Journal of Material Cycles and Waste Management最新文献

The objective of this study is to investigate the intention of waste pickers to participate in waste picker cooperatives. According to research, cooperatives improve waste pickers' quality of life. However, it is unclear how waste pickers perceive and interpret what is provided to them and if these advantages affect their attitudes and intentions. We provide a unique theoretical model that explains waste pickers’ intentions to join cooperatives by incorporating the theory of planned behavior. A total of 112 waste pickers, consisting of both Turkish individuals and immigrants, were included in the data collection process. The data were analyzed using partial least squares structural equation modeling, utilizing multi-group analysis by including social exclusion and nationality as moderators. One of the most striking findings is that pickers’ feeling of control over their planned action does not affect their intention to join cooperatives without an attitude. To clarify, waste pickers must initially develop a positive attitude towards perceiving the joining behavior as effortless. Our research also shows that socially excluded people trust and value cooperatives more, regardless of their nationality. This pioneering study on waste pickers’ willingness to join cooperatives and other novel findings will benefit scholars and policymakers.

The implementation of life-cycle assessment (LCA) was to quantify the potential environmental impact of activated carbon production from sewage sludge by the molten salt and impregnation methods. Based on the experiments of the molten salt and impregnation methods, a flowchart was developed and the environmental impact was determined. The results showed that the environmental impacts dominated by roasting, followed by grinding or impregnating and finally by washing and drying. The uses of electricity and ZnCl₂ in the production of activated carbon were the main factors causing environmental impact. The energy consumptions of the molten salt and impregnation methods were 56.16 and 73.44 MJ/kg activated carbon, respectively. The global warming potential of the molten salt and impregnation methods was found to be 14.68 and 17.15 kg CO₂ eq/kg activated carbon, respectively. The impregnation method had higher energy consumption and CO₂ emissions than those for the molten salt method. The LCA showed that the molten salt method offered environmental advantages in most impact categories in comparison with the impregnation method.

Photopolymers, which are composed of monomer, oligomer polymer, and their combinations and exhibit photochemical reactions when exposed to light, are now commonly employed in 3D printers, particularly in the flexographic printing industry, and are becoming waste. The utilization of waste solid sheet Photopolymer Plates (PhP) for bitumen modification is an efficient way of disposing of post-consumer items and an alternate method of obtaining new, high-quality modifiers. The consequences of using waste PhP in bitumen modification, both independently and in conjunction with Styrene–Butadiene–Styrene (SBS) were explored. By combining PhP and SBS, it is hoped that savings can be made without sacrificing performance due to the high rate of single SBS modification. The modified binders prepared using PhP and SBS both separately and together were subjected to conventional and rheological tests. The performance of 5% SBS modification could not be achieved at the highest rate that PhP can be used alone without creating a workability problem. The use of 5–7% PhP in combination with 2% SBS outperformed the single 5% SBS modification. This combined binder did not cause workability problems and showed good low and high-temperature behavior and was found to be an economical alternative to SBS modification.

The current study aims to model and optimize the catalytic pyrolysis of plastics, incorporating an agricultural biomass waste-derived catalyst. Polystyrene (PSW) and polypropylene (PPW) are experimented with thermal and catalytic pyrolysis. Agricultural biomass waste (wheat husk) was selected and acid treated with sulfuric acid (HZSM-5_SA) and hydrochloric acid (HZSM-5_CA), and then used as catalyst. Thermal and catalytic pyrolysis were conducted in a semi batch reactor, with reaction temperature (500 ℃) and different ratios (10:1, 10:2 & 10:3). At a ratio 10:2, PSW with HZSM-5_SA produced 91.19 wt.% of oil yield and PPW with HZSM-5_SA produced 85.73 wt.% of oil yield. The catalyst HZSM-5_SA was effective in the reduction of reaction temperature and time, it decreased from 450 ℃ to 437 ℃ and 22 min to 14 min for PSW. Catalyst activity was also observed for PPW, the reaction temperature decreased from 471 ℃ to 456 ℃ and 34 min to 19 min. Oil properties were determined and it was found that the kinematic viscosity of oil obtained from PSW with HZSM-5_SA was 2.53 cSt, which coincide with the diesel Bharat Stage (BS VI 2020). Total conversion of pyrolysis products was predicted using six Machine Learning (ML) models such as Random Forest, Support Vector, K-Nearest Neighbor, Decision Tree, AdaBoost, and Gradient Boost. Among all the models, the Gradient Boost regressor model had a good evaluation metrics of R² value of 0.984 and RMSE of 0.019, respectively. This study illustrates the use of ML models to predict the total conversion and their correlation matrix with target and feature variables. This study also highlights that cost-effective catalyst can be prepared from biomass (wheat husk) and the use of ML models to train the datasets and evaluate the actual and predicted values.

Engaging aspiring pre-service teachers (PsTs) is crucial for achieving sustainable waste separation and recycling levels within the academic community. In this study, we considered three supplementary factors from the Theory of Planned Behavior (TPB) to elucidate the formation of actions related to engaging in waste separation and recycling intention on campus (WSRIs). An online survey, utilizing a questionnaire, was administered to over 530 PsTs in East Java, Indonesia, comprising 380 females and 152 males. Structural equation modeling was employed to analyze the main factors and paths influencing WSRIs. The waste separation and recycling intention of PsTs were primarily influenced by five internal subjective factors and three external factors. Among these, environmental education (EE), perceived behavioral control, and environmental knowledge (EK) displayed the most significant associations, with EE having the greatest direct effect. Conversely, attitude had minimal effect on WSRIs. Moreover, to improve waste separation and recycling practices on campus, it is recommended to integrate EK into daily life, emphasizing its importance in achieving these sustainable goals.

In China, large amounts of industrial byproduct gypsum (IBG) end up as waste and excessive stockpiling due to its low whiteness and high impurity content. In this study, two typical IBG including phosphogypsum (PG) and flue gas desulfurization gypsum (FGDG) were the research object. The impurities removal and the whiteness improvement by the tandem pyro-hydro process were investigated. Species of impurities, mechanism of whiteness improvement and the evolution of the gypsum phase during the tandem process were revealed. The results indicate that the impurities responsible for the poor whiteness of IBG included organic matter, carbon particles, and silicates. The temperature of the pyro process is the critical factor. The IBG is calcinated at 400–500 °C to fully remove organic matter and carbon particles, while decompose silicates to silica. Following, in the hydro step, the calcined IBG was treated with dilute sulfuric acid (0.2–1.0 M) to remove ion impurities such as Fe(III), the higher temperature and higher acidity are favorable to the production of valuable CaSO₄. After treatment, the whiteness of IBG was improved from below 40% to above 80%, and the soluble impurity content can meet the standards. Moreover, both PG and FGDG products exhibited a compressive strength exceeding 10.0 MPa of curing for 7 d. This work provides theoretical guidance to promote the resource utilization of IBG, especially as plastering materials after purification and whitening.

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