Journal of Material Cycles and Waste Management最新文献

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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Circular bioeconomy (CBE) strategies purpose to attain sustainable development goals (SDGs) with mitigating greenhouse gasses emissions. By employing a portfolio theory, we have been shown that an enhancement in the circularity of resources can be occurred utilizing the choice of suitable economic securities in relation to the food wastes. An integrated method of a CBE-based fuzzy inference system and portfolio decision analysis is considered to analyze the biomass and bioenergy applications (economic securities) of generated wastes from the rice production process as food waste. The results show that among the ten economic securities, five applications have the highest weights with regard to the effectiveness of CBE strategies. They are (1) soil incorporation, (2) srganic fertilizers, (3) she industry of paper, wood, and building materials, (4) Clean electrical energy production, and (5) snimal feeding. These are selected as the most appropriate economic securities for the sustainable management of rice production waste in Behbahan city, Iran. This review can give a deeper analysis of circular solutions to extant linear pathways that play a significant role in the enhancement of food security and environmental sustainability in future. Implementing this method in food-waste management can facilitate the realization of SDGs.

The research reported in this paper was designed to investigate the interconnection between students’ environmental education (EE) and their waste-separation behaviour, with students’ attitude, knowledge and sense of responsibility being the mediate factors, and explores how EE in schools could be improved. A questionnaire-based survey was employed and the views of 600 primary- and middle-school (PMS) students and 175 teachers in Yingtan City, Jiangxi Province, China were obtained. The results indicate that EE in Chinese schools positively affects students’ waste separation behaviour by affecting their attitude to waste separation. But the current EE in Chinese schools has not been able to improve students’ sense of responsibility for environmental protection. The incentives for teachers to include EE in their teaching includes the belief that EE in school would pass environmental knowledge to the students and cultivate their pro-environmental attitude which would eventually benefit the environment and society in the long run and the school’s requirement of using EE in the classroom. The main barriers are the schools’ neglect of EE and the teachers’ lack of EE knowledge. Suggestions for teachers and policy-makers at school level and local government level are put forward to improve EE in school and thereby improve students’ waste separation behaviour.

Nowadays, due to inadequate resource utilization and a lack of comprehensive accounting procedures, many firms face substantial issues in controlling their environmental and cost-related implications. As the global emphasis on sustainability and resource efficiency grows, there is an increasing need for Material Flow Cost Accounting (MFCA) adoption to meet these concerns. In this case study, a small and medium-scaled enterprise (SME) i.e., Corrugation Packages Industry in Pakistan has been selected. The formation of a corrugation box has been considered to evaluate the process waste based on MFCA analysis. The identified areas with high negative costs and their reasons are also elaborated with proposed MFCA-based solutions. The positive and negative costs of entire process have been further examined by material cost (MC), system cost (SC), energy cost (EC), and waste management cost (WC). By successful implementation of the MFCA, it has been found that an improvement in the total cost of about 11.11% (MC), 29.61% (SC), 9.32% (EC), 92.57% (WC) have been obtained, whereas the enhancement in positive costs of about 9.82% (MC), 31.31% (SC), 9.88% (EC), 95.08% (WC) have been recorded, and reduction in negative costs of about 29.50% (MC), 36.56% (SC), 35.52% (EC), and 69.83% (WC) have been noted.

Leaching, especially using mixtures of organic acids, can reduce the chemical requirement of organic acid leaching of metals. This work investigates the performance of maleic acid and citric acid and their potential synergy in a mixed-acid leaching system for the recovery of valuable metals from the cathode material of spent lithium-ion batteries (LIBs). The influence of key leaching parameters such as acid concentration, temperature and reducing agent (fructose) were examined. As single acids, citric acid proved to be a stronger lixiviant than maleic acid. 83% Li, 84%Mn, 80% Co and 80%Ni was leached using 0.5 M citric acid at a temperature of 90 °C after 60 min. As mixtures, the leaching of the metals showed significant dependence on the ratio of the acids and increased with the proportion of citric acid, indicating that citric acid is the dominant lixiviant. However, the performance of the mixtures of citric acid and maleic acid was lower than that of the individual acids, thus demonstrating lack of synergy. Spectra analysis of the leachates confirmed the formation of metal complexes and interactions between citric and maleic acid, and explains the observed performance of the acid mixtures. Overall, this work reveals that not all organic acid mixtures are synergic.

Cement industries generate massive amounts of greenhouse gas (GHG) emissions. As a fast-growing economy in Southeast Asia, Indonesia consumed more than 62 Mtons of cement in 2020. To cut down the impacts from extensive resource extraction and GHG emissions from cement industries, utilizing secondary raw materials such as concrete is an option to simultaneously reduce the limestone requirement at cement plants. This study aims to estimate yearly concrete waste flow from residential building stocks and the environmental impacts of utilizing those concrete waste in a cement-producing region in West Java, Indonesia by combining dynamic material flow analysis, stock modeling, and life cycle assessment (LCA). We found Cirebon Regency’s residential buildings would accumulate 46.2 Mtons concrete stocks by 2050. The estimated concrete waste from demolished residential buildings in Cirebon would reach up to 2 Mtons by 2050 depending on building lifetimes. At the baseline scenario, environmental impacts per ton cement are 647.35 kg CO₂ eq. of Global Warming Potential (GWP), 90.25 kg C deficit of Land Use (LU), and 4,707.24 MJ of Cumulative Energy Demand (CED). By utilizing 1 Mtons of recycled concrete, the cement production facility would decrease those values by up to 5.42 kg CO₂ eq./ton cement, 0.09 kg C deficit/ton cement, and 0.43 MJ/ton cement, respectively. Our results help inform decision-makers to formulate policy options on utilizing concrete waste to reduce cement production environmental impacts.

Spent hydrodesulfurization catalyst (HDS) is considered as the important secondary resource for Mo and Ni. The separation of Mo from HDS was usually conducted by soda roasting and water leaching, while Ni remained in the leached residue. This study proposed a method to recover Ni from leached residue by H₂SO₄ leaching and solvent extraction, and Ni was recycled in the form of NiO. The results showed that the optimum Ni leaching process were conducted using 30% H₂SO₄ with liquid–solid ratio of 10 at 70 ℃ for 120 min. The optimal extraction was accomplished using 30% di-(2-ethylhexyl) phosphate (P204) saponification at pH value 6.0 with organic/aqueous (O/A ratio) of 1 for 1 min. Additionally, 20% H₂SO₄ could be used to strip Ni from organic phase with O/A ratio of 10. Finally, NiSO₄ was calcined at 850 ℃ for 1.0 h to obtain NiO. The Ni leaching kinetic analysis showed that the activation energy of Ni leaching process was 16.10 kJ/mol, which was accorded with the shrinkage unreacted kernel model controlled by internal diffusion. This study provided an alternative method to recycle Ni and given a deeper insight to the leaching mechanism during H₂SO₄ leaching Ni from spent catalyst.

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Chlorine-containing Ti-extraction blast furnace slag (TEBFS) is a solid waste produced during titanium removal from high-titanium blast furnace slag. Large amounts of TEBFS affect the local environment and severely limit further process development. A lightweight calcium silicate board was successfully prepared via hydrothermal synthesis. When the mass ratio of TEBFS: Portland cement: diatomite: calcium hydroxide: quartz was 46∶15∶17∶13.9∶8.1, the bulk density, bending strength, and thermal conductivity of the sample were 1.23 g/cm³, 8.2 MPa, and 0.299 W/(m·K), respectively. The overall sample performance met the D1.3 category requirements in the national standard. After being immersed in water with stirring at 30 °C for 60 min, the sample exhibited a curing chlorine efficiency of 40.6%. Mechanical grinding increased slag activity and sample performance. Grinding for 3 min, the activity index of the slag was 72.74%, and the bending strength of the sample increased to 8.7 MPa. Increasing the pozzolanic activity of the slag and reducing the amount of aggregate produced between particles had a positive effect on optimizing sample performance. This paper provides a feasible method for the diversification and clean utilization of TEBFS.

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