Cleaner Materials最新文献

The global scientific research circle and government agencies face a number of serious environmental challenges, one of which is the recycling of “End of Life Tires” (ELT). An estimation of one billion tires is expected to end their useful life annually, of which only roughly 50% are recycled at the moment, with the remainder ending up in landfills. Consequently, to solve this gap in the ELT's utilization rate, it is imperative to enhance the current application and furthermore create new applications for recycled tire materials. One of such areas that is currently being investigated is the introduction of waste tire into concrete as partial replacement of natural aggregates in concrete production. Despite its great prospects, it has drawbacks such as lack of proper bonding with the cement matrix and weak rubber intrinsic strength, which make it unsuitable for widespread usage as an aggregate. To get past this obstacle, numerous rubber treatment techniques that enhance the mechanical characteristics of rubber concrete remarkably as well as the bonding properties have been studied by researchers. The impact of rubber percentage replacement, rubber aggregate size and different treatment techniques on various mechanical characteristics of rubber concrete are examined in this review paper. But in order for the concrete industry to embrace it, the researchers need to devise a rubber treatment technique that can tackle the issues of high combustible and the harmful gases that are released from the rubber aggregates when they come in contact with fire.

This study intends to investigate the influence of benzaldehyde and dioctyl phthalate (DOP) on the rheological properties and microstructure of direct coal liquefaction residue (DCLR) modified asphalt binder. The high and low temperature rheological properties and fatigue properties were obtained by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) tests were conducted to evaluate the mechanism of property improvement in the DCLR modified asphalt binder. The results showed that the addition of DCLR increased the complex shear modulus G*, rutting factor G*/sin $\delta$ and fatigue life N_f of base asphalt binder, significantly improving the high temperature deformation resistance and fatigue resistance of base asphalt binder. This was attributed to the hardening effect resulting from the addition of DCLR, which enhanced the elastic properties, weakened the viscous properties and fluidity of asphalt binder. Additionally, the use of benzaldehyde and DOP reduced the creep stiffness S and lower continuous grading temperature Tc of DCLR modified asphalt binder, which compensated for the shortcomings of low temperature rheological properties of asphalt binder. The SEM images indicated that benzaldehyde and DOP significantly increased the compatibility of DCLR with the base asphalt binder. The FTIR tests showed that the addition of benzaldehyde and DOP introduced the aldehyde and ester groups, which were interacted with more polar functional groups in the asphalt to reduce the resistance to movement between the heavy components in the DCLR modified asphalt binder, which promoted the flow of asphalt and the dispersion of DCLR, and as a result, the benzaldehyde and DOP modified DCLR asphalt binder exhibited satisfied rheological properties.

Due to rapid population growth and urbanization, construction activities have increased worldwide resulting in generation of enormous volume of construction and demolition (C&D) waste. On one hand, C&D waste is generated during the construction, destruction, and rehabilitation of existing structures. While on the other, the transportation sector consumes large volumes of aggregates for pavement construction and maintenance. The extraction of finite natural aggregates causes potential damage to the environment. Recycled C&D waste, once converted into recycled aggregates, has the potential to be utilized in pavement layers due to its sound quality and composition; also resulting in lowering the landfill loads. This review article critically summarizes the environmental risks regarding chemical composition and leaching behavior of C&D wastes in pavements. Additionally, this review evaluates the environmental impacts of C&D waste aggregate production and application in pavements using life cycle assessment (LCA). Overall, the aim of this study is to investigate the environmental impacts and benefits of C&D waste to enable highway administrations to adopt and promote the use of C&D waste in development of sustainable road infrastructure. In this way, the review article attempts to promote a new era of sustainable road construction and achieve net zero waste goal.

Oil spills represent a critical environmental threat, particularly to marine ecosystems, necessitating the development of efficient and eco-friendly remediation technologies. This study explores the application of pulsed laser ablation (PLA) in fabricating polymer-based magnetic nanocomposites, with a focus on polyvinylpyrrolidone, chitosan, and methyl cellulose. These polymers, renowned for their proficiency in adsorbing pollutants from various oils, were combined with magnetite nanoparticles (NPs) in a compressed tablet form. The PLA process facilitated the generation of nanocomposites, which were subsequently collected using an external magnetic field. The chemical composition of these composites was analyzed through Fourier-transform infrared (FTIR) and Raman spectroscopy, while particle sizes were determined using the Leica Image Processing and Analysis System. The study revealed that PLA is a green, single-step, and effective technique for preparing magnetic nanocomposites, producing particles predominantly in the 400 nm–4 µm size range. Furthermore, the application of these composites in oil/water separation demonstrated with separation commencing approximately 1 s after the application of a magnetic field. These findings underscore the potential of PLA in crafting magnetic nanocomposites for the rapid and environmentally sustainable remediation of oil spills.

This paper analysed the possibility of using recycled powders (<75 µm) and recycling fine aggregates (<1.18 mm) obtained during the crushing and grinding of concrete waste (CoW), ceramic waste (CeW) and red clay brick waste (RCBW) when designing cementitious pastes and mortars for 3D printing. The effects of the type of powder (CoW-powder, CeW-powder and RCBW-powder) and of the liquid/solid (L/S) ratio on the mixture properties in the fresh and hardened states were studied. In the fresh state, the level of flowability (mini-slump), flow index (flow table), buildability and setting time characteristics of the cementitious pastes were evaluated. In addition, the rheological behaviour was analysed through a rotational rheometer. In the hardened state, the compressive strength was determined at 3, 7, 28 and 90 days. The effects of the type of recycled fine aggregate (RFA − CoW, RFA − CeW and RFA − RCBW) were evaluated for mortars with a cement:aggregate ratio of 1:0.5. Based on the results obtained, the most suitable mixtures were selected to carry out 3D printing tests on a laboratory scale. From the 3D printing of beam-type specimens, it was possible to determine the flexural and compressive strengths (28 days) of the selected mixtures. The results obtained validated the possibility of using recycled powders (CoW, CeW and RCBW) to replace 30 % of ordinary Portland cement (OPC) and to incorporate 100 % recycled fine aggregates in the design of cementitious materials (pastes and mortars) for 3D printing. In this regard, the recycled powders and recycled fine aggregates increase the buildability and thixotropy of cementitious mixtures. With an adjustment in the L/S (liquid/solids) ratio, their application in 3D printing becomes feasible. This alternative for the use of powders and fine aggregates from construction and demolition waste (CDW) could be considered a contribution towards the sustainability of the sector and the implementation of a circular economy.

The significance of Mg (alloy) extends to both the mechanical engineering and medical sectors. However, Mg is known for its high reactivity, posing significant challenges to its widespread utilization in large-scale lightweight applications. Research has shown that adding small amounts of reactive elements, such as Ca, can substantially improve the high-temperature oxidation resistance of numerous Mg alloys. This can diminish the reliance on greenhouse gases with high global warming potential, typically used as protective gases during processing. In a similar vein, the patented Environment-COnscious Mg technology offers distinct advantages by utilizing the cost-effective and more stable oxide form of the desired alloying element, notably alkaline earth metals like Ca, instead of their elemental forms, in the alloying of Mg. This development holds considerable importance in mitigating the carbon footprint throughout manufacturing. While the patents for Environment-COnscious production outline a method employing various versatile oxides, practical application has primarily relied on adding calcium oxide, as indicated by the literature. Therefore, this review brings to light the state of the art concerning the interaction between calcium oxide and molten Mg (alloy), and its influence on the technical properties, potential challenges, and areas requiring further investigation in this field. Until now, this issue has not been discussed from a critical and holistic approach.

Given the current growth in consumer environmental concerns, this study assessed green customers’ consumption value for mango waste-based vegan leather bags. The consumer values and market choices theories guided semi-structured interviews and grounded theory-based induction data gathering and analysis. The project provides lasting answers and theoretical insights for vegan leather bags and mango waste management. The five main values are functional, social, emotional, conditional, and epistemic. Ten consumption-related topics emerged. Vegan leather bags were valued for their durability and multifunctionality by green shoppers. The data also show that social media, family, and peers impact sustainable product selections. For sustainable vegan leather purses created from mango waste, beautiful design and customization, green behavior, convenience, and environmental and green experience were the emotional and conditional values. Green customers’ openness to experience and green information can drive them to buy sustainable vegan leather bags, the study revealed.

Production of zeolite-Y catalyst from natural substrate has been a research trend in the scientific community. Published articles revealed that zeolite-Y recovery from locally sourced metakaolin is confined to laboratory practice. Scale-up process design and its economic feasibility for zeolite-Y catalyst recovery are rarely found in the scientific bibliography. Therefore, this study presented conceptual scale-up process design, base-case techno-economics and Monte-Carlo simulation of zeolite Y recovery from Nigerian metakaoline. ASPEN Base Case Simulation (ABCS), scale-up design and economics were accomplished using inherent design and costing algorithms in ASPEN Batch Process Developer (ABPD) V10. Process economic parameters: Net Present Value (NPV), Internal Rate of Return (IRR), Return on Investment (ROI) and Payback Time (PBT), were modelled and optimized using Design Expert V13 software; while zeolite Unit Production Cost (UPC), Annual Production Cost (APC), Total Capital Investment (TCI) and interest/discount rate were considered as model inputs. Monte-Carlo Simulation (MCS) in Crystal Ball Oracle software was used to perform the sensitivity and uncertainty analyses. The base-case techno-economic results of process design of 600,000 kg/year zeolite production gave batch size 5000 kg/batch with 104 batches/year, batch time (4149 min), TCI ($15,930,306), APC ($147,145), NPV ($41,983,375), ROI (38.13 %) and PBT (2.14 years). The coefficient of determination (R²) of the economic models were 0.9978, 0.9989 and 0.9986 for NPV, ROI and IRR respectively. The optimum economic variables that maximized synthesis of 5000 kg/batch zeolite Y are UPC ($11.68), APC ($100,033) and TPC ($15,930,200). MCS uncertainty for NPV, IRR and ROI are negligible. Therefore, this study demonstrated that scale-up zeolite-Y production from the local substrate is economically feasible.

The utilization of marble waste powder (MWP) as a supplementary cementitious material in concrete, serving as a replacement for cement, holds the potential to enhance split tensile strength (STS) and flexural strength (FS), alongside offering environmental advantages. However, it is crucial to determine the optimal dosage of MWP, ensuring meticulous mix design and testing procedures to maximize the concrete's strength and overall performance. This research endeavor seeks to investigate a supervised data-driven approach for predicting STS and FS in concrete composites incorporating MWP, along with other cementitious materials such as silica fume (SF), granite powder (GP), and fly ash (FA), and their influence on the STS and FS of MWP-incorporated concrete. Ten distinct machine learning (ML) algorithms, including multivariate linear regression (MVLR), support vector regression (SVR), artificial neural networks (ANN), decision tree regressor (DT), random forest regressor (RF), adaptive boosting regressor (AdB), light gradient boosting machine (LGBM), gradient boosting regressor (GBR), extreme gradient boosting (XGB), and cat boost, are employed to assess the predictive capabilities of these models for FS and STS datasets. Statistical metrics like correlation coefficient (R2), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) are used to evaluate the performance of each ML algorithm. To enhance model efficiency, hyperparameter tuning and a 5-fold cross-validation technique are implemented. Among the ML algorithms tested, the cat boost algorithm demonstrates superior performance in predicting STS, while the ANN algorithm excels in predicting FS. Additionally, SHAP dependency plots are utilized to ascertain the feature importance in the best-performing models. The analysis reveals that features such as curing age, water, and cement play a more significant role in predicting STS, whereas attributes like cement, concrete type, and sand hold greater importance in predicting FS.

Environmentally friendly technology is being used by industries all over the world, and engineers in the manufacturing and materials industry are embracing sustainable business models. In this paradigm, materials are processed using economically and environmentally sound methods. The use of microwave-absorbing materials (MAMs) in low-altitude observatory aircraft and the rise in electromagnetic pollution have brought them to light. The main aim of this study is to select an ideal MAM with excellent physical, electromagnetic, chemical, and thermal properties, which also fulfills sustainability aspects based on expert judgments. In this regard, we have proposed a new hybrid framework consisting of Modified Digital Logic (MDL), a subjective weighting method in combination with the measurement of alternatives and ranking according to compromise solution (MARCOS) under an interval-valued intuitionistic fuzzy (IVIF) environment to select an optimum MAM. Furthermore, this research work contributes to streamlining the selection process by consolidating the plethora of work available in the literature on the synthesis and characterization of MAMs. A database is created for 160 potential candidate materials in C, S, X, and Ku bands for carbon-based materials, including carbon nanotubes (CNT), graphene, reduced graphene oxide (rGO), carbon fibers, and biomass-derived materials. These materials are then passed through successive screening stages to shortlist 14 materials, which are ranked subsequently over a set of 15 crisp and ambiguous criteria. This comprehensive study simultaneously caters to quantitative and qualitative information extracted from experimental work, material resource packs, or expert evaluations. The findings highlight CNT/Fe (20 wt%, E) (Al1) as the most suitable candidate for MAM application with outstanding electromagnetic properties. Finally, the results are compared with extant approaches to check the reliability of the proposed framework. In addition, sensitivity analysis is carried out to establish the feasibility and robustness of the obtained results.