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Antunes M, Santos RL, Horta RB, Colaço R. Novel Amorphous-Wollastonitic Low-Calcium Hydraulic Binders: A State-of-the-Art Review. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4874. [PMID: 37445188 DOI: 10.3390/ma16134874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/24/2023] [Accepted: 07/04/2023] [Indexed: 07/15/2023]
Abstract
Because of the severe environmental impact of the CO2 emissions associated with the production of ordinary Portland cement (OPC) and the increasing demand for this commodity material, the development of alternative products has become a global concern. One alternative to OPC, or alitic-based clinkers, are amorphous-wollastonitic low-calcium hydraulic binders (AWLCs). This new class of hydraulic binders, described in the literature for the first time in 2015, may significantly reduce the CO2 emissions associated with its production, resulting from its lower calcium content, but also from the fact that its production technology can be fully electrified. In this paper, a state-of-the-art review is presented, providing a comprehensive description of the latest research, summarizing both the physicochemical and mechanical characteristics of this type of hydraulic binder, as well as possible routes for its production at an industrial scale.
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Affiliation(s)
- Mónica Antunes
- Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- IDMEC-Instituto de Engenharia Mecânica, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Rodrigo L Santos
- CIMPOR-Cimentos de Portugal, SGPS S.A., 1099-020 Lisbon, Portugal
| | - Ricardo B Horta
- Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Rogério Colaço
- Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- IDMEC-Instituto de Engenharia Mecânica, University of Lisbon, 1049-001 Lisbon, Portugal
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Qin J, Yuan S, Córdova-Udaeta M, Oyama K, Tokoro C. Highly Efficient Cd 2+ Removal Using Tobermorite with pH Self-Adjustment Ability from Aqueous Solution. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1314. [PMID: 36770321 PMCID: PMC9919889 DOI: 10.3390/ma16031314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Cadmium (Cd), as a type of heavy metal, can increase the incidence of many diseases, even in low concentrations. In this study, tobermorite was hydrothermally synthesized and then applied to adsorb Cd2+ from an aqueous solution. The physicochemical characteristics of the synthesized tobermorite were detected, and the results indicated that the well-crystallized tobermorite had a lot of mesopores and a large specific surface area of 140.92 m2/g. It acquired a pH self-adjustment ability via spontaneously releasing Ca2+ and OH- into the aqueous solution. The effects of different factors on Cd2+ removal were investigated. For Cd2+, the removal efficiency could reach 99.71% and the maximum adsorption capacity was 39.18 mg/g using tobermorite. The adsorption data was best fitted with the pseudo-second-order kinetic and Langmuir isotherm models. In addition, there was no strict limit on the solution pH in Cd2+ adsorption because the tobermorite could adjust the solution pH to an alkaline atmosphere spontaneously. The efficient removal of Cd2+ using tobermorite was a result of surface complexation and ion exchange.
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Affiliation(s)
- Juan Qin
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, China
| | - Sujuan Yuan
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, China
| | - Mauricio Córdova-Udaeta
- Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Keishi Oyama
- Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Chiharu Tokoro
- Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
- Faculty of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Cho YJ, Kwon YJ, Jin S, Choi H, Lee JH, Yang SM, Choi SW, Jeong YK. Two-Dimensional calcium silicate nanosheets for trapping atmospheric water molecules in humidity-immune gas sensors. JOURNAL OF HAZARDOUS MATERIALS 2022; 432:128671. [PMID: 35303661 DOI: 10.1016/j.jhazmat.2022.128671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/23/2022] [Accepted: 03/08/2022] [Indexed: 05/27/2023]
Abstract
In humid conditions, water vapor can easily neutralize the surface active sites of metal oxide sensors, leading to a lowering in the sensitivity of the gas sensor and a resultant inaccurate signal in practical applications. Herein, we present a new hybrid sensor by introducing a two-dimensional calcium silicate (CS) nanosheet as a water-trapping layer in SnO2 nanowires. Unlike the heavily wrinkled and aggregated morphology of conventional CS nanosheets, our nanosheet in the hybrid material is ultrathin and flat. Moreover, it was grown in the empty spaces between the spider-web-like networks of SnO2 nanowires without covering the nanowire surface. These two morphological features improve moisture trapping with minimal reduction in the active sensing area. Consequently, stable and sensitive gas detection under humid conditions was achieved in this hybrid sensor. The superior humidity-independent sensing is ascribed to the preferential adsorption of water molecules on hydroscopic CS nanosheets through the hydrogen bond. Based on density functional theory calculations, we determined that the improved gas response is driven by the additional formation of oxygen vacancy in SnO2 due to the diffusion of aliovalent Ca ions from the CS nanosheet.
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Affiliation(s)
- Young Ju Cho
- Functional Materials & Components R&D group, Korea Institute of Industrial Technology (KITECH), 137-41 Gwahakdanji-ro, Gangneung-si, Gangwon 25440, Republic of Korea
| | - Yong Jung Kwon
- Functional Materials & Components R&D group, Korea Institute of Industrial Technology (KITECH), 137-41 Gwahakdanji-ro, Gangneung-si, Gangwon 25440, Republic of Korea
| | - Sunghwan Jin
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 Republic of Korea
| | - Hyeunseok Choi
- Smart Manufacturing System R&D Department, Korea Institute of Industrial Technology (KITECH), 89, Yangdaegiro-gil, Ipjang-myeon, Seobuk-gu, Cheonan-si, Chungnam 31056, Republic of Korea
| | - Jung-Hoon Lee
- Computational Science Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Seung-Min Yang
- Functional Materials & Components R&D group, Korea Institute of Industrial Technology (KITECH), 137-41 Gwahakdanji-ro, Gangneung-si, Gangwon 25440, Republic of Korea
| | - Sun-Woo Choi
- Department of Materials Science and Engineering, Kangwon National University, Samcheok-si, Gangwon-do 25913, Republic of Korea.
| | - Young Kyu Jeong
- Functional Materials & Components R&D group, Korea Institute of Industrial Technology (KITECH), 137-41 Gwahakdanji-ro, Gangneung-si, Gangwon 25440, Republic of Korea.
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Liao W, Li W, Fang Z, Lu C, Xu Z. Effect of Different Aluminum Substitution Rates on the Structure of Tobermorite. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E3765. [PMID: 31731827 PMCID: PMC6888367 DOI: 10.3390/ma12223765] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/13/2019] [Accepted: 11/13/2019] [Indexed: 12/04/2022]
Abstract
Tobermorite and Al-substituted tobermorite with varying Al/(Si + Al) molar ratios were synthesized via the static hydrothermal method. The effect of different Al substitution ratios on the structure of tobermorite was investigated by XRD, SEM-EDS, TG-DSC, FT-IR, 29Si, and 27Al MAS-NMR. The interplanar crystal spacing of (002) increased with the increment of the Al substitution ratio. The maximum ratio of the Al substitution for Si in the structure of tobermorite was about 15 at %, which was limited by the compositions of tobermorite and the electrostatic repulsive forces caused by Al substitution. The DSC curve of the tobermorite with an Al/(Al + Si) molar ratio of 0.15 showed a larger exothermic peak area at 850 °C, indicating that the Al-O-Si bond was formed in the structure of tobermorite and the Al participated in the recrystallization. The 29Si and 27Al MAS-NMR results confirmed that tetrahedral Al was introduced into the structure of the tobermorite. New silicon sites, Q2(1Al) and Q3(1Al), formed by the Al substitution for Si in bridging and non-bridging sites, were detected. Compared to the tobermorite without Al substitution, the adsorption capacity of Al-substituted tobermorite with Al/(Al + Si) = 0.15 to Na+ was improved by 44%.
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Affiliation(s)
| | | | | | - Chunhua Lu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China
| | - Zhongzi Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China
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