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Sharma R, Das KK, Siddique S, Jang JG. Cesium immobilization of high pH and low pH belite-rich cement under varying temperature. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133995. [PMID: 38492390 DOI: 10.1016/j.jhazmat.2024.133995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 01/29/2024] [Accepted: 03/07/2024] [Indexed: 03/18/2024]
Abstract
Low-pH cement is being studied in radioactive waste repositories. The belite-rich cement (BRC) recently gained attention due to its higher CO2 sequestration and low pH attainment under carbonation exposure. Therefore, this study evaluated the effects of pH and temperature on cesium immobilization of BRC. High pH (12.6) and low pH (9.9) BRC were produced via air curing and carbonation treatment, respectively. The high and low pH BRC samples were placed in a leaching environment at 25 °C and 45 °C for 90 days. An inverse correlation between pH and cesium mobilization of BRC was observed. The high pH BRC achieved the lowest effective diffusion coefficient (4.05E-09 cm2/s), whereas the highest value (2.64E-07 cm2/s) was achieved in case of low pH BRC. The physicochemical and morphological properties unveiled the decrease in Si/Ca ratio of gel, precipitation of Ca2+ ions in calcite formation, and increment in pore structure connectivity (pore size > 100 nm) in low pH BRC. However, the high pH BRC demonstrated the high Si/Ca ratio in C-S-H gel, hydroxide phases and higher disconnected pores. Thermodynamic modeling revealed the presence of significant carbonated phases beyond 15% CO2 uptake. The findings contributed to the BRC's feasibility in developing nuclear waste storage facility.
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Affiliation(s)
- Raju Sharma
- Division of Architecture and Urban Design, Urban Science Institute, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - Kunal Krishna Das
- Division of Architecture and Urban Design, Urban Science Institute, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - Salman Siddique
- Interdisciplinary Research Center for Construction and Building Materials, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Jeong Gook Jang
- Division of Architecture and Urban Design, Urban Science Institute, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea.
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2
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Barbhuiya S, Das BB, Qureshi T, Adak D. Cement-based solidification of nuclear waste: Mechanisms, formulations and regulatory considerations. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 356:120712. [PMID: 38531127 DOI: 10.1016/j.jenvman.2024.120712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 03/10/2024] [Accepted: 03/19/2024] [Indexed: 03/28/2024]
Abstract
This review paper provides a comprehensive analysis of cement-based solidification and immobilisation of nuclear waste. It covers various aspects including mechanisms, formulations, testing and regulatory considerations. The paper begins by emphasizing the importance of nuclear waste management and the associated challenges. It explores the mechanisms and principles in cement-based solidification, with a particular focus on the interaction between cement and nuclear waste components. Different formulation considerations are discussed, encompassing factors such as cement types, the role of additives and modifiers. The review paper also examines testing and characterisation methods used to assess the physical, chemical and mechanical properties of solidified waste forms. Then the paper addresses the regulatory considerations and compliance requirements for cement-based solidification. The paper concludes by critically elaborating on the current challenges, emerging trends and future research needs in the field. Overall, this review paper offers a comprehensive overview of cement-based solidification, providing valuable insights for researchers, practitioners and regulatory bodies involved in nuclear waste management.
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Affiliation(s)
- Salim Barbhuiya
- Department of Engineering and Construction, University of East London, London, UK.
| | | | - Tanvir Qureshi
- Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada; Department of Engineering Design and Mathematics, University of the West of England, Bristol, UK
| | - Dibyendu Adak
- Department of Civil Engineering, NIT Meghalaya, Shillong, India
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Park EA, Kim TY, Son JS, Lee SY. Kapok fiber composites minimizing secondary waste and disposal costs for large-scale radioactive liquid treatment. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 357:120851. [PMID: 38581894 DOI: 10.1016/j.jenvman.2024.120851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 03/30/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
Conventional liquid treatments for large-scale, low-level radioactive wastewater, such as ion exchange and waste solidification, face challenges due to the large amounts of secondary waste and high disposal costs. A new large-scale decontamination method is proposed that uses kapok fiber composites for rapid radionuclide adsorption and high volume reduction to minimize secondary waste. The composite consists of natural zeolite and kapok holocellulose, which has high water-soaking ability and low-temperature pyrolysis. The kapok composites, fabricated using a commercial wet-laid nonwoven manufacturing process, absorbs 99% of low-level radioactive cesium in 20 min, reducing the volume by 98% and the weight by 47% at 300 °C. The low-temperature pyrolysis process below 300 °C prevents cesium desorption and gasification by avoiding zeolite destruction. The mass-producible kapok composites can be used for adsorbing various radionuclides in large-scale wastewater by attaching specific adsorbents for target isotopes to the composites.
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Affiliation(s)
- Eun Ae Park
- Department of Mechanical Engineering, Sogang University, Baekbeom-ro 35, Mapo-gu, Seoul, Republic of Korea
| | - Tae Yoon Kim
- Department of Biomedical Engineering, Sogang University, Baekbeom-ro 35, Mapo-gu, Seoul, Republic of Korea
| | - Jun Sik Son
- Korea Textile Development Institute, Kukchaebosang-ro 136, Seo-gu, Daegu, Republic of Korea
| | - Seung-Yop Lee
- Department of Mechanical Engineering, Sogang University, Baekbeom-ro 35, Mapo-gu, Seoul, Republic of Korea; Department of Biomedical Engineering, Sogang University, Baekbeom-ro 35, Mapo-gu, Seoul, Republic of Korea.
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4
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Chen X, Zhou X, Fan Z, Peng Z, Lu Q. Competitive encapsulation of multiple heavy metals by magnesium potassium phosphate cement: Hydration characteristics and leaching toxicity properties. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 177:115-124. [PMID: 38320451 DOI: 10.1016/j.wasman.2024.01.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 01/09/2024] [Accepted: 01/27/2024] [Indexed: 02/08/2024]
Abstract
Magnesium potassium phosphate cement (MKPC) is increasingly used in the solidification/stabilization (SS) of heavy metal (HM) pollutants. However, research on composite HM pollutants remains limited. In this study, four heavy metals (Pb/Zn/Cu/Cd) were individually and simultaneously introduced into MKPC systems with different magnesium/phosphorus (M/P) molar ratios. The introduction of HMs altered the extent of hydration and morphology of MgKPO4·6H2O. Among the MKPC pastes, those with M/P = 2 and 3 had the highest HM solidification efficiency and strength, respectively. The HM solidification efficiency of all specimens exceeded 99 %. In samples with M/P = 3, the codoping of four HMs slightly increased the M/P ratio, thereby increasing MgKPO4·6H2O content and enhancing strength. Pb could generate additional low-solubility precipitates, such as PbHPO4, Pb3 (PO4)2, Pb5 (OH) (PO4)3, and Pb (OH)2, which easily accumulated in pores and were encapsulated by MgKPO4·6H2O, leading to the highest solidification efficiency of Pb by MKPC. Pb and Cu could also form the composite phosphate products Pb2Cu (PO4)3 (OH)·4H2O, thus promoting the S/S effect of Cu. Therefore, the use of MKPC with M/P ratio of 2-3 for the S/S of complex pollutants containing Pb and Cu is a promising approach.
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Affiliation(s)
- Xia Chen
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China.
| | - Xian Zhou
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China.
| | - Zeyu Fan
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
| | - Ziling Peng
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
| | - Qi Lu
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
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Qiu Z, Cheng W, He X, Yan J, Lan H, Ding C, Shu X, Wu D, Lu X. Research on the Properties of Wasteforms after Direct Involvement of Uranium-Containing Silica Gel in Glass Network Formation. Inorg Chem 2024; 63:5497-5508. [PMID: 38483825 DOI: 10.1021/acs.inorgchem.3c04365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
Uranium-containing silica gel (UCSG) is a secondary waste generated during the advanced treatment of nuclear wastewater. In order to reduce the growing storage pressure for UCSG, from the perspective of building a borosilicate glass network, UCSG was used to replace SiO2 in the glass-cured formula to directly achieve the immobilization of UCSG. SEM-EDS results showed that uranium was uniformly distributed in the matrix, and the maximum solid solubility of UCSG (two components: silica gel and uranyl ions) in the formula was as high as 55 wt %. At the same time, TG-MS proved that silica gel lost OH groups (down about 4.61 wt %) and formed Si-O-Si bond by condensation. FT-IR and XPS proved a change in the number of Si-O-Si bond, and new Si-O-B and Si-O-Al bond appeared on the spectrum. This was evidence that silica gel could self-involved participate in the construction of glass networks. EPR analysis obtained the changes in the coordination environment of U atom, the U atom decreased spin electrons number in the glass than in uranyl crystals. The glass also has good physical properties (hardness: 6.51 ± 0.23 GPa; density: 2.3977 ± 0.0056 g/cm3) and chemical durability (normalized leaching rate: LRU = 2.34 × 10-4 ± 2.05 × 10-6 g·m2·days-1 after 42 days), this research provided tactics for simple treatment of uranium-containing silica gel in one step.
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Affiliation(s)
- Ze Qiu
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Wencai Cheng
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Xiyang He
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Jing Yan
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Hao Lan
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Congcong Ding
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Xiaoyan Shu
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Dong Wu
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, P. R. China
| | - Xirui Lu
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, P. R. China
- Tianfu Institute of Research and Innovation, Southwest University of Science and Technology, Chengdu 610299, China
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6
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Kim B, Kang J, Shin Y, Yeo TM, Heo J, Um W. Effect of Si/Al molar ratio and curing temperatures on the immobilization of radioactive borate waste in metakaolin-based geopolymer waste form. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:131884. [PMID: 37348372 DOI: 10.1016/j.jhazmat.2023.131884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 06/24/2023]
Abstract
Immobilization of radioactive borate waste (RBW) using a geopolymer with a high Si/Al ratio has been challenging because boron-silicon networks lower the compressive strength and delay the setting time. In this study, metakaolin-based geopolymer waste form to immobilize simulant RBW was fabricated using different Si/Al ratios (1.0-1.4) and curing temperatures (26 and 60 ℃). The 7-day compressive strength results revealed that a certain amount of silicon and an elevated curing temperature are required to achieve high compressive strength and waste loading. Following waste acceptance criteria tests, all geopolymers exhibited compressive strengths higher than 3.445 MPa. The leachability index of boron was higher than 6.0, and the leaching mechanism was identified as diffusion. No significant structural changes in the geopolymer were observed after thermal cycling and gamma irradiation tests. The physically bound or unincorporated RBW was leached out of the geopolymer during water immersion and leaching tests; however, boron, which was chemically connected with silicon, was present as an inert phase together with a geopolymer binder. Consequently, immobilizing RBW using a geopolymer with a low Si/Al ratio (1.4) is beneficial in terms of RBW loading and structural durability.
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Affiliation(s)
- Byoungkwan Kim
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Jaehyuk Kang
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea; Department of Electrical and Energy Engineering, Jeju National University, 102, Jejudaehak-ro, Jeju-si, Jeju Special Self-Governing Province, 63243, Republic of Korea
| | - Younglim Shin
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Tae-Min Yeo
- Graduate Institute of Ferrous & Energy Materials Technology (GIFT), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Jong Heo
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea
| | - Wooyong Um
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea; Nuclear Environmental Technology Institute (NETI), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea; Division of Environmental Science and Engineering (DESE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
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Tong W, Du X, Wang J, Yan H, Xie T, Wang Y, Zhang Y. Degradation and phosphorus immobilization treatment of organophosphate esters hazardous waste by Fe-Mn bimetallic oxide. JOURNAL OF HAZARDOUS MATERIALS 2023; 449:131049. [PMID: 36840987 DOI: 10.1016/j.jhazmat.2023.131049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 02/02/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
Organophosphate esters (OPEs) waste is difficult to dispose effectively because of its stability and the potential risk of P element. In this study, taking one typical organic extractant of tributyl phosphate (TBP) as an example, we proposed a strategy to treat OPEs inspired by chemical looping combustion (CLC) technology-oxygen carrier immobilization process (OCIP), aiming at efficient TBP degradation and simultaneous P immobilization. Adopting Fe-Mn bimetallic oxide (FMBO) as oxygen carrier, an almost 100% P immobilization efficiency was achieved under recommended conditions which were obtained by response surface methodology. Meanwhile, gaseous products released from TBP degradation, e.g., non-methane hydrocarbon, was lower than the maximum allowable emission concentration limit. Further characterizations implied that P-species released from reaction process were mainly immobilized as stable inorganic forms of metaphosphate, phosphate and pyrophosphate. On the basis of identifying degradation intermediates, we proposed a possible degradation pathways. FMBO as an oxygen carrier provided sufficient oxygen molecules for flameless combustion of OCIP process. Electron paramagnetic resonance measurement confirmed the existence of oxygen vacancies on FMBO surface, which contributed to the formation of •O2-. Oxidation by oxygen molecules and •O2- attack resulted in the degradation and mineralization of TBP, with simultaneously achieving P stabilization.
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Affiliation(s)
- Wenhua Tong
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Xinhang Du
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Jiepeng Wang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Hao Yan
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Tonghui Xie
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Yabo Wang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
| | - Yongkui Zhang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
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Wang S, Yu G, Wang J. Treatment of tributyl phosphate by fenton oxidation: Optimization of parameter, degradation kinetics and pathway. CHEMOSPHERE 2023; 317:137889. [PMID: 36657574 DOI: 10.1016/j.chemosphere.2023.137889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/14/2023] [Accepted: 01/15/2023] [Indexed: 06/17/2023]
Abstract
In nuclear industry, tributyl phosphate (TBP) is used as organic extracting solvent to separate uranium and plutonium. The spent TBP is finally discarded as the radioactive organic waste, which should be treated due to its potential risk. In this study, TBP degradation by Fenton oxidation was investigated in detail, including the optimization of operational conditions, degradation kinetics and degradation products. The optimal conditions for TBP degradation (per 10 ml) by Fenton oxidation was: 95 °C, pH 2, 150 ml 30% H2O2, and 105 ml 0.2 M Fe(II). H2O2 was continuously added with the flow rate of 0.5 ml/min, Fe(II) was intermittently added with the flow rate of 3 ml/10 min. The oil phase volume decreased with time and completely disappeared at the third hour. In contrast, the COD in water phase increased firstly and then decreased. At the end of the experiments, the COD achieved 23.8 g/L. The detection of phosphorus in water phase further confirmed the decomposition of TBP. Mono-butyl phosphate and di-butyl phosphate were identified as the intermediate products of TBP degradation. In addition, other four degradation products with the same m/z of 154 were identified, which may be derived from the hydroxylation of mono-butyl phosphate and di-butyl phosphate. Based on the degradation products, the degradation pathway of TBP was proposed. This study could provide an insight into the TBP degradation by Fenton oxidation, and an potential strategy for treating the spent radioactive organic solvent.
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Affiliation(s)
- Shizong Wang
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China; Energy Science Building, INET, Tsinghua University, Beijing, 100084, China.
| | - Guoce Yu
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China; Energy Science Building, INET, Tsinghua University, Beijing, 100084, China.
| | - Jianlong Wang
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China; Beijing Key Laboratory of Radioactive Wastes Treatment, Tsinghua University, Beijing, 100084, China.
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Yang P, Liu L, Suo Y, Qu H, Xie G, Zhang C, Deng S, Lv Y. Basic characteristics of magnesium-coal slag solid waste backfill material: Part I. preliminary study on flow, mechanics, hydration and leaching characteristics. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 329:117016. [PMID: 36586328 DOI: 10.1016/j.jenvman.2022.117016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/06/2022] [Accepted: 12/10/2022] [Indexed: 06/17/2023]
Abstract
The environmental damage caused by surface subsidence and coal-based solid waste (CBSW) is a common problem in the process of coal mining. Backfill mining can control the mining-induced subsidence and solve the problem of bulk solid waste storage. In the present work, a magnesium-coal slag solid waste backfill material (MCB) with modified magnesium slag (MS) as binder and CBSW (fly ash (FA), flue gas desulfurization gypsum (FDG) and coal gasification slag (CGS)) as supplementary cementitious material/aggregate was proposed to meet the needs of coal mining in Northern Shaanxi, China, to realize the comprehensive treatment of goaf and CBSW. The results show that: (1) The rheological curve of the fresh MCB slurry is highly consistent with the Herschel-Bulkley (H-B) model, and its fluidity meets the basic requirements of mine backfill pumping. With the addition of FDG and MS, the yield stress, apparent viscosity and thixotropy of MCB slurry increase, while the pseudoplastic index and slump decrease. (2) The strength of MCB develops slowly in the early stage (0∼14 days) and increases rapidly in the later stage (14∼90 days). Except for the ratio of M20F1 and FDG = 0%, the strength of samples at other ratios (at 28 days) is between 6.06∼11.68 MPa, which meets the strength requirement of 6 MPa for coal mine backfill. The addition of MS and appropriate amount of FDG is beneficial to the development of strength. In contrast, MS exhibits a significant improvement in early strength, and FDG has a significant improvement in late-age strength. (3) Corresponding to the compressive strength, the hydration products C-S(A)-H and AFt of MCB are less in the early stage and greatly increased in the later stage. The active substance in FA/CGS will undergo pozzolanic reaction with the MS hydration product CH. The addition of FDG and MS can promote the reaction and increase the amount of hydration product, but in contrast, the promotion effect of FDG is more significant. (4) The amount of heavy metal leaching of MCB meets the requirements of national standards. The hardened MCB has a solidification/stabilization effect on heavy metal elements, which can significantly reduce the amount of heavy metal leaching. The results imply that MCB is a safe, reliable, and eco-friendly solid waste backfill material, and its application is conducive to the coordinated development of coal resource mining and environmental protection.
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Affiliation(s)
- Pan Yang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Lang Liu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an, 710054, China.
| | - Yonglu Suo
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an, 710054, China.
| | - Huisheng Qu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Geng Xie
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Caixin Zhang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Shunchun Deng
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Yin Lv
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
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Al-Ghamdi H, Tashlykov O, Sayyed M, Almuqrin AA, Khandaker MU, Mahmoud K. Suggested two layers container for shielding the low and intermediate activity gamma-ray sources. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Shon JS, Lee HK, Kim GY, Kim TJ, Ju JS. Evaluation of disposal stability of cement waste forms mixed with concentrated liquid waste for efficient treatment of AUC process waste. J Radioanal Nucl Chem 2022. [DOI: 10.1007/s10967-022-08495-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Tong W, Wang J, Du X, Wang X, Wang Y, Zhang Y. Tributyl phosphate degradation and phosphorus immobilization by MnO 2: Reaction condition optimization and mechanism exploration. JOURNAL OF HAZARDOUS MATERIALS 2022; 432:128725. [PMID: 35338934 DOI: 10.1016/j.jhazmat.2022.128725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/27/2022] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
The treatment of tributyl phosphate (TBP) extractant waste from specific industry, eg., nuclear industry, is a great challenge due to its stability and high environmental risk of phosphorus-containing species releasing. Inspired by chemical looping combustion (CLC) technology, a MnO2-assisted thermal oxidation strategy is proposed for TBP degradation and simultaneously P immobilization. Under recommended reaction conditions of 220 °C, 10 g MnO2 mL-1 TBP and 3 h reaction duration, a high P immobilization efficiency of 93.99% is achieved. Material characterization results indicate that P is mainly immobilized in the form of Mn2P2O7, which greatly reduces the environmental risk of P-containing species. TBP degradation intermediates are further identified by thermogravimetric-gas chromatography-mass spectrometry (TG-GC-MS), liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), which facilitates understanding of reaction mechanisms as well as proposing possible pathways of TBP degradation. It is suggested that MnO2 provides essential oxygen as oxygen carrier for flameless combustion. Meantime, MnO2 reduction leads to the generation of Mn(III) species. The existence of oxygen vacancy in MnO2 also facilitates •O2- radical generation. Under flameless combustion and attacks of Mn(III) and •O2-, TBP is firstly degraded into intermediates and finally mineralized into CO2 and H2O, while P is mainly immobilized as pyrophosphate.
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Affiliation(s)
- Wenhua Tong
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Jiepeng Wang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Xinhang Du
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Xuqian Wang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
| | - Yabo Wang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
| | - Yongkui Zhang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
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P VA, Mishra S, Rajeev R, Desigan N, Venkatesan K, Ananthasivan K. Hydrolysis of tri-butyl phosphate in n-dodecane using sodium hydroxide: Factors affecting the hydrolysis process. PROGRESS IN NUCLEAR ENERGY 2022. [DOI: 10.1016/j.pnucene.2022.104247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Toward Sustainable Cementitious Radioactive Waste Forms: Immobilization of Problematic Operational Wastes. SUSTAINABILITY 2021. [DOI: 10.3390/su132111992] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Developing effective radioactive waste management practices is essential for ensuring the sustainability of the nuclear industry. The immobilization of radioactive wastes is one of the main activities conducted during the management of these wastes; it aims to produce a durable waste form that has sustainable performance over long periods of time. In this work, the challenges that face the design of durable cementitious waste forms are addressed for problematic operational wastes. In this respect, the problematic characteristics of evaporator concentrates, spent ion exchangers, and organic liquid wastes are overviewed, and the factors that affect the durability of their cementitious waste forms are identified. A summary of potential conventional and innovative cementitious matrices is presented by reviewing the cementation practices in national programs and recent research devoted to developing durable matrices. Finally, a guide to optimize the mix design of these waste forms was proposed that includes the selection of the testing procedure, factors that affect the waste form performance, and the optimization technique. This guide was presented with special focus on leaching tests, which are a means to test the stabilization performance of nuclear waste forms.
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