Interaction of Phosphate with Lithium Cobalt Oxide Nanoparticles: A Combined Spectroscopic and Calorimetric Study

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS), part II. Recent noteworthy developments

This comprehensive survey review compiles noteworthy developments and new concepts of two-dimensional correlation spectroscopy (2D-COS) for the last two years. It covers review articles, books, proceedings, and numerous research papers published on 2D-COS, as well as patent and publication trends. 2D-COS continues to evolve and grow with new significant developments and versatile applications in diverse scientific fields. The healthy, vigorous, and diverse progress of 2D-COS studies in many fields strongly confirms that it is well accepted as a powerful analytical technique to provide an in-depth understanding of systems of interest.

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS): Part III. Versatile applications

In this review, the comprehensive summary of two-dimensional correlation spectroscopy (2D-COS) for the last two years is covered. The remarkable applications of 2D-COS in diverse fields using many types of probes and perturbations for the last two years are highlighted. IR spectroscopy is still the most popular probe in 2D-COS during the last two years. Applications in fluorescence and Raman spectroscopy are also very popularly used. In the external perturbations applied in 2D-COS, variations in concentration, pH, and relative compositions are dramatically increased during the last two years. Temperature is still the most used effect, but it is slightly decreased compared to two years ago. 2D-COS has been applied to diverse systems, such as environments, natural products, polymers, food, proteins and peptides, solutions, mixtures, nano materials, pharmaceuticals, and others. Especially, biological and environmental applications have significantly emerged. This survey review paper shows that 2D-COS is an actively evolving and expanding field.

Toxic waste sludge derived hierarchical porous adsorbent for efficient phosphate removal

Global effective treatment of phosphorus crisis and toxic waste sludge in one way is urgently needed but still insufficient due to single function, environmental damage, and complicated fabrication process. Herein, we proposed a facile, low-cost, and sustainable strategy to fabricate NiAl layered double oxides/nickel-containing sludge (LDOs/NCS) adsorbent using toxic NCS as raw material via two-step method including hydrothermal process and calcination. The as-designed hierarchical porous adsorbent with large specific surface area and pore volume exhibited excellent adsorption properties towards phosphate. Langmuir adsorption model exhibited the best fit to the experimental data, which illustrated that the adsorption process was dominated by monolayer adsorption. Moreover, even in various double anions systems or in a wide pH range environment (2-12), the as-designed LDOs/NCS still maintained relatively stable adsorption capacity. A possible adsorption mechanism involving surface complexation and electrostatic interactions was investigated. Besides, the LDOs/NCS also displayed admirable durability and reusability. Therefore, this waste-control-waste strategy not only simultaneously addresses phosphorus crisis treatment and toxic NCS management, but also could be potentially extended towards rational design of other metals-containing sludge derived functional materials.

Binding of polar and hydrophobic molecules at the LiCoO2 (001)-water interface: force field development and molecular dynamics simulations

A classical model in the framework of the INTERFACE force field has been developed for treating the LiCoO₂ (LCO) (001)/water interface. In comparison to ab initio molecular dynamics (MD) simulations based on density functional theory, MD simulations using the classical model lead to generally reliable descriptions of interfacial properties, such as the density distribution of water molecules. Water molecules in close contact with the LCO surface form a strongly adsorbed layer, which leads to a free energy barrier for the adsorption of polar or charged molecules to the LCO surface. Moreover, due to the strong hydrogen bonding interactions with the LCO surface, the first water layer forms an interface that exhibits hydrophobic characters, leading to favorable adsorption of non-polar molecules to the interface. Therefore, despite its highly polar nature, the LCO (001) surface binds not only polar/charged but also non-polar solutes. As an application, the model is used to analyze the adsorption of reduced nicotinamide adenine dinucleotide (NADH) and its molecular components to the LCO (001) surface in water. The results suggest that recently observed redox activity of NADH at the LCO/water interface was due to the co-operativity between the ribose component, which drives binding to the LCO surface, and the nicotinamide moiety, which undergoes oxidation.

Adsorption of small organic acids and polyphenols on hematite surfaces: Density Functional Theory + thermodynamics analysis

HYPOTHESIS

The interactions of organic molecules with mineral surfaces are influenced by several factors such as adsorbate speciation, surface atomic and electronic structure, and environmental conditions. When coupled with thermodynamic techniques, energetics from atomistic modeling can provide a molecular-level picture of which factors determine reactivity. This is paramount for evaluating the chemical processes which control the fate of these species in the environment.

EXPERIMENTS

Inner-sphere adsorption of oxalate and pyrocatechol on (001), (110), and (012) α-Fe₂O₃ surfaces was modeled using Density Functional Theory (DFT). Unique bidentate binding modes were sampled along each facet to study how different adsorbate and surface factors govern site preference. Adsorption energetics were then calculated using a DFT + thermodynamics approach which combines DFT energies with tabulated data and Nernst-based corrective terms to incorporate different experimental parameters.

FINDINGS

Instead of a universal trend, each facet displays a unique factor that dominates site preference based on either strain (001), functional groups (110), or topography (012). Adsorption energies predict favorable inner-sphere adsorption for both molecules but opposite energetic trends with varying pH. Additionally, vibrational analysis was conducted for each system and compared to experimental IR data. The work presented here provides an effective, computational methodology to study numerous adsorption processes occurring at the surface-aqueous interface.

Density Functional Theory and Thermodynamics Modeling of Inner-Sphere Oxyanion Adsorption on the Hydroxylated α-Al2O3(001) Surface

The inner-sphere adsorption of AsO₄^3-, PO₄^3-, and SO₄^2- on the hydroxylated α-Al₂O₃(001) surface was modeled with the goal of adapting a density functional theory (DFT) and thermodynamics framework for calculating the adsorption energetics. While DFT is a reliable method for predicting various properties of solids, including crystalline materials comprised of hundreds (or even thousands) of atoms, adding aqueous energetics in heterogeneous systems poses steep challenges for modeling. This is in part due to the fact that environmentally relevant variations in the chemical surroundings cannot be captured atomistically without increasing the system size beyond tractable limits. The DFT + thermodynamics approach to this conundrum is to combine the DFT total energies with tabulated solution-phase data and Nernst-based corrective terms to incorporate experimentally tunable parameters such as concentration. Central to this approach is the design of thermodynamic cycles that partition the overall reaction (here, inner-sphere adsorption proceeding via ligand exchange) into elementary steps that can either be fully calculated or for which tabulated data are available. The ultimate goal is to develop a modeling framework that takes into account subtleties of the substrate (such as adsorption-induced surface relaxation) and energies associated with the aqueous environment such that adsorption at mineral-water interfaces can be reliably predicted, allowing for comparisons in the denticity and protonation state of the adsorbing species. Based on the relative amount of experimental information available for AsO₄^3-, PO₄^3-, and SO₄^2- adsorbates and the well-characterized hydroxylated α-Al₂O₃(001) surface, these systems are chosen to form a basis for assessing the model predictions. We discuss how the DFT + thermodynamics results are in line with the experimental information about the oxyanion sorption behavior. Additionally, a vibrational analysis was conducted for the charge-neutral oxyanion complexes and is compared to the available experimental findings to discern the inner-sphere adsorption phonon modes. The DFT + thermodynamics framework used here is readily extendable to other chemical processes at solid-liquid interfaces, and we discuss future directions for modeling surface processes at mineral-water and environmental interfaces.

Mechanism of phosphate adsorption on superparamagnetic microparticles modified with transitional elements: Experimental observation and computational modelling

Microparticle sorbents (MPSs) containing nano-Fe₃O₄ core, nano-layered double hydroxides shell modified with different transitional elements (TE-MPSs) are effective for capturing phosphate from wastewater. In present article, different TE-MPSs loaded with Ce, La, Zr and Hf were synthesized and the phosphorous removal performances were compared. The molecular-level mechanism of phosphate adsorption was successfully simulated by pseudo-atom model based on virtual crystal approximation method, which was in line with the spectroscopic data. The results confirmed the inter-sphere complexation reaction between phosphate and TE-MPSs under neutral pH. And the adsorption mechanism probably changed during cycles of adsorption/regeneration. As revealed by elemental composition analysis, ion exchange mechanism probably played an important part in phosphate adsorption in Cycle 1 while the ligand complexation became dominant after regenerated with NaOH in the following cycles. This work indicates that the highly effective, easily separable and repeatedly usable TE-MPSs has the potential for phosphate sequestration and recovery from sewage wastewater.

Regulating the Performance of Lithium-Ion Battery Focus on the Electrode-Electrolyte Interface

The development of lithium-ion battery (LIB) has gone through nearly 40 year of research. The solid electrolyte interface film in LIBs is one of most vital research topics, its behavior affects the cycle life and safety of LIBs significantly. Progress in understanding the interfacial layer on the negative and positive electrodes in LIBs has been the focus of considerable research in the past few decades, but there remains a number of problem to be understood at the fundamental level, and there is still a great deal of controversy regarding the composition and formation mechanism of the interfacial film. In this article, we summarize recent research conducted on the interfacial film in LIBs, including the film formation mechanism, the composition, and stability of the interfacial film on the positive electrodes (in both diluted and high-concentration electrolytes). And the methodologies and advanced techniques implemented for the characterization of the interfacial film. Finally, we put forward some of the future development direction for the interfacial film and urgent problems that need to be solved.