Pub Date : 2024-09-02DOI: 10.1038/s44296-024-00033-9
Weiwei Zhang, Binbin Yin, Arslan Akbar, Wen-Wei Li, Yitao Dai, K. M. Liew
Microscopic scrutiny aids in alkali-activated materials’ (AAM) application in construction industry. This study delves into the pore structure and properties of one-part alkali-activated slag (AAS) mortar modified by carbon black (CB) and recycled carbon fiber (rCF). The additives enhanced flexural strength by 51.82% (12.16 MPa) with lower water absorption (10.24%). Refinement of pore size and reduction of connectivity are key factors in improving properties. The densification effect of CB and the strong interface between rCF and gel were observed. Furthermore, AAS mortars exhibited multifractal characteristics within the range of micropores and capillary pores. Despite altering fractal regions, the additives did not affect its size dependence. The backbone fractal dimension increases with the addition of CB and rCF, exhibiting strong correlations with various macro properties, thus serving as a comprehensive parameter to characterize pore shape and distribution. This study deepens understanding of AAM composites, facilitating their adoption of low-carbon building materials.
{"title":"Nano-micro pore structure characteristics of carbon black and recycled carbon fiber reinforced alkali-activated materials","authors":"Weiwei Zhang, Binbin Yin, Arslan Akbar, Wen-Wei Li, Yitao Dai, K. M. Liew","doi":"10.1038/s44296-024-00033-9","DOIUrl":"10.1038/s44296-024-00033-9","url":null,"abstract":"Microscopic scrutiny aids in alkali-activated materials’ (AAM) application in construction industry. This study delves into the pore structure and properties of one-part alkali-activated slag (AAS) mortar modified by carbon black (CB) and recycled carbon fiber (rCF). The additives enhanced flexural strength by 51.82% (12.16 MPa) with lower water absorption (10.24%). Refinement of pore size and reduction of connectivity are key factors in improving properties. The densification effect of CB and the strong interface between rCF and gel were observed. Furthermore, AAS mortars exhibited multifractal characteristics within the range of micropores and capillary pores. Despite altering fractal regions, the additives did not affect its size dependence. The backbone fractal dimension increases with the addition of CB and rCF, exhibiting strong correlations with various macro properties, thus serving as a comprehensive parameter to characterize pore shape and distribution. This study deepens understanding of AAM composites, facilitating their adoption of low-carbon building materials.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00033-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1038/s44296-024-00031-x
Irene Walker, Robert Bell, Kerry Rippy
Ex-situ mineralization processes leverage the reaction of alkaline materials with CO2 to form solid carbonate minerals for carbon capture, utilization, and storage. Annually, enough alkaline waste is generated to reduce global CO2 emissions by a significant percentage via mineralization. However, while the reaction is thermodynamically favorable and occurs spontaneously, it is kinetically limited. Thus, a number of techniques have emerged to increase the efficiency of mineralization to achieve a scalable process. In this review, we discuss mineralization of waste streams with significant potential to scale to high levels of CO2 sequestration. Focus is placed on the effect of operating parameters on carbonation kinetics and efficiency, methods, cost, and current scale of technologies.
{"title":"Mineralization of alkaline waste for CCUS","authors":"Irene Walker, Robert Bell, Kerry Rippy","doi":"10.1038/s44296-024-00031-x","DOIUrl":"10.1038/s44296-024-00031-x","url":null,"abstract":"Ex-situ mineralization processes leverage the reaction of alkaline materials with CO2 to form solid carbonate minerals for carbon capture, utilization, and storage. Annually, enough alkaline waste is generated to reduce global CO2 emissions by a significant percentage via mineralization. However, while the reaction is thermodynamically favorable and occurs spontaneously, it is kinetically limited. Thus, a number of techniques have emerged to increase the efficiency of mineralization to achieve a scalable process. In this review, we discuss mineralization of waste streams with significant potential to scale to high levels of CO2 sequestration. Focus is placed on the effect of operating parameters on carbonation kinetics and efficiency, methods, cost, and current scale of technologies.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-17"},"PeriodicalIF":0.0,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00031-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.1038/s44296-024-00032-w
Zheyuan Zhang, Ying Lei, J. Y. Richard Liew, Mi Liu, Gloria Wong, Hongjian Du
Material production and construction activities are key contributors to global carbon footprints, necessitating sustainable alternatives. This study aims to investigate the potential of integrating recycled materials as Supplementary Cementitious Materials (SCMs) in concrete production to mitigate the substantial carbon emissions of Singapore’s building and construction sector. The research focuses on Ground Granulated Blast-furnace Slag (GGBFS), waste glass powder, and calcined marine clay as alternative SCMs, aiming to reduce environmental impact and waste disposal emissions in Singapore. Employing a cradle-to-gate Life Cycle Assessment (LCA) methodology for 1 m3 of concrete with different grades, this study quantifies embodied carbon savings and assesses the feasibility of substituting these SCMs in concrete. The results reveal that substituting Ordinary Portland Cement (OPC) with GGBFS in concrete offers the most significant reduction, up to 56%, in 1 m3 of concrete. In contrast, the use of calcined marine clay and glass powder in concrete results in reductions of up to 21% and 16%, respectively. Two case studies were used to exemplify the impact of using SCM concrete at the project scale. Results indicate that up to 31% of the total embodied carbon could be saved in the building. Additionally, scenario analysis suggests that the total emissions from cementitious materials in Singapore could decrease by 20% through the incorporation of locally recycled marine clay and glass powder. This reduction could potentially reach 56% if the GGBFS supply is not constrained. To further enhance sustainability in Singapore’s construction sector, the study proposes sourcing GGBFS from neighboring countries to minimize transportation emissions and localizing the production and usage of calcined marine clay and glass powder. These measures can improve material circularity and significantly contribute to achieving carbon reduction targets.
{"title":"Embodied carbon saving potential of using recycled materials as cement substitute in Singapore’s buildings","authors":"Zheyuan Zhang, Ying Lei, J. Y. Richard Liew, Mi Liu, Gloria Wong, Hongjian Du","doi":"10.1038/s44296-024-00032-w","DOIUrl":"10.1038/s44296-024-00032-w","url":null,"abstract":"Material production and construction activities are key contributors to global carbon footprints, necessitating sustainable alternatives. This study aims to investigate the potential of integrating recycled materials as Supplementary Cementitious Materials (SCMs) in concrete production to mitigate the substantial carbon emissions of Singapore’s building and construction sector. The research focuses on Ground Granulated Blast-furnace Slag (GGBFS), waste glass powder, and calcined marine clay as alternative SCMs, aiming to reduce environmental impact and waste disposal emissions in Singapore. Employing a cradle-to-gate Life Cycle Assessment (LCA) methodology for 1 m3 of concrete with different grades, this study quantifies embodied carbon savings and assesses the feasibility of substituting these SCMs in concrete. The results reveal that substituting Ordinary Portland Cement (OPC) with GGBFS in concrete offers the most significant reduction, up to 56%, in 1 m3 of concrete. In contrast, the use of calcined marine clay and glass powder in concrete results in reductions of up to 21% and 16%, respectively. Two case studies were used to exemplify the impact of using SCM concrete at the project scale. Results indicate that up to 31% of the total embodied carbon could be saved in the building. Additionally, scenario analysis suggests that the total emissions from cementitious materials in Singapore could decrease by 20% through the incorporation of locally recycled marine clay and glass powder. This reduction could potentially reach 56% if the GGBFS supply is not constrained. To further enhance sustainability in Singapore’s construction sector, the study proposes sourcing GGBFS from neighboring countries to minimize transportation emissions and localizing the production and usage of calcined marine clay and glass powder. These measures can improve material circularity and significantly contribute to achieving carbon reduction targets.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00032-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The escalating atmospheric CO2 concentration has become a global concern due to its substantial influence on climate change, emphasizing the necessity of carbon capture to achieve carbon neutrality. Adsorption-based CO2 separation is a promising approach for carbon capture, highlighting the importance of developing solid porous materials as effective adsorbents. Among these porous materials, zeolites stand out as promising adsorbents due to their extensively tunable adsorption/separation properties, superior structural stability, non-toxicity, and cost-effectiveness. This review provides a comprehensive overview of the mechanisms, strategies, and prospects for zeolite development in separating CO2 from critical scenarios, encompassing flue gas (CO2/N2), natural/bio/landfill gases (CO2/CH4), and air, respectively. This review outlines general mechanisms for CO2 separation using zeolites, discusses specific strategies for zeolite development, and concludes with a summary of current findings and an outlook for future research.
{"title":"Development of zeolite adsorbents for CO2 separation in achieving carbon neutrality","authors":"Zeyu Tao, Yuanmeng Tian, Wei Wu, Zhendong Liu, Weiqi Fu, Chung-Wei Kung, Jin Shang","doi":"10.1038/s44296-024-00023-x","DOIUrl":"10.1038/s44296-024-00023-x","url":null,"abstract":"The escalating atmospheric CO2 concentration has become a global concern due to its substantial influence on climate change, emphasizing the necessity of carbon capture to achieve carbon neutrality. Adsorption-based CO2 separation is a promising approach for carbon capture, highlighting the importance of developing solid porous materials as effective adsorbents. Among these porous materials, zeolites stand out as promising adsorbents due to their extensively tunable adsorption/separation properties, superior structural stability, non-toxicity, and cost-effectiveness. This review provides a comprehensive overview of the mechanisms, strategies, and prospects for zeolite development in separating CO2 from critical scenarios, encompassing flue gas (CO2/N2), natural/bio/landfill gases (CO2/CH4), and air, respectively. This review outlines general mechanisms for CO2 separation using zeolites, discusses specific strategies for zeolite development, and concludes with a summary of current findings and an outlook for future research.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-16"},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00023-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1038/s44296-024-00024-w
Nisha Singh, Tony R. Walker
Increasing plastic waste is a critical global challenge to ecological and human health requiring focused solutions to reduce omnipresent plastic pollution in the environment. While recycling has been touted as one solution to counter plastic waste and resource utilization, it has been largely ineffective in offsetting the impact of rising global plastic production of more than 400 million metric tonnes annually, due to low global recycling rates of only 9%. Over three decades since implementing plastic resin codes, recycling has favoured thermoplastics, neglecting thermoset plastics. There is a constant need to enhance overall recycling efficiency by exploring advanced methods, as enormous gaps exist in fully unlocking the potential of plastic recycling. We identify critical gaps associated with plastic waste recycling and its potential environmental impacts. We discuss substantial progress in recycling technology, designs-for-recyclability with controlled chemical use, and economic incentives to expand markets for recycled plastics and to curb plastic leakage into the environment. Additionally, we highlight some emerging strategies and legally binding international policy instruments, such as the Global Plastics Treaty that require further development to reduce plastic waste and improve plastic recyclability.
{"title":"Plastic recycling: A panacea or environmental pollution problem","authors":"Nisha Singh, Tony R. Walker","doi":"10.1038/s44296-024-00024-w","DOIUrl":"10.1038/s44296-024-00024-w","url":null,"abstract":"Increasing plastic waste is a critical global challenge to ecological and human health requiring focused solutions to reduce omnipresent plastic pollution in the environment. While recycling has been touted as one solution to counter plastic waste and resource utilization, it has been largely ineffective in offsetting the impact of rising global plastic production of more than 400 million metric tonnes annually, due to low global recycling rates of only 9%. Over three decades since implementing plastic resin codes, recycling has favoured thermoplastics, neglecting thermoset plastics. There is a constant need to enhance overall recycling efficiency by exploring advanced methods, as enormous gaps exist in fully unlocking the potential of plastic recycling. We identify critical gaps associated with plastic waste recycling and its potential environmental impacts. We discuss substantial progress in recycling technology, designs-for-recyclability with controlled chemical use, and economic incentives to expand markets for recycled plastics and to curb plastic leakage into the environment. Additionally, we highlight some emerging strategies and legally binding international policy instruments, such as the Global Plastics Treaty that require further development to reduce plastic waste and improve plastic recyclability.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11304528/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141904135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1038/s44296-024-00028-6
Wei Chen, Xuan Tao, Xiaolei Shi, Wenjuan Guo, Yurou Wang, Biao Liu, Haiping Yang
Alkali metal compounds have vital influence on biomass pyrolysis conversion. In this study, cellulose, and bamboo catalytic pyrolysis with different alkali metal salts catalysts (KCl, K2SO4, K2CO3, NaCl, Na2SO4, and Na2CO3) were investigated in the fixed-bed reaction system. The effects of cations (K+ and Na+) and anions (Cl-, SO42−, and CO32-) on the evolution properties of biochar, bio-oil, and gas products were explored under both in-situ and ex-situ catalytic pyrolysis. Results showed that alkali metal salts facilitated the yields of biochar and gases at the expense of that of bio-oil. Alkali metal chloride and sulfate showed a weaker catalytic effect, while alkali metal carbonate greatly promoted the generation of gas products and increased the condensation degree of biochar. With the addition of K2CO3 and Na2CO3, cyclopentanones content was over 50% from cellulose catalytic pyrolysis, and phenols content (mainly alkylphenols) reached over 80% from bamboo catalytic pyrolysis. Moreover, solid-solid catalytic reactions with K2CO3 and Na2CO3 catalysts had an important role in strikingly promoting conversion of pyrolysis products, and the solid-solid and gas-solid catalytic reactions with alkali metal carbonate catalysts were stronger than those with alkali metal chloride and sulfate catalysts. Furthermore, the possible catalytic pyrolysis mechanism of alkali metal salts on biomass pyrolysis was proposed, which is important to the high-value utilization of biomass.
{"title":"Insight into catalytic effects of alkali metal salts addition on bamboo and cellulose pyrolysis","authors":"Wei Chen, Xuan Tao, Xiaolei Shi, Wenjuan Guo, Yurou Wang, Biao Liu, Haiping Yang","doi":"10.1038/s44296-024-00028-6","DOIUrl":"10.1038/s44296-024-00028-6","url":null,"abstract":"Alkali metal compounds have vital influence on biomass pyrolysis conversion. In this study, cellulose, and bamboo catalytic pyrolysis with different alkali metal salts catalysts (KCl, K2SO4, K2CO3, NaCl, Na2SO4, and Na2CO3) were investigated in the fixed-bed reaction system. The effects of cations (K+ and Na+) and anions (Cl-, SO42−, and CO32-) on the evolution properties of biochar, bio-oil, and gas products were explored under both in-situ and ex-situ catalytic pyrolysis. Results showed that alkali metal salts facilitated the yields of biochar and gases at the expense of that of bio-oil. Alkali metal chloride and sulfate showed a weaker catalytic effect, while alkali metal carbonate greatly promoted the generation of gas products and increased the condensation degree of biochar. With the addition of K2CO3 and Na2CO3, cyclopentanones content was over 50% from cellulose catalytic pyrolysis, and phenols content (mainly alkylphenols) reached over 80% from bamboo catalytic pyrolysis. Moreover, solid-solid catalytic reactions with K2CO3 and Na2CO3 catalysts had an important role in strikingly promoting conversion of pyrolysis products, and the solid-solid and gas-solid catalytic reactions with alkali metal carbonate catalysts were stronger than those with alkali metal chloride and sulfate catalysts. Furthermore, the possible catalytic pyrolysis mechanism of alkali metal salts on biomass pyrolysis was proposed, which is important to the high-value utilization of biomass.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00028-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141804486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1038/s44296-024-00030-y
Raj Mukhopadhyay, Barbara Drigo, Binoy Sarkar
Antibiotic resistance genes (ARGs) are considered a contaminant of emerging concern in the environment. ARGs are widely distributed in the environment (e.g., soil, biosolids, plants, wastewater), companion and food-producing animals, wildlife, and insects. Soils are important reservoirs of ARGs and constitute a major pathway for the exchange of ARGs among microorganisms, including clinically relevant pathogens. Naturally available clays and clay minerals show high affinity to ARGs and antibiotics, which can be exploited to develop methods for mitigating ARGs contamination in soil, biosolids, and water. The mechanism of ARGs retention, degradation, and transformation on natural and modified clay surfaces is complex and requires further understanding to develop scalable remediation methods. Here, we discuss the source, availability, and distribution of antibiotics and ARGs in wastewater and soil, and their interactions with natural and modified clays and clay minerals to seek effective strategies for mitigating the overlooked pandemic of antimicrobial resistance (AMR). We shed light on future research requirements to extend the use of inexpensive clay adsorbents and develop nature-based solutions using these materials for mitigating AMR in the environment.
{"title":"Mitigation potential of antibiotic resistance genes in water and soil by clay-based adsorbents","authors":"Raj Mukhopadhyay, Barbara Drigo, Binoy Sarkar","doi":"10.1038/s44296-024-00030-y","DOIUrl":"10.1038/s44296-024-00030-y","url":null,"abstract":"Antibiotic resistance genes (ARGs) are considered a contaminant of emerging concern in the environment. ARGs are widely distributed in the environment (e.g., soil, biosolids, plants, wastewater), companion and food-producing animals, wildlife, and insects. Soils are important reservoirs of ARGs and constitute a major pathway for the exchange of ARGs among microorganisms, including clinically relevant pathogens. Naturally available clays and clay minerals show high affinity to ARGs and antibiotics, which can be exploited to develop methods for mitigating ARGs contamination in soil, biosolids, and water. The mechanism of ARGs retention, degradation, and transformation on natural and modified clay surfaces is complex and requires further understanding to develop scalable remediation methods. Here, we discuss the source, availability, and distribution of antibiotics and ARGs in wastewater and soil, and their interactions with natural and modified clays and clay minerals to seek effective strategies for mitigating the overlooked pandemic of antimicrobial resistance (AMR). We shed light on future research requirements to extend the use of inexpensive clay adsorbents and develop nature-based solutions using these materials for mitigating AMR in the environment.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00030-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141805943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1038/s44296-024-00025-9
Bin Ma, John L. Provis, Dengquan Wang, Georg Kosakowski
Cement-based materials are integral to radioactive waste repositories, providing versatile solutions for diverse disposal strategies. They are part of the multi-barrier system, and serve to immobilize waste materials, limit the release of radionuclides, contribute to an alkaline near-field to inhibit steel corrosion, reduce microbial activity, and slow down radionuclide transport in the repository near-field. This work delves into the adaptability of the multi-barrier systems for long-term safety, examining cases in clay and granite. Highlighting the disposal case in clay, the study emphasizes the role of cement in ensuring repository stability. The barrier system aims to minimize radionuclide release and demonstrate long-term isolation and containment of waste. The containment duration is relevant to the radionuclide’s half-life, with consideration for extended safety over extremely long periods. Cement evolves under geological conditions, undergoing a progressive process of degradation that is influenced by intricate aggregate-cement reactions and external factors, e.g., sulfates and chlorides in groundwater, the host rocks (including clays and granites), and the engineered barrier materials (including bentonite and steel), and in turn influencing mechanical stress generation and porosity. The very slow chemical alteration processes that take place at the concrete/granite interface underscore the repository stability. Corrosion of steel in the cement is expected to be slow, but its long-term structural and chemical changes remain quite unknown. Challenges remain in accurately predicting the long-term performance of the cement due to uncertainties in chemical reactivity, the impact of partial water saturation, and the kinetics of degradation processes. The manuscript advances the development of predictive modeling tools for assessing the long-term performance of cement-based barriers. The integration of experimental results with modeling efforts offers a robust framework for predicting the behavior of cementitious materials under various environmental conditions, thereby contributing to more reliable safety assessments of radioactive waste repositories. The role of cement phases in ensuring repository safety remains pivotal.
{"title":"The essential role of cement-based materials in a radioactive waste repository","authors":"Bin Ma, John L. Provis, Dengquan Wang, Georg Kosakowski","doi":"10.1038/s44296-024-00025-9","DOIUrl":"10.1038/s44296-024-00025-9","url":null,"abstract":"Cement-based materials are integral to radioactive waste repositories, providing versatile solutions for diverse disposal strategies. They are part of the multi-barrier system, and serve to immobilize waste materials, limit the release of radionuclides, contribute to an alkaline near-field to inhibit steel corrosion, reduce microbial activity, and slow down radionuclide transport in the repository near-field. This work delves into the adaptability of the multi-barrier systems for long-term safety, examining cases in clay and granite. Highlighting the disposal case in clay, the study emphasizes the role of cement in ensuring repository stability. The barrier system aims to minimize radionuclide release and demonstrate long-term isolation and containment of waste. The containment duration is relevant to the radionuclide’s half-life, with consideration for extended safety over extremely long periods. Cement evolves under geological conditions, undergoing a progressive process of degradation that is influenced by intricate aggregate-cement reactions and external factors, e.g., sulfates and chlorides in groundwater, the host rocks (including clays and granites), and the engineered barrier materials (including bentonite and steel), and in turn influencing mechanical stress generation and porosity. The very slow chemical alteration processes that take place at the concrete/granite interface underscore the repository stability. Corrosion of steel in the cement is expected to be slow, but its long-term structural and chemical changes remain quite unknown. Challenges remain in accurately predicting the long-term performance of the cement due to uncertainties in chemical reactivity, the impact of partial water saturation, and the kinetics of degradation processes. The manuscript advances the development of predictive modeling tools for assessing the long-term performance of cement-based barriers. The integration of experimental results with modeling efforts offers a robust framework for predicting the behavior of cementitious materials under various environmental conditions, thereby contributing to more reliable safety assessments of radioactive waste repositories. The role of cement phases in ensuring repository safety remains pivotal.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00025-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141815077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1038/s44296-024-00027-7
Linyao Ke, Nan Zhou, Qiuhao Wu, Yuan Zeng, Xiaojie Tian, Jiahui Zhang, Liangliang Fan, Roger Ruan, Yunpu Wang
The quest for low-carbon alternatives to fossil fuels and the carbon emissions associated with the natural degradation of biomass have accelerated the development of biomass processing technologies. Microwave catalytic pyrolysis is emerging as a technology for efficient conversion of biomass into energy, fuels and chemicals. However, due to the inherent poor dielectric properties and complex composition of biomass, two main technical challenges faced by microwave catalytic pyrolysis of biomass are efficient heating of biomass and improving the selectivity of target products. Potential solutions involve the use of microwave absorbents and catalysts, respectively. This review begins by addressing the difficulty in balancing energy efficiency and conversion efficiency by introducing microwave absorbents that play a positive role in improving heating efficiency. The principle of microwave absorbents in assisting biomass heating is revealed, and the impacts of the microwave absorbent type (related to microwave properties and physical properties) and the additive amount on the heating effect and biomass pyrolysis product distribution are discussed. Subsequently, the search for catalysts applied in biomass microwave pyrolysis for modulation of product distribution is explored. Special attention has been paid to the catalysts with microwave absorption properties, including activated carbon, zeolites, some metal oxides and metal salts. In addition, the energy efficiency, economic feasibility, and environmental impacts of this processing technology utilizing microwave absorbents and catalysts are examined based on energy analysis, techno-economic assessment, and life cycle assessment. The current scale-up challenges of microwave catalytic pyrolysis of biomass and some potential solutions to enhance the commercial feasibility of this technology are also discussed. Finally, the review provides some future development directions of this technology.
{"title":"Microwave catalytic pyrolysis of biomass: a review focusing on absorbents and catalysts","authors":"Linyao Ke, Nan Zhou, Qiuhao Wu, Yuan Zeng, Xiaojie Tian, Jiahui Zhang, Liangliang Fan, Roger Ruan, Yunpu Wang","doi":"10.1038/s44296-024-00027-7","DOIUrl":"10.1038/s44296-024-00027-7","url":null,"abstract":"The quest for low-carbon alternatives to fossil fuels and the carbon emissions associated with the natural degradation of biomass have accelerated the development of biomass processing technologies. Microwave catalytic pyrolysis is emerging as a technology for efficient conversion of biomass into energy, fuels and chemicals. However, due to the inherent poor dielectric properties and complex composition of biomass, two main technical challenges faced by microwave catalytic pyrolysis of biomass are efficient heating of biomass and improving the selectivity of target products. Potential solutions involve the use of microwave absorbents and catalysts, respectively. This review begins by addressing the difficulty in balancing energy efficiency and conversion efficiency by introducing microwave absorbents that play a positive role in improving heating efficiency. The principle of microwave absorbents in assisting biomass heating is revealed, and the impacts of the microwave absorbent type (related to microwave properties and physical properties) and the additive amount on the heating effect and biomass pyrolysis product distribution are discussed. Subsequently, the search for catalysts applied in biomass microwave pyrolysis for modulation of product distribution is explored. Special attention has been paid to the catalysts with microwave absorption properties, including activated carbon, zeolites, some metal oxides and metal salts. In addition, the energy efficiency, economic feasibility, and environmental impacts of this processing technology utilizing microwave absorbents and catalysts are examined based on energy analysis, techno-economic assessment, and life cycle assessment. The current scale-up challenges of microwave catalytic pyrolysis of biomass and some potential solutions to enhance the commercial feasibility of this technology are also discussed. Finally, the review provides some future development directions of this technology.","PeriodicalId":471646,"journal":{"name":"npj Materials Sustainability","volume":" ","pages":"1-20"},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44296-024-00027-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141817463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1038/s44296-024-00026-8
Yao Du, Chuang Liu, Qihan Qiu, Haidong Zhang, Bo Li, Xincai Chen, Honghai Lou, Qiang Zeng
The continual large-scale urbanization and urban renewal in coastal cities of China have accumulated massive silty residue (SR) that may alter the coastal lines and always exerts high stresses to local environments. To meet China’s sustainable development policy, the need for green and high-efficient industrial treatments and reuse of SR is urgent. In this work, we may, for the first time, report a megaton-scale industrial project to upcycle low-quality SR and recycled aggregate (RA) to manufacture construction materials with hydrothermal mineralization (HM). In-situ pilot tests on five batches of SR-RA blocks were conducted. Results demonstrate that the produced blocks possess the compressive strengths of 11.4–15.8 MPa, densities of 1280–1430 kg/m3, porosities of 35–44%, CO2 emissions of 170.22–187.29 kg e-CO2/m3 and costs of 126.49–156.51 CNY/m3, comparable with or superior than the commercial blocks. The silica in SR could react with lime to produce tobermorite with stable pseudohexagonal plate under HM treatment, which improved the microstructure of the material. The findings validate the industrial practicability of upcycling low-quality SR and RA with HM for valuable construction block manufacture.
中国沿海城市持续的大规模城市化和城市改造积累了大量的淤泥质残渣（SR），这些残渣可能会改变海岸线，并始终对当地环境造成巨大压力。为了适应中国的可持续发展政策，迫切需要对淤泥质残渣进行绿色、高效的工业处理和再利用。在这项工作中，我们首次报道了一个百万吨级的工业项目，利用热液矿化（HM）将低质石英砂和再生骨料（RA）回收利用，制造建筑材料。我们对五批 SR-RA 块料进行了现场试验。结果表明，所生产的砌块抗压强度为 11.4-15.8 MPa，密度为 1280-1430 kg/m3，孔隙率为 35-44%，二氧化碳排放量为 170.22-187.29 kg e-CO2/m3，成本为 126.49-156.51 元人民币/m3，与商用砌块相当或优于商用砌块。在 HM 处理下，SR 中的二氧化硅可与石灰反应生成具有稳定假六方板的托勃莫来石，从而改善了材料的微观结构。这些研究结果验证了用 HM 对低质 SR 和 RA 进行升级再循环以制造有价值的建筑砌块的工业实用性。
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