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Tang L, Li X, Feng H, Ma C, Chang Q, Zhang J. Infiltration of salt solutions through illite particles: Effect of nanochannel size and cation type. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jiang J, Guo L, Tang L, Zhang Y. The manner and extent to which the hydration shell impacts interactions between hydrated species. Phys Chem Chem Phys 2021; 23:20496-20508. [PMID: 34499068 DOI: 10.1039/d1cp03368a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydration shell (HS) has a critical impact on every contact between hydrated species, which is a prerequisite for a great many physical and chemical processes, such as ion adsorption at the solution-solid interface. This paper reveals the extent and manner to which the HS interferes with ion adsorption utilizing molecular dynamics. The single-layer HS is the smallest unit that maintains the ionic hydration structure and the force on it. The energy penalty incurred by partial dehydration upon adsorption is one of the approaches through which HS influences ion adsorption, yet the collision of water molecules in HS may be the critical one. The repulsive force during dehydration is, to great extent, neutralized by HS collision. The index for estimating the extent of the influence of the HS is not the hydration energy, but the quantification of the contest between HS' collision and the binding of adsorption sites. The hydration energy is larger for charged functional groups, but the HS' impact is much smaller, as compared with electroneutral group cases. As a result, the order of the adsorption capacity for different ionic species may be quite different between charged and electroneutral cases.
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Affiliation(s)
- Jinyang Jiang
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China.
| | - Le Guo
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China.
| | - Luping Tang
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Yu Zhang
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China.
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Li Y, Zhang G, Hou D, Wang Z. Nanoscale insight on the durability of magnesium phosphate cement: a molecular dynamics study. RSC Adv 2020; 10:40180-40195. [PMID: 35520862 PMCID: PMC9057513 DOI: 10.1039/d0ra07717h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/26/2020] [Indexed: 11/21/2022] Open
Abstract
The sustainable green building material magnesium phosphate cement (MPC) is widely used in the fields of solidifying heavy metals and nuclear waste and repair and reinforcement. Magnesium potassium phosphate hexahydrate (MKP) is the main hydration product of MPC. The transport of water and ions in MKP nanochannels determines the mechanical properties and durability of MPC materials. Herein, the interface models of MKP crystals with sodium chloride solution in the [001], [010] and [100] direction were established by molecular dynamics. The interaction of the MKP interface with water and ions was studied and the durability of MPC in sodium chloride solution was explained at the molecular level. The results show that a large number of water molecules are adsorbed on the MKP crystal surface through hydrogen bonds and Coulomb interactions; the surface water molecules have the bigger dipole moment and the dipole vector of most of the water molecules points to the solid matrix, when the crystal surfaces of the three models all show hydrophilicity. In addition, plenty of sodium ions are adsorbed at the MKP interface, and some potassium ions are desorbed from the matrix. In the MKP[001] model, the amount of potassium ions separated from the matrix and diffused into the solution is the highest and the interface crystal is the most disordered. Due to the attack of water and ions, the K-Os bond loses its chemical stability and the order of the MKP crystal is destroyed, which explains the decline of MPC performance after the erosion of sodium chloride solution at the molecular level. Besides, in the three models, the Na-Cl ion bond is more unstable than the K-Cl ion bond due to the smaller radius of the sodium atom. The stability of ionic bonds in the models is as follows: MKP[010] > MKP[100] > MKP[001].
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Affiliation(s)
- Yue Li
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing 100124 China
| | - Guosheng Zhang
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing 100124 China
| | - Dongshuai Hou
- Department of Civil Engineering, Qingdao University of Technology Qingdao China 266033
| | - Zigeng Wang
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing 100124 China
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Study of the Effects of the Addition of Fly Ash from Carwash Sludge in Lime and Cement Pastes. SUSTAINABILITY 2020. [DOI: 10.3390/su12166451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sludge from carwash wastewater treatment plants has been evaluated as substitute for lime paste, as well as its behavior in cement mortars. Dry sludge waste was used with (CSlud) and without (USlud) pretreatment and have been characterized. The pastes were prepared with weight replacement of 5, 10, 15, and 20% of sludge. The formation of calcium silicate hydrate was determined by TGA, both in lime and cement pastes. The compressive strength properties were evaluated in mortars. It was found the mixtures which present the best results were those of 5 and 10% for USlud, and 10 and 20% for CSlud.
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Yu J, Gao S, Hou D, Wang P, Sun G. Water Transport Mechanisms of Poly(acrylic acid), Poly(vinyl alcohol), and Poly(ethylene glycol) in C-S-H Nanochannels: A Molecular Dynamics Study. J Phys Chem B 2020; 124:6095-6104. [PMID: 32551670 DOI: 10.1021/acs.jpcb.0c03017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transport properties of water molecules in nanochannels are critical to the durability of porous materials. In this article, molecular dynamics simulations are used to study the effects of poly(acrylic acid) (PAA), poly(vinyl alcohol) (PAA), and poly(ethylene glycol) (PEG) on the durability of modified cement-based materials. By establishing ideal composite nanopores, the absorption of water molecules in the channel is simulated. The results show that PEG has the best water-blocking effect under the same simulated conditions, followed by PVA, and PAA is the most unfavorable. This difference in the water-blocking effect can be explained by two factors. On the one hand, hydrophobic alkane groups in these polymers can inhibit water molecule transport. A large number of -COOH and -OH functional groups in PAA and PVA will form a complex H-bond network with the water molecules in the nanopore, dragging the water molecules forward, thereby speeding up the water molecule transmission to a certain extent. However, PEG, which mainly contains low-polar oxygen (C-O-C), has weak hydrogen bonding with water molecules, so the water-blocking effect is more obvious. On the other hand, the van der Waals interaction and the electrostatic interaction mainly derived from Op-Caw-Os can ensure the absorption of the polymer on the C-S-H surface during the transport process. The -COOH in PAA ensures its strongest absorption. But PVA and PEG will morphologically agglomerate during the water absorption, occupying pores and hindering the transport of water molecules.
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Affiliation(s)
- Jiao Yu
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266000, China
| | - Song Gao
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266000, China
| | - Dongshuai Hou
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266000, China
| | - Pan Wang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266000, China
| | - Guoxing Sun
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau SAR 999078, China
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The first evaluation of the dynamic hydration number of hydrated ions confined in mesoporous silica MCM-41. ADSORPTION 2019. [DOI: 10.1007/s10450-019-00061-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Zhang Y, Li T, Hou D, Zhang J, Jiang J. Insights on magnesium and sulfate ions' adsorption on the surface of sodium alumino-silicate hydrate (NASH) gel: a molecular dynamics study. Phys Chem Chem Phys 2018; 20:18297-18310. [PMID: 29966028 DOI: 10.1039/c8cp02469c] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The movement of water and ions in sodium alumino-silicate hydrate gel (NASH) influences the physical and chemical properties of the geopolymer material. In this paper, in order to better understand the structure and dynamics of water and ions in the interfacial region of the NASH gel, molecular dynamics was utilized to model Na2SO4 and MgSO4 solutions (both at 0.44 mol L-1) near the NASH surface. The broken silicate-aluminate surface network, with predominant percentage of randomly connected Q1 and Q2 silicate and aluminate species, provides plenty of non-bridging oxygen sites to accept the H bond from the surface water molecules, contributing toward a strongly adsorbed hydration layer with a thickness of around 5 Å. Consequently, the water molecule in the hydration layer exhibits increased density, increased dipole moment magnitude, orientation preference, and slow diffusivity. In contrast, up to 36.4% of the counter sodium ions, originally caged in the vacancies on the NASH surface, gradually dissociate from the silicate-aluminate skeleton and migrate into the bulk solution, which is consistent with the experimentally observed leaching process of alkali ions in the geopolymer material. In the MgSO4 solution, the magnesium ions-with a smaller ionic radius-penetrate into the silicate-aluminate skeleton vacancy, have 1.8 to 2.5 coordinated solid oxygen atoms, and remain on the NASH surface for a fairly longer time due to the stable Mg-O bonds. Mg species adsorbed on the inner sphere got rooted onto the hydroxyl layer, healing the damaged silicate-aluminate structures and stabilizing the network by inhibiting Na ion immigration into the solution. Mg ions in the outer layer, on average, associated with around one neighboring SO4 ion, forming ionic pairs and accumulating into large Mg-SO4 clusters, to help the immobilization of sulfate ions on the NASH surface.
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Affiliation(s)
- Yu Zhang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
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Ho TA, Greathouse JA, Lee AS, Criscenti LJ. Enhanced Ion Adsorption on Mineral Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5926-5934. [PMID: 29746135 DOI: 10.1021/acs.langmuir.8b00680] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Classical molecular dynamics simulation was used to study the adsorption of Na+, Ca2+, Ba2+, and Cl- ions on gibbsite edge (1 0 0), basal (0 0 1), and nanoparticle (NP) surfaces. The gibbsite NP consists of both basal and edge surfaces. Simulation results indicate that Na+ and Cl- ions adsorb on both (1 0 0) and (0 0 1) surfaces as inner-sphere species (i.e., no water molecules between an ion and the surface). Outer-sphere Cl- ions (i.e., one water molecule between an ion and the surface) were also found on these surfaces. On the (1 0 0) edge, Ca2+ ions adsorb as inner-sphere and outer-sphere complexes, whereas on the (0 0 1) surface, outer-sphere Ca2+ ions are the dominant species. Ba2+ ions were found as inner-sphere and outer-sphere complexes on both surfaces. Calculated ion surface coverages indicate that, for all ions, surface coverages are always higher on the basal surface compared to those on the edge surface. More importantly, surface coverages for cations on the gibbsite NP are always higher than those calculated for the (1 0 0) and (0 0 1) surfaces. This enhanced ion adsorption behavior for the NP is due to the significant number of inner-sphere cations found at NP corners. Outer-sphere cations do not contribute to the enhanced surface coverage. In addition, there is no ion adsorption enhancement observed for the Cl- ion. Our work provides a molecular-scale understanding of the relative significance of ion adsorption onto gibbsite basal versus edge surfaces and demonstrates the corner effect on ion adsorption on NPs.
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Affiliation(s)
- Tuan A Ho
- Geochemistry Department , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
| | - Jeffery A Greathouse
- Geochemistry Department , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
| | - Andrew S Lee
- Geochemistry Department , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
| | - Louise J Criscenti
- Geochemistry Department , Sandia National Laboratories , Albuquerque , New Mexico 87185 , United States
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