Preferential Adsorption Behaviour Research Articles

High donor-number and low content electrolyte additive for stabilizing zinc metal anode

The aqueous zinc ion batteries (AZIBs) are thought as promising competitors for electrochemical energy storage, though their wide application is curbed by the uncontrollable dendrite growth and gas evolution side reactions. Herein, to stabilize both zinc anodes and water molecules, we developed a modified electrolyte by adding a trace amount of N,N-diethylformanmide (DEF) into the ZnSO4 electrolyte for the first time in zinc ion batteries. The effectiveness of DEF is predicted by the comparison of donor number and its preferential adsorption behavior on the zinc anode is further demonstrated by several spectroscopy characterizations, electrochemical methods, and molecular dynamics simulation. The modified electrolyte with 5% v.t. DEF content can ensure a stable cycling life longer than 3400 h of Zn||Zn symmetric cells and an ultra-reversible Zn stripping/plating process with a high coulombic efficiency of 99.7%. The Zn||VO2 full cell maintains a capacity retention of 83.5% and a 104 mA h g−1 mass capacity after 1000 cycles. This work provides insights into the role of interfacial adsorption behavior and the donor number of additive molecules in designing low-content and effective aqueous electrolytes.

Regulating the inner Helmholtz plane structure at the electrolyte-electrode interface for highly reversible aqueous Zn batteries

The development of aqueous Zn batteries is limited by parasitic water reactions, corrosion, and dendrite growth. To address these challenges, an inner Helmholtz plane (IHP) regulation method is proposed by employing low-cost, non-toxic maltitol as the electrolyte additive. The preferential adsorption behavior of maltitol can expel the water from the inner Helmholtz plane, and thus hinder the immediate contact between Zn metal and H2O. Meanwhile, strong interaction between maltitol and H2O molecules can restrain the activity of H2O. Besides, the “IHP adsorption effect” along with the low LUMO energy level of maltitol-CF3SO3- can promote the in-situ formation of an organic–inorganic complex solid electrolyte interface (SEI) layer. As a result, the hydrogen/oxygen evolution side reaction, corrosion, and dendrites issues are effectively suppressed, thereby leading to highly reversible and dendrite-free Zn plating/stripping. The Zn||I2 battery with hybrid electrolytes also demonstrates high electrochemical performance and ultralong cycling stability, showing a capacity retention of 75% over 20000 charge-discharge cycles at a large current density of 5 A g−1. In addition, the capacity of the device has almost no obvious decay over 20000 cycles even at −30 °C. This work offers a successful electrolyte regulation strategy via the IHP adsorption effect to design electrolytes for high-performance rechargeable Zn-ion batteries.

A thermostable calcium-based metal–organic framework for efficient capture and separation of acetylene from ternary mixture

High-efficiency and eco-friendly selective separation of C2H2 from industrial gaseous mixtures such as CO2 and CH4 is of great importance in the purification and production of downstream commodity chemicals. Herein, we report a thermostable calcium-based metal–organic framework, namely NUM-20, which could preferentially capture C2H2 from C2H2-containing gaseous mixtures. NUM-20 exhibits a higher capacity and preferential adsorption behavior of C2H2 versus the competing gases including CO2 and CH4, as reflected by single component gas sorption isotherms and the heat of adsorption. The IAST selectivity calculations indicate that NUM-20 possesses multiple component separation capacity, and the transient breakthrough simulations were performed to validate the capture and separation of C2H2 from multiple components. Furthermore, computational simulations were carried out to unveil the host–guest interactions under the molecular-level. This study on Ca-based MOF materials will enrich the three-dimensional Ca-based MOF adsorbents for gas capture and separation applications and address the industrial challenging separation process.

Unravelling the complex adsorption behavior of extracellular polymeric substances onto pristine and UV-aged microplastics using two-dimensional correlation spectroscopy

In this study, we examined the preferential adsorption behavior of extracellular polymeric substances (EPS) on two commonly used microplastics (MPs), including polyethylene (PE) and polypropylene (PP), through adsorption kinetics and isotherm experiments. The effects of UV aging on EPS adsorption were also explored. The results showed that EPS adsorption was greater on UV-aged MPs than on pristine MPs, with an adsorption capacity of approximately 27.0 mg-C/m2 for aged PP-MPs and 23.5 mg-C/m2 for pristine PP-MPs, and 16.4 mg-C/m2 for aged PE-MPs and 12.5 mg-C/m2 for pristine PE-MPs. Fourier transform infrared (FTIR) spectra revealed that EPS adsorption was governed by hydrogen bonds between EPS molecules and methylene groups in pristine MPs and CO, C–O groups in UV-aged MPs, as evidenced by the addition and the reduction of the related peaks shown in MP surfaces and residual EPS after adsorption, respectively. Fluorescence spectroscopy revealed that protein-like components exhibited higher Freundlich adsorption affinity (i.e., Kf), ranging from 0.34 to 1.29 (RU⋅L m−2) (RU⋅L−1)n than humic-like components (0.01 to 0.12 (RU⋅L m−2) (RU⋅L−1)n). The EPS molecular distribution was consistent with the FTIR results, showing preferable adsorption of biopolymer versus humic substances fraction. Two-dimensional correlation spectroscopy combined with FTIR (2D-COS-IR) revealed that polysaccharides in EPS were more preferentially adsorbed onto MPs and the order of the sequence was polysaccharides > proteins > humic-like substances for all MPs tested. This study provides new insight into the complex adsorption behavior of heterogeneous EPS on MPs and the associated alterations in the potential environmental fate of MPs.

Fabrication of metal-organic frameworks with trimesic linkers for europium adsorption and recovery from aqueous solutions

This work reports on the effective sequestration of Eu(III) ions from aqueous solutions using three types of metal-organic frameworks (MOFs) constructed from benzene-1,3,5-tricarboxylic acid (H3BTC) linker and Ca2+, Cu2+, or Al3+ metal nodes. The MOFs possessed an exceptionally high Eu adsorption capacity of 635 (91% removal), 642 (92% removal), and 628 mg g−1 (90% removal) for Cu-BTC, Ca-BTC, and Al-BTC, respectively, at pH 7 for an initial Eu concentration of 350 mg L−1. The MOFs were hydrolytically stable and possessed a high Eu adsorption capacity in a wide pH range of 4–8. While the pseudo-second-order model explained the adsorption kinetics, the adsorption process followed the Langmuir-Freundlich isotherms. The analysis confirmed that the Eu adsorption process was governed by chemical interactions between the carboxylic acid/carboxylate group and Eu(III) ions via complexation or ion exchange mechanism. A multi-metal adsorption study confirmed a preferential adsorption behaviour for trivalent lanthanides over divalent cations due to comparatively stronger interactions between Ln3+ ions and carboxylate groups. The XPS findings suggested Eu−OOC and Eu(OH)3 formed over the MOFs' surface after Eu adsorption. These MOFs were effectively regenerated for multiple cycles using 0.1 mol L−1 EDTA solution. Thus, the study demonstrated low-cost MOFs with superior regeneration capabilities for the capture of Eu(III) ions from waste solutions.

Efficient C2H2-selective separation in a microporous Zn(II)-based metal-organic framework via the dual-ligand strategy.

Implementing the dual-ligand strategy, a microporous Zn-based MOF 1 with nitro and amino groups was effectively produced. The activated interconnected pores of 1 exhibited high C2H2 uptake capacity and preferential adsorption behaviour for C2H2 over CO2, as identified by the experiments and simulations. This work provides a new approach for designing and synthesizing the MOFs with desired structures and properties by optimizing their pore environment via the dual-ligand strategy.

Inhibition mechanism of interaction effect between charged character of inhibitor and rare earth elements for Mg-Gd-Y alloy

The inhibition mechanism of four inhibitors with different charge on Mg-Gd-Y alloy was investigated experimentally and theoretically. The different charge of inhibitor evoked the preferential adsorption behavior, changing the susceptibility of Mg-Gd-Y alloy to micro-galvanic corrosion. Moreover, the adsorption of inhibitor changed the surface energy of embryos of corrosion product, and strongly suppressed the nucleation rate of corrosion product, leading to poor protective performance. Thus, the inhibitor with anion, exhibiting satisfactory inhibition efficiency for AZ/AM series alloys, showed worse inhibition for the Mg-Gd-Y alloy. Finally, the strategy to select and/or synthesize inhibitors for Mg-RE alloys was presented.

Stable Bimetallic Metal–Organic Framework with Dual-Functional Pyrazolate-Carboxylate Ligand: Rational Construction and C2H2/CO2 Separation

With the guidance of the hard/soft acid/base principle, we adopt a strategy to construct a novel robust metal–organic framework (MOF) by using a dual-functional ligand to coordinate with different types of metal ions in a one-pot reaction through coordination self-selection. A bimetallic MOF, namely BUT-85 (BUT = Beijing University of Technology), has been successfully synthesized with a rationally designed pyrazolate-carboxylate ligand. Its robust [Ni2(OH)(H2O)2Pz3]n chain (Pz = pyrazolate) with bridging OH–/H2O and pyrazolate groups is reported for the first time. This material shows good chemical stability in water and aqueous solutions with a pH range from 3 to 13. In addition, BUT-85 exhibits preferential adsorption behavior of C2H2 over CO2. It is proposed to be attributed to the abundant exposed bridging OH–/H2O sites in [Ni2(OH)(H2O)2Pz3]n chains, which is supported by the results of molecular simulations. Column breakthrough experiments further confirm that this MOF can realize efficient C2H2/CO2 separation. This strategy can not only enrich the structural library of MOFs but also optimize their properties and functions for promoting applications.

Molecular Dynamics Simulation of Water-Based Fracturing Fluids in Kaolinite Slit Pores

The adsorption behavior inside kaolinite mesopores of aqueous solutions of various salts and additives is investigated using Molecular Dynamics simulations. In particular, we examine the various combinations of water + salt, water + additive, and water + salt + additive mixtures, where the salts are NaCl, CsCl, SrCl2, and RaCl2 and the additives are methanol and citric acid. Citric acid is modeled in two forms, namely, fully protonated (H3A) and fully deprotonated (A3–), the latter being prevalent in neutral pH conditions, in accordance with the kaolinite structure employed. The force fields used for the individual system components include CLAYFF for the kaolinite mesopores, SPC/E for water, parameters optimized for the SPC/E water model based on hydration free energies (HFE) for ions, and general Amber force field (GAFF) for the additives. The spatial distributions along the kaolinite pore are delineated and reveal the preferential adsorption behavior of the various species with respect to the gibbsite ...

Adsorption Behavior of Polymer Chain with Different Topology Structure at the Polymer-Nanoparticle Interface.

The effect of the polymer chain topology structure on the adsorption behavior in the polymer-nanoparticle (NP) interface is investigated by employing coarse-grained molecular dynamics simulations in various polymer-NP interaction and chain stiffness. At a weak polymer-NP interaction, ring chain with a closed topology structure has a slight priority to occupy the interfacial region than linear chain. At a strong polymer-NP interaction, the “middle” adsorption mechanism dominates the polymer local packing in the interface. As the increase of chain stiffness, an interesting transition from ring to linear chain preferential adsorption behavior occurs. The semiflexible linear chain squeezes ring chain out of the interfacial region by forming a helical structure and wrapping tightly the surface of NP. In particular, this selective adsorption behavior becomes more dramatic for the case of rigid-like chain, in which 3D tangent conformation of linear chain is absolutely prior to the 2D plane orbital structure of ring chain. The local packing and competitive adsorption behavior of bidisperse matrix in polymer-NP interface can be explained based on the adsorption mechanism of monodisperse (pure ring or linear) case. These investigations may provide some insights into polymer-NP interfacial adsorption behavior and guide the design of high-performance nanocomposites.

Preferential adsorption behavior of methylene blue dye onto surface hydroxyl group enriched TiO2 nanotube and its photocatalytic regeneration

The present manuscript focus on the synthesis of surface hydroxyl group enriched titanium dioxide nanotube (TNT) by hydrothermal method for preferential adsorption of methylene blue (MB) dye. The mixture of methylene blue (MB) and rhodamine B (RhB) dye was used to study the preferential adsorption nature of TNT. The synthesized TNT were characterized by various techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, and ammonia-temperature programmed desorption (NH3-TPD) analysis. Result demonstrated that enhancement in the surface area of TNT and higher number of hydroxyl group on the surface of TNT. In the binary mixture, the adsorption of MB dye was 12.9 times higher as compared to RhB dye, which clearly indicated the preferential adsorption of MB dye on TNT surface. The preferential interaction of MB on TNT is due to the electrostatic interaction between the cationic MB and negatively charged TNT surface. The preferential adsorption of MB dye was studied by applying Langmuir, Freundlich and Sips isotherm; pseudo-first and second-order kinetic model. Furthermore, the regeneration of dye adsorbed TNT was carried out by eco-friendly photocatalytic process under the irradiation of ultraviolet light.

Preferential adsorption behaviour of CH4 and CO2 on high-rank coal from Qinshui Basin, China

In order to better understand the prevailing mechanism of CO2 storage in coal and estimate CO2 sequestration capacity of a coal seam and enhanced coalbed methane recovery (ECBM) with CO2 injection into coal, we investigated the preferential adsorption of CH4 and CO2 on coals. Adsorption of pure CO2, CH4 and their binary mixtures on high-rank coals from Qinshui Basin in China were employed to study the preferential adsorption behaviour. Multiple regression equations were presented to predict CH4 equilibrium concentration from equilibrium pressure and its initial-composition in feed gas. The results show that preferential adsorption of CO2 on coals over the entire pressure range under competitive sorption conditions was observed, however, preferential adsorption of CH4 over CO2 on low-volatile bituminous coal from higher CH4-compostion in source gas was found at up to 10MPa pressure. Preferential adsorption of CO2 increases with increase of CH4 concentration in source gas, and decreases with increasing pressure. Although there was no systematic investigation of the effect of coal rank on preferential adsorption, there are obvious differences in preferential adsorption of gas between low-volatile bituminous coal and anthracite. The obtained preferential adsorption gives rise to the assumption that CO2 sequestration in coal beds with subsequent CO2-ECBM might be an option in Qinshui Basins, China.

Selective adsorption and photocatalysis of low-temperature base-modified anatase nanocrystals

Anatase titania photocatalysts with positive (TSC60) and negative (TAH60) surface charge were synthesized by extraction with Na2CO3 and NH4OH, respectively, from an acid stabilized sol at low temperature. XRD, TEM, N2 adsorption and ζ –potential were conducted and revealed that the low-temperature synthesized catalysts differ mainly in their surface charge. These catalysts exhibited opposing preferential adsorption and fully selective photocatalysis of methylene blue (MB) and methyl orange (MO) dyes from their aqueous mixture. The preferential adsorption behaviour toward MB and MO was attributed to the catalyst's surface charge whereas the selective photocatalysis was explained by a combined effect of surface charge and crystallinity. On the other hand, the calcined catalysts showed considerable reduction in their dye adsorption capacity and loss of their selective dye degradation. The reduction in surface charge and increase in crystallinity after calcination were found to be responsible for these observations. Degussa P25 was also tested and compared with synthesized catalysts with regard to dye adsorption and photocatalysis. A mechanism for the selective dye positioning on TSC60 and TAH60 coated FTO/ITO plate is also proposed.

Application of the solid state NMR to the study of the alcohol/alkane mixtures adsorption onto graphite

The mixing of molecules adsorbed from solution to different interfaces has both industrial and academic relevance and the mixing behaviour at the interface is a key to understanding for example, that the surface tension of a mixture of two surfactants is lower than either of the two pure materials and many other effects. In this paper, we report, for the first time, the application of Solid State NMR to the study of alkane/alcohol mixtures, in a range of relative size ratio between 0 and 0.35, adsorbed onto graphite at high, multilayer coverage. Moreover, this paper evaluated, for the first time, the utility of the combined used of 1H and 2H NMR for: (i) determining the surface composition and (ii) making a theoretical approach to the sorption isotherm. A variety of preferential adsorption behaviour is reported. Preferential adsorption of the longer molecule (decane vs. heptanol) from a mixture has been observed. However, if both components are of similar length, the alcohol is preferentially adsorbed (heptanol vs. octane and octanol vs. octane). Finally, a linear relation between the relative size ratio and the amount of alcohol at monolayer coverage is observed.

Preferential Adsorption Phenomena in Polyelectrolytes in Methanol/Water Solution: Effect of the Counterion

The preferential adsorption behaviour of nitrate and chloride salts of poly(N,N-dimethyl-N-(2-hydroxypropyl)ammonium) in solutions of methanol/ water mixtures is analysed. At low methanol content both polyions show an adsorption of methanol which is 2·5 times larger for chloride polyion than that for nitrate salt. In the former case, the amount of methanol adsorption is enough to produce an important change in the average distances between charges. This change induces an anomalous behaviour of the conductimetric interaction parameter with solvent composition. This effect is not observed in the case of nitrate polyion and the trend of the conductimetric interaction parameter correlates well with the nature of the medium. This effect is attributed to the low methanol adsorption in this case. © of SCI.

Preferential adsorption behaviour of several vinyl polymers in poly(ethylene glycol)(1)/THF(2)

The preferential sorption coefficient in the ternary systems vinyl polymers (3)/Poly (ethylene glycol) (1)/THF(2) has been determined in dilute solutions by dialysis equilibrium differential refractometry at 633 nm and 298 K. A series of vinyl polymers of different side groups (Polystyrene, Poly (p-iodostyrene), Poly (n-vinyl carbazole), Poly (vinyl chloride) and Poly (methyl methacrylate)) has been studied.

Preferential adsorption behavior of poly(vinylpyrrolidone) in tetrahydrofuran-water mixtures

The preferential adsorption behavior of poly(vinylpyrrolidone) (PVP) and one alternating copolymer of vinylpyrrolidone-co-maleic acid (CP1H) in the binary solvent mixture THF/water were studied. Water is preferentially adsorbed by PVP and THF by the copolymer at low THF compositions. Both systems show enhancement of the solubility and an inversion point in the preferential solvation. The results are discussed in terms of specific interactions between solvents and side chains of the polymers. The conformational arrangements of the side groups are considered.

Preferential adsorption behaviour of poly(alkyl methacrylate)s in 1,4‐dioxane/methanol

AbstractThe preferential adsorption of dilute solutions of poly(methyl methacrylate) and some poly(alkyl methacrylate)s in 1,4‐dioxane/methanol, at 298 K, was studied by laser light scattering. It was found that the inversion composition depends on the molar volume or the number of carbon atoms of the polymer side group. This result can be explained in terms of specific interactions between the carbonyl group of the esters and methanol.

Polymer cosolvent systems—III. Viscometric and preferential adsorption behaviour of poly(4-tert-butylphenyl methacrylate) in tetrahydrofuran/water

The viscometric behaviour and the preferential solvation of poly(4-tert-butylphenyl methacrylate) (PBPh) in tetrahydrofuran/water mixtures have been studied. The results show that water enhances the solubility of this polymer. The system PBPh-tetrahydrofuran-water was studied in detail for 6 fractions of polymer. Analysis of the data shows a variation in the confirmational parameter K o . This viscometric behaviour and preferential solvation are compared with those of polystyrene (PS) in the same mixture. The results are discussed.

Viscometric and preferential adsorption behaviour of poly(4-tert-butylphenyl methacrylate) in tetrahydrofuran/chloroform

The viscometric behaviour of poly(4-tert-butylphenyl methacrylate) in the solvent mixture tetrahydrofuran/chloroform has been investigated. There is qualitative agreement between variations in [η] and predictions from the Dondos and Patterson theory. The role of the preferential adsorption of one of the solvents on the polymer was considered. The experimental adsorption coefficients λ∗ are discussed in this particular mixture where GE < 0. In this binary solvent rthe kθ values of the polymer are similar in the three different mixed solvent compositions studied.