The concise yet authoritative presentation of key techniques for basic mixtures experiments Inspired by the author's bestselling advanced book on the topic, A Primer on Experiments with Mixtures ...provides an introductory presentation of the key principles behind experimenting with mixtures. Outlining useful techniques through an applied approach with examples from real research situations, the book supplies a comprehensive discussion of how to design and set up basic mixture experiments, then analyze the data and draw inferences from results. Drawing from his extensive experience teaching the topic at various levels, the author presents the mixture experiments in an easy-to-follow manner that is void of unnecessary formulas and theory. Succinct presentations explore key methods and techniques for carrying out basic mixture experiments, including: * Designs and models for exploring the entire simplex factor space, with coverage of simplex-lattice and simplex-centroid designs, canonical polynomials, the plotting of individual residuals, and axial designs * Multiple constraints on the component proportions in the form of lower and/or upper bounds, introducing L-Pseudocomponents, multicomponent constraints, and multiple lattice designs for major and minor component classifications * Techniques for analyzing mixture data such as model reduction and screening components, as well as additional topics such as measuring the leverage of certain design points * Models containing ratios of the components, Cox's mixture polynomials, and the fitting of a slack variable model * A review of least squares and the analysis of variance for fitting data Each chapter concludes with a summary and appendices with details on the technical aspects of the material. Throughout the book, exercise sets with selected answers allow readers to test their comprehension of the material, and References and Recommended Reading sections outline further resources for study of the presented topics. A Primer on Experiments with Mixtures is an excellent book for one-semester courses on mixture designs and can also serve as a supplement for design of experiments courses at the upper-undergraduate and graduate levels. It is also a suitable reference for practitioners and researchers who have an interest in experiments with mixtures and would like to learn more about the related mixture designs and models.
PS microplastic particle (<5 mm) is an emerging contaminant of concern in aquatic and sediment systems with reported negative impacts on environmental and human health. TCS is a broad-spectrum ...antimicrobial which can affect ecosystems and result in long-term human health risks. The interaction between TCS and PS microplastic, partly determines the behavior and dispersion of TCS in the environment. In this study, the sorption kinetics and isotherms for TCS and PS microplastic were investigated. The influences of temperature, pH, ionic strength and coexisting heavy metals were assessed in batch experiments. The pseudo-second-order model (PSOM) was found to effectively describe the sorption kinetics of TCS on PS. TCS sorption on PS was found to be higher within the pH range of 3.0–6.0, while a decrease occurred at pH > 6.0. This result indicates that TCS0 was the major species contributing to the sorption process through hydrophobic interaction. Temperature did not affect the sorption of TCS on polystyrene, with sorption Kd values of 0.15, 0.16, 0.18 and 0.17 L/g at 288, 298, 308 and 318 K, respectively. Furthermore, the sorption amount of TCS showed no obvious variation with NaCl concentrations varying between 0.001 and 0.1 M. Finally, the coexistence of Cu(II)/Zn(II) had no significant influence on TCS sorption on PS, as Cu(II)/Zn(II) and TCS had different mechanisms of sorption on PS.
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•Triclosan (TCS) sorption on Polystyrene (PS) microplastic was assessed.•The sorption capacity of TCS increased with decreasing particle size of PS.•pH value plays an important role in the sorption of TCS on PS microplastic.•Hydrophobic interaction is the main mechanism of TCS sorption on PS.•Temperature, ionic strength and Cu(II)/Zn(II) had no effect on TCS sorption.
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Electrochemistry serves as a powerful method for generating reactive intermediates, such as organic cations. In general, there are two ways to use reactive intermediates for chemical reactions: (1) ...generation in the presence of a reaction partner and (2) generation in the absence of a reaction partner with accumulation in solution as a “pool” followed by reaction with a subsequently added reaction partner. The former approach is more popular because reactive intermediates are usually short-lived transient species, but the latter method is more flexible and versatile. This review focuses on the latter approach and provides a concise overview of the current methods for the generation and accumulation of cationic reactive intermediates as a pool using modern techniques of electrochemistry and their reactions with subsequently added nucleophilic reaction partners.
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Valuable information about the local environment of the aluminum nucleus can be obtained through (27)Al Nuclear Magnetic Resonance (NMR) parameters like the isotropic chemical shift, scalar and ...quadrupolar coupling constants, and relaxation rate. With nearly 250 scientific articles per year dealing with (27)Al NMR spectroscopy, this analytical tool has become popular because of the recent progress that has made the acquisition and interpretation of the NMR data much easier. The application of (27)Al NMR techniques to various classes of compounds, either in solution or solid-state, has been shown to be extremely informative concerning local structure and chemistry of aluminum in its various environments. The development of experimental methodologies combined with theoretical approaches and modeling has contributed to major advances in spectroscopic characterization especially in materials sciences where long-range periodicity and classical local NMR probes are lacking. In this review we will present an overview of results obtained by (27)Al NMR as well as the most relevant methodological developments over the last 25years, concerning particularly on progress in the application of liquid- and solid-state (27)Al NMR to the study of aluminum-based materials such as aluminum polyoxoanions, zeolites, aluminophosphates, and metal-organic-frameworks.
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Biodegradable plastics (BPs) have seen a continuous increase in annual production and application due to their environmentally sustainable characteristics. However, research on the formation of ...disinfection byproducts (DBPs) from biodegradable microplastics (BMPs) during chlorination is limited, and the effects of aqueous solution chemistry on this process have yet to be explored. Therefore, two biodegradable microplastics, polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT), were investigated in this study to examine the changes in their physicochemical properties before and after chlorination, and the formation of DBPs under different environmental conditions. The results showed that PLA was more chlorine-responsive, and generated more DBPs. The pH converted some of the intermediates into more stable DBPs by affecting the concentration of HClO and base-catalyzed reactions, whereas ionic strength slightly reduced DBP concentration by ion adsorption and promoting the aggregation of BMPs. Finally, since PLA has a slightly greater volume of mesopores and micropores compared to PBAT, it may more effectively adsorb DBP precursors beyond natural organic matter (NOM), such as some anthropogenic pollutants, thus potentially decreasing the formation of chlorinated DBPs in surface water. This research explored the potentiality for DBP formation by BMPs under different water quality conditions during the disinfection process, which is useful for assessing the environmental hazards of BMPs.
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•PLA yields more DBPs than PBAT with its porous structure and reactive ester bonds.•Rising pH converts DBP intermediates to stable DBPs.•NaCl may reduce DBP production by impacting BP reaction sites and agglomeration.•PLA might adsorb non-NOM DBP precursors in surface water to reduce DBP formation.
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Over the last several years, inorganic-organic hybrid perovskites have shown dramatic achievements in photovoltaic performance and device stability. Despite the significant progress in photovoltaic ...application, an in-depth understanding of the fundamentals of precursor solution chemistry is still lacking. In this review, the fundamental background knowledge of nucleation and crystal growth processes in solution including the LaMer model and Ostwald ripening process is described. This review article also highlights the recent progress in precursor-coordinating molecule interaction in solution along with the role of anti-solvent in the solvent engineering process to control nucleation and crystal growth. Moreover, chemical pathways from precursor solution to perovskite film formation are given. This represents identification of the intermediate phase induced by precursor-coordinating molecule interaction and responsible intermediate species for uniform and dense perovskite film formation. Further to the description of chemical phenomena in solution, the contemporary progress in chemical precursor composition is also provided to comprehend the current research approaches to further enhance photovoltaic performance and device stability. On the basis of the critical and comprehensive review, we provide some perspectives to further achieve high-performance perovskite solar cells with long-term device stability through precisely controlled nucleation and crystal growth in precursor solution.
The perovskite precursor solution chemistry is of paramount importance for well-controlled nucleation/crystal growth in solution-processed perovskite solar cells.
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•PBTCA strongly depresses the flotation of dolomite rather than that of fluorapatite.•PBTCA is selectively adsorbed onto dolomite in the form of HL4− and L5− at pH 9.5.•Many Mg sites ...enhance the adsorption of PBTCA onto dolomite.•NaOL is still selectively adsorbed onto fluorapatite in the existence of PBTCA.•PBTCA can improve the selective flotation of fluorapatite from dolomite.
At present, traditional inhibitors applied for selective flotation of fluorapatite from dolomite generally own low selectivity, high toxicity, large dosages and high costs. Thus, this research offers a novel non-toxic and eco-friendly dolomite depressant, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), for selective flotation of fluorapatite with sodium oleate (NaOL) as a collector. The selectively depressing effect and adsorption mechanism of PBTCA in the selective flotation of fluorapatite from dolomite were investigated via a series of experiments and analyses. The results from zeta potential and Fourier transform infrared (FTIR) spectroscopy revealed that the chemisorption of PBTCA onto dolomite was much stronger than fluorapatite. Crystal chemistry calculation and X-ray photoelectron spectroscopy (XPS) further confirmed that large amounts of Mg sites only exposed on the dolomite surface mainly accounted for the selective adsorption of PBTCA onto dolomite due to the strong affinity to PBTCA. Moreover, the chemisorption of NaOL onto fluorapatite was hardly affected by the pre-addition of PBTCA, whereas the intensive chemisorption of PBTCA prevented the adsorption of NaOL onto dolomite. As a result, in the presence of PBTCA, dolomite exhibited a poor flotation performance while there was good floatability for fluorapatite, which benefited the efficient recovery of fluorapatite from dolomite by froth flotation.
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Microplastics are an emerging contaminants of concern in aquatic environments. The aggregation behaviors of microplastics governing their fate and ecological risks in aquatic environments is in need ...of evaluation. In this study, the aggregation behavior of polystyrene microspheres (micro-PS) in aquatic environments was systematically investigated over a range of monovalent and divalent electrolytes with and without natural organic matter (i.e., Suwannee River humic acid (HA)), at pH 6.0, respectively. The zeta potentials and hydrodynamic diameters of micro-PS were measured and the subsequent aggregation kinetics and attachment efficiencies (α) were calculated. The aggregation kinetics of micro-PS exhibited reaction- and diffusion-limited regimes in the presence of monovalent or divalent electrolytes with distinct critical coagulation concentration (CCC) values, followed the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The CCC values of micro-PS were14.9, 13.7, 14.8, 2.95 and 3.20 mM for NaCl, NaNO3, KNO3, CaCl2 and BaCl2, respectively. As expected, divalent electrolytes (i.e., CaCl2 and BaCl2) had stronger influence on the aggregation behaviors of micro-PS as compared to monovalent electrolytes (i.e., NaCl, NaNO3 and KNO3). HA enhanced micro-PS stability and shifted the CCC values to higher electrolyte concentrations for all types of electrolytes. The CCC values of micro-PS were lower than reported carbonaceous nanoparticles CCC values. The CCCCa2+/CCC Na+ ratios in the absence and presence of HA at pH 6.0 were proportional to Z−2.34 and Z−2.30, respectively. These ratios were in accordance with the theoretical Schulze–Hardy rule, which considers that the CCC is proportional to z−6–z−2. These results indicate that the stability of micro-PS in the natural aquatic environment and the possibility of significant aqueous transport of micro-PS.
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•Complex roles of electrolytes, pH, and NOM on the aggregation behavior of micro-PS were firstly evaluated.•The increment of CCC values was dominated by the HA coatings on micro-PS.•The aggregation kinetics of micro-PS were elucidated by the DLVO theory.•The CCC values of micro-PS offered information for the fate of microplastics.
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9.
The ONIOM Method and Its Applications Chung, Lung Wa; Sameera, W. M. C; Ramozzi, Romain ...
Chemical reviews,
06/2015, Volume:
115, Issue:
12
Journal Article
Peer reviewed
Open access
Chung et al present an in-depth investigation of the ONIOM method and related method developments. They focus on applications of the ONIOM method to organic systems, inorganic compoounds and ...homogeneous catalysis, heterogeneous catalysis, nanomaterials, excited states, solution chemistry, and biological macromolecules.
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