomplished overcomes a fundamental limitation of bioprocesses carried out in the presence of solids. This strategy represents an important step for biorefineries development, with potential applicability to other bioprocesses using solid substrates. Full article

Latin America faces growing challenges in the management of municipal solid waste (MSW). This is particularly evident in medium-sized and metropolitan cities where rapid urbanization, limited infrastructure, and high proportions of organic waste (40–70%) converge. This review synthesizes the most recent advances in organic waste management, valorization strategies, environmental performance, and policy frameworks in Mexico and Latin America. To provide a comprehensive overview, evidence from studies on informal recycling systems, route optimization, sustainable landfill siting, food waste valorization, life cycle assessments (LCAs), and biogas production is integrated. Techno-economic analyses of energy recovery from organic fractions are specifically reviewed. This review highlights that valorization of organic waste through composting, anaerobic digestion, food supplementation, and bioproduct generation can reduce greenhouse gas emissions by 40–70% compared to landfilling, with AD–composting hybrids achieving the highest reductions of 60–70%. Community composting achieved moderate reductions, 30–50%, but at significantly lower cost and with greater social co-benefits. These alternatives for valorizing the organic fraction extend the lifespan of both confined and open landfills. It also contributes to mitigating the public health impacts related to open dumping, disease vectors, and contaminated leachate. In short, this review also highlights shortcomings in policy coherence, financial mechanisms, source separation, and technology adoption. A strategic framework is proposed that prioritizes decentralized treatment systems, the integration of informal recyclers, tax incentives, community-based waste separation, and planning based on Life Cycle Assessment (LCA). The findings point to a viable strategy for transitioning from landfill dependency to circular waste management systems that improve the quality of life for the population of Latin America and the Caribbean. Full article

The use of one-step products and their applications in sensory applications has gained much importance. Herein, Schiff’s base fluorescent turn-on sensor, namely FBTS, was synthesised via a condensation reaction between 6-fluorobenzo[d]thiazol-2-amine and 2-hydroxybenzaldehyde. The probe FBTS exhibits an intense “turn-on” blue fluorescence upon binding to Al³⁺ ions in a dimethyl sulfoxide–water (DMSO–H₂O (8:2, v/v)) medium. From photoluminescence (PL) titrations, the detection limit (LOD) for Al³⁺ is estimated to be 0.14 microM, and the Benesi–Hildebrand plot-based association constant (K_a) of 5.4 × 10⁴ M⁻¹ confirm a strong association between FBTS and Al³⁺. Negligible interference is observed in the presence of other metal ions. From the pH effect studies, the optimal pH range for Al³⁺ detection is 7–9. The recyclable reversibility of FBTS + Al³⁺ complex has been demonstrated via the sodium salt of ethylenediaminetetraacetic acid (Na₂-EDTA) chelation. A Job’s plot and interrogations, such as high-resolution mass spectrometry (HR-MS), ¹H-nuclear magnetic resonance (NMR) titration, and density functional theory (DFT), verified the 1:1 stoichiometry of binding between FBTS and Al³⁺. Based on multiple analyses, the binding mode and mechanism have been detailed. In addition, the practical application of FBTS for detecting Al³⁺ is demonstrated using the strip paper method, fish analysis, spiked real sample analysis, and cellular imaging. Full article

A method has been developed to delaminate the organic components (paint, foam) from the steel skins of composite polyisocyanurate (PIR) steel insulation panels at ambient temperature and in 20 min using selected solvents combined with ultrasonication. Using this method, polyisocyanurate foam can be selectively delaminated from polymer-based paint (PVC plastisol) and, in turn, the polymer paint can be selectively delaminated from the galvanised steel. Both the foam and paint are removed as intact layers, leaving the galvanised steel intact for the next steps of recycling, enabling the subsequent individualised recycling of each sub-component or layer. Several solvents have been tested, and the data show that H-bonding solvents (e.g., H₂O, alcohols) are less effective at delaminating these polymers. Whilst high polarity, medium H-bonding acetonitrile and DMSO remove PVC paint and some PIR foam, the most effective solvent for both PIR foam and PVC paint removal is medium polarity, medium H-bonding acetone. Full article

The role of Corporate Social Responsibility (CSR) in advancing economic, social, and environmental well-being has been increasingly acknowledged in the broader context of the United Nations Sustainable Development Goals. For instance, CSR in Saudi Arabia is increasingly framed as a mechanism to support Vision 2030—a national strategy aimed at transforming Saudi Arabia to a sustainable economy. However, evidence on how financial institutions disclose and prioritize CSR at the country level remains fragmented. This study examines the extent and patterns of CSR disclosure across the Saudi banking sector by analyzing publicly available documents, e.g., annual reports and ESG/CSR reports (n = 36) from 10 banks (4 Islamic and 6 commercial). Findings indicate that CSR disclosures were primarily clustered into four macro themes—society, economic contribution, internal stakeholders, and environment—with a strong thematic emphasis on philanthropic activities, financial donations, disability support, and financing for Small and Medium Enterprises (SMEs). Environmental initiatives were disclosed less frequently and were generally narrower in scope, focusing on resource efficiency, recycling, and selective green financing. In addition, a comparative analysis between Commercial and Islamic banks revealed that the latter focused on values-based CSR, while commercial ones emphasized governance-oriented CSR. Full article

Conventional life cycle assessment (LCA) of wood products often lacks a dynamic representation of biogenic carbon flows, leading to an oversimplified account of their climate impact. This study introduces a novel methodological framework by integrating a four-stage carbon storage cycle (carbon sequestration, first carbon emission, extension of carbon storage, and second carbon emission) with the ISO 14067:2018 standard for product carbon footprinting. We developed a transparent calculation model to partition CO₂ emissions across production, transportation, and disposal stages using a representative medium-density fiberboard (MDF) production case in China for empirical validation. The results reveal a total emission of 32.8135 kg CO₂/m², with a striking 59% originating from the disposal and recycling stage, overshadowing production (39%) and transportation (2%). This finding underscores the critical, yet often neglected, role of end-of-life management in the carbon footprint of manufactured wood panels. The study provides a replicable template for dynamic carbon accounting of wood products. Full article

Illegal solid waste dumping is a key urban sustainability challenge due to increased urbanisation and human consumption, but its prevalence and impacts across a socially differentiated gradient are seldom considered. We used street and off-street road surveys to examine the extent of illegal solid waste dumping across an income gradient in two medium-sized towns of Makhanda and Knysna in South Africa. We enumerated all dumpsites encountered in low- and high-income areas, recorded their GPS coordinates, and visually estimated size and composition using a standardised typology. We encountered 215 illegal solid waste dumpsites unevenly distributed by town (155 in Makhanda and 60 in Knysna) and income status, with the majority located in low-income areas compared to high-income areas. Most illegal solid waste dumpsites in low-income areas were small and located along roadsides and vacant plots. In both towns, illegal solid waste dumpsites were dominated by household and garden waste. The findings suggest that social differentiation matters in illegal solid waste dumping and should be factored into service provision strategies for ensuring environmental justice. We recommend that (i) municipalities should consider income heterogeneity in designing effective and equitable waste management plans, (ii) the national government should consider additional human and financial support to municipalities for efficient and equitable residential waste management, (iii) waste recycling at source (within households) should be mainstreamed in waste management strategies, and (iv) cleanup campaigns should be considered as a short-term solution to manage existing illegal solid waste dumpsites. Full article

Carbon Fiber Reinforced Thermoplastic Polymer (CFRTP) composites, particularly those utilizing Polyetheretherketone (PEEK) matrices, are becoming more demanding in the automotive and aerospace industries because of their outstanding strength, resilience to impact, and capacity for recycling. The employed heating methodology to prepare these materials is important both to improve them through uniform temperature distribution and to manage the energy consumption. The current study aims to address the encountered issues by experimentally comparing the radiative–thermal performance of medium-wave (1.4–2.5 µm) Quartz Tungsten (QTM) and long-wave (3.5–5.5 µm) Ceramic (FFEH) infrared emitters using a modular laboratory-scale heating system. While QTM emitters provided rapid heating rates, they induce significant through-thickness thermal gradients and surface degradation risks due to spectral mismatch with the polymer. In contrast, long-wave Ceramic emitters demonstrate superior spectral compatibility with PEEK, expanding the safe processing window and achieving complete melting at 343 °C with high thermal uniformity and approximately 18% lower effective energy demand compared to QTM systems. Furthermore, the structural integrity of the consolidated laminates has been validated through tensile testing, yielding an average tensile strength of 873 MPa and a tensile modulus of 56.3 GPa. These findings confirm the importance of optimizing the emitter wavelength not only for energy efficiency, but also for ensuring matrix integrity and mechanical performance in high-performance composite manufacturing. Full article

The use of Type III Deep Eutectic Solvents (DESs) as both solvents and cocatalysts enable the one-pot synthesis of several β-ketosulfides, structural motifs commonly found in biologically active compounds, via a multicomponent reaction (MCR) involving 2-bromoketones, alkyl or benzyl halides, and potassium thioacetate in basic medium. Under these conditions, it was possible to avoid not only the use of the non-eco-friendly solvent dimethylformamide (DMF), but also an additional hydrolytic step previously reported for the preparation of these molecules. The MCR conducted in the presence of the DES ChCl:Gly (1:2) was optimized through the evaluation of different reaction parameters. Notably, the non-conventional medium could be recycled up to four times without any appreciable loss of catalytic activity. Environmental metrics, including the E factor, E+ factor, and Global Warming Potential (GWP), were calculated for the process both in the presence and absence of the DES, demonstrating improved environmental performance when the DES was employed. Full article

The increasing production and accumulation of plastic waste, coupled with insufficient recycling practices, contribute to the growing presence of plastic in the environment. Nanoplastic particles are of particular concern, as they pose greater (health and environmental) risks and exhibit wider dispersion compared to macroplastics. The blood–brain barrier may be exposed to nanoplastics present in the blood, which could affect its functionality or even pass through and damage the central nervous system. This study examined the effects of polystyrene (PS) nanoparticles with different chemical surface modifications (pristine, carboxylated, aminated) and sizes (50 nm and 100 nm) on cells of the neurovascular unit (NVU): human brain endothelial cells, astrocytes, and pericytes. Results indicated that only high concentrations of nanoparticles (100 μg/mL and 300 μg/mL) applied for 48 h decreased cell viability and barrier integrity significantly. Specifically, 50 nm carboxylated PS particles reduced barrier integrity and altered tight junction gene expression substantially. Fluorescent labelling of the investigated particles enabled to confirm their uptake by all tested cell types of the NVU, but also highlighted that the labelling changes the particles’ properties. Furthermore, cell culture medium-dependent particle agglomeration and increase of size were inversely correlated with cellular internalisation, which has to be considered for future risk assessments. Full article

Owing to population expansion, widespread diseases and pandemics, climate alterations, and evolving consumer preferences, the optimization of production processes and technological advancements in food processing have become imperative. The integration of nanotechnology with food processing technology, characterized by numerous advantages, holds the promise to establish a secure, efficient, and sustainable food supply system. Nanoparticles can mitigate the risk of microbial contamination through the generation of reactive oxygen species and by leveraging their electrical charge properties to exert antibacterial effects or detoxify; they can serve as an energy transfer medium to enhance food quality; or utilize its high catalytic efficiency for the recycling and decomposition of food waste. When integrated with food processing technologies, they demonstrate a synergistic or additive effect. This paper reviews representative instances of the convergence between nanotechnology and food processing technologies, elucidates the practical application effects and underlying mechanisms, aims to inform the development of more advantageous application strategies for nanotechnology in the realm of food processing. Full article

The growing environmental impact of conventional textile dyeing processes, particularly their high water consumption, chemical usage, and wastewater generation, has intensified the need for alternatives. For this reason, the textile industry faces increasing pressure to adopt sustainable production routes that minimize environmental loads. The utilization of recycled polyester fabrics, natural dyes, and waste-derived bio-resources within waterless dyeing systems represents a holistic approach toward environmentally responsible textile manufacturing. This study focuses on the production of sustainable textiles by dyeing recycled polyester fabrics with natural madder dye and eggshell powder in a waterless supercritical CO₂ medium. The samples were characterized via SEM, TGA, wash fastness tests, and tensile strength measurements. SEM images clearly revealed the presence of eggshell powder (ESP) on the fabric surfaces. After UV aging, the samples containing 20% ESP exhibited higher tensile strength and more pronounced color stability compared to the control sample. The CaCO₃ component of the ESP contributed to UV resistance, while the TGA results showed higher residual mass for ESP-treated samples, indicating improved thermal stability. Moreover, the persistence of ESP on the fabric surface after repeated washing and the satisfactory wash fastness results confirmed the durability of the treatment. Overall, the results demonstrate that the combination of natural dye, recycled polyester, and eggshell-derived bio-additives in a waterless scCO₂ dyeing system offers a promising and environmentally benign strategy for producing sustainable and functional textile materials. Full article

Reducing fuel costs, maximizing waste utilization, and improving energy efficiency are critical challenges in agricultural thermal processes. This study addresses these issues by developing and evaluating a mixed-fuel burner and furnace system for steaming mushroom substrate cubes using crude glycerol and recycled vegetable oil as low-cost alternative energy sources. The experimental investigation assessed boiler thermal efficiency, combustion efficiency, exhaust-gas composition, temperature distribution, steam generation, and combustion-gas dispersion within the furnace. In parallel, analytical modeling of pressure, temperature, and gas-flow behavior was performed to validate the experimental observations. Five fuel compositions were examined, including 100% used vegetable oil, 100% crude glycerol, and blended ratios of 50/50, 25/75, and 10/90 (glycerol/vegetable oil), with all tests conducted in accordance with DIN EN 203-1 standards. The results demonstrate that blending used vegetable oil with glycerol significantly improves flame stability, increases peak combustion temperatures, and suppresses incomplete-combustion byproducts compared with pure glycerol operation. Combustion efficiencies of 90–99% and boiler thermal efficiencies of 72–73% were achieved. Among the tested fuels, the optimal balance between combustion stability, efficiency, and cost was achieved with a 25% glycerol and 75% used vegetable oil mixture. Economic analysis revealed that the proposed mixed-fuel system offers superior viability compared with LPG, reducing annual fuel costs by approximately 50%, shortening steaming time by 2 h per batch, and achieving a payback period of only 3.26 months. These findings confirm the feasibility of the proposed waste-to-energy system for small- and medium-scale agricultural applications. To further enhance sustainability and renewable fuel utilization, future work should focus on improving air–fuel mixing for higher glycerol fractions, scaling the system for larger farms, and extending its application to other agricultural thermal processes. Full article

Transparent polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET) are widely used as glass alternatives in algal bioreactors, where optical clarity and mechanical stability are crucial. However, their long-term use is limited by surface degradation processes. Photodegradation, hydrolysis, and biofilm accumulation can reduce light transmission in the 400–700 nm range essential for photosynthesis. This study examined the aging of PMMA, PC, and PET under bioreactor conditions. Samples were exposed for 70 days to illumination, culture medium, and aquatic environments. Changes in their optical transmittance, surface roughness, and wettability were analyzed. All polymers exhibited measurable surface degradation, characterized by an average 15% loss in transparency, significant increases in surface roughness, and reduced contact angles. PMMA demonstrated the highest optical stability, maintaining strong transmission in key blue and red spectral regions, while PET performed the worst, showing low initial clarity and the steepest decline. The most severe surface degradation occurred in areas exposed to the receding liquid interface, highlighting the need for targeted cleaning and/or a reduction in the size of the liquid–vapor transition zone. Overall, the results identify PMMA and recycled PMMA (PMMA_R) as durable, cost-effective materials for transparent bioreactor walls. Full article

1,4-Dihydropyridines (1,4-DHPs) are privileged heterocycles with broad relevance in medicinal chemistry and redox-related applications. However, conventional Hantzsch syntheses typically require prolonged thermal heating and often suffer from limited efficiency and regioselectivity. Herein, we report a sustainable and efficient microwave-assisted protocol for the synthesis of 1,4-DHPs, employing phosphotungstic acid (HPW) as a heteropolyacid catalyst in PEG-400 as a green reaction medium. The multicomponent cyclocondensation proceeds rapidly under microwave irradiation, affording the desired 1,4-DHP derivatives in good to excellent yields within short reaction times. Compared with classical acid-catalyzed conditions, the HPW/PEG-400 system markedly enhances regioselectivity toward the 1,4-DHP framework while simultaneously reducing energy input. Moreover, the catalytic system exhibits good recyclability, underscoring its potential as a practical and environmentally responsible platform for the synthesis of bioactive 1,4-dihydropyridine scaffolds. Full article