Search Results (3,517)

This paper describes a highly alkaline low-grade copper oxide ore. Copper can be selectively leached out while other metals are retained. A thermodynamic model of the CuO-(NH₄)₂SO₄-NH₃-H₂O system was established for the leaching of tenorite (CuO) under conditions of mass and charge conservation. MATLAB’s fitting functions, along with the diff and solve functions, were used to calculate the optimal ammonia concentration and total copper ion concentration of tenorite under different ammonium sulfate concentrations. The effects of various ammonia–ammonium salt solutions (ammonium sulfate, ammonium carbonate, ammonium chloride) on the copper leaching rate were investigated. Results show that under the conditions of an ammonia concentration of 1.2 mol/L, an ammonia–ammonium ratio of 2:1, a liquid–solid ratio of 3:1, a temperature of 25 °C, and a leaching time of 4 h, the copper leaching rate from the ammonium sulfate and ammonium chloride solutions reaches 70%, which is slightly higher than that of ammonium carbonate. Therefore, an ammonia–ammonium sulfate system is selected for leaching low-grade copper oxide due to its lower corrosion to equipment compared to the chlorination system. The impact of this study on industrial applications includes the potential to find more sustainable and cost-effective methods for resource recovery. The industry can reduce its dependence on resources and mitigate its environmental impact. Readers engaged in low-grade oxidized copper research will benefit from this study. Full article

This study delves into the effects of carbonation curing and autoclave–carbonation curing on the properties of calcium oxide–belite–calcium sulfoaluminate (CBSAC) cementitious material aerated concrete. The objective is to produce aerated concrete that adheres to the strength index in the Chinese standard GB/T 11968 while simultaneously mitigating CO₂ emissions from cement factories. Results show that the compressive strength of CBSAC aerated concrete with different curing regimes (autoclave curing, carbonation curing, and autoclave–carbonation curing) can reach 4.3, 0.8, and 4.1 MPa, respectively. In autoclave–carbonation curing, delaying CO₂ injection allows for better CO₂ diffusion and reaction within the pores, increases the carbonation degree from 19.1% to 55.1%, and the bulk density from 603.7 kg/m³ to 640.2 kg/m³. Additionally, microstructural analysis reveals that delaying the injection of CO₂ minimally disrupts internal hydrothermal synthesis, along with the formation of calcium carbonate clusters and needle-like silica gels, leading to a higher pore wall density. The industrial implementation of autoclavecarbonation curing results in CBSAC aerated concrete with a CO₂ sequestration capacity ranging from 40 to 60 kg/m³ and a compressive strength spanning from 3.6 to 4.2 MPa. This innovative approach effectively mitigates the carbon emission pressures faced by CBSAC manufacturers. Full article

In the context of constructing new power systems, the intermittency and volatility of high-penetration renewable generation pose new challenges to the stability and secure operation of power systems. Enhancing the ramping capability of power systems has become a crucial measure for addressing these challenges. Therefore, this paper proposes a bi-level peak regulation optimization model for power systems considering ramping capability and demand response, aiming to mitigate the challenges that the uncertainty and volatility of renewable energy generation impose on power system operations. Firstly, the upper-level model focuses on minimizing the ramping demand caused by the uncertainty, taking into account concerned constraints such as the constraint of price-guided demand response, the constraint of satisfaction with electricity usage patterns, and the constraint of cost satisfaction. By solving the upper-level model, the ramping demand of the power system can be reduced. Secondly, the lower-level model aims to minimize the overall cost of the power system, considering constraints such as power balance constraints, power flow constraints, ramping capability constraints of thermal power units, stepwise ramp rate calculation constraints, and constraints of carbon capture units. Based on the ramping demand obtained by solving the upper-level model, the outputs of the generation units are optimized to reduce operation cost of power systems. Finally, the proposed peak regulation optimization model is verified through simulation based on the IEEE 39-bus system. The results indicate that the proposed model, which incorporates ramping capability and demand response, effectively reduces the comprehensive operational cost of the power system. Full article

Logistics is becoming more cost competitive while customers and regulatory bodies pressure businesses to disclose their carbon footprints, creating interest in alternative fuels as a decarbonization strategy. This paper provides a thematic review of the role of alternative fuels in sustainable air, land, and sea logistics, their challenges, and potential mitigations. Through an extensive literature survey, we determined that biofuels, synthetic kerosene, natural gas, ammonia, alcohols, hydrogen, and electricity are the primary alternative fuels of interest in terms of environmental sustainability and techno-economic feasibility. In air logistics, synthetic kerosene from hydrogenated esters and fatty acids is the most promising route due to its high technical maturity, although it is limited by biomass sourcing. Electrical vehicles are favorable in road logistics due to cheaper green power and efficient vehicle designs, although they are constrained by recharging infrastructure deployment. In sea logistics, liquified natural gas is advantageous owing to its supply chain maturity, but it is limited by methane slip control and storage requirements. Overall, our examination indicates that alternative fuels will play a pivotal role in the logistics networks of the future. Full article

Vanadium (V) was successfully extracted from a high phosphorus vanadium residue (HPVR) through a carbonation process. Vanadium within HPVR substitutes for Fe in the mineral structure of Ca₉(Fe,V)(PO₄)₇ at elevated temperatures, Na₂CO₃ reacts with V to form sodium metavanadate (NaVO₃), concurrently generating calcium carbonate (CaCO₃) through its interaction with Ca₉(Fe,V)(PO₄)₇. Subsequently, V is liberated and leached by water, dissolving in the aqueous phase as metavanadate ions (VO³⁻). Crucial factors influencing V leaching efficiency include roasting time, roasting temperature, and the amount of Na₂CO₃ utilized. Response Surface Methodology (RSM) was employed. The optimized parameters determined were as follows: a roasting temperature of 850 °C, a roasting duration of 120 min, a Na₂CO₃ dosage of 8.01%, a liquid-to-solid ratio (L/S) of 3, and a leaching time of 60 min. Under these conditions, a remarkable V leaching efficiency of 83.82% was achieved. This study underscores the viability of a simplified approach for treating solid waste containing metal slag, which not only mitigates environmental pollution but also yields valuable metals. Full article

Composite materials, particularly carbon fiber-reinforced polymers (CFRPs), have become a cornerstone in industries requiring high-performance materials due to their exceptional mechanical properties, such as high strength-to-weight ratios, and their inherent lightweight nature. These attributes make CFRPs highly desirable in aerospace, automotive, and other advanced engineering applications. However, the compressive behavior of CFRP structures remains a challenge, primarily due to the material sensitivity to structural instability, leading to matrix cracking and premature failure under compressive loads. Isogrid structures, characterized by their unique geometric patterns, have shown promise in enhancing the compressive behavior of CFRP panels by providing additional support that mitigates these issues. Traditionally, these structures are manufactured using automated techniques like automated fiber placement (AFP) and automated tape laying (ATL), which, despite their efficacy, are often cost-prohibitive for small-scale or custom applications. Recent advancements in 3D-printing technology, particularly those involving continuous fiber reinforcement, present a cost-effective and flexible alternative for producing complex CFRP structures. This study investigates the compressive behavior of 3D-printed isogrid structures, fabricated using continuous carbon fiber reinforcement via an Anisoprint Composer A3 printer equipped with towpreg coextrusion technology. A total of eight isogrid panels with varying infill percentages were produced and subjected to buckling tests to assess their performance. The experimental results indicate a direct correlation between infill density and buckling resistance, with higher infill densities leading to increased buckling loads. Additionally, the failure modes were observed to shift from local to global buckling as the infill density increased, suggesting a more uniform distribution of compressive stresses. Post-test analyses using optical microscopy and scanning electron microscopy (SEM) revealed the presence of voids within the 3D-printed structures, which were found to negatively impact the mechanical performance of the isogrid panels. The findings of this study demonstrate that 3D-printed isogrid CFRP structures can achieve significant buckling resistance, making them a viable option for high-performance applications. However, the presence of voids remains a critical issue, highlighting the need for process optimizations in 3D-printing techniques to enhance the overall performance and reliability of these structures. Full article

Considering the dataset of information related to Chinese coal-fired thermal power plants during the 2005–2017 period, we initially investigated the orthogonalized response of the carbon emission to energy consumption and power generation by using Bayesian vector autoregressions and feedback solutions for impulse control technology. The results showed that the effects of energy consumption and power generation on carbon emissions were significant. The Chinese government has launched a program aimed at curbing carbon emission peaks and neutralizing or decreasing carbon emissions. The causal relationship concludes that China still needs further investment in emission abatement, improvement related to the level of openness to the outside world, and the strengthening of the construction of green zones for industrial transfer to mitigate carbon emissions. Full article

To mitigate the issues of severe farmland soil salinization, the environmental degradation stemming from the overuse of chemical fertilizers, and suboptimal soil composition, a study was conducted to investigate the influence of different types and ratios of organic fertilizers on the physical and chemical attributes of saline–alkali soil. This study aimed to investigate the relationship between different types and proportions of organic fertilizers, soil moisture, organic fertilizer application rates, organic carbon molecular structure, and the soil environment in saline–alkali soils. Reducing the application of chemical fertilizers and substituting them with organic fertilizers can improve the soil quality of saline–alkali lands. The results indicated that replacing a part of the urea with organic fertilizer in saline–alkali farmland reduced the soil salinity by 11.1 to 22.8% in the 0–60 cm soil layer, decreased the soil pH by 0.11 to 1.52%, and increased the soil redox potential (Eh) values by 2.5 to 4.3% in the 0–20 cm layer of the mild and moderate saline–alkali soils. It also decreased the accumulation of the soil organic matter (OM) during the growing season. Compared to commercial organic fertilizers, natural organic fertilizers increased the accumulation of the soil soluble carbon (DOC) and nitrogen (DON), resulting in less soil salinity accumulation. When commercial organic fertilizer was applied in a 1:1 ratio with inorganic fertilizer, the salt accumulation was minimized. Compared to conventional fertilization, organic fertilizer reduced the accumulation of the NH₄⁺-N (ammonium nitrogen) and NO₃⁻-N (nitrate nitrogen) in the soil by 3.1 to 22.6%. In comparison to conventional chemical fertilizers, the application of organic fertilizer in the mild and moderate saline–alkali soils increased the accumulation of the DOC, DON, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial quotient during the grain-filling stage. Specifically, it increased the DOC, DON, and DOC/DON by 12.7 to 26.7%, 12 to 59.3%, and 15.2 to 35.5%, respectively. The application of commercial organic fertilizer in the mild saline–alkali soils increased the MBC, MBN, MBC/SOC, and MBN/TN by 37.1, 65.6, 36.7, and 4.7%, respectively. Through analyzing the relative proportions of soil surface organic carbon functional groups during the grain filling period, we observed that, after the application of organic fertilizer, the OM in the mildly salinized soils primarily originated from terrestrial plant litter, whereas, in moderately salinized soils, the OM was mainly derived from microbial sources. Full article

Annually, over 10 billion tons of construction and demolition waste is transported globally from sites to reception facilities. Optimal and effective planning of waste transportation holds the potential to mitigate cost and carbon emissions, and alleviate road congestion. A major challenge for developing an effective transportation plan is the uncertainty of the precise volume of waste at each site during the planning stage. However, the existing studies have assumed known demand in planning models but the assumption does not reflect real-world volatility. Taking advantage of the problem structure, this study adopts the stochastic programming methodology to approach the construction waste planning problem. An integer programming model is developed that adeptly addresses the uncertainty of the amount of waste in an elegant manner. The proposed stochastic programming model can efficiently handle practical scale problems. Our numerical experiments amass a comprehensive dataset comprising nearly 4300 records of the actual amount of construction waste generated in Hong Kong. The results demonstrate that incorporating demand uncertainty can reduce the transportation cost by 1% correlating with an increase in profit of 14% compared to those that do not consider the demand uncertainty. Full article

With few measurement sites and a great need to validate satellite data to characterize the exchange of energy and carbon fluxes in tropical forest areas, quantified by the Net Ecosystem Exchange (NEE) and associated with phenological measurements, there is an increasing need for studies aimed at characterizing the Amazonian environment in its biosphere–atmosphere interaction, considering the accelerated deforestation in recent years. Using data from a flux measurement tower in the Caxiuanã-PA forest (2005–2008), climatic data, CO₂ exchange estimated by eddy covariance, as well as Gross Primary Productivity (GPP) data and satellite vegetation indices (from MODIS), this work aimed to describe the site’s energy, climatic and carbon cycle flux patterns, correlating its gross primary productivity with satellite vegetation indices. The results found were: (1) marked seasonality of climatic variables and energy flows, with evapotranspiration and air temperature on the site following the annual march of solar radiation and precipitation; (2) energy fluxes in phase and dependent on available energy; (3) the site as a carbon sink (−569.7 ± 444.9 gC m⁻² year⁻¹), with intensity varying according to the site’s annual water availability; (4) low correlation between productivity data and vegetation indices, corroborating data in the literature on these variables in this type of ecosystem. The results show the importance of preserving this type of environment for the mitigation of global warming and the need to improve satellite estimates for this region. NDVI and EVI patterns follow radiative availability, as does LAI, but without direct capture related to GPP data, which correlates better with satellite data only in the months with the highest LAI. The results show the significant difference at a point measurement to a satellite interpolation, presenting how important preserving any type of environment is, even related to its size, for the global climate balance, and also the need to improve satellite estimates for smaller areas. Full article

Vegetation net primary productivity (NPP) is a key indicator for assessing vegetation dynamics and carbon cycle balance. Xinjiang is located in an arid and ecologically fragile region in northwest China, but the current understanding of vegetation dynamics in the region is still limited. This study aims to analyze Xinjiang’s NPP spatial and temporal trends, using random forest regression to quantify the extent to which climate change and human activities affect vegetation productivity. CMIP6 (Coupled Model Intercomparison Project Phase 6) climate scenario data help assess vegetation restoration potential and future risks. Our findings indicate that (1) Xinjiang’s NPP exhibits a significant increasing trend from 2001 to 2020, with three-quarters of the region experiencing an increase, 2.64% of the area showing significant decrease (p < 0.05), and the Ili River Basin showing a nonsignificant decreasing trend; (2) precipitation and radiation are major drivers of NPP variations, with contribution ratios of 35.13% and 30.17%, respectively; (3) noteworthy restoration potential exists on the Tian Shan northern slope and the Irtysh River Basin, where average restoration potentials surpass 80% relative to 2020, while the Ili River Basin has the highest future risk. This study explores the factors influencing the current vegetation dynamics in Xinjiang, aiming to provide references for vegetation restoration and future risk mitigation, thereby promoting sustainable ecological development in Xinjiang. Full article

The impact of fertilization and irrigation on heavy metal accumulation in saline–alkali soil and its underlying mechanisms are critical issues given the constraints that soil salinization places on agricultural development and crop quality. This study addressed these issues by investigating the effects of adjusting organic fertilizer types, proportions, and irrigation volumes on the physicochemical properties of lightly to moderately saline–alkali soils and analyzing the interaction mechanisms between microorganisms and heavy metals. The results indicate that the rational application of organic fertilizers combined with supplemental irrigation can mitigate soil salinity accumulation and water deficits, and reduce the soil pH, thereby enhancing soil oxidation, promoting nitrogen transformation and increasing nitrate–nitrogen levels. As the proportion of organic fertilizers increased, heavy metal residues, enrichment, and risk indices in the crop grains also increased. Compared to no irrigation, supplemental irrigation of 22 mm during the grain-filling stage increased soil surface Cd content, Zn content, and the potential ecological risk index (HRI) by 10.2%, 3.1%, and 8%, respectively, while simultaneously reducing the heavy metal content in grains by 12–13.5% and decreasing heavy metal enrichment. Principal component analysis revealed the primary factors influencing Cu and Zn residues and Cd accumulation in the crop grains. Soil salinity was significantly negatively correlated with soil pH, organic matter, total nitrogen, and ammonium nitrogen, whereas soil organic matter, total nitrogen, ammonium nitrogen, soil pH, oxidation–reduction potential, soluble nitrogen, and microbial biomass nitrogen were positively correlated. The accumulation and residues of Zn and Cu in the soil were more closely correlated with the soil properties compared to those of Cd. Specifically, Zn accumulation on the soil surface was primarily related to aliphatic organic functional groups, followed by soil salinity. Residual Zn in the crop grains was primarily associated with soil oxidation–reduction properties, followed by soil moisture content. The accumulation of Cu on the soil surface was mainly correlated with the microbial biomass carbon (MBC), whereas the residual Cu in the crop grains was primarily linked to the soil moisture content. These findings provide theoretical insights for improving saline–alkali soils and managing heavy metal contamination, with implications for sustainable agriculture and environmental protection. Full article

Transitioning to low-carbon energy systems is crucial for sustainable development, particularly in oil-rich developing countries (ORDCs) that face intertwined economic and environmental challenges. This review uses the PRISMA methodology to systematically assess the current state and prospects of low-carbon thermal electricity generation and utilization technologies in ORDCs. The study emphasizes clean thermal technologies such as biogas, biofuels, biomass, hydrogen, and geothermal energy, focusing on solutions that are technically feasible, economically viable, and efficient in combustion processes. These nations face significant challenges, including heavy reliance on fossil fuels, transmission losses, and financial constraints, making energy diversification urgent. The global shift towards renewable energy and the need to mitigate climate change presents an opportunity to adopt low-carbon solutions that align with Sustainable Development Goals related to energy access, economic growth, and climate action. This review aims to (1) evaluate the current state of low-carbon thermal electricity technologies, (2) analyze the technical and economic challenges related to combustion processes and energy efficiency, and (3) provide recommendations for research and policy initiatives to advance the transition toward sustainable thermal energy systems in ORDCs. The review highlights practical approaches for diversifying energy sources in these nations, focusing on overcoming existing barriers and supporting the implementation of clean thermal technologies. Full article

GDP is a common and essential indicator for evaluating a country’s overall economy. However, environmental issues may be overlooked in the pursuit of GDP growth for some countries. It may be beneficial to adopt more sustainable criteria for assessing economic health. In this study, green GDP (GGDP) is discussed using mathematical approaches. Multiple dataset indicators were selected for the evaluation of GGDP and its impact on climate mitigation. The k-means clustering algorithm was utilized to classify 16 countries into three distinct categories for specific analysis. The potential impact of transitioning to GGDP was investigated through changes in a quantitative parameter, the climate impact factor. Ridge regression was applied to predict the impact of switching to GGDP for the three country categories. The consequences of transitioning to GGDP on the quantified improvement of climate indicators were graphically demonstrated over time on a global scale. The entropy weight method (EWM) and TOPSIS were used to obtain the value. Countries in category 2, as divided by k-means clustering, were predicted to show a greater improvement in scores as one of the world’s largest carbon emitters, China, which belongs to category 2 countries, plays a significant role in global climate governance. A specific analysis of China was performed after obtaining the EWM-TOPSIS results. Gray relational analysis and Pearson correlation were carried out to analyze the relationships between specific indicators, followed by a prediction of CO₂ emissions based on the analyzed critical indicators. Full article

Elevated temperatures in urban centers have become a common problem in cities around the world. However, the climate problems in suburban areas are equally severe; there is an urgent need to find zero-carbon ways to mitigate this problem. Recent studies have revealed the thermal performance of vegetation, buildings, and water surfaces. They functioned differently regarding the climate at different periods of the day. Accordingly, this study synthesizes remote sensing technology and meteorology station observation data to deeply explore the differences in the role of each climate-influencing factor in the suburban areas of Chengdu. The land surface temperature (LST) and air temperature (T_a) were used as thermal environmental indicators, while the normalized difference vegetation index (NDVI), normalized difference water index (NDWI), normalized difference built-up index (NDBI), and altitude were used as environmental factors. The results showed that the relevant influences of the environmental factors on the climate in the sample areas were significantly affected by the time of the day. The NDVI (R² = 0.5884), NDBI (R² = 0.3012), and altitude (R² = 0.5638) all showed strong correlations with T_a during the night (20:00–7:00), which gradually weakened after sunrise, yet the NDWI showed a poorer cooling effect during the night, which gradually strengthened after sunrise, reaching a maximum at 15:00 (R² = 0.5012). One reason for this phenomenon was the daily weather changes. These findings facilitate the advancement of the understanding of the climate in suburban areas and provide clear directions for further thermal services targeted towards people in different urban areas. Full article