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Clean Technol., Volume 7, Issue 3 (September 2025) – 10 articles

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34 pages, 2617 KiB  
Article
Toward Low-Carbon Mobility: Greenhouse Gas Emissions and Reduction Opportunities in Thailand’s Road Transport Sector
by Pantitcha Thanatrakolsri and Duanpen Sirithian
Clean Technol. 2025, 7(3), 60; https://doi.org/10.3390/cleantechnol7030060 - 11 Jul 2025
Abstract
Road transportation is a major contributor to greenhouse gas (GHG) emissions in Thailand. This study assesses the potential for GHG mitigation in the road transport sector from 2018 to 2030. Emission factors for various vehicle types and technologies were derived using the International [...] Read more.
Road transportation is a major contributor to greenhouse gas (GHG) emissions in Thailand. This study assesses the potential for GHG mitigation in the road transport sector from 2018 to 2030. Emission factors for various vehicle types and technologies were derived using the International Vehicle Emissions (IVE) model. Emissions were then estimated based on country-specific vehicle data. In the baseline year 2018, total emissions were estimated at 23,914.02 GgCO2eq, primarily from pickups (24.38%), trucks (20.96%), passenger cars (19.48%), and buses (16.95%). Multiple mitigation scenarios were evaluated, including the adoption of electric vehicles (EVs), improvements in fuel efficiency, and a shift to renewable energy. Results indicate that transitioning all newly registered passenger cars (PCs) to EVs while phasing out older models could lead to a 16.42% reduction in total GHG emissions by 2030. The most effective integrated scenario, combining the expansion of electric vehicles with improvements in internal combustion engine efficiency, could achieve a 41.96% reduction, equivalent to 18,378.04 GgCO2eq. These findings highlight the importance of clean technology deployment and fuel transition policies in meeting Thailand’s climate goals, while providing a valuable database to support strategic planning and implementation. Full article
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22 pages, 1200 KiB  
Review
Valorization of Agricultural Ashes from Cold and Temperate Regions as Alternative Supplementary Cementitious Materials: A Review
by A. Sadoon, M. T. Bassuoni and A. Ghazy
Clean Technol. 2025, 7(3), 59; https://doi.org/10.3390/cleantechnol7030059 - 11 Jul 2025
Abstract
The pursuit of sustainable alternatives to portland cement has become a global imperative within the construction sector, driven by the need to reduce carbon dioxide emissions and energy consumption. Among the promising alternatives, agricultural ashes have garnered attention for their potential as alternative [...] Read more.
The pursuit of sustainable alternatives to portland cement has become a global imperative within the construction sector, driven by the need to reduce carbon dioxide emissions and energy consumption. Among the promising alternatives, agricultural ashes have garnered attention for their potential as alternative supplementary cementitious materials (ASCMs), owing to their inherent pozzolanic properties when appropriately processed. However, the availability and utilization of these ashes have predominantly been concentrated in tropical and subtropical regions, where such biomass is more abundant. This review offers a comprehensive bibliometric analysis to identify and assess agricultural ashes (specifically switchgrass, barley, sunflower, and oat husks) that are cultivated in temperate and cold climates and exhibit potential for SCM application. The analysis aims to bridge the knowledge gap by systematically mapping the existing research landscape and highlighting underexplored resources suitable for cold-region implementation. Key processing parameters, including incineration temperature, retention duration, and post-combustion grinding techniques, are critically examined for their influence on the resulting ash’s physicochemical characteristics and pozzolanic reactivity. In addition, the effect on fresh, hardened, and durability properties was evaluated. Findings reveal that several crops grown in colder regions may produce ashes rich in reactive silica, thereby qualifying them as viable ASCM candidates and bioenergy sources. Notably, the ashes derived from switchgrass, barley, oats, and sunflowers demonstrate significant reactive silica content, reinforcing their potential in sustainable construction practices. Hence, this study underscores the multifaceted benefits of contributing to the decarbonization of the cement industry and circular economy, while addressing environmental challenges associated with biomass waste disposal and uncontrolled open-air combustion. Full article
48 pages, 5755 KiB  
Review
Accelerated Carbonation of Waste Incineration Residues: Reactor Design and Process Layout from Laboratory to Field Scales—A Review
by Quentin Wehrung, Davide Bernasconi, Fabien Michel, Enrico Destefanis, Caterina Caviglia, Nadia Curetti, Meissem Mezni, Alessandro Pavese and Linda Pastero
Clean Technol. 2025, 7(3), 58; https://doi.org/10.3390/cleantechnol7030058 - 11 Jul 2025
Abstract
Municipal solid waste (MSW) and refuse-derived fuel (RDF) incineration generate over 20 million tons of residues annually in the EU. These include bottom ash (IBA), fly ash (FA), and air pollution control residues (APCr), which pose significant environmental challenges due to their leaching [...] Read more.
Municipal solid waste (MSW) and refuse-derived fuel (RDF) incineration generate over 20 million tons of residues annually in the EU. These include bottom ash (IBA), fly ash (FA), and air pollution control residues (APCr), which pose significant environmental challenges due to their leaching potential and hazardous properties. While these residues contain valuable metals and reactive mineral phases suitable for carbonation or alkaline activation, chemical, techno-economic, and policy barriers have hindered the implementation of sustainable, full-scale management solutions. Accelerated carbonation technology (ACT) offers a promising approach to simultaneously sequester CO2 and enhance residue stability. This review provides a comprehensive assessment of waste incineration residue carbonation, covering 227 documents ranging from laboratory studies to field applications. The analysis examines reactor designs and process layouts, with a detailed classification based on material characteristics, operating conditions, investigated parameters, and the resulting pollutant stabilization, CO2 uptake, or product performance. In conclusion, carbonation-based approaches must be seamlessly integrated into broader waste management strategies, including metal recovery and material repurposing. Carbonation should be recognized not only as a CO2 sequestration process, but also as a binding and stabilization strategy. The most critical barrier remains chemical: the persistent leaching of sulfates, chromium(VI), and antimony(V). We highlight what we refer to as the antimony problem, as this element can become mobilized by up to three orders of magnitude in leachate concentrations. The most pressing research gap hindering industrial deployment is the need to design stabilization approaches specifically tailored to critical anionic species, particularly Sb(V), Cr(VI), and SO42−. Full article
(This article belongs to the Collection Review Papers in Clean Technologies)
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16 pages, 2609 KiB  
Article
Comparative Life Cycle and Techno-Economic Assessment of Constructed Wetland, Microbial Fuel Cell, and Their Integration for Wastewater Treatment
by Nicholas Miwornunyuie, Samuel O. Alamu, Guozhu Mao, Nihed Benani, James Hunter and Gbekeloluwa Oguntimein
Clean Technol. 2025, 7(3), 57; https://doi.org/10.3390/cleantechnol7030057 - 10 Jul 2025
Abstract
This study systematically compares the environmental and economic performance of three wastewater treatment systems: constructed wetlands (CWs), microbial fuel cells (MFCs), and their integration (CW–MFC). Lab-scale units of each system were constructed using a multi-media matrix (gravel, zeolite, and granular activated carbon), composite [...] Read more.
This study systematically compares the environmental and economic performance of three wastewater treatment systems: constructed wetlands (CWs), microbial fuel cells (MFCs), and their integration (CW–MFC). Lab-scale units of each system were constructed using a multi-media matrix (gravel, zeolite, and granular activated carbon), composite native wetland species (Juncus effusus, Iris sp., and Typha angustifolia), carbon-based electrodes (graphite), and standard inoculum for CW and CW–MFC. The MFC system employed carbon-based electrodes and proton-exchange membrane. The experimental design included a parallel operation of all systems treating domestic wastewater under identical hydraulic and organic loading rates. Environmental impacts were quantified across construction and operational phases using life cycle assessment (LCA) with GaBi software 9.2, employing TRACI 2021 and ReCiPe 2016 methods, while techno-economic analysis (TEA) evaluated capital and operational costs. The key results indicate that CW demonstrates the lowest global warming potential (142.26 kg CO2-eq) due to its reliance on natural biological processes. The integrated CW–MFC system achieved enhanced pollutant removal (82.8%, 87.13%, 78.13%, and 90.3% for COD, NO3, TN, and TP) and bioenergy generation of 2.68 kWh, balancing environmental benefits with superior treatment efficiency. In contrast, the stand-alone MFC shows higher environmental burdens, primarily due to energy-intensive material requirements and fabrication processes. TEA results highlight CW as the most cost-effective solution (USD 627/m3), with CW–MFC emerging as a competitive alternative when considering environmental benefits and operational efficiencies (USD 718/m3). This study highlights the potential of hybrid systems, such as CW–MFC, to advance sustainable wastewater treatment technologies by minimizing environmental impacts and enhancing resource recovery, supporting their broader adoption in future water management strategies. Future research should focus on optimizing materials and energy use to improve scalability and feasibility. Full article
(This article belongs to the Collection Water and Wastewater Treatment Technologies)
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27 pages, 1431 KiB  
Article
Environmental and Behavioral Dimensions of Private Autonomous Vehicles in Sustainable Urban Mobility
by Iulia Ioana Mircea, Eugen Rosca, Ciprian Sorin Vlad and Larisa Ivascu
Clean Technol. 2025, 7(3), 56; https://doi.org/10.3390/cleantechnol7030056 - 7 Jul 2025
Viewed by 278
Abstract
In the current context, where environmental concerns are gaining increased attention, the transition toward sustainable urban mobility stands out as a necessary and responsible step. Technological advancements over the past decade have brought private autonomous vehicles, particularly those defined by the Society of [...] Read more.
In the current context, where environmental concerns are gaining increased attention, the transition toward sustainable urban mobility stands out as a necessary and responsible step. Technological advancements over the past decade have brought private autonomous vehicles, particularly those defined by the Society of Automotive Engineers Levels 4 and 5, into focus as promising solutions for mitigating road congestion and reducing greenhouse gas emissions. However, the extent to which Autonomous Vehicles can fulfill this potential depends largely on user acceptance, patterns of use, and their integration within broader green energy and sustainability policies. The present paper aims to develop an integrated conceptual model that links behavioral determinants to environmental outcomes, assessing how individuals’ intention to adopt private autonomous vehicles can contribute to sustainable urban mobility. The model integrates five psychosocial determinants—perceived usefulness, trust in technology, social influence, environmental concern, and perceived behavioral control—with contextual variables such as energy source, infrastructure availability, and public policy. These components interact to predict users’ intention to adopt AVs and their perceived contribution to urban sustainability. Methodologically, the study builds on a narrative synthesis of the literature and proposes a framework applicable to empirical validation through structural equation modeling (SEM). The model draws on established frameworks such as Technology Acceptance Model (TAM), Theory of Planned Behavior, and Unified Theory of Acceptance and Use of Technology, incorporating constructs including perceived usefulness, trust in technology, social influence, environmental concern, and perceived behavioral control, constructs later to be examined in relation to key contextual variables, including the energy source powering Autonomous Vehicles—such as electricity from mixed or renewable grids, hydrogen, or hybrid systems—and the broader policy environment (regulatory frameworks, infrastructure investment, fiscal incentives, and alignment with climate and mobility strategies and others). The research provides relevant directions for public policy and behavioral interventions in support of the development of clean and smart urban transport in the age of automation. Full article
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20 pages, 9651 KiB  
Article
Recovery of Vegetable Fibers from Licorice Processing Waste and a Case Study for Their Use in Green Building Products
by Luigi Madeo, Anastasia Macario, Sebastiano Candamano and Pierantonio De Luca
Clean Technol. 2025, 7(3), 55; https://doi.org/10.3390/cleantechnol7030055 - 7 Jul 2025
Viewed by 169
Abstract
The present research is aimed at the recovery of vegetable fibers from licorice root processing waste through simple methods that do not involve the use of chemical reagents to guarantee a complete eco-sustainability approach and for their use in the production of fiber-reinforced [...] Read more.
The present research is aimed at the recovery of vegetable fibers from licorice root processing waste through simple methods that do not involve the use of chemical reagents to guarantee a complete eco-sustainability approach and for their use in the production of fiber-reinforced ecomaterials. The waste was treated through several washing cycles with only water at different temperatures to identify the optimal conditions to obtain clean fibers. The clean fibers and the waste were analyzed and characterized in advance by scanning electron microscopy (SEM), microanalysis (EDS) and thermal analysis (DSC). Subsequently, both the clean fibers and the waste were used to produce fiber-reinforced plaster artifacts. The mechanical properties of the artifacts were measured as a function of % clean fibers or untreated waste. The results obtained showed that it is possible to effectively recover clean vegetable fibers from licorice waste through repeated washing cycles of 30 min with only water. By increasing the temperature, the necessary washing cycles decrease, and a good compromise is five washes at 100 °C. The yield of clean fibers compared to waste is 50%. The creation of prototypes of gypsum matrix panels, which incorporate fibers recovered from licorice processing waste through the methodology tested in this study, has also been successfully realized, representing a significant step forward towards practical applications in the field of eco-friendly construction. Full article
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15 pages, 2650 KiB  
Article
The Impact of Tetraethyl Pyrophosphate (TEPP) Pesticide on the Development and Behavior of Danio rerio: Evaluating the Potential of Cork Granules as a Natural Adsorbent for TEPP Removal from Aqueous Environments
by Fernanda Blini Marengo Malheiros, Lorrainy Victoria Rodrigues de Souza, Angélica Gois Morales, Eduardo Festozo Vicente, Paulo C. Meletti and Carlos Alberto-Silva
Clean Technol. 2025, 7(3), 54; https://doi.org/10.3390/cleantechnol7030054 (registering DOI) - 28 Jun 2025
Viewed by 258
Abstract
Toxicological studies of pesticides in animal models provide critical insights into their mechanisms of action, while adsorption strategies offer potential solutions for decontaminating polluted waters. We evaluated toxicity induced by tetraethyl pyrophosphate (TEPP), an organophosphate pesticide and AChE inhibitor, on zebrafish (Danio [...] Read more.
Toxicological studies of pesticides in animal models provide critical insights into their mechanisms of action, while adsorption strategies offer potential solutions for decontaminating polluted waters. We evaluated toxicity induced by tetraethyl pyrophosphate (TEPP), an organophosphate pesticide and AChE inhibitor, on zebrafish (Danio rerio) development and behavior, alongside the efficacy of wine cork granules as a natural adsorbent. TEPP exposure reduced embryo viability following an inverted U-shaped dose–response curve, suggesting non-monotonic neurodevelopmental effects, but did not alter developmental timing or morphology in survivors. In juveniles, TEPP increased preference for dark environments (33% vs. controls) and enhanced swimming endurance approximately 3-fold, indicating disrupted phototaxis and stress responses. Most strikingly, water treated with cork granules retained toxicity, increasing mortality, delaying embryogenesis, and altering behavior. This directly contradicts in vitro adsorption studies that suggested cork’s efficacy. These results demonstrate the high sensitivity of zebrafish to TEPP at nanomolar concentrations, which contrasts with in vitro models that require doses approximately 1000 times higher. Our findings not only highlight TEPP’s ecological risks but also reveal unexpected limitations of cork granules for environmental remediation, urging caution in their application. Full article
(This article belongs to the Special Issue Pollutant Removal from Aqueous Solutions by Adsorptive Biomaterials)
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23 pages, 3474 KiB  
Article
Performance of Ventilation, Filtration, and Upper-Room UVGI in Mitigating PM2.5 and SARS-CoV-2 Levels
by Atefeh Abbaspour, Hamidreza Seraj, Ali Bahadori-Jahromi and Alan Janbey
Clean Technol. 2025, 7(3), 53; https://doi.org/10.3390/cleantechnol7030053 - 23 Jun 2025
Viewed by 394
Abstract
This study aimed to improve indoor air quality (IAQ) in an existing college building in London by addressing two key pollutants: PM2.5 particles (from indoor and outdoor sources) and SARS-CoV-2 as a biological contaminant. Various mitigation strategies were assessed, including hybrid ventilation [...] Read more.
This study aimed to improve indoor air quality (IAQ) in an existing college building in London by addressing two key pollutants: PM2.5 particles (from indoor and outdoor sources) and SARS-CoV-2 as a biological contaminant. Various mitigation strategies were assessed, including hybrid ventilation that combined CIBSE-recommended rates with partial window and door opening. The effectiveness of HEPA-based air purifiers (APs) and upper-room ultraviolet germicidal irradiation (UVGI) systems with different intensities was also evaluated for reducing viral transmission and the basic reproduction number (R0). To manage PM2.5 in the kitchen, HEPA and in-duct MERV13 filters were integrated into the ventilation system. Results showed that hybrid ventilation outperformed mechanical systems by achieving greater reductions in infection probability (PI) and maintained higher performance as the number of infectors increased, showing only a 2.5–16% drop, compared to 35% with mechanical ventilation. An R0 analysis indicated that UVGI is more suitable in high-risk settings, while APs combined with hybrid ventilation are effective in lower-risk scenarios. The findings also emphasize that combining Supply–Exhaust ventilation with APs or MERV13 filters is crucial for maintaining safe IAQ in kitchens, aligning with the WHO’s short- and long-term exposure limits. Full article
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37 pages, 11435 KiB  
Article
Hybrid Energy-Powered Electrochemical Direct Ocean Capture Model
by James Salvador Niffenegger, Kaitlin Brunik, Todd Deutsch, Michael Lawson and Robert Thresher
Clean Technol. 2025, 7(3), 52; https://doi.org/10.3390/cleantechnol7030052 - 23 Jun 2025
Viewed by 270
Abstract
Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require [...] Read more.
Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require a variety of low-carbon energy sources to operate, such as variable renewable energy. However, the impacts of variable power on direct ocean capture have not yet been thoroughly investigated. To facilitate future deployments, a generalizable model for electrodialysis-based direct ocean capture plants is created to evaluate plant performance and electricity costs under intermittent power availability. This open-source Python-based model captures key aspects of the electrochemistry, ocean chemistry, post-processing, and operation scenarios under various conditions. To incorporate realistic energy supply dynamics and cost estimates, the model is coupled with the National Renewable Energy Laboratory’s H2Integrate tool, which simulates hybrid energy system performance profiles and costs. This integrated framework is designed to provide system-level insights while maintaining computational efficiency and flexibility for scenario exploration. Initial evaluations show similar results to those predicted by the industry, and demonstrate how a given plant could function with variable power in different deployment locations, such as with wind energy off the coast of Texas and with wind and wave energy off the coast of Oregon. The results suggest that electrochemical systems with greater tolerances for power variability and low minimum power requirements may offer operational advantages in variable-energy contexts. However, further research is needed to quantify these benefits and evaluate their implications across different deployment scenarios. Full article
(This article belongs to the Topic CO2 Capture and Renewable Energy, 2nd Edition)
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25 pages, 3287 KiB  
Article
Evaluation of Properties and Bioactivity of Silver (Ag) Nanoparticles (NPs) Fabricated Using Nixtamalization Wastewater (Nejayote)
by Alejandra Ortiz-De Lira, J. A. Lozano-Álvarez, N. A. Chávez-Vela, C. E. Escárcega-González, Enrique D. Barriga-Castro, Hilda E. Reynel-Ávila and Iliana E. Medina-Ramírez
Clean Technol. 2025, 7(3), 51; https://doi.org/10.3390/cleantechnol7030051 - 20 Jun 2025
Viewed by 358
Abstract
Nejayote (Nej), an effluent from nixtamalization process, has an alkaline pH and contains a high load of organic matter in suspension and dissolution, which makes it a highly polluting waste when discharged directly into the environment. However, the sustainable reuse of this effluent [...] Read more.
Nejayote (Nej), an effluent from nixtamalization process, has an alkaline pH and contains a high load of organic matter in suspension and dissolution, which makes it a highly polluting waste when discharged directly into the environment. However, the sustainable reuse of this effluent is relevant since it contains high-value compounds (ferulic acid (FA)) with appropriate activity for the ecological synthesis of silver nanoparticles (AgNPs). This study explores the synthesis of AgNPs using Nej as a reducing and stabilizing agent and evaluates the antibacterial effectiveness of AgNPs against Escherichia coli (E. coli). The AgNPs under study possess excellent optical (UV-Vis) and structural properties (XRD). HR-TEM images show predominantly spherical particles, with an average size of 20 nm. FTIR spectroscopy identified functional groups, including phenols and flavonoids, on the nanoparticle surface, acting as stabilizing agents. HPLC supports the existence of FA in the AgNPs. Biogenic AgNPs exhibit enhanced antibacterial activity due to the adsorption of these functional groups onto their surface, which contributes to bacterial membrane disruption. Finally, no hemolytic or cytotoxic activity was observed, suggesting that the AgNPs exert antimicrobial activity without potentially harmful doses (biocompatibility). The study highlights the potential of Nej as a sustainable source for use in nanoparticle synthesis, promoting the recycling of agro-industrial waste and the production of materials with technological applications. Full article
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