Hydration Chemistry Research Articles

Hofmeister effect induced water activation of hydrogel and its applications for the accelerated solar evaporation in brine

Solar-driven desalination has emerged as a promising approach to address water scarcity caused by the decreasing supply of freshwater. Reducing the enthalpy of water vaporization is crucial for enhancing the efficiency of solar-powered desalination. In this study, inspired by the Hofmeister effect, we developed a highly hydratable network hydrogel evaporator to achieve a superior evaporation rate in brine compared with pure water. The evaporator comprised a carbonized layer as the photothermal layer and a chitosan aerogel hydrogel as the hydratable matrix. The hydrogel exhibited a dramatically reduced vaporization enthalpy of 1397 J/g and a significant evaporation rate of 2.38 kg m−2 h−1 when exposed to seawater. These results demonstrated the superior performance of hydrogel compared with pure water (1.91 kg m−2 h−1). Excellent evaporation rates and outstanding salt resistance ensured efficient coordination for practical long-term desalination applications. Further investigations revealed that the remarkable evaporation performance of the carbonized chitosan (CCS) hydrogel in brine environments was attributed to its hydrability, which was regulated by Cl−. According to the Hofmeister effect, Cl− accelerated the hydration chemistry in CCS and suppressed the associated crystallinity, which resulted in a lower enthalpy of vaporisation owing to a higher amount of intermediate water. With its superior evaporation performance in brine and comprehensive theoretical simulation analysis, this study presents an achievable and economical strategy for simultaneously addressing the water and energy crises.

Enhancing fluidity and mechanical properties in Limestone Calcined Clay cements with one-third Portland clinker content

Limestone Calcined Clay Cements (LC3) are attracting considerable attention due to their low CO2 footprints and relatively fast hydration kinetics. LC3-50 formulations (approximately 50 % Portland clinker, 30 % kaolinitic calcined clay, 15 % limestone and 5 % gypsum) are being extensively investigated and the hydration chemistry, rheology, mechanical strength developments and durability performances are starting to be well established. LC3 binders with lower clinker factors are possible, offering an opportunity for further CO2 footprint reduction. However, these blends have been much less studied. This work contributes to fill this gap. Here, a LC3-35 binder (i.e. 35 % Portland clinker content) is investigated and its performances are compared to those of the original Portland cement (PC) and a standard LC3-50 binder. The effects of two superplasticizers and a strength-enhancing admixture are thoroughly investigated in mortars and pastes. Larger calcined clay contents result in an exacerbation of the slump retention problem, but this issue is solved by the use of a new superplasticizer. Moreover, the low mechanical strengths at early ages can be partly mitigated with a C-S-H nucleation seeding admixture. Employing the right admixtures, LC3-35 binders can develop strength values similar to those of neat PC and LC3-50 at 7 and 28 days. The laboratory X-ray powder diffraction results for LC3-35 pastes, when using the strength-enhancing admixture, show that C4AF exhibits an accelerated reaction rate, leading to the formation of larger amounts of AFt and AFm phases. Approximate mass balance calculations are carried out to estimate the metakaolin reaction degree. Finally, an environmental performance indicator is used to place the footprints of the reported binders within the LC3 landscape.

Inorganic intumescing alkali silicate particles

New generation intumescent coatings apply self-intumescing particles to induce expansion in a controlled manner. Various studies have investigated alkali silicate-based coatings due to their inherent expansion with the release of H2O. The presented work investigated the self-intumescing concept of alkali silicates as particles. A thorough study of inorganic alkali silicate particles as potential intumescent ingredients in passive fire protection systems was carried out by applying HSDM, TGA, FTIR, XRD, and SEM. Herein, particles of lithium-, sodium-, and potassium silicates were synthesized with varying silica-to-alkali oxide molar ratios and curing humidity. Subsequently, the hydration chemistry and thermal behavior were examined. The results revealed increased expansion potential with decreasing SiO2/M2O molar ratio (M = Na, Li, or K) in the range 3.1–7.4 and increasing curing humidity in the range 35, 50, and 90% RH. Previous studies have emphasized the effect of solid-bound H2O to induce intumescence. In this study, the influence of the softening of the silicate matrix and H2O release is highlighted to allow increased expansion potential. Here, the coupling of thermal analysis with microscopy suggests an intumescence mechanism in the order of 1) initial shrinkage due to loss of free and physical bound H2O, 2) sphere formation to minimize surface energy, 3) expansion as a result of H2O evolution and viscoelastic melt formation, and 4) second shrinkage due to sintering before 5) melting. The sodium alkali silicate particles with a SiO2/M2O molar ratio of 3.4 exhibited a timely softening of the silicate matrix from about 155 °C to provide a distinct spherical particle followed by ionic H2O evolution. As a result, hereof, hollow, spherical particles with relative solid expansions of up to 550% were obtained and maintained until a second shrinkage at 650 °C with a subsequent melting at 950 °C. In comparison, the imbalance in viscoelastic melt formation and H2O release of lithium- and potassium silicate particles resulted in less expansion. Considering the expansion potential and thermal behavior of the alkali silicate particles, it is suggested as a possible, sustainable intumescence ingredient.

Hofmeister Effect-Enhanced Hydration Chemistry of Hydrogel for High-Efficiency Solar-Driven Interfacial Desalination.

Solar-driven water evaporation technology holds great potential for mitigating the global water scarcity due to its high energy conversion efficiency. Lowering the vaporization enthalpy of water is key to boost the performance of solar-driven desalination. Herein, a highly hydratable hydrogel (PMH) network, consisting of modified needle coke as photothermal material and polyvinyl alcohol (PVA) as hydratable matrix, is crafted via simple physical cross-linking method. When capitalizing on the PMH as evaporator for 3.5wt% NaCl solution, a high evaporation rate of 3.18kgm-2 h-1 under one sun illumination is deliver ed, unexpectedly outperforming that in pure water (2.53kgm-2 h-1 ). More importantly, the PMH shows a robust desalination durability, thus enabling a self-cleaning system. Further investigations reveal that the outstanding evaporation performance of PMH in brine roots in its hydrability tuned by chaotropic Cl- , wherein the Cl- can mediate the hydration chemistry of PVA in PMH and suppress related crystallinity, thus contributing to the increased content of intermediate water and the lowered vaporization enthalpy of brine. This work first scrutinizes the Hofmeister effect on the evaporation behavior of PMH evaporator in brine and provides insights for high-efficiency solar-driven interfacial desalination.

The Role of Water Network Chemistry in Proteins: A Structural Bioinformatics Perspective in Drug Discovery and Development.

Although water is regarded as a simple molecule, its ability to create hydrogen bonds makes it a highly complex molecule that is crucial to molecular biology. Water molecules are extremely small and are made up of two different types of atoms, each of which plays a particular role in biological processes. Despite substantial research, understanding the hydration chemistry of protein-ligand complexes remains difficult. Researchers are working on harnessing water molecules to solve unsolved challenges due to the development of computer technologies. The goal of this review is to highlight the relevance of water molecules in protein environments, as well as to demonstrate how the lack of well-resolved crystal structures of proteins functions as a bottleneck in developing molecules that target critical therapeutic targets. In addition, the purpose of this article is to provide a common platform for researchers to consider numerous aspects connected to water molecules. Considering structure-based drug design, this review will make readers aware of the different aspects related to water molecules. It will provide an amalgamation of information related to the protein environment, linking the thermodynamic fingerprints of water with key therapeutic targets. It also demonstrates that a large number of computational tools are available to study the water network chemistry with the surrounding protein environment. It also emphasizes the need for computational methods in addressing gaps left by a poorly resolved crystallized protein structure.

Interfacial interactions and reinforcing mechanisms of cellulose and chitin nanomaterials and starch derivatives for cement and concrete strength and durability enhancement: A review

AbstractNanomaterials have been widely researched for use in construction materials. Numerous studies demonstrate that nanomaterials in small quantities can significantly improve the macroscopic properties of cement paste, mortar, or concrete through various mechanisms. Nanomaterials retrieved from biomass sources have recently gained particular research interest due to remarkable structural properties and the source material’s abundance and renewability. Cellulose and chitin are the most abundant polysaccharides in nature; thus, they are candidates for nanomaterials extraction as multifunctional additives in cementitious systems. In recent years, cellulose nanomaterials in cementitious composites have been extensively investigated, but chitin nanomaterials and starch derivatives for cement and concrete are still emerging research areas. This review article starts with an overview of polysaccharide nanomaterials’ (PNMs) physicochemical properties as a result of different chemical and mechanical extraction processes. Next a brief overview of cement hydration chemistry and microstructure and the interfacial interactions between the cement and the various surface chemical functionalities of PNMs are discussed. Then, the key mechanisms governing the cement strength enhancement by PNMs, such as bridging, nucleating and filling effect, and internal curing, are described. Finally, the impacts of PNMs on other properties of the cement are discussed.

Effects for partial replacement of Portland cement by low water absorption porcelain insulator

The side effects caused by the low water absorption capacity of ground electrical porcelain insulator (GEPI) as a partial substitute for ordinary Portland cement (OPC) was evaluated. Despite the wide use of alternative eco-friendly materials in order to minimize the carbon footprint of the cement industry, the complex chemistry of cement hydration requires deeper studies to comprehend the influence of such admixtures. GEPI was characterized by granulometric analysis, as well as by XRF, PXRD and SEM. Its pozzolanic activity was determined by the Modified Chapelle assay, and the mechanical tests were performed in order to measure the compressive and flexural strengths of the specimens. For this reason, prismatic specimens were prepared by the replacement of 5.0, 10.0 and 20.0 wt.% of OPC by GEPI. The specimen strength showed a dependence on the level of substitution and a delay in the strength gain was observed over time. PXRD allowed the analysis of the variation in the quartz peaks intensities and to monitor the role played by the low water absorption of porcelain in the ettringite decomposition. A crystalline phase of γ-Al2O3, which was formed by the dehydration of the gel-like Al2O3, was identified. SEM images allowed us to indicate a fibre bundle-shaped C-H-S massive phase embedded in the mortar, as well as portlandite plates and angular crystallites of quartz. GEPI influenced the OPC hydration process and did not drastically compromise the strength of the mortar; therefore, it may be further investigated as a support material to prevent early OPC stiffening.

The physicochemical properties of Portland cement blended with calcium carbonate with different morphologies as a supplementary cementitious material

This study proposes the addition of calcium carbonate produced from flue-gas carbon dioxide to reduce carbon emissions of Portland cement manufacturing from 0.96 kgCO2/kg of Portland cement to 0.33 kgCO2/kg of Portland cement with comparable strengths. This study reviews the impact of calcite addition on properties of cement based on the literature. Experimental findings are presented on how the addition of different polymorphs of calcium carbonate influence physicochemical behaviour of Portland cement in terms of hydration chemistry, compressive and flexural strength and thermal analysis. Three polymorphs of calcium carbonate (amorphous, micro calcite and nano calcite) are studied. This is the first study to report the impact of three different calcium carbonate polymorphs especially that in the amorphous form. The addition of CaCO3 in Portland cement can increase the compressive strength by about 20% when compared to the benchmark. Examining the hydration shows the formation of scawtite and tilleyite with competing effect on the product strength during hydration. Formation of 8 mass% of combined scawtite–tilleyite phases at ambient conditions using CaCO3 is a new discovery; it results first in an increase in compressive strength and then, above 8 mass% it negatively impacts compressive strength. This study also provides avenues to use calcite as a sustainable supplementary cementitious material to reduce carbon emissions as well as improve early strengths. These characteristics are evidence that calcium carbonates provide a new regime of carbonate activity, modified hydration reactions, and can be used as a step towards the next generation of low-carbon Portland cements utilising mineral carbon capture technologies.

Stabilizing MXene by Hydration Chemistry in Aqueous Solution

AbstractMXenes attract interest in diverse fields but suffer from fast structural degradation by attacking of dissolved oxygen and water molecules in aqueous solution. This drawback hinders the long‐term storage, applications and understanding of the chemical nature of MXenes. Herein, we report a cost‐effective and environmentally sustainable way for long‐term storage of MXenes in aqueous solution by hydration chemistry of nontoxic inorganic salts. The attacking of MXene by free water and dissolved oxygen molecules is inhibited by decreasing the water activity, which simultaneously lowers the dissolved oxygen concentration, of saline solution. As a result, the storage life of MXene can be prolonged to up to 400 days at ambient conditions without loss of intrinsic surface chemistry and bulk carrier properties. Over 90 % of salt protectant can be recycled by simply evaporating the final waste liquor after fully extracting the MXene to minimize the waste discharge and processing cost. This work offers a commercializable approach with high cost‐effectiveness, processing sustainability and environmental benefit for extending the shelf life of MXenes.

Stabilizing MXene by Hydration Chemistry in Aqueous Solution.

MXenes attract interest in diverse fields but suffer from fast structural degradation by attacking of dissolved oxygen and water molecules in aqueous solution. This drawback hinders the long-term storage, applications and understanding of the chemical nature of MXenes. Herein, we report a cost-effective and environmentally sustainable way for long-term storage of MXenes in aqueous solution by hydration chemistry of nontoxic inorganic salts. The attacking of MXene by free water and dissolved oxygen molecules is inhibited by decreasing the water activity, which simultaneously lowers the dissolved oxygen concentration, of saline solution. As a result, the storage life of MXene can be prolonged to up to 400 days at ambient conditions without loss of intrinsic surface chemistry and bulk carrier properties. Over 90 % of salt protectant can be recycled by simply evaporating the final waste liquor after fully extracting the MXene to minimize the waste discharge and processing cost. This work offers a commercializable approach with high cost-effectiveness, processing sustainability and environmental benefit for extending the shelf life of MXenes.

Limestone calcined clay cement and concrete: A state-of-the-art review

This article reviews the rapidly developing state-of-the-art literature available on the subject of the recently developed limestone calcined clay cement (LC3). An introduction to the background leading to the development of LC3 is first discussed. The chemistry of LC3 hydration and its production are detailed. The influence of the properties of the raw materials and production conditions are discussed. The mixture design of concrete using LC3 and the mechanical and durability properties of LC3 cement and concrete are then compared with other cements. At the end the economic and environmental aspects of the production and use of LC3 are discussed. The paper ends with suggestions on subjects on which further research is required.

Thermodynamic Modeling of Aqueous LiCl, LiBr, LiI, and LiNO3 Solutions

Thermodynamic models are essential to facilitate the advancement of process design, optimization, and operation of electrolyte systems. In this work, a comprehensive thermodynamic framework based on the Electrolyte Nonrandom Two-Liquid model is developed to calculate phase equilibria behavior and salt solubility of aqueous LiCl, LiBr, LiI, and LiNO3 solutions. The model describes the non-ideality of the electrolyte solutions by using two binary interaction parameters for each molecule-electrolyte pair in the system. Each binary interaction parameter is further expressed with up to three temperature coefficients which are regressed from experimental data. To take into account the hydration of lithium ion, two separate chemistries for the dissociation of lithium salts are investigated. In the first case, the lithium ion is considered as a bare ion, Li+, while in the second case hydration of the lithium ion from Li+ to Li(H2O)+ is considered. The calculated thermodynamic properties compare adequately with the experimental data for both sets of chemistries for concentrations up to saturation and temperatures from 273.15 K up to 623.15 K. Moderate to significant improvements are observed with the incorporation of the hydration chemistry for aqueous LiCl, LiBr, and LiI solutions when compared to the non-hydrated lithium ion model results.

Apparent crystallite domain size growth in metal oxide nanocrystal ensembles: The importance of surface reactivity of powders for processing

A major challenge related to metastable oxide nanoparticles as starting materials for ceramics is to achieve control over their processing related property changes. We compared MgO nanoparticles with those of Ba2+-admixtures exhibiting enhanced surface reactivity. The enhanced surface reactivity promotes particle coarsening and gives rise to a multimodal particle size distribution with a fine fraction of nanocubes (d ​< ​10 ​nm) and a coarse fraction of larger particles. Water adsorption from the ambient has a key influence on sintering and resulting microstructures. After sample exposure to water vapor there arise significant changes in structure and crystallite domain size that originate from size dependent dissolution effects transforming only the fine fraction of particles (<10 ​nm) into hydroxides. Thus, controlled Ba-admixture and segregation at the single particle level provides means to address the impact of surface basicity, hydration and consecutive surface chemistry on microstructure evolution during processing.

On the theoretical carbon storage and carbon sequestration potential of hempcrete

Hempcrete is a natural insulation material that is well known for exhibiting favorable thermal properties and low manufacturing emissions. Hempcrete is a biocomposite, consisting of hemp shiv and a lime-based binder composed of hydrated lime and either a hydraulic (e.g., natural hydraulic lime and ordinary portland cement) or pozzolanic binder (e.g., metakaolin). While long-term biogenic carbon storage can be achieved via utilization of hemp shiv in hempcrete, additional carbon storage can be achieved via carbonation of the binder. This study advances previous carbonation modeling approaches by deriving a theoretical model based on the fundamentals of cement hydration and carbonation chemistry to quantify the total theoretical in situ CO2e sequestration potential of hempcrete binders. To estimate the percentage of manufacturing CO2e emissions that can be recovered through in situ binder carbonation, the model is implemented in life cycle assessments of 36 hempcrete formulations of various binder contents and densities using an equivalent functional unit (FU) of a 1 m2 wall assembly with a U-value of 0.27 W/(m2K). Our model estimates between 18.5% and 38.4% of initial carbon emissions associated with binder production can be sequestered through in situ carbonation. Considering biogenic carbon storage, we predict that the total life cycle CO2e emissions of hempcrete can be negative, with a minimum of −16.0 kg CO2e/FU for the hempcrete mixture formulations considered herein. However, we estimate that some hempcrete formulations can exhibit net-positive emissions, especially high-density mixes (>300 kg/m3) containing portland cement, thereby illustrating the importance of materials selection and proportioning in designing carbon-storing hempcrete.

Hydration development and thermal performance of calcium sulphoaluminate cements containing microencapsulated phase change materials

Microencapsulated phase change materials (MPCM) incorporated in buildings walls can reduce indoor temperature fluctuations, conserving energy and enhancing thermal comfort. MPCM were incorporated in calcium sulphoaluminate cement (CSA) at high concentrations to achieve a significant effect on the thermal properties. The cement hydration development was studied by isothermal calorimetry and laboratory X-ray powder diffraction (LXRPD). The hydration mechanism was not affected by the addition of MPCM. In order to obtain homogeneous mortars in the presence of MPCM, a superplasticizer (SP) was used. However, the SP causes a significant delay of the hydration. Although the mineralogical composition of the hydrated pastes did not change with the addition of MPCM, the mechanical strengths decrease dramatically. This decrease is well described by the Bolomey equation, assuming MPCMs act as air voids. This is a physical effect due to the high volume of MPCM, and not due to a change in the hydration chemistry.

Cage occupancy of methane clathrate hydrates in the ternary H2O-NH3-CH4 system.

The incorporation of ammonia inside methane clathrate hydrate is of great interest to the hydrate chemistry community. We investigated the phase behavior of methane clathrate formed from aqueous ammonia solution. Ammonia's presence decreases methane occupancy in the large cages, without definitive Raman spectroscopic evidence for its incorporation inside the structure.

Effect of nanopore on hydration of hafnium investigated by TDPAC as a hyperfine tool

The Time Differential Perturbed γ-γ Angular Correlation (TDPAC) measurement has been carried out with the hydrolysis product of Hafnium(Hf)-IV ion at pH1 both in bulk and under nano confinement using 181Hf/Ta as PAC probe. The experiment was performed at two different temperatures, viz., 300 K and 280 K. Three different probe sites could be identified for the bulk complex while it is four in case the complex is inside the nanopore, at both the measuring temperatures. The major site, in case of bulk complex, has a quadrupole frequency ωQ ~ 105 Mrad/s and η ~ 0.6. However, the major site, in case the complex is inside nanopore having an average pore size of 6 nm, has ωQ ~ 210 Mrad/s and η ~ 0.3. Two different values of PAC parameters corresponding to the major probe sites for the bulk and nano-confined complex, indicate completely different hydration chemistry in the present two cases.

Investigation of Nitrile Hydration Chemistry by Two Transition Metal Hydroxide Complexes: Mn–OH and Ni–OH Nitrile Insertion Chemistry

Herein we describe the synthesis of a series of nickel complexes, including the formation of [(iPrPNHP)Ni(PMe3)][BPh4] (iPrPNHP = HN(CH2CH2(PiPr2))2). The ability of this phosphine complex to perform the 1,2-addition of H2O to produce the Ni–OH species [(iPrPNHP)NiOH][BPh4] has been investigated. The nucleophilicity of the hydroxide moiety of both [(iPrPNHP)NiOH][BPh4] and the previously reported (iPrPNHP)MnOH(CO)2 was investigated through the hydration of aryl and alkyl nitriles, leading to the formation of a number of metal carboxamide (RC(O)NH–) bonds. This reactivity generated complexes with the general structures of [(iPrPNHP)Ni(NHC(O)R)][BPh4] for nickel and (iPrPNHP)Mn(NHC(O)R)(CO)2 for manganese. Under catalytic conditions, the hydration of nitriles using nickel complexes yielded only a single turnover. However, (iPrPNHP)MnOH(CO)2 produced several turnovers, and the reaction conditions were probed for optimization.

Metal Ion Interactions with Crude Oil Components: Specificity of Ca2+ Binding to Naphthenic Acid at an Oil/Water Interface

On the basis of dynamic interfacial tension measurements, Ca2+ has been shown specifically to interact with naphthenic acid (NA) at the n-heptane/water interface, consistent with NA adsorption followed by interfacial complexation and formation of a more ordered interfacial film. Optimum concentrations of Ca2+ and NA have been found to yield lower, time-dependent interfacial tensions, not evident for Mg2+ and Sr2+ or for several alkali metal ions studied. The results reflect the specific hydration and coordination chemistry of Ca2+ seen in biology. Owing to the ubiquitous presence of Ca2+ in oilfield waters, this finding has potential relevance to the surface chemistry underlying crude oil recovery. For example, “locking” acidic components at water/oil interfaces may be important for crude oil emulsion stability, or in bonding bulk oil to mineral surfaces through an aqueous phase, potentially relevant for carbonate reservoirs. The relevance of the present results to low salinity waterflooding as an enhanced crude oil recovery technique is also discussed.

Characterization of Mg components in reactive MgO – Portland cement blends during hydration and carbonation

Abstract A carbonated binder system containing reactive MgO (r-MgO) and Portland cement (PC) has the potential to provide sufficient mechanical properties and reduce carbon the footprint. However, the understanding of the chemistry of hydration and carbonation of the r-MgO-PC system remains unclear. The purpose of this study is to characterize the Mg components that form blends of r-MgO and PC during hydration and carbonation. Paste specimens of r-MgO and PC with r-MgO replacement levels from 10% to 90% were cast, carbonated and examined. Experimental observations reveal that: (1) nesquehonite only occurs in the carbonated r-MgO-PC paste with r-MgO replacement ≥ 60%; (2) an amorphous phase of hydrated Mg carbonate was identified in the carbonated paste with 50% r-MgO replacement; and (3) hydrotalcite and magnesium silicate hydrate are major hydration products of r-MgO during the hydration of the paste containing 30% and 40% r-MgO, which are expected to be the precursors of amorphous hydrated Mg carbonate.