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China is becoming the world's biggest energy consumer and carbon dioxide emitter due to the excessive worldwide emissions of carbon dioxide. As a result, resource utilization and carbon emission reduction have taken center stage in China's energy growth. This paper provides an overview and analysis of China's annual total carbon emissions from 2012 to 2021, as well as a projection of the country's key carbon emission industries' carbon dioxide emissions over the next several decades. With the help of the Web of Science bibliometric analysis function and the CiteSpace software visual analysis function, it analyzes the systematic knowledge mapping of the research literature related to carbon emission reduction, which corroborates that carbon emission reduction is the future. Further strengthening the research on carbon dioxide resource utilization is expected to add bricks and mortar to the beautiful vision of "carbon neutrality" by 2060. The consumption of hydrogenated carbon dioxide (CO2) for the production of one ton of methanol can reach up to 1431 tons. This process is an effective and environmentally friendly method for reducing carbon emissions. The methodology and mechanism of utilizing carbon dioxide resources for methanol preparation are systematically summarized, with a specific focus on the application of green methanol as ship fuel. The analysis primarily examines the calculation of carbon emissions throughout the entire life cycle of carbon dioxide and the production of green hydrogen for methanol. The hypothesis is that low-carbon methanol emissions are one-third lower than those of fuel oil, and this conclusion is further supported by evidence showing that low-carbon methanol has a significant carbon reduction effect. Simapro 9.0 software was used to evaluate the life cycle of carbon dioxide preparation for methanol production. The results indicated that the factors with the greatest influence are CO2utilization and green hydrogen production. To make the process more environmentally friendly, the capture process should be improved, and efforts should be made to reduce electricity consumption and coal usage. These measures can effectively reduce the environmental impact of the entire production chain. Furthermore, it anticipates the future utilization of carbon dioxide resources in the application market of the new materials industry, and aims to further advance the development of the methanol industry.

The application range of fly ash in mortar products is gradually expanding, and the harm of heavy metals and environmental damage are also deepening. This study centers around the plastering mortar prepared from fly ash from three provinces in southwestern China (FA1 in Sichuan, FA2 in Chongqing, and FA3 in Guizhou), and systematically studies its basic properties, heavy metal leaching rule and coupling mechanism, life cycle assessment. The research results indicate that there is a certain regularity between the performance of fly ash plastering mortar and the content of fly ash added, but there is no obvious regularity of different origins in the performance. The experimental results showed that the heavy metal content in fly ash plastering mortar showed a significant trend of gradually decreasing over time. The leaching kinetics fitting results showed that the Parabolic equation model was suitable for the leaching of Cr, the Elovich leaching model was suitable for the leaching of Hg, and the Elovich and Second-order kinetics equations were suitable for the leaching of Cd. In fly ash plastering mortar products, Cr, Cd, and Hg elements exist in the forms of Cr3+, Cr6+, Cd2+, and Hg2+. The relative atomic mass of Cr in these two forms is influenced by factors such as the origin, content, and strength grade of fly ash. The occurrence and coupling mechanism of heavy metals in cementitious materials and hydration products were also explored. The results of the life cycle assessment showed that fly ash plastering mortar provides better environmental benefits compared to conventional ones and has a greenhouse effect carbon emissions of about 983 kgCO2eq, which can be reduced by approximately 30% compared to conventional plastering mortar.

With the acceleration of urbanization, the production of waste concrete is getting higher and higher. A large amount of outdoor accumulations of waste concrete will leach heavy metals, not only causing harm to the soil, but also posing a risk to human health. Based on this, this paper systematically studies the basic physical properties and microstructure (XRF, XRD, and SEM–EDS) of outdoor natural accumulation waste concrete, and analyzes the heavy metals in waste concrete from the aspects of existing state, leaching mechanism, human health risk analysis, and summarized the direction of resource utilization of waste concrete, calculated the carbon emission reduction during recycling. The study found that heavy metals in waste concrete mainly exist in hydration products in the form of precipitation, adsorption, and replacement, summarized the leaching mechanism from the micro- and macro-aspects. The leaching mechanism of heavy metals can be assigned to chemical (mineral dissolution and effective amount of components) and physical (advection, surface erosion, and diffusion) processes from the macro-perspective. From the micro-analysis, it can be assigned to the following five processes: acid migrates from solution to liquid–solid surface, acid migration through leaching layer, rapid dissolution reaction controlled by diffusion at leaching boundary, heavy metal through leaching layer, and heavy metals through the solid/liquid surface to the solution. In addition, the concentration and the leaching rate of heavy metals in waste concrete were analyzed. It was found that the concentration of Cr was the highest reached to 4.7 mg/kg and the leaching rate of Cd was the highest, its leaching coefficient was calculated as a result of 1.713 × 10–6. However, there was no obvious regularity in the leaching of heavy metals in different accumulate particle sizes. Through the establishment of risk assessment system was found the concentration of heavy metals in waste concrete will not cause significant harm to human health. The effective limit of heavy metals after 3 months of accumulation of waste concrete was calculated as: Cr < 0.09 mg/kg, Cd < 0.00715 mg/kg, As < 0.392 mg/kg, and Pb < 0.732 mg/kg. And the carbon emission reduction of waste concrete recycling was calculated to be 28.764kgCO2/t. All the results of this study can promote the safe and environmentally friendly utilization of waste concrete.