Atomic Insights into the Relationship between Molecular Structure and Dispersion Performance of Phenyl Polymer on Graphene Oxide.

The adsorption of organic polymers onto the surface of graphene oxide is known to improve its dispersibility in cement-based materials. However, the mechanism of this improvement at the atomic level is not yet fully understood. In this study, we employ a combination of DFT static calculation and umbrella sampling to explore the reactivity of polymers and investigate the effects of varying amounts of phenyl groups on their adsorption capacity on the surface of graphene oxide. Quantitative analysis is utilized to study the structural reconstruction and charge transfer caused by polymers from multiple perspectives. The interfacial reaction between the polymer and graphene oxide surface is further clarified, indicating that the adsorption process is promoted by hydrogen bond interactions and π-π stacking effects. This study sheds light on the adsorption mechanism of polymer-graphene oxide systems and has important implications for the design of more effective graphene oxide dispersants at the atomic level.

Unraveling the molecular freezing behavior of water on a calcium silicate hydrate matrix.

The hydration process of cement-based materials primarily results in the formation of calcium silicate hydrate (CSH), which is crucial in deciding how long concrete will last. This study utilizes molecular dynamics simulation technology to explore the freezing behavior of pure water solutions within various calcium silicate hydrate (CSH) matrices. The investigated matrices encompass four different Ca/Si ratios. According to the simulation, as ice crystals develop close to the surface of CSH, the CSH matrix strengthens its hydrogen and ionic interactions with water molecules, which effectively prevents water molecules from crystallizing and nucleating. Consequently, these molecules compose an unfrozen water film structure that bridges between ice crystals and the CSH matrix. The research also reveals an intriguing relationship between silica chain behavior on the Ca/Si ratio and the CSH surface. Surface flaws arise as a result of the silica chains of CSH breaking into shorter segments as the Ca/Si ratio increases. These surface defects manifest as grooves on the matrix's surface, effectively capturing and retaining specific water molecules. The CSH matrix's hydrogen bonds with water molecules are weakened as a result of this process, facilitating their participation in the crystallization process, and leading to a thinner unfrozen water film thickness with an increased Ca/Si ratio. This study contributes to a greater knowledge of the performance and dependability of cement-based products by offering molecular-level insights into the freezing actions of liquids in gel pores.

The mechanism of fluidity improvement of cement slurry by graphene oxide: a study on nanofriction.

Graphene oxide (GO) as a nano-reinforcing material has received extensive attention in cement composite materials. This paper employed molecular dynamics to simulate the friction process of calcium silicate hydrate (CSH) particles in the presence of double-sided and single-sided GCOOH (graphene oxide with a -COOH functional group, covering 10% of the surface). The investigation uncovered the lubricating effects of bifacial and unifacial GCOOH on the CSH interface. The findings indicate that the interfacial friction among CSH particles follows the sequence of double-sided GCOOH > pure CSH > single-sided GCOOH. In the double-sided GCOOH system, a greater external force is needed on the opposing side to alter the interaction with water molecules, calcium ions, and silica-oxygen tetrahedra, thereby enhancing friction. In contrast, the majority of the carboxyl groups on the single-sided GCOOH surface are strongly adsorbed onto the CSH surface, facilitating the entry of additional water molecules into the interlayer. Conversely, the unmodified side of the GCOOH has lower interactions with water molecules, hence improving its lubricating properties.

Surface Engineering of Migratory Corrosion Inhibitors: Controlling the Wettability of Calcium Silicate Hydrate in the Nanoscale.

Migratory corrosion inhibitors (MCIs) are regarded as effective additives to prevent harmful ion transmission and improve concrete durability, but their behavior in the porosity of concrete is still unclarified. This paper proposes a unique perspective to evaluate the effects of surfactant-like MCIs in calcium silicate hydrate (C-S-H) nanoporosity through molecular and electronic structural information. Advanced enhanced sampling methods and perturbation theory methods were applied to evaluate the role of different MCIs. The reduced density gradient of MCI molecules was obtained by using quantum chemical calculations. This calculation is instrumental in elucidating the intensity of interactions among distinct MCI molecule head groups and the C-S-H matrix. It is found that MCIs can effectively improve the interfacial tension (IFT) between C-S-H and water, which corresponds to the inhibitory ability of transmission. Free energy indicates that the MCI has the properties of strong adsorption and weak dissolution, facilitating the improvement of IFT. The relationship between the MCI functional group and the ability of adsorption and dissolution is revealed. This study suggests that MCIs work as surface controllers of C-S-H pores and that their properties can be assessed on the nanoscale.

Molecular Insight into the Pozzolanic Reaction of Metakaolin and Calcium Hydroxide.

The reaction mechanism of the pozzolanic reaction of metakaolin (MK) from the atomic point of view has not yet been explored. To explain the process and mechanism of the pozzolanic reaction from the atomic point of view, molecular insight into the pozzolanic reaction of MK and calcium hydroxide (CH) was analyzed through the reaction molecular dynamics (MD) simulation. The results show that the pozzolanic reaction of MK and CH can be essentially regarded as the CH decomposition and penetration into MK. Also, the structure evolution after the pozzolanic reaction shows that the water molecules cannot penetrate the MK structure till the participation of Ca2+ and OH- ions of CH. The Ca2+ and OH- ions have strong interaction with MK and drill into the MK structure, followed by the destruction of a part of the MK structure and water penetration. The final structure of CH removed by MK can be regarded as the precursor of the CASH gel structure.

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio.

Silane is known as an effective coating for enhancing the resistance of concrete to harmful acids and radicals that are usually produced by the metabolism of microorganisms. However, the mechanism of silane protection is still unclear due to its nanoscale attributes. Here, the protective behavior of silane on the calcium silicate hydrate (C-S-H) surface is examined under the attack environment of nitrate/sulfate ions using molecular dynamics simulations. The findings revealed that silane coating improved the resistance of C-S-H to nitrate/sulfate ions. This resistance is considered the origin of silane protection against harmful ion attacks. Further research on the details of molecular structures suggests that the interaction between the oxygen in the silane molecule and the calcium in C-S-H, which can prevent the coordination of sulfate and nitrate to calcium on the C-S-H surface, is the cause of the silane molecules' strong adsorption. These results are also proved in terms of free energy, which found that the adsorption free energy on the C-S-H surface followed the order silane > sulfate > nitrate. This research confirms the excellent protection performance of silane on the nanoscale. The revealed mechanism can be further used to help the development of high-performance composite coatings.

Atomistic Insights into the Deposition of Corrosion Products on the Surfaces of Steels and Passivation Films.

The deposition of corrosion products on the surface of the steel is a key step for understanding the generation of corrosion products. To clarify the molecular mechanism for corrosion product deposition, the reactive molecular dynamics were utilized to study the deposition process of ferric hydroxide (Fe(OH)3) on iron and passivation film substrates. It is shown that the deposition phenomenon mainly occurs on the iron surface, while the surface of the passivation film cannot adsorb Fe(OH)3. Further analysis indicates that the interaction between hydroxyl groups in γ-FeOOH and Fe(OH)3 is very weak, which is unfavorable to the deposition of Fe(OH)3. Moreover, the degree of ordered water in the two systems is affected slightly by deposition but the oxygen in water corrodes Fe(OH)3, breaking its Fe-O bonds, which is more obvious in the Fe system due to its instability. This work has revealed the nanoscale deposition process of corrosion products on the passivation film in a solution environment by reproducing the bonding and breaking of atoms at the molecular level, which is a case in point to the conclusion of the protection of steel bars by passivation film.

The inhibitory effect of excess calcium ions on the polymerization process of calcium aluminate silicate hydrate (CASH) gel.

Calcium ion, as an essential component in CASH, affects the aggregation and formation process of CASH, thereby influencing its microstructure and mechanical properties. However, the mechanism by which calcium ions affect the polymerization process of CASH is not yet fully understood. In this study, the effects of calcium ions on the polymerization process, coagulation state, and microstructure of CASH are investigated via molecular dynamics simulation. The results indicate that the presence of a trace amount of Ca2+ attracts oligomers towards the calcium-rich region, thus speeding up the polymerization to some extent, but as the Ca2+ content increases, more Ca2+ binds to the oxygen atoms in silica-oxygen tetrahedra and aluminum-oxygen tetrahedra, forming tight ion pairs and occupying the hydroxyl binding sites required for the polycondensation reaction. This inhibits the continuous aggregation of CASH gel and slows down the rate of polymerization. Additionally, Ca2+ attracts oxygen atoms from free water molecules and free OH-, forming Ca(OH)2 dispersed in the spatial structure, which hinders the formation of larger clusters. As a result, the higher the Ca ion content in the system, the lower the overall polymerization degree of the CASH gel, resulting in a decrease in the conversion of the Q1 dimer to Q2 and Q3 chain structures, a shorter average chain length, poorer overall connectivity, and a transition from large clusters in a better-aggregated state to dispersed small clusters. This study sheds light on the polymerization reaction mechanism of CASH gels.

Molecular Insights into the Reaction Process of Alkali-Activated Metakaolin by Sodium Hydroxide.

When metakaolin (MK) is alkalized with an alkaline activator, it depolymerizes under the action of the alkali. However, the process of MK alkalinization is still unrevealed. Here, we supplied a molecular insight into the process of MK alkalinization through reaction molecular dynamics (MD) simulation. The structure, dynamics, and process of MK alkalinization are systematically investigated. The results showed that the layered structure of MK was destroyed and the silicates in MK were dissolved by sodium hydroxide solution during the alkalinization reaction of MK. The aluminates in MK are not dissolved, indicating that aluminates are more stable than silicates. Moreover, the equilibrium structures of MK with H2O and MK with NaOH solution show that only when both sodium hydroxide and water are involved in the alkalinization reaction, the silicates in MK undergo depolymerization. Also, the observed final state of MK alkalinization can be recognized as the precursor of alkali-activated materials (AAMs).

Understanding the wetting discrepancy in calcium alumino silicate hydrate induced by Al/Si ratio.

The application of supplementary cementitious materials (SCMs) in concrete can improve its durability in the marine environment. Calcium alumino silicate hydrate (CASH) is the main hydration product of SCMs; however, to date, the mechanism of the wetting discrepancy in CASH with different Al/Si ratios has not been revealed at the molecular scale. Herein, the molecular dynamics simulation method was used to study the wettability of water nanodroplets on the surface of CASH substrates with different Al/Si ratios, aiming to reveal the influence of CASH gel with different Al contents on the wettability of water molecules. The simulation results suggested that the CASH interface with a high Al/Si ratio has better wettability for nanodroplets. The microcosmic analysis showed that the interaction between particles and the CASH substrate is affected by the Al content. The electronegativity of the CASH substrate increases due to the substitution of Al-O tetrahedrons, which makes it stronger to solidify Ca ions on its surface and easier to form hydrogen bonds with water molecules in a nanodroplet. The orientation distribution of water molecules further revealed the source of the force of the CASH substrate on nanodroplets at the atomic level. The analysis of the dynamic properties showed that the H-bonds between CASH substrate with a high Al/Si ratio and water molecules are more stable, and thus the nanodroplets have better stability on the surface of CASH.

Structure, dynamics and transport behavior of migrating corrosion inhibitors on the surface of calcium silicate hydrate: a molecular dynamics study.

The incorporation of a corrosion inhibitor into a cement-based material can enhance the durability of the reinforced concrete. In this study, molecular dynamics simulation is utilized to study the interfacial structure and dynamic behavior of a solution with three migrating corrosion inhibitors (MCI) functionalized by hydroxyl (-OH), carboxyl (-COO-), and phenyl (-PH) groups in calcium silicate hydrate (CSH) gel pores. The transport rate of inhibitors is greatly dependent on the polarity of the functional group: -PH > -OH > -COO-. The slow migration rate of the inhibitor with -OH and -COO- is attributed to the chemical bond formed between CSH and MCI. The silicate chains near the CSH surface can provide plenty of non-bridging oxygen sites to accept the H-bond from the hydroxyl group in the inhibitor molecule. The surface calcium atom can capture the -COO- by forming an ionic COO-Ca bond. Furthermore, the hydration structure of the inhibitor molecule also influences its transport properties. The inhibitor functionalized by the carboxyl group, associating with the neighboring water molecules, forms ion-water clusters, and the inhibitor molecule and its hydration shell with a long resident time retard the migration rate. Hopefully, this study is able to provide molecules for the development of a migration-type corrosion inhibitor to elongate the service life of cement-based materials.

Concentration-induced wettability alteration of nanoscale NaCl solution droplets on the CSH surface.

Due to the hydrophilic nature of concrete, moisture and corrosive ions adsorbed on its surface pose a severe challenge to the durability of concrete structures; therefore, investigating the wettability of a concrete surface is an indispensable prerequisite for designing durable and sustainable concrete. This paper utilizes molecular dynamics to simulate the concentration-induced wettability alteration of nanoscale NaCl droplets on a CSH surface, and verifies the feasibility and rationality of predicting the contact angle of a droplet on the CSH surface based on the surface tension. Results suggest that the wetting ability of droplets on the CSH surface is weakened with the increase of the NaCl mass fraction. Microscopic analysis reveals that water molecules clustered around Na+ and Cl- ions to form an ion hydration shell (Na+-Ow and Cl--Hw pairs); the binding energy barrier of these ion pairs is much larger than the dissociation energy barrier, which enhances the associative ability of the NaCl droplets. The particles on the CSH surface attract Na+ and Cl- ions by forming Oh(Os)-Na+ and Ca(Ho)-Cl- connections with droplets, which further weakens the spreading ability of water molecules on the CSH surface.

Correction: Hydrophobic silane coating films for the inhibition of water ingress into the nanometer pore of calcium silicate hydrate gels.

Correction for 'Hydrophobic silane coating films for the inhibition of water ingress into the nanometer pore of calcium silicate hydrate gels' by Jiao Yu et al., Phys. Chem. Chem. Phys., 2019, DOI: .

Hydrophobic silane coating films for the inhibition of water ingress into the nanometer pore of calcium silicate hydrate gels.

The super-hydrophobic nature of surfaces is greatly dependent on the interfacial molecular structure of coating materials. In this study, to understand the structure, dynamics and interfacial behavior of hydrophobic coating, molecular dynamics is utilized to study the capillary transport of water molecules through the nanometer channel of calcium silicate hydrate (C-S-H) with the interior surface impregnated with silane. The C-S-H surface is coated by connecting the bridging silicate tetrahedron with an oxygen-containing group in isobutyl-triethoxysilane (C10H24O3Si) with a silane molecule coverage rate ranging from 25% to 100%. We demonstrated that the silane coating with a coverage exceeding 25% can effectively inhibit the water molecule and detrimental ion invasion in the gel pore. The grafted silane groups reduce the number of non-bridging oxygen atoms in the surface silicate chains that provide plenty of sites to accept the H bonds from the surface water molecules. This results in the reduction of the dipole moment of the surface water molecules and transforms the hydrophilic C-S-H substrate to hydrophobic. The silane molecules, immobilized by the Si-O-Si bond on the C-S-H substrate, are protruded to the gel pore with the hydrophobic tail of branch-like isobutyl groups. It transforms the smooth surface to a lotus-leaf-like rough surface with distributed nanoscale papillae. The isobutyl groups, freely vibrating and rotating, further blocks the connectivity of the transport channel and weakens the interaction between penetrated ions and C-S-H substrates. Furthermore, spatial correlation analysis demonstrates that the immobilized silane molecules disturb the tetrahedron distribution of water molecules in the gel pore and break the hydration shell of the counter Ca ions that associate with less water molecules. The dramatic degradation of the time correlation function for the surface solution species in the presence of isobutyl-triethoxysilane exhibits that the coated C-S-H surface can repel the surface water molecules and calcium ions by weakening the H bond and the Ca-O ionic bond strength. These nanostructure results provide guidance for the construction of artificial super-hydrophobic surfaces and the design of cementing materials with controllable wettability.

Atomistic insights into cesium chloride solution transport through the ultra-confined calcium-silicate-hydrate channel.

The transport of water and ions in the gel pores of calcium silicate hydrate (C-S-H) determines the durability of cement material. In this study, molecular dynamics was employed to investigate the capillary imbibition process of CsCl solution in the C-S-H channel. The advanced frontier of CsCl solution flow inside the C-S-H capillary shows a concave meniscus shape, which reflects the hydrophilic properties of the C-S-H substrate. Reynolds number calculations show that the transport process is laminar flow and dominated by viscous forces. The invading depth of the CsCl solution deviates from the theoretical prediction of the classic Lucas-Washburn (L-W) equation, but the modified theoretical equation, by incorporating the effect of slip length, dynamic contact angle, and effective viscosity into the L-W equation, can describe the penetration curve of the solution very well. The validity of our developed theoretical equation was confirmed by additional systems with different ion concentrations. In addition, the local structure of ions was analyzed to elucidate the effect of ion concentration on the transport process. The adsorption and accumulation of ions retard the transport process of water. With an increase in the ionic concentration, the effects of immobilization and cluster accumulation became more pronounced, further reducing the transport rate of water. This study provides fundamental insight into the transport behavior of liquid in the gel pores of cement-based material.

Influence of aluminates on the structure and dynamics of water and ions in the nanometer channel of calcium silicate hydrate (C-S-H) gel.

The transport and adsorption behavior of ions and water in nanometer pores is influenced by the composition of the substrate. In this paper, to understand the effect of Al species on the properties of confined nanofluids, molecular dynamics is utilized to study the structure, dynamics and interfacial adsorption behavior of NaCl solution confined in the gel pores of C-S-H and C-A-S-H. The bridging silicate tetrahedron substituted by the aluminate species enhances the hydrophilic properties of C-S-H gel. As compared with water on the C-S-H surface, the water layered packing is densified and the magnitude of dipole moment is enlarged for water located in the vicinity of the C-A-S-H surface. This is mainly attributed to the increasing number of H bonds contributed by oxygen atoms in the aluminate silicate chains sharing more negativity. Furthermore, C-A-S-H gel immobilizes more sodium and chloride ions on the surface than C-S-H. Sodium ions can coordinate with about two to three oxygen atoms in the aluminate tetrahedron tessellated in the narrow vacancy of the silicate channel, forming inner adsorbed species. Weak interactions between Cl and the substrate are due to the few ionic pairs between Cl ions and surface-accumulated Na ions. Due to the strong Na-Os binding on the C-A-S-H surface, the diffusion coefficient of the Na ions confined in the nanometer pores is reduced by 50% and the hydration time for the Na ions associated with surrounding water is increased by 40% as compared with bulk solution.

A reactive molecular dynamics study of graphene oxide sheets in different saturated states: structure, reactivity and mechanical properties.

For GO related nanocomposite design, it is of great importance to understand the behavior of water molecules ultra-confined in the interlayer region of graphene oxide (GO) sheets. In this research, to gain molecular insights into the influence of water on the properties of GO sheets, reactive force field molecular dynamics was employed to model a GO sheet with a water content of 1.3 wt%, 11.5 wt%, 18 wt% and 23.5 wt%. The epoxy and hydroxyl groups in the GO sheet exhibit high reactivity: the proton transferred from hydroxyl to dissociated epoxy contributes to carbonyl formation, which enhances the polarity of the GO sheet and strengthens the H-bond network between the functional groups. The epoxy, hydroxyl and newly formed carbonyl groups contribute to the structural hydrogen bonding with high stability. With increasing water content, the interlayer structural H-bonds between functional groups are gradually substituted by those contributed by water molecules, which weakens the interlayer stiffness and cohesive strength for GO sheets. Furthermore, the reactive force field allows coupling between the mechanical response and chemical reactions during uniaxial tensile deformation in the intra-layer direction. On the one hand, the relative epoxy bond is stretched until it is broken and transformed into a carbonyl group to resist tensile loading. On the other hand, interlayer water molecules, attacking the deformed GO sheets, are dissociated into carboxyl groups in the broken region.

Molecular dynamics study on ions and water confined in the nanometer channel of Friedel's salt: structure, dynamics and interfacial interaction.

As a promising layered double hydroxide, Friedel's salt has gained popularity. The transport and adsorption behavior of ions and water molecules at the interface is the basis for investigating the durability of concrete, in marine environments in particular. In this paper, the transport behavior of water and ions in the nanopores of Friedel's salt and the adsorption mechanism of the ions were systematically investigated by molecular dynamics. The water molecules share a larger bulk density and good orientations at the interface while the adsorption rate of chloride ions climbs to 66.62%, owing to the desorption of the surface structural anions forming Ca-Clw ion clusters. The time correlation function was employed to examine the stability of the Ca-Clw bonds formed near the Friedel's salt interface. The Ca-Clw bonds were demonstrated to be very stable, implying that the aqueous chloride ion is difficult to desorb once it is adsorbed by the interface. The surface of the ordered Friedel's salt structure could form a hydrated shell to hinder the interaction between sodium ions and oxygen atoms. In addition, Friedel's salt exhibits a poor adsorption capacity for sodium ions since it provides few adsorption sites due to the limited amount of structural chloride ions. After all, the interaction between Friedel's salt and the external environment on the nano scale was explored for a better understanding of the inherent mechanism from a molecular simulation perspective.

Reactive force-field molecular dynamics study on graphene oxide reinforced cement composite: functional group de-protonation, interfacial bonding and strengthening mechanism.

Graphene oxide (GO) reinforced cement nanocomposites open up a new path for sustainable concrete design. In this paper, reactive force-field molecular dynamics was utilized to investigate the structure, reactivity and interfacial bonding of calcium silicate hydrate (C-S-H)/GO nanocomposite functionalized by hydroxyl (C-OH), epoxy (C-O-C), carboxyl (COOH) and sulfonic (SO3H) groups with a coverage of 10%. The silicate chains in the hydrophilic C-S-H substrate provided numerous non-bridging oxygen sites and counter ions (Ca ions) with high reactivity, which allowed interlayer water molecules to dissociate into Si-OH and Ca-OH. On the other hand, protons dissociated from the functional groups and transferred to non-bridging sites in C-S-H, producing carbonyl (C[double bond, length as m-dash]O) and Si-OH. The de-protonation degree of the different groups in the vicinity of the C-S-H surface was in the following order: COOH (SO3H) > C-OH > C-O-C. In the GO-COOH sheet, most COOH groups were de-protonated to COO- groups, which enhanced the polarity and hydrophilicity of the GO sheets and formed stable COOCa bonds with neighboring Ca ions. The de-protonated COO- could also accept H bonds from Si-OH in the C-S-H gel, which further strengthened the interfacial connection. On the contrary, in the GO-Oo sheet, only 8% of the epoxy group was stretched open by the Ca ions and transformed to carbonyl group, showing weak polarity and connection with the C-S-H sheet. Furthermore, uniaxial tensile test on different C-S-H/GO models revealed that C-S-H reinforced with GO-COOH and GO-OH had better interfacial cohesive strength and ductility than that observed under tensile loading. Under the reaction force field, the dissociation of water, the proton exchange between the C-S-H and GO structure, and Oc-Ca-Os bond breakage occurred to resist tensile loading. The weakest mechanical behavior observed in the G/C-S-H, GO-Oo/C-S-H and GO-SO3H/C-S-H composites was attributed to the poor bonding, dissociation of functional groups and instability of atoms in the interface region. Hopefully, the molecular-scale strengthening mechanisms could provide a scientific guide for sustainable design of cement composites.

Insights on magnesium and sulfate ions' adsorption on the surface of sodium alumino-silicate hydrate (NASH) gel: a molecular dynamics study.

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.