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It is widely recognized that electrostatics plays a central role in the intermolecular interactions in condensed phases, as evidenced by the "electrostatics + Lennard-Jones" form of the potential functions that are commonly used in classical molecular dynamics simulations. Then, do we understand all about electrostatics in condensed phases? In this review, recent theoretical advances in relation to this topic will be discussed: (1) vibrational spectroscopic probing of the electrostatics in condensed phases, and (2) some phenomena affected by deviation from the scheme of isotropic fixed atomic partial charges, i.e., anisotropy and intermolecular transfer of electron distributions. A theoretical basis for better understanding on them and some theoretical models for practical calculations will be shown with some typical example cases of hydrogen- and halogen-bonded systems. [ABSTRACT FROM AUTHOR]

Chemical speciation studies, i.e., the study of the distribution of an element or compound among its various species in a system of interest, are of fundamental importance. Chemical speciation investigations can be performed mainly by either the direct measurement of the chemical species by different analytical techniques, or by chemical modeling through equilibrium thermodynamic data, based on the use of stability constants (and other thermodynamic parameters) of the formed species. For these purposes, a series of techniques can be used. As soon as the complexity of the systems of interest increases, the need for more detailed information arises. As such, a multi-technique approach is essential to derive complementary data to define a chemical system. In this tutorial review we analyzed the most common instrumental techniques employed for chemical speciation studies and equilibrium data analysis. The main advantages and disadvantages of potentiometry, voltammetry, coulometry, UV–vis spectrophotometry, spectrofluorimetry, NMR, EPR, ITC, HRMS and quantum mechanical calculations, together with brief mention to other less common techniques, are discussed together with a series of practical examples of their application. The main aim of this tutorial review is to provide a practical guide to all scientists interested in the field. [ABSTRACT FROM AUTHOR]

When the theoretical research results of the laboratory are applied to the production practice, it is often found that there are obvious differences between them, which greatly decrease the practicability of flotation research, especially pure mineral research. The reason for the difference between the theoretical research and practical application results lies in the complexity of the flotation process, it is not only necessary to pay attention to the chemical principle of the chemicals adsorption on the mineral surface, but also to comprehensively consider and analyze the chemical environment of flotation (solution conditions and associated minerals). In recent years, the proposed coordination chemical model of mineral flotation, together with the continuous development of solution chemistry theory, provides the possibility to realize the goal of theoretical research guiding practical production. In this paper, the application examples of coordination chemical model of mineral flotation, solution chemical calculation and extended DLVO theory in the study of mineral flotation mechanism at home and abroad are collected and summarized. Introduction and comments are given regarding the theoretical content, calculation process and application examples of the three theories, so as to provide a reference for the future flotation research. [ABSTRACT FROM AUTHOR]

Citric acid/tartaric acid can cause mineral dissolution and biomineralization of calcite, so the study on reaction pattern between them is of great significance for the assessment of the stability of calcite minerals and the study on the corresponding geochemical effects in organic acid-rich environments. The reaction between calcite and citric acid/tartaric acid and the corresponding solution chemistry change were studied by batch equilibrium method under open system conditions. The results show that at the initial concentration of 20 mg.L-1, the reaction removal of citric acid and tartaric acid decreases significantly when the initial pH value increases from 7.7 to 9.7; this is attributed to the electrostatic effect on the surface of calcite and the increasing competition between HCO-3 and CO2-3 in the solution, which inhibit the surface adsorption reaction of the two acids on calcite. At the initial pH of 7.7 and 8.3, the reaction of the two acids with an initial concentration of 20 mg.L-1 and calcite reaches equilibrium after 7 h; compared with the blank values, the pH and Ca concentration have little change, which prove that the dominant mechanism of the reaction is surface adsorption. In the concentration range of 0-900 mg.L-1, the reaction removal results of citric acid and tartaric acid at the initial pH of 8.3 could be well fitted by the Langmuir adsorption model, which proves that both of the above removal mechanisms are surface adsorption; at the initial pH of 7.7, the reaction removal results of citric acid still could be fitted by the Langmuir adsorption model, and the removal mechanism is still surface adsorption; while the removal of tartaric acid shows a continuous steep increase, which cannot be fitted by the Langmuir or Freundlich adsorption model, and this is due to the fact that the dominant mechanism of tartaric acid removal by reaction is precipitation reaction. At an initial pH of 8.3, a concentration range of 0-900 mg.L-1 and the temperatures of 5 ℃, 20 ℃, and 35℃, the removal results of both acids could be fitted by the Langmuir adsorption model, and the removal mechanism is still surface adsorption; the increase in the saturation adsorption of citric acid with increasing temperature is greater than that of tartaric acid; meanwhile, citric acid at all three temperatures brings about a greater increase in pH and Ca concentration than that of tartaric acid. [ABSTRACT FROM AUTHOR]

This paper examines the impact of supervised laboratory instruction (SLI) on grade 12 students' understanding of acid–base and solution chemistry topics in the context of Ethiopian secondary schools. A mixed-methods research design was employed, with a purposive sampling of 160 secondary students from six schools in Northwest Ethiopia. The students were divided into two groups: an experimental group (n = 76) and a control group (n = 84). The experimental group attended sessions that were designed based on self-regulated learning (SRL) strategies with SLI, and the control group attended regular instruction designed by the course teacher. Both quantitative and qualitative data were collected to explore the impacts of the experimental and control lessons on improving students' conceptual understanding and motivation. Descriptive and inferential statistics (for the quantitative data)and reflexive thematic analysis(for the qualitative data)were employed to analyse the data. The findings showed that the SLI-SRL teaching approach for the experimental group resulted in a significantly higher conceptual understanding of the selected chemistry topics than the regular instruction for the control group. In addition, participants from the experimental group indicated that the SLI approach enhanced their motivation towards chemistry. These findings suggest that improving high-school students' motivation and their conceptual understanding of chemistry requires paying attention to the lesson design. [ABSTRACT FROM AUTHOR]

Germanium dioxide (GeO2) is a versatile material with several different crystalline polymorphs and interesting applications in, e.g., optics, microelectronics, and Li-ion batteries. In particular, many of the material's properties depend on the size of the prepared crystallites, and thus, nanocrystalline GeO2 is of special interest. Here, GeO2 nanoparticles are prepared via sol–gel processes by the hydrolysis of Ge isopropoxide (Ge(OCH(CH3)2)4). The precipitated powders are dried at room temperature and annealed in ambient air using temperatures between 500 °C and 1000 °C from 3 to 24 h. The samples were characterized by X-ray diffraction, X-ray absorption fine structure spectroscopy, and scanning electron microscopy, providing the crystalline structures, the phase composition, as well as the morphology and crystallite size of the formed particles and their changes upon heating. According to the structural analysis, the samples are crystalline with a dominant β- (low temperature) quartz phase without any heat treatment directly after drying and increasing contributions of α- (high-temperature modification) quartz and quartz-like GeO2 structures with increasing temperature and annealing time were found. According to electron microscopy and the X-ray analysis, the particle size ranges from about 40 to 50 nm for the pristine particles and to about 100 nm and more for the annealed materials. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have presented excellent behaviors in the separation of azeotropes in extractive distillation. However, the intrinsic molecular nature of ILs in the separation of azeotropic systems is not clear. In this paper, Fourier-transform infrared spectroscopy (FTIR) and theoretical calculations were applied to screen the microstructures of ethyl propionate–n-propanol–1-ethyl-3-methylimidzolium acetate ([EMIM][OAC]) systems before and after azeotropy breaking. A detailed vibrational analysis was carried out on the v(C=O) region of ethyl propionate and v(O–D) region of n-propanol-d1. Different species, including multiple sizes of propanol and ethyl propionate self-aggregators, ethyl propionate–n-propanol interaction complexes, and different IL–n-propanol interaction complexes, were identified using excess spectroscopy and confirmed with theoretical calculations. Their changes in relative amounts were also observed. The hydrogen bond between n-propanol and ethyl propionate/[EMIM][OAC] was detected, and the interaction properties were also revealed. Overall, the intrinsic molecular nature of the azeotropy breaking was clear. First, the interactions between [EMIM][OAC] and n-propanol were stronger than those between [EMIM][OAC] and ethyl propionate, which influenced the relative volatilities of the two components in the system. Second, the interactions between n-propanol and [EMIM][OAC] were stronger than those between n-propanol and ethyl propionate. Hence, adding [EMIM][OAC] could break apart the ethyl propionate–n-propanol complex (causing the azeotropy in the studied system). When x([EMIM][OAC]) was lower than 0.04, the azeotropy still existed mainly because the low IL could not destroy the whole ethyl propionate–n-propanol interaction complex. At x(IL) > 0.04, the whole ethyl propionate–n-propanol complex was destroyed, and the azeotropy disappeared. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSBs) are promising to be next-generation battery that provides high energy density and intrinsic safety. Research in the field of ASSBs has so far focused on the development of highly conductive solid electrolytes (SEs). The commercialization of ASSBs requires well-established large-scale manufacturing for sulfide SEs with high ionic conductivity. However, the synthesis for sulfide SEs remains at the laboratory scale with limited scalability owing to their air sensitivity. The liquid-phase synthesis would be an economically viable manufacturing technology for sulfide SEs. Herein, we review a chemical perspective in liquid-phase synthesis that offers high scalability, low cost, and high reaction kinetics. This review provides a guideline for desirable solvent selection based on the solubility and polarity characterized by the donor number and dielectric permittivity of solvents. Additionally, we offer a deeper understanding of the recent works on scalable liquid-phase synthesis using solubilizers and reactant agents. We present an outlook on a universal liquid-phase synthesis of sulfide SEs toward the commercialization of sulfide-based ASSBs. [ABSTRACT FROM AUTHOR]

Metakaolin concrete is a kind of porous material, which contains a variety of chemical ions in the pores. Solutions in these pores are exposed to the atmosphere and exist evaporation and condensation processes, therefore, the pore solution volume of concrete changes all the time. When the ion concentration in the pore solution changes, it has an important impact on the strength development and durability of concrete. However, the real-time monitoring of the concentration of pore solution was difficult. To study the chemical evolution of pore solution in concrete, the variation of saturated vapor pressure on the surface of metakaolin concrete was studied based on the Cisternas-Lam rule. The evaporation rate of solvent in the pore solution of concrete under the corresponding saturated vapor pressure in this paper was studied by the Stefan diffusion method. The dynamic equilibrium process equation of ions in pore solution was then established based on the thermodynamic equilibrium equation. Based on the above model, the change process of the pore solution of metakaolin concrete was studied, and it was verified by the results of the literature.

A free energy-based conceptual theoretical framework from which the conditional equilibrium constant can be comprehensibly understood is presented. This constant is found to be a weighted geometric mean of the equilibrium constants of the reactions of all forms of the conditioned species under buffering conditions, where the weight is given by a function of their predominance in terms of their mole fractions. Once it is shown that this type of equilibrium constant can be easily deduced form free energy functions, it is shown how corrections for activity coefficient can be incorporated as well. The framework additionally permits to interpret side-reactions coefficients as free energy terms related to the chemical speciation of the system, allowing the use of the generalization of Hess' law to obtain conditional constants and a straightforward deduction of multiconditional equilibrium constants. Furthermore, different uses of the conditional constants along the actual literature are reviewed as well allowing to have a complete and updated panorama of the employment of this important concept in chemical and speciation analysis in many areas of research. [ABSTRACT FROM AUTHOR]

Flotation is often used to separate valuable minerals from calcite. The flotation reagents and surface properties difference determines the flotation separation efficiency of calcite and its associated minerals. However, the interaction of minerals particles, as well as the adsorption and chemical reaction of soluble component with other minerals, change the surface properties and selectivity performance of flotation reagents. Minerals interactive effect is an important factor that makes it difficult to separate complex ores, and also an important reason for the loss of selectivity of high efficiency flotation reagent in mixed minerals or actual ores system. In this paper, the interaction mechanism and regulation methods of oxidation minerals, carbonate minerals and calcium salt minerals with calcite were summarized, and the research status and development trend of mineral interaction were preliminary clarified, so as to provide reference for further research of mineral interactive effect. [ABSTRACT FROM AUTHOR]

The solution precursor plasma spray (SPPS) process involves injecting atomized droplets of a precursor solution into the plasma plume. In this study, two different solution precursors were used in the SPPS process including zirconium oxynitrate and zirconium acetate to make thermal barrier coatings (TBC). The effect of these solutions on microstructure and high-temperature properties of thermal barrier coating made by SPPS has been studied. The results showed that the use of zirconium acetate as a precursor compared to zirconium oxynitrate led to the formation of more vertical cracks with an average spacing of 150-200 μm in the microstructure of coatings. This was due to the presence of more un-pyrolysis or semi-pyrolysis materials in the coating structure and their shrinkage stresses during the deposition that was dependent on the solution chemistry in the plasma plume. The oxidation test at 1000 °C for various times of 12, 50, 120, and 250 h showed similar behavior for both coatings. In addition, the coating obtained from zirconium acetate precursor exhibited an average life of 648 cycles in a 1-h 1000 °C thermal cycling test, which was more than about 1.5 times that of SPPS-TBC coating made of zirconium oxynitrate precursor (431 cycles) due to the presence of much more vertical cracks in its structure. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) have received extensive attention due to their various harmful effects. In this study, the adsorptive removal of 10 legacy and emerging PFASs by four anion-exchange resins (including gel and macroreticular resins) were systematically investigated. Our results showed that the capacities of resins absorbing PFASs were ranked in the following order: gel strong base HPR4700 (297~300 μg/g) ≈ macroreticular strong base S6368 (294~300 μg/g) ≈ macroreticular weak base A111S (289~300 μg/g) > gel weak base WA10 (233~297 μg/g). Adsorption kinetic results indicated that the adsorption process might involve chemical and Henry regime adsorption or reaction control. Intraparticle diffusion was probably the major removal step. Co-existing fulvic acid (0.5, 1, 5 mg/L) and inorganic anions (5 mg/L of sulfate, carbonate, bicarbonate) would hinder the PFAS removal by resins with WA10 showing the highest inhibition rate of 17% and 71%, respectively. The adsorption capacities of PFBA decreased from 233 μg/g to 194 μg/g, and from 233 μg/g to 67 μg/g in the presence of fulvic acid and inorganic anions, respectively. PFASs were more easily removed by HPR4700, S6368, and A111S under neutral and alkaline environment. Moreover, WA10 was not able to remove PFASs under an alkaline medium. This study offered theoretical support for removing PFASs from aqueous phases with various resins. [ABSTRACT FROM AUTHOR]

Biochar nanoparticles (BC-NP) have attracted significant attention because of their unique environmental behavior, some of which could potentially limit large-scale field application of biochar. Accurate prediction of the fate and transportability of BC-NP in soil matrix is the key to evaluating their environmental influence. This study investigated the effects of soil grain size and environmentally relevant solution chemistry, such as ionic strength (cation concentration, 0.1 mM–50 mM; cation type, Na+, and Ca2+), and humic acid (HA; 0–10 mg/L), on the transport behavior of BC-NP via systematic column experiments. The transportability of BC-NP in the soil-packed column decreased with decreasing soil grain size and was inversely proportional to soil clay content. At low cation concentrations (0.1–1.0 mM), a considerable proportion of BC-NP (15.95%–67.17%) penetrated the soil columns. Compared with Na+, Ca2+ inhibited the transportability of BC-NP in the soil through a charge shielding effect. With increasing HA concentration, the transportability of BC-NP increased, likely due to an enhanced repulsion force between BC-NP and soil particles. However, at a high HA concentration (10 mg/L), Ca2+ bridging reduced the transportability of BC-NP in the soil. Breakthrough curves of BC-NP were explained by the two-site kinetic retention model. The antagonistic effects of ionic strength and HA indicated that the transport behavior of BC-NP in the soil was governed by competitive effects of some environmental factors, including soil grain size, environmental solution chemistry, and natural organic matter content.

The formation of ZnO nanomaterials from different Zn acetylacetonate precursor solutions was studied in situ by employing simultaneous, time-resolved X-ray diffraction (XRD) and X-ray absorption spectroscopy (EXAFS) at the Zn K-edge. The precursor solutions were heated from room temperature to the desired reaction temperatures in a hermetically sealed cell dedicated to X-ray experiments. In general, the first indications for the formation of hexagonal ZnO were found for elevated temperatures of about 80 °C both by XRD and EXAFS, and the contributions increase with temperature and time. However, no reaction intermediates could be proved in addition to the Zn precursors and the formed hexagonal ZnO materials. Furthermore, the results show that the efficiency of the reaction, i.e., the conversion of the precursor material to the ZnO product, strongly depends on the solvent used and the reaction temperature. ZnO formation is accelerated by an increased temperature of 165 °C and the use of 1-octanol, with a conversion to ZnO of more than 80% after only a ca. 35 min reaction time according to a detailed analysis of the EXAFS data. For comparison, an identical concentration of Zn acetylacetonate in water or dilute alkaline NaOH solutions and a reaction temperature of around 90 °C leads to a smaller conversion of approximately 50% only, even after several hours of reaction. The particle size determined from XRD for different orientations shows a preferred orientation along the c-direction of the hexagonal crystal system, as well in accordance with scanning electron microscopy. The LaMer model explained this highly non-uniform growth of needle-like ZnO crystallites. [ABSTRACT FROM AUTHOR]

Germanium dioxide (GeO2) is a versatile material with several different crystalline polymorphs and interesting applications in, e.g., optics, microelectronics, and Li-ion batteries. In particular, many of the material’s properties depend on the size of the prepared crystallites, and thus, nanocrystalline GeO2 is of special interest. Here, GeO2 nanoparticles are prepared via sol–gel processes by the hydrolysis of Ge isopropoxide (Ge(OCH(CH3)2)4). The precipitated powders are dried at room temperature and annealed in ambient air using temperatures between 500 °C and 1000 °C from 3 to 24 h. The samples were characterized by X-ray diffraction, X-ray absorption fine structure spectroscopy, and scanning electron microscopy, providing the crystalline structures, the phase composition, as well as the morphology and crystallite size of the formed particles and their changes upon heating. According to the structural analysis, the samples are crystalline with a dominant β- (low temperature) quartz phase without any heat treatment directly after drying and increasing contributions of α- (high-temperature modification) quartz and quartz-like GeO2 structures with increasing temperature and annealing time were found. According to electron microscopy and the X-ray analysis, the particle size ranges from about 40 to 50 nm for the pristine particles and to about 100 nm and more for the annealed materials.

This paper examines the impact of supervised laboratory instruction (SLI) on grade 12 students’ understanding of acid–base and solution chemistry topics in the context of Ethiopian secondary schools. A mixed-methods research design was employed, with a purposive sampling of 160 secondary students from six schools in Northwest Ethiopia. The students were divided into two groups: an experimental group (n = 76) and a control group (n = 84). The experimental group attended sessions that were designed based on self-regulated learning (SRL) strategies with SLI, and the control group attended regular instruction designed by the course teacher. Both quantitative and qualitative data were collected to explore the impacts of the experimental and control lessons on improving students’ conceptual understanding and motivation. Descriptive and inferential statistics (for the quantitative data)and reflexive thematic analysis(for the qualitative data)were employed to analyse the data. The findings showed that the SLI-SRL teaching approach for the experimental group resulted in a significantly higher conceptual understanding of the selected chemistry topics than the regular instruction for the control group. In addition, participants from the experimental group indicated that the SLI approach enhanced their motivation towards chemistry. These findings suggest that improving high-school students’ motivation and their conceptual understanding of chemistry requires paying attention to the lesson design.

All-solid-state batteries (ASSBs) are promising to be next-generation battery that provides high energy density and intrinsic safety. Research in the field of ASSBs has so far focused on the development of highly conductive solid electrolytes (SEs). The commercialization of ASSBs requires well-established large-scale manufacturing for sulfide SEs with high ionic conductivity. However, the synthesis for sulfide SEs remains at the laboratory scale with limited scalability owing to their air sensitivity. The liquid-phase synthesis would be an economically viable manufacturing technology for sulfide SEs. Herein, we review a chemical perspective in liquid-phase synthesis that offers high scalability, low cost, and high reaction kinetics. This review provides a guideline for desirable solvent selection based on the solubility and polarity characterized by the donor number and dielectric permittivity of solvents. Additionally, we offer a deeper understanding of the recent works on scalable liquid-phase synthesis using solubilizers and reactant agents. We present an outlook on a universal liquid-phase synthesis of sulfide SEs toward the commercialization of sulfide-based ASSBs.

The influence of phosphates on the transport of plastic particles in porous media is environmentally relevant due to their ubiquitous coexistence in the subsurface environment. This study investigated the transport of plastic nanoparticles (PNPs) via column experiments, paired with Derjaguin–Landau–Verwey–Overbeek calculations and numerical simulations. The trends of PNP transport vary with increasing concentrations of NaH2PO4 and Na2HPO4 due to the coupled effects of increased electrostatic repulsion, the competition for retention sites, and the compression of the double layer. Higher pH tends to increase PNP transport due to the enhanced deprotonation of surfaces. The release of retained PNPs under reduced IS and increased pH is limited because most of the PNPs were irreversibly captured in deep primary minima. The presence of physicochemical heterogeneities on solid surfaces can reduce PNP transport and increase the sensitivity of the transport to IS. Furthermore, variations in the hydrogen bonding when the two phosphates act as proton donors will result in different influences on PNP transport at the same IS. This study highlights the sensitivity of PNP transport to phosphates associated with the solution chemistries (e.g., IS and pH) and is helpful for better understanding the fate of PNPs and other colloidal contaminants in the subsurface environment. [ABSTRACT FROM AUTHOR]

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Pore solution expression (PSE) is the most commonly used method to obtain the aqueous phase in cementitious material. However, the high pressure applied on the sample during PSE can affect the composition of the solid phase. An experimental study on the chemical and mineral composition of cement paste before and after PSE was conducted. The results indicate that a small part of the alkali contained in the samples was excluded during PSE, depending mainly on the alkali concentration in the pore solution. Due to the expulsion of interlayer water in calcium silicate hydrate under high pressure, PSE reduced the bound water content (measured by thermogravimetric analysis (TGA)). The portlandite content determined by TGA was not affected by PSE, but it led to an overestimation of portlandite by means of quantitative X-ray diffraction, because of the enhanced preferred orientation of the (001) plane under the applied high pressure. In addition, the size of the portlandite crystals decreased to some extent due to the creep caused by pressure. The content of the hemicarbonate phase was found to decrease slightly after PSE, which may be due to increased solubility under high pressure. [ABSTRACT FROM AUTHOR]

Cerium(IV) hydrolysis in sulfate solutions is studied spectrophoto- and photometrically, pH-metrically and potentiometrically at the ionic strength I = 2 in the pH range 0.2–3.0 at 294.95 K. The equilibrium constants of hydrolysis of cerium(IV) sulfate complexes are calculated; the yield diagram of cerium(IV) hydrolytic species occurring in sulfate solutions is plotted. The stability constants of binuclear cerium(IV) hydroxo complexes with dioxysuccinic (tartaric) carboxylic acid are calculated in terms of the advanced hydrolysis model. [ABSTRACT FROM AUTHOR]

Crystal nucleation determining the formation and assembly pathway of first organic materials is the central science of various scientific disciplines such as chemical, geochemical, biological, and synthetic materials. However, our current understanding of the molecular mechanisms of nucleation remains limited. Over the past decades, the advancements of new experimental and computational techniques have renewed numerous interests in detailed molecular mechanisms of crystal nucleation, especially structure evolution and solution chemistry. These efforts bifurcate into two categories: (modified) classical nucleation theory (CNT) and non-classical nucleation mechanisms. In this review, we briefly introduce the two nucleation mechanisms and summarize current molecular understandings of crystal nucleation that are specifically applied in polymorphic crystallization systems of small organic molecules. Many important aspects of crystal nucleation including molecular association, solvation, aromatic interactions, and hierarchy in intermolecular interactions were examined and discussed for a series of organic molecular systems. The new understandings relating to molecular self-assembly in nucleating systems have suggested more complex multiple nucleation pathways that are associated with the formation and evolution of molecular aggregates in solution. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have presented excellent behaviors in the separation of azeotropes in extractive distillation. However, the intrinsic molecular nature of ILs in the separation of azeotropic systems is not clear. In this paper, Fourier-transform infrared spectroscopy (FTIR) and theoretical calculations were applied to screen the microstructures of ethyl propionate–n-propanol–1-ethyl-3-methylimidzolium acetate ([EMIM][OAC]) systems before and after azeotropy breaking. A detailed vibrational analysis was carried out on the v(C=O) region of ethyl propionate and v(O–D) region of n-propanol-d1. Different species, including multiple sizes of propanol and ethyl propionate self-aggregators, ethyl propionate–n-propanol interaction complexes, and different IL–n-propanol interaction complexes, were identified using excess spectroscopy and confirmed with theoretical calculations. Their changes in relative amounts were also observed. The hydrogen bond between n-propanol and ethyl propionate/[EMIM][OAC] was detected, and the interaction properties were also revealed. Overall, the intrinsic molecular nature of the azeotropy breaking was clear. First, the interactions between [EMIM][OAC] and n-propanol were stronger than those between [EMIM][OAC] and ethyl propionate, which influenced the relative volatilities of the two components in the system. Second, the interactions between n-propanol and [EMIM][OAC] were stronger than those between n-propanol and ethyl propionate. Hence, adding [EMIM][OAC] could break apart the ethyl propionate–n-propanol complex (causing the azeotropy in the studied system). When x([EMIM][OAC]) was lower than 0.04, the azeotropy still existed mainly because the low IL could not destroy the whole ethyl propionate–n-propanol interaction complex. At x(IL) > 0.04, the whole ethyl propionate–n-propanol complex was destroyed, and the azeotropy disappeared.

Functional oxide materials have become crucial in the continuous development of various fields, including those for energy applications. In this aspect, the synthesis of nanomaterials for low-cost green hydrogen production represents a huge challenge that needs to be overcome to move toward the next generation of efficient systems and devices. This perspective presents a critical assessment of hydrothermal and polymeric precursor methods as potential approaches to designing photoelectrodes for future industrial implementation. The main conditions that can affect the photoanode's physical and chemical characteristics, such as morphology, particle size, defects chemistry, dimensionality, and crystal orientation, and how they influence the photoelectrochemical performance are highlighted in this report. Strategies to tune and engineer photoelectrode and an outlook for developing efficient solar-to-hydrogen conversion using an inexpensive and stable material will also be addressed. [ABSTRACT FROM AUTHOR]

This research aimed to develop a multiple-choice chemical literacy test on solution chemistry as an instrument that specifically focuses on learners' knowledge and competency aspects; applying the test instrument by surveying 12th-grade high school students. The development of the test instrument adapted the R&D model by Borg and Gall. The Cronbach's Alpha reliability of the test was obtained after small-scale and wide-scale trials are 0.793 and 0.833, respectively, with 35 valid items. Data were collected using random cluster sampling with a total of 463 respondents. The result shows that the mean score of chemical literacy for the students in this study is 46.27. This indicated that the students' level of chemical literacy is low, and further improvement is required.

The significant inhabitation of Portland cement hydration by zinc restricts the utilization of zinc-bearing solid wastes in cementitious materials. The influence of zinc, in the form of (Zn(NO 3) 2 ·6H 2 O and ZnCl 2 , on the hydration of Portland cement and tricalcium silicate (C 3 S) was investigated both experimentally and by thermodynamic modelling. The reaction of C 3 S in zinc-rich solutions is strongly retarded and initially results in the formation of Zn(OH) 2 , Zn 5 (OH) 8 Cl 2 ·H 2 O, CaZn 2 Si 2 O 7 ·H 2 O, Zn 2 SiO 4 and (ZnO) 2x (SiO 2) x ·2xH 2 O, while the pH values remain low. At higher C 3 S reaction, Zn2+ concentrations decrease and the pH starts to rise as Ca2+ gradually accumulates in pore solution. Such retarding effect of zinc may be due to i) chemisorption of Zn2+ on the surface of C 3 S in particular at lower pH values and ii) the lowering of pH by addition of zinc salts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Weak hydrogen bonding is present in binary solutions. • Simulations of the HB modes with DFT are in good agreement with experiment. • HB and high pressure tune the FR of the CS 2 molecule differently. In the spectroscopic study of polyatomic molecules, Fermi resonance (FR) is a vibrational coupling and energy transfer phenomenon that widely exists intra- and intermolecular. In particular, the FR coupling between the fundamental mode ν 1 and the doubling mode 2ν 2 of the CS 2 molecule has attracted extensive research. In this work, we investigate the effect of local field on tuning the FR of CS 2. By analyzing the Raman spectra of CS 2 mixed with methanol and ethanol with different mole fractions, the results indicated that weak HBs interactions in binary solutions can be reflected by the linear frequency shift of the C–H bond vibrations (in methanol and ethanol) with different molar concentrations. Furthermore, the geometrical structure was optimized using DFT simulation, and the vibration analysis and interaction energy were carried out. The simulated Raman spectra are in good agreement with the experiments. In addition, high-pressure Raman spectra of CS 2 were obtained by diamond anvil cell technique (up to 9.19 GPa) and a pressure-induced phase transition was observed at 1.71 GPa. The results demonstrated that the pressure-induced polymerization phase transition of CS 2 molecules causes the close packing and more orderly arrangement of molecules, resulting in the enhancement of FR coupling. HB and high pressure tune the FR of the CS 2 molecule differently. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) have received extensive attention due to their various harmful effects. In this study, the adsorptive removal of 10 legacy and emerging PFASs by four anion-exchange resins (including gel and macroreticular resins) were systematically investigated. Our results showed that the capacities of resins absorbing PFASs were ranked in the following order: gel strong base HPR4700 (297~300 μg/g) ≈ macroreticular strong base S6368 (294~300 μg/g) ≈ macroreticular weak base A111S (289~300 μg/g) > gel weak base WA10 (233~297 μg/g). Adsorption kinetic results indicated that the adsorption process might involve chemical and Henry regime adsorption or reaction control. Intraparticle diffusion was probably the major removal step. Co-existing fulvic acid (0.5, 1, 5 mg/L) and inorganic anions (5 mg/L of sulfate, carbonate, bicarbonate) would hinder the PFAS removal by resins with WA10 showing the highest inhibition rate of 17% and 71%, respectively. The adsorption capacities of PFBA decreased from 233 μg/g to 194 μg/g, and from 233 μg/g to 67 μg/g in the presence of fulvic acid and inorganic anions, respectively. PFASs were more easily removed by HPR4700, S6368, and A111S under neutral and alkaline environment. Moreover, WA10 was not able to remove PFASs under an alkaline medium. This study offered theoretical support for removing PFASs from aqueous phases with various resins.

[Display omitted] Crystalline hydrates of swelling clay minerals (smectites) exhibit a strong coupling between their ion exchange and hydration/dehydration reactions. The uptake or removal of water from smectite interlayers as a result of a change in the environmental conditions also leads to the partitioning of cations. Three factors, the solid ion composition, the solid basal spacing/water content, and the aqueous solution composition, are all implicated in controlling the thermodynamics of ion exchange. However, conventional approaches to measuring the exchange free energy cannot separate the influence of each of these individual factors. Here, we explore the energetics of the swelling and ion exchange reactions in montmorillonite using a potential of mean force approach and the thermodynamic integration method within molecular simulations. We investigate the influence of solution and clay composition on the spontaneity of the reactions, focusing on the 2 water-layer hydration state. The swelling simulations provide the equilibrium water content, interlayer water structure, and basal spacings, while thermodynamic integration of sodium–potassium exchange in the aqueous solution and solid phase are combined to calculate ion exchange free energies as a function of solution composition. Results confirm the tendency of the clay to collapse to lower hydration states as the concentration of the solution increases. Changes to the equilibrium water content, even at fixed hydration states, and the composition of the mixed electrolyte solution play a critical role in driving ion exchange and the selectivities of the clay to the exchanged cation, while the composition of the solid phase is shown to be insignificant. These findings underscore the extreme sensitivity of clay swelling and ion exchange thermodynamics to small (tenths of an Angstrom) deviations in layer spacing. [ABSTRACT FROM AUTHOR]

Interactions between plasmas and liquids lead to the formation of a variety of unique reactive species for chemical and materials applications that makes plasma-induced liquid chemistry attractive for industrial applications. While formation of various chemical species have been observed, a complete understanding of the chemistry occurring at the plasma–liquid interface remains unclear. Here, we study the properties of water exposed to a helium plasma at atmospheric pressure in open air and in argon-controlled environments with systematic changes to process conditions. The pH, temperature, and conductivity are monitored as a function of plasma current and processing time. In addition, molecular oxygen (O2) and hydrogen peroxide (H2O2) are quantitatively measured. We find that the electron density which is controlled by plasma current plays an important role and the number of electrons injected from the plasma into water can be related to the number of H2O2 molecules generated. We support this result with a mechanistic description of reaction pathways at the plasma-water interface. [ABSTRACT FROM AUTHOR]

The adsorption characteristics of Eu(III) on colloidal bentonite particles were investigated by batch experiments as functions of colloid concentration, pH, foreign ions, and temperature. Bentonite colloids displayed remarkable adsorption ability to Eu(III), the Eu(III) adsorption was significantly affected by solution chemistry. The Eu(III) adsorption increased with colloids concentration and pH increasing. Divalent cations (Ca2+, Mg2+ and Sr2+) and anions (Cl− and SO42−) inhibited Eu(III) adsorption, whereas PO43− greatly enhanced Eu(III) adsorption. High temperature was beneficial for Eu(III) adsorption, the adsorption process was a spontaneous endothermic process. The results suggested that colloids could acted as an efficient carrier for Eu(III) transport. [ABSTRACT FROM AUTHOR]

A heterometallic copper‐neodymium complex CuNd2(CCl3COO)8 ⋅ 6MeCN (1) was synthesized from an aqueous‐organic salt system and structurally characterized by single crystal X‐Ray diffraction analysis. Thermal stability of 1 was studied. The crystal of 1 is tetragonal, with the space group I4, a=11.5904(3), c=23.9195(8) Å, V=3213.3(2) Å3, Z=8. Two crystallographically unsymmetrical Nd atoms and one Cu atom are bridged by trichloroacetic ligands into one‐dimensional molecular chains. According to our experimental data on magnetic properties of 1, the compound could be classified as paramagnet at observed temperature range 2–300 K. In addition, the structure of the obtained Nd (III) trichloroacetate Nd(CCl3COO)3(H2O)2 ⋅ 2H2O (2) was determined. The structural data of 1 and 2 were compared to the one for known rare‐earth trichloroacetates. [ABSTRACT FROM AUTHOR]

This review highlights the recent advances of employing the perovskite crystals redissolution strategy in perovskite photovoltaics, with particular emphasis on comparing different methodologies for synthesizing perovskites, elucidating the distinct solution chemistry, analyzing the cost advantages, as well as underlining the desirable thin-film superiority with improved quality and enhanced optoelectronic properties. [Display omitted] High-efficiency perovskite solar cells (PSCs) normally rely on costly, high purity (>99.99%), air-sensitive raw materials that vary batch-to-batch. The perovskite films and devices derived from conventional raw materials mixture method suffer from inferior reproducibility of optoelectronic properties and performance, as well as discounted promise towards low-cost scalable manufacturing. Distinguished from the direct mixing of raw materials, the preparation of perovskite films with precursors made by the redissolution of perovskite crystals holds the promise to make PSCs more affordable, reproducible, efficient and stable. The resultant perovskite films inherit the exceptional characteristics of the parent perovskite crystals, such as high crystallinity, high purity, accurate stoichiometric ratio, and low trap-state density, as well as good ambient and phase stability. Herein, we summarize recent progress on the employment of the perovskite crystals redissolution strategy for achieving low-cost, efficient perovskite-based solar-to-electricity conversion, which will help both popularize the redissolution strategy and reveal unprecedented advantages gained by its adoption. [ABSTRACT FROM AUTHOR]

The formation of ZnO nanomaterials from different Zn acetylacetonate precursor solutions was studied in situ by employing simultaneous, time-resolved X-ray diffraction (XRD) and X-ray absorption spectroscopy (EXAFS) at the Zn K-edge. The precursor solutions were heated from room temperature to the desired reaction temperatures in a hermetically sealed cell dedicated to X-ray experiments. In general, the first indications for the formation of hexagonal ZnO were found for elevated temperatures of about 80 °C both by XRD and EXAFS, and the contributions increase with temperature and time. However, no reaction intermediates could be proved in addition to the Zn precursors and the formed hexagonal ZnO materials. Furthermore, the results show that the efficiency of the reaction, i.e., the conversion of the precursor material to the ZnO product, strongly depends on the solvent used and the reaction temperature. ZnO formation is accelerated by an increased temperature of 165 °C and the use of 1-octanol, with a conversion to ZnO of more than 80% after only a ca. 35 min reaction time according to a detailed analysis of the EXAFS data. For comparison, an identical concentration of Zn acetylacetonate in water or dilute alkaline NaOH solutions and a reaction temperature of around 90 °C leads to a smaller conversion of approximately 50% only, even after several hours of reaction. The particle size determined from XRD for different orientations shows a preferred orientation along the c-direction of the hexagonal crystal system, as well in accordance with scanning electron microscopy. The LaMer model explained this highly non-uniform growth of needle-like ZnO crystallites.

Nucleation from solution is fundamental to many natural and industrial processes. The understanding of molecular mechanism of nucleation from solution is conducive to predict crystal structure, control polymorph and design desired crystal materials. In this review, the nucleation theories, including classical nucleation theory (CNT), nonclassical nucleation theory, as well as other new proposed theories, were reprised, and the molecular mechanism of these theories was compared. Then, the molecular process of nucleation, including the current study techniques, the effect of molecular self-assembly in solutions, desolvation process, as well as the properties of solvent and crystal structure on nucleation from solution were summarized. Furthermore, the relationship of molecular conformation in solution and in crystal, and the effect of solute molecular flexibility on nucleation were discussed. Finally, the current challenges and future scopes of crystal nucleation from solution were discussed. [ABSTRACT FROM AUTHOR]

Divalent metal (Mg, Ca, etc.) battery chemistries potentially provide a sustainable long‐term technical solution for large‐scale energy storage because of the high natural abundance of divalent metal elements in the earth crust. Good progress has been made on materials especially electrolyte development in the past years; however, significant challenges exist, particularly the very limited fundamental understanding of electrolyte solution chemistry and interfacial electrochemistry. In this perspective, we review and discuss key discoveries and understanding of divalent battery chemistry with a focus on electrolyte‐dependent interfacial electrochemistry of divalent metal anodes. A concise review of electrolyte development, operando studies of the electrified interfaces, and unique charge‐transfer process is provided; the knowledge gaps and future research directions are discussed. [ABSTRACT FROM AUTHOR]

This paper presents the influence of mineral additions in blended cement, or 'green' concrete, on the divalent ions of the cement paste pore solution. Because of the lack of data concerning the direct comparison between the pore solution of cement and mineral additions-based material, six types of hardened cement pastes were tested. For this purpose, Portland cement (CEM I or CEM V) and mineral additions (limestone filler, fly ash, blast-furnace slag and silica fume) were used. Results from chemical analyses by ionic chromatography show significant concentrations of divalent ions, such as sulfates and calcium, in the pore solution. In fact, the reference cement paste based on CEM I contains about 1.8 mmol/l of calcium and 1.6 mmol/l of sulfates. However, the use of mineral addition significantly modifies the pore solution. In particular, a substitution of cement by 10% of silica fume increases the calcium and sulfates concentrations to 12.2 mmol/l and 6.7 mmol/l, respectively. This change in the chemical composition, the pH and the ionic strength should be taken into account in multispecies transfer modelling and the thermodynamic equilibrium. The time evolution of the chemical composition, pH and ionic strength of the pore solutions was also investigated. [ABSTRACT FROM AUTHOR]

Tracer and indicator microbe runoff experiments were conducted to investigate the influence of solution chemistry on the transport, retention, and release of Escherichia coli D21g. Experiments were conducted in a chamber (2.25 m long, 0.15 m wide, and 0.16 m high) packed with ultrapure quartz sand (to a depth of 0.10 m) that was placed on a metal frame at slopes of 5.6%, 8.6%, or 11.8%. Runoff studies were initiated by adding a step pulse of salt tracer or D21g suspension at a steady flow rate to the top side of the chamber and then monitoring the runoff effluent concentrations. The runoff breakthrough curves (BTCs) were asymmetric and exhibited significant amounts of concentration tailing. The peak concentration levels were lower and the concentration tailing was higher with increasing chamber slope because of greater amounts of exchange with the sand and/or extents of physical nonequilibrium (e.g., water flow in rills and incomplete mixing) in the runoff layer. Lower amounts of tailing in the runoff BTC and enhanced D21g retention in the sand occurred when the solution ionic strength (IS) was 100 mM NaCl compared with 1 mM NaCl, due to compression of the double layer thickness which eliminated the energy barrier to attachment. Retained cells were slowly released to the runoff water when the IS of the runoff water was reduced to deionized water. The amount and rate of cell release was greatest at the highest chamber slope, which controlled the amount of exchange with the sand and/or the extent of physical nonequilibrium in the runoff layer, and the amount of retained cells. The observed runoff BTCs were well described using a transient storage model, but fitted parameters were not always physically realistic. A model that accounted for the full coupling between flow and transport in the runoff and sand layers provided useful information on exchange processes at the sand surface, but did not accurately describe the runoff BTCs which were influenced by physical nonequilibrium in the runoff layer.

Tracer and indicator microbe runoff experiments were conducted to investigate the influence of solution chemistry on the transport, retention, and release of Escherichia coli D21g. Experiments were conducted in a chamber (2.25 m long, 0.15 m wide, and 0.16 m high) packed with ultrapure quartz sand (to a depth of 0.10 m) that was placed on a metal frame at slopes of 5.6%, 8.6%, or 11.8%. Runoff studies were initiated by adding a step pulse of salt tracer or D21g suspension at a steady flow rate to the top side of the chamber and then monitoring the runoff effluent concentrations. The runoff breakthrough curves (BTCs) were asymmetric and exhibited significant amounts of concentration tailing. The peak concentration levels were lower and the concentration tailing was higher with increasing chamber slope because of greater amounts of exchange with the sand and/or extents of physical nonequilibrium (e.g., water flow in rills and incomplete mixing) in the runoff layer. Lower amounts of tailing in the runoff BTC and enhanced D21g retention in the sand occurred when the solution ionic strength (IS) was 100 mM NaCl compared with 1 mM NaCl, due to compression of the double layer thickness which eliminated the energy barrier to attachment. Retained cells were slowly released to the runoff water when the IS of the runoff water was reduced to deionized water. The amount and rate of cell release was greatest at the highest chamber slope, which controlled the amount of exchange with the sand and/or the extent of physical nonequilibrium in the runoff layer, and the amount of retained cells. The observed runoff BTCs were well described using a transient storage model, but fitted parameters were not always physically realistic. A model that accounted for the full coupling between flow and transport in the runoff and sand layers provided useful information on exchange processes at the sand surface, but did not accurately describe the runoff BTCs which were influenced by physical nonequilibrium in the runoff layer.

The influence of phosphates on the transport of plastic particles in porous media is environmentally relevant due to their ubiquitous coexistence in the subsurface environment. This study investigated the transport of plastic nanoparticles (PNPs) via column experiments, paired with Derjaguin–Landau–Verwey–Overbeek calculations and numerical simulations. The trends of PNP transport vary with increasing concentrations of NaH2PO4 and Na2HPO4 due to the coupled effects of increased electrostatic repulsion, the competition for retention sites, and the compression of the double layer. Higher pH tends to increase PNP transport due to the enhanced deprotonation of surfaces. The release of retained PNPs under reduced IS and increased pH is limited because most of the PNPs were irreversibly captured in deep primary minima. The presence of physicochemical heterogeneities on solid surfaces can reduce PNP transport and increase the sensitivity of the transport to IS. Furthermore, variations in the hydrogen bonding when the two phosphates act as proton donors will result in different influences on PNP transport at the same IS. This study highlights the sensitivity of PNP transport to phosphates associated with the solution chemistries (e.g., IS and pH) and is helpful for better understanding the fate of PNPs and other colloidal contaminants in the subsurface environment.

Crystal nucleation determining the formation and assembly pathway of first organic materials is the central science of various scientific disciplines such as chemical, geochemical, biological, and synthetic materials. However, our current understanding of the molecular mechanisms of nucleation remains limited. Over the past decades, the advancements of new experimental and computational techniques have renewed numerous interests in detailed molecular mechanisms of crystal nucleation, especially structure evolution and solution chemistry. These efforts bifurcate into two categories: (modified) classical nucleation theory (CNT) and non-classical nucleation mechanisms. In this review, we briefly introduce the two nucleation mechanisms and summarize current molecular understandings of crystal nucleation that are specifically applied in polymorphic crystallization systems of small organic molecules. Many important aspects of crystal nucleation including molecular association, solvation, aromatic interactions, and hierarchy in intermolecular interactions were examined and discussed for a series of organic molecular systems. The new understandings relating to molecular self-assembly in nucleating systems have suggested more complex multiple nucleation pathways that are associated with the formation and evolution of molecular aggregates in solution.

The development of stable perovskite precursor solutions is critical if solution‐processable perovskite solar cells (PSCs) are to be practically manufacturable. Ideally, such precursors should combine high solution stability without using chemical additives that might compromise PSC performance. Here, it was shown that the shelf‐life of high‐performing perovskite precursors could be greatly improved by storing solutions at low‐temperature without the need to alter chemical composition. Devices fabricated from solutions stored for 31 days at 4 °C achieved a champion power conversion efficiency (PCE) of 18.6 % (97 % of original PCE). The choice of precursor solvent also impacted solution shelf‐life, with DMSO‐based solutions having enhanced solution stability compared to those including DMF. The compositions of aged precursors were explored using NMR spectroscopy, and films made from these solutions were analysed using X‐ray diffraction. It was concluded that the improvement in precursor solution stability is directly linked to the suppression of an addition‐elimination reaction and the preservation of higher amounts of methylammonium within solution. [ABSTRACT FROM AUTHOR]

Solution chemistry is of great importance to the removal of arsenic by coagulation through influencing the speciation of arsenic, the in situ precipitation of metal salts coupled with the adsorption and coprecipitation behavior of arsenic during coagulation. While the researches on the influence of solution chemistry in As(III) removal by titanium salts, a promising candidate for drinking water treatment was still deficient. Batch tests were performed to evaluate the removal of As(III) by titanium salts coagulation under solution chemistry influences. The results indicated that As(III) removal by Ti(SO4)2 and TiCl4 increased first and then decreased with the rising of solution pH from 4 to 10. TiCl4 preformed better in As(III) removal than Ti(SO4)2 at pH 4–8, but the opposite trends were observed at pH 9–10. XPS analysis indicated that the involvement of surface hydroxyl groups was primarily responsible for As(III) adsorption on Ti(IV) precipitates. As(III) removal was inhibited in the presence of SO42− mainly by competitive adsorption, especially at elevated SO42− concentration under acidic and alkaline conditions. F− exerted a greater suppressive effect than SO42− via indirectly hindering Ti(IV) precipitate formation, and through direct competitive adsorption with H3AsO3, the inhibitive effect increased as F− concentration increased and depended highly on solution pH. As(III) removal was promoted by co-existing Fe(II) primarily through the facilitation of Ti(IV) precipitation, especially under neutral and alkaline conditions, while it was inhibited to a different extent by the presence of high-concentration Mn(II) possibly via competitive adsorption. The presence of Ca2+ and Mg2+ enhanced the removal of As(III), but the positive effect did not increase as ionic concentration elevated. [ABSTRACT FROM AUTHOR]