Cleaner Engineering and Technology最新文献

The greater demand for energy has led to a surge in the utilization of fossil fuels, resulting in the rapid depletion of crude oil sources. Regrettably, this trend has engendered a significant negative environmental impact, primarily due to the release of unwanted carbon emissions into the atmosphere. Biodiesel has been considered a suitable substitute for fossil fuels owing to its availability from renewable feedstock, less polluting, sustainable and high biodegradability. However, the production of biodiesel from edible oils is very expensive due to the food versus fuel competition of the oil feedstock. Therefore, non-edible oils such as rubber seed oils have been considered suitable biodiesel feedstock due to their wide availability and abundance in different parts of the world. Rubber plantations are widely cultivated for their latex and the discarded seeds from rubber plantations could be considered as a potential source for biodiesel production. Hence, this review considers the extraction of oil from rubber seeds, the free fatty acid compositions, and physicochemical properties. It investigates biodiesel production from rubber seed oil and explores the variations in its physicochemical properties. The various kinds of catalysts that have been developed for biodiesel production from rubber seed oil were examined; the techno-economic analysis was discussed; the merits and challenges associated with the use of rubber seed oil as a suitable feedstock for biodiesel production were analyzed.

Sustainability and life-cycle assessment (LCA) studies of circular product value chains show evidence of considerable difficulty in capturing events such as product reuse and repair, because of unclear and uncertain representation of product displacement and behavioural-related factors. The present study examines how an approach based on displacement of product function and direct calculation of environmental impacts across partial life cycles might remedy these issues. A calculation framework based on the concept of environmental value and its depreciation along a life cycle is presented. Results for two value chains with qualitatively quite different features illustrate the utility and flexibility of the framework. The work offers significant conceptual advances in both recognising and measuring the relative impacts of using newer or older products providing the same function. As such it determines tangible environmental benefits for the use of older products which is a pre-requisite for reduced overall consumption and macro-level sustainability improvement.

Waste electrical and electronic equipment (WEEE, or e-waste) has been largely generated worldwide, but the estimated proportion of WEEE that undergoes the correct disposal is very low. The objective of this study was to evaluate e-waste trace metals in the leachate from disposal of WEEE in soil, using different analytical approaches to determine how these methods may interfere in the results. Different forms of WEEE and MSW landfilling and open dumping were simulated in column reactors to analyse the resultant leachates. Analyses of heavy metals in the leachates were performed in two ways: via inductively coupled plasma-mass-spectrometry with acid digestion of samples, following American Standard 3015A, and via inductively coupled plasma-optical emission spectrometry without acid digestion (US Environmental Protection Agency - USEPA, 2007). Metal concentrations found in the landfill and dumping simulations were similar, but a higher concentration of metals was found in samples with e-waste content, and those undergoing acid digestion prior to ICP analyses. Exceptions were Ba e Zn with a higher concentration without digestion, what may indicate the appearance of matrix effect. Concentrations of Pb, Cu and Mn in the leachates indicate possible interference with MSW. Additionally, it was evident that the timescale of observation influenced the results.

The objective of this study was to identify the optimal geopolymer binder compositions produced from local industrial by-products and compare them with commercially available materials. The first part investigated the optimal binder composition by studying 27 mixtures. In this part of the research, three series of binders were created: the first series of 18 mixtures was Na-based fly ash-slag, the second series consisted of 8 mixtures of K-based fly ash-slag, and the third series were a mixture of metakaolin-slag based geopolymer. The compressive strengths of the mixtures at the age of seven days ranged from 2.18 to 96.23 MPa. The strength development is clearly defined by the components and proportions of the blends. Geopolymers reach about 80% of their 28-day strength in seven days. The 25% water content was optimal for slag-fly ash geopolymers. The strength of the material increased from 68.08 to 96.23 MPa when the Blaine surface area of the slag increased from 3500 to 4500 cm²/g. The optimal proportions of the alkali solution were the intermediate ratios: SiO₂/Na₂O = 2.0 and SiO₂/K₂O = 1.5. In the case where Visonta fly ash is prepared for blending, the fly ash content can be maximized by 30%–50% in addition to the blast-furnace slag. In the second part of the research, mortars were prepared from the selected binders: 4 mixtures were prepared with two different binders. In one of these mortars, the solid part of the binder consisted of local raw materials originating from Hungary. This mixture was prepared with 43 m% fine aggregates. The optimal composition of the tested 27 binders tested was selected as the geopolymer matrix for the production of three further mortar mixtures. In these geopolymer mortars, 55, 65, and 75 m% of aggregate applied. The flowtable values of fresh mortars decreased when the proportion of sand increased. The lower the additive content was, the higher the strength of the geopolymer mortar. The 28-day compressive strengths of filtered fly ash-slag mortar sample with 55%, 65%, and 75% of fine aggregate (F–S-a55, F–S-a65, and F–S-a75) made with the selected optimised filtered fly ash-slag geopolymer binder of group A-I.3 (F–S-A-I.3) varied between 11.39 and 40.15 MPa, whereas the Visont fly ash-slag mortar sample with 43% of fine aggregate (V–S-a43) has been 25.05 MPa. For 28 days, the density ranged between 1870 and 2204 kg/m³. The V–S-a43 is found to be the lowest-density blend. The chloride migration test revealed that geopolymer mortars with higher slag content have higher resistance to Cl⁻ ions.

Floods pose recurrent threats to numerous countries, carrying substantial social, economic and at times, catastrophic implications, especially in extreme scenarios. In addition, coastal areas are strongly threatened by extreme weather events and climate change impacts. Given these pressing challenges, it becomes imperative to conduct thorough assessments of future flood impacts, particularly in areas of significant environmental and socio-economic importance. This study addresses this need by focusing on the potential consequences of flooding in the Loira River, situated in the municipality of Marín, Pontevedra, Northwestern Spain. For this purpose, the free software IBER has been used, these is a free software that solves the 2D depth-averaged shallow water equations (SWEs) by using a finite volume scheme, with the domain being discretized with both structured and unstructured triangular or quadrilateral elements. The hydrological model has been established from the maximum flow for different return periods (T10, T100 and T500). Field observations, including channel widths, bridge configurations, and various parameters, further inform our analysis. Our findings reveal critical insights, including a maximum height differential of 0.48 m, particularly significant at the upstream bridge, exacerbating flooding risks in adjacent plains. Moreover, velocities along riverbanks reach hazardous levels, notably during the 500-year return period, necessitating urgent protective measures for local residents. The hydrological model also indicates that small-scale forestation has no significant effect on flood prevention. This research underscores the utility of advanced hydrological modelling in informing risk management strategies and underscores the necessity of pre-emptive hydrological analyses to mitigate future flood risks effectively.

Many entrepreneurs across the US are the key players in building a greener economy. Their agility and innovative spirit offer a source of potential solutions. This is especially true for small businesses, which can quickly adapt to sustainable practices. Therefore, this research investigated the direct and indirect (mediating) roles of waste management and green innovations in green supply chain management and enviropreneurship performance, which is a transition from environmental to enviropreneurship advocacy. This study used a deductive approach with a quantitative research method. A study of a survey for 835 supply chain professionals in US small and medium enterprises used a Structural Equation Modeling technique to test specific research hypotheses. The findings of this study unveiled a positive and significant effect of exogenous variables on endogenous variables. Besides waste management and green innovation, a significant mediation was found between the relationships between green supply chain management and entrepreneurship performance. This research highlights key strategies to boost entrepreneurial performance. Green practices enhance environmental outcomes, minimize waste, bolster stakeholder relationships, lead to cost savings, and improve brand reputation and regulatory compliance. The study identifies areas needing improvement and supports sustainable development. Adhering to environmental regulations shows a commitment to sustainability and helps avoid legal issues. By following these recommendations, managers can foster a greener future for their organizations. This research presented "enviropreneurship performance" as a key factor for businesses implementing green supply chains and practices. It proposes an innovative model that connects green practices to this performance, providing important insights for future studies. The study validated this concept by employing a Resource-based View and testing the hypotheses using structural equation modeling, which enhanced the understanding of enviropreneurship within a developed economy.

Biolubricants are sustainable alternatives to mineral lubricants and offer environmental, economic and social benefits, including the possibility of producing bioproducts on-farm. Previous research showed that Indian mustard seed oil (IMSO) could be converted into biolubricants by double transesterification using potassium hydroxide as a homogeneous catalyst. The objective of this work was to study the effectiveness of the heterogeneous catalyst potassium bicarbonate (K₂CO₃) for the conversion of IMSO into biolubricant using an ethyl biodiesel precursor in a double transesterification-based process. The first transesterification reaction aimed to convert IMSO into ethyl biodiesel (IMSOEEs) by conducting the ethanolysis under various operating conditions to optimize the process. The optimal operating conditions obtained were: 78 °C, 1.01 bar, 4 wt% K₂CO₃, ethanol to oil molar ratio of 8, and a reaction time of 60 min (with addition of 25 wt% recycled glycerol at 60 min to improve demixing). The second transesterification reaction converted IMSOEEs into biolubricants through reactive distillation with 2-ethylhexanol (2 EH) under the following optimized operating conditions: 100 °C, 0.05 bar, 4 wt% K₂CO₃, 2 EH to IMSOEEs molar ratio of 4, and a reaction time of 120 min. Both ethyl biodiesel and biolubricant were produced with very satisfactory purity (≥96 wt%), thus meeting the expected functional properties.

This study looks at pro-environmental behaviors (PEBs) for waste reduction in Ecuador's heavily populated Guayas area. The research, which focuses on green consumer, recycler, and waste-preventer behaviors, applying an Extended Theory of Planned Behavior (TPB) to investigate the influence of attitudes, subjective norms, and perceived behavioral control on people's intentions to behave environmentally and uses external influences as moderating role variable. This research intends to contribute to targeted treatments and strategies promoting sustainable behaviors and environmental consciousness by better understanding the factors that drive waste reduction PEBs. A total of 3805 people were polled, and confirmatory analysis and structural equation modeling was utilized to review the data. The study finds that attitudes, perceived behavioral control, and subjective norms significantly influence citizens' intentions to engage in green consumer and waste-preventer behaviors. However, the intention to behave ecologically does not significantly affect recycler behavior. External influences also moderate the relationship between intentions and all three-waste reduction pro-environmental behaviors. This investigation illuminates the psychological dimensions underlying the observed variability in pro-environmental waste reduction behaviors among residents in a metropolitan area situated in South America, specifically within a developing world context. Finally, the study emphasizes the importance of addressing citizens' attitudes and norms to promote green consumerism, waste prevention, and recycling. Limitations include self-report bias and demographic bias. Future research should expand to include other regions and countries.

Strategies, plans, and techniques that a building follows from cradle to grave to reduce carbon emission and their evaluation processes are highly recommended by green building concepts. The existing methods do not compressively cover all the parameters and their interconnections. The objectives of this study are to evaluate the effectiveness of parameters that dominate the carbon emission of the building sector and to develop a priority weight-based rating model to evaluate the carbon emission of buildings. The rating model was developed using Fuzzy Analytic Hierarchy Process (FAHP) which is ideal for multi-criteria decision-making. The entire life cycle of a building was divided into five stages; material production, material transportation, construction, operation, and demolition, and each stage was divided into several sub-parameters. The relative significance of each parameter and each stage was compared and developed priority weight-based equations. The analysis of carbon emissions reveals the following distribution: Material Production (MP) contributed approximately 27%, Material Transportation (MT) accounted for 3%, the Construction Stage (CS) represented 10%, the Operation Stage (OS) dominated with 55%, while the Demolition Stage (DS) contributed 5%. The developed rating model was applied to ten building structures including small-scale, medium scale and large-scale buildings. The developed rating model would be provided a numerical framework-based solution for the owners and construction parties to identify low carbon emissions techniques.

Managing microgrid energy presents a complex challenge due to unpredictable renewable sources, fluctuating demand, and diverse equipment like batteries, distributed generators, and electric vehicles. This paper introduces a novel two-step optimization model, the Robust Day-Ahead Scheduling for Enhanced Resilience, tailored for microgrid operations. The model addresses the integration of electronic generation, uncertain demand patterns, and small-scale renewable resources. Detailed formulations optimize microgrid energy use, including strategic battery usage, efficient electric vehicle charging, balancing device utilization, and distributed generation dispatch. This multi-faceted approach aims to minimize costs over 24 h, including energy loss, power purchases, reduced power usage, generator operation, and battery/EV expenses. Employing a column-and-constraint generation (C&CG) algorithm ensures efficient problem solving. The proposed model achieved a significant reduction in operational costs, outperforming existing methods by at least 8%. Notably, it minimized energy purchases, energy losses, and load shedding while improving voltage stability, showcasing its effectiveness in enhancing microgrid performance and resilience.