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In recent years, photoredox chemistry has been intensively investigated due to its sustainability and low energy-cost. Here, we propose a physicochemical concept – called {2-phases 2-reactions 1-catalyst} – to perform two chemical reactions simultaneously with only one catalyst using a liquid–liquid biphasic system. The well-known and commercially available α-Keggin polyoxometalate (POM), PW12O403−, was used as a photocatalyst for oxidizing a hydrophobic compound in an organic phase. The reduced POM, PW12O404−, being more hydrophilic, diffuses then in the aqueous phase where it reduces a hydrophilic compound. After this step, the re-oxidized POM migrates back to the organic phase closing the catalytic cycle. We applied this concept to several basic reactions: oxidations of organic compounds (e.g. alcohol to aldehyde), degradation of organic dyes, metal recovery by reduction of metal ions, and in situ metal–organic complexation reactions. This concept is proposed as a powerful, simple and sustainable tool to couple diverse photo-oxidation/reduction reactions. As an example, oxidative dye degradation/metal (silver) recovery were performed using this general methodology. The main advantage of the {2-phases 2-reactions 1-catalyst} concept is the economy of one reactor and one catalyst, including its self-regeneration by another useful reaction. [ABSTRACT FROM AUTHOR]

A nanocomposite of α-Fe2O3/alkalinized C3N4 (α-Fe2O3/A-C3N4) electrocatalyst for oxygen reduction reaction (ORR) was synthesized by a simple in situ electrostatic adsorption of A-C3N4 and iron-based ionic liquid [Omim]FeCl4 complexation reaction using sonication treatment followed by pyrolysis process. The as-prepared α-Fe2O3/A-C3N4 nanocomposite can act as a superior electrocatalyst for ORR in terms of excellent ORR activity with onset potential of 0.82 V vs. reversible hydrogen electrodes (RHE), current density of 5.2 mA cm−2 and outstanding methanol resistance. This cost-effective starting materials and simple preparation method paves the way to large-scale fabrication of low-cost and highly active noble metal-free electrocatalyst and promotes their practical applications in electrochemical power conversion and storage system. [ABSTRACT FROM AUTHOR]

Coulombic interactions between charged species in pore water and at surface/solution interfaces are of pivotal importance for multicomponent reactive transport in porous media. In this study, we investigate the impact of domain dimensionality on electrostatically coupled dispersion and surface-solution reactions during transport of acidic plumes and major ions in porous media. Column and quasi two-dimensional flow-through experiments were performed, with identical silica porous media and under the same advection-dominated conditions. Equal mass fluxes of different electrolyte solutions (i.e., HCl - pH ∼ 2.8, NaBr - 100 mM, HCl - pH ∼ 2.8 plus NaBr - 100 mM) were continuously injected in the 1-D and 2-D experiments and breakthrough curves of pH and major ions were measured at the outlet of the domains. The presence of pronounced ionic strength gradients in the transverse direction in the 2-D setup caused distinct retardation and transport behaviors of protons and major ions which were not observed in the one-dimensional column experiments. Furthermore, in the cases of salt electrolytes injection, considerably enhanced release of H+ (>61%) from the quartz surface was observed in the multidimensional system compared to the one-dimensional setup. Reactive transport modeling was performed to reproduce the experimental outcomes and to analyse the coupling between transport processes, based on the Nernst-Planck formulation of diffusive/dispersive fluxes and on surface complexation reactions at the solid-solution interface. Electrostatic interactions between Na+, Br−, and H+, and deprotonation of the quartz surface upon the formation of sodium outer-sphere complexes, are the primary controllers of the spatial and temporal features displayed by the pH and major ions measurements. The reactive transport simulations allowed us to interpret the experimental observations, to visualize the distribution and spatio-temporal evolution of dissolved and solid species, to identify a spatially heterogeneous zonation of Coulombic interactions with distinct behavior at the fringe and core of the injected plumes in the multidimensional setup, and to quantify the different components of the Nerst-Planck fluxes of the charged solutes. This study demonstrates that the domain dimensionality directly affects electrostatic interactions between charged aqueous species in the pore water and surface complexation reactions at the solid-solution interface. The non-trivial effects of dimensionality on multicomponent ionic transport result in a significantly different behavior in 1-D and 2-D systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel mathematical model combining kinetics and surface complexation reactions is developed. • Flowing water alters Si binding mechanisms onto α-FeOOH. • Si monomeric species occupy no more than ~ 22% of the reactive OH groups on goethite. • Surface oligomerization/polymerization is a rate-limited process in column. • Stepwise polymerization of silicate is crucial to adequately predicting the reactive transport of quinolones. Although silicates are the most common anions in aquatic systems, little is known on the roles they play on the transport of emerging contaminants, such as antibiotics. Using dynamic column experiments, we revealed the controls of Si loadings on goethite (α-FeOOH) coated sands on the transport of a widely used quinolone antibiotic, here focusing on Nalidixic Acid (NA). We find that dynamic flow-through conditions (Darcy velocities of 2.98 cm/h and 14.92 cm/h) sustain monomeric Si species with loadings of up to ~ 0.8 Si/nm2 but that oligomeric species can form at the goethite surfaces under static (batch, no-flow conditions). While these monomeric species occupy no more than ~ 22% of the reactive OH groups on goethite, they can effectively suppress NA binding, and therefore enhance NA mobility in dynamic conditions. NA can also bind on goethite when it is simultaneously injected with high concentrations of Si (2000 µM), yet it becomes progressively replaced by Si over time. Combining kinetics and surface complexation modeling, we present a new transport model to account for the stepwise polymerization of Si on goethite and NA transport. Our findings show that dissolved Si, common to natural surface waters, can play a determining role on the surface speciation and transport of antibiotics in the environment. [ABSTRACT FROM AUTHOR]

Some podand sulfonamides were designed to Cu2+ ion recognition. Some green chemistry metrics were evaluated in order to know the environmental impact of the reactions. Cu2+ complexes studio with the ligands were done, given adequate complexation constants for Cu2+ recognition by ligands LA2 y LA6. All complexes precipitated instantaneously when directly react with copper ions resulting in blue complexes. For LA2 a color change to olive green in 8 minutes was observed maybe due to a molecular reorganization. LA2 can be used as a part of an ion recognition kit that detect concentration in the order of 10-3 mol·dm-3. [ABSTRACT FROM AUTHOR]

The adsorption of metal ions from wastewater using Schiff base cellulose bearing pendulant heterocyclic chelating groups (MC-Tz) as a sorbent is the subject of this paper. Solid state 13C-NMR, FT-IR, SEM, and XRD spectroscopy, as well as TGA and XRD were utilized to examine the adsorbent. The batch sorption process used pH, adsorbent dose, initial adsorbate concentration, temperature, as well as contact time to calculate the metal ion levels. The optimum pH-6.0, with the complexation reaction and ion exchange phase as the mechanisms at work. To investigate the equilibrium concentration and temperature-dependent rate constants, various models, such as the Langmuir, Freund, Temkin, and Redlich–Peterson adsorption isotherm were utilized. Maximum adsorption capacity of the modified cellulose (MC-Tz) towards Lead(II), Copper(II), Nickel(II), and Cadmium(II) were found to be 453.2, 485.5, 473.2, and 455.6 mg/g respectively. A Kinetic study shows that the Langmuir is more in agreement with the Pseudo-second order Kinetic model. Adsorption–Desorption experiments over four cycles demonstrated the feasibility of the sorbent's regeneration potential and the measured values of enthalpy and entropy explain the essence of the adsorption process. The objective of this research is to discover non-toxic, environmentally friendly adsorbent biodegradable components and to conduct evaluations to determine their use in wastewater treatment. [ABSTRACT FROM AUTHOR]

Iron species that occur in natural surface water could affect the photochemical behavior of pollutants. Complexation between iron species and polycarboxylate or heavy metals has been widely reported, where the ligands could be oxidized via ligand-to-metal charge transfer (LMCT) by light inducement. Such complexation and photochemical reactions might also occur for low valance metal-containing organic compounds, which is worthy of investigation. This work studied the phototransformation of p-arsanilic acid (ASA), an organic arsenic compound that is widely used as a feed additive in the poultry industry, by colloidal ferric hydroxide (CFH) using black light lamps (λ = 365 nm) as the light source. The results revealed the contribution to ASA transformation at circumneutral conditions by CFH through an LMCT process, which is the same as that for As(III). The complexation between ASA and CFH was investigated using UV–vis spectroscopy. The estimated equilibrium constant for the CFH–ASA complex was log Kf271 = 4.22. The analysis of the photoproducts found the generation of both inorganic and organic arsenic. Our findings confirmed the similarities in the photochemical mechanisms of ASA and As(III) in the presence of CFH. The results help in further understanding the fate of organoarsenicals in the surface water environment. [ABSTRACT FROM AUTHOR]

3,7,23,27‐Tetrabromo[36]octaphyrin 2 was synthesized as a novel octaphyrin bearing two meso‐free positions. Surprisingly, its ZnII and NiII complexation reactions produced a directly fused porphyrin(2.1.1.1) dimer 6, and a meso‐α fused N‐confused porphyrin (NCP) dimer 7, as the first example of NCP tape, respectively, via transannular C−C bond formation. While 6 exhibits a diatropic ring‐current effect owing to the global 36π Möbius aromaticity, 7 shows a paratropic ring‐current effect due to the global Hückel 36π antiaromaticity. In addition, the oxidation of 7 with PbO2 allowed for formation of its two‐electron oxidized species 9 that exhibited a diatropic ring‐current effect due to the global Hückel 34π aromaticity. This work has demonstrated that meso‐free large expanded porphyrins can be a promising platform to produce novel fused porphyrinoids. [ABSTRACT FROM AUTHOR]

In the sake of enhancing the thermal stability of α-Tocopheryl acetate (α-TA) and Strawberry Anthocyanins (AN), their encapsulation with starch or β-Cyclodextrin were prepared and characterized by UV-Vis and IR spectra in addition to thermal analysis. Thermal stability was investigated by comparing the thermographs of each host and guest with that of the prepared complex. Both hosts provided extra thermal stability to both guests where α- TA is stabilized from 230 to 291oC by complexation with starch and to 285oC by encapsulation with β-CD. AN was also stabilized from 40.02oC to 75.57 and 79.46oC by complexation with starch and β-CD respectively. [ABSTRACT FROM AUTHOR]

In order to improve the removal efficiency of clays in oil refining, to explore the related factors and to clarify the removal mechanism of alkaline nitride, a series of modified clays was prepared to test removal of alkaline nitride from lubricating oil. After the addition of 1 wt.% FeCl3, the removal rate of alkaline nitride increased from 33.6% to 43.3%. Furthermore, the acidity and chlorine content did not exceed acceptable levels. The testing methods of N2 adsorption-desorption, particle-size distribution, Fourier-transform infrared spectroscopy and X-ray diffraction were conducted to verify the removal mechanism. The removal rate of alkaline nitride is mainly related to the density of Lewis acid sites. The Fourier-transform infrared spectra confirmed the existence of the complexation reaction. The basic nitrides were removed by chemical adsorption via Fe3+-complexation. [ABSTRACT FROM AUTHOR]

Utilization of subsurface reservoirs, including fluid extraction/injection, can induce stress changes and modify in‐situ chemical equilibrium causing subcritical fracturing and deformation. Here, we show that chemical complexation reactions at the newly created fracture surfaces within the crack tip limit fracturing during consolidation of granular calcite assemblages. Previously, we showed that analogous chemical complexation reactions can increase in‐situ fracture toughness in pre‐fractured single crystal calcite. To test the chemical complexation effect under subsurface conditions, we consolidated samples under increasing hydrostatic pressure to induce widespread intergranular fracturing in the presence of fluid containing common anions. Measured consolidation, acoustic emissions, and microfracturing demonstrate that deformation correlates with complexation affinity for calcium in calcite and aqueous anions. We observed that deformation is lowest in the presence of strongly complexing anions (e.g., sulphate), provided sufficient anion diffusion rates. This understanding is important for predicting reservoir effective strength in the presence of complex aqueous fluids. Plain Language Summary: The current study identifies chemical reactions at the crack tip of calcite that control the extent of fracturing during consolidation. Calcite is one of the most abundant minerals in the Earth's crust; however, the chemical mechanisms that could promote or arrest crack growth in calcite are poorly understood. Microscopic cracks in individual calcite grains could affect reservoir‐scale processes such as deformation and subsidence. Here, we show that chemical reactions at the crack tips of calcite define fracturing behavior and, therefore, consolidation at pressures typical for geologic formations. Key Points: We examined how the formation of surface complexes affects fracture‐driven consolidation in granular assemblages of calciteMore fracturing and faster consolidation of calcite grain packs are observed in fluids containing anions with weak affinity for calciumStrongly complexing anions can effectively shield crack tips from hydrolysis reaction and modify deformation rates and total strains [ABSTRACT FROM AUTHOR]

Hyperbranched polymers, as a unique highly branched polymers with low viscosity, simple synthesis, mixability and high reactivity, have received intensive attention and applied to many fields of resin modification, catalysts, and film materials. In this paper, hyperbranched polymers (P1 and P2) are designed and developed by the thiol‐yne "click" reaction with controlled molar ratio of reactant. After that, lanthanide ions are coordinated with P1 and P2 to prepare new hyperbranched polymer fluorescent products (P1‐Ln3+ and P2‐Ln3+). P1‐Ln3+ and P2‐Ln3+ exhibit excellent fluorescent properties, superb stability, and economic feasibility. Moreover, bioimaging experiments clearly exhibit that P1‐Ln3+ and P2‐Ln3+ has great potential in further biological applications. [ABSTRACT FROM AUTHOR]

The removal of complexed heavy metals in complexation plating effluents is always a problem. Here molybdenum disulfide/copper sulfide (MoS2/CuS) composite was synthesized to activate peroxosulfate (PMS) to treat complexation nickel simulated plating effluents. MoS2/CuS showed excellent PMS activation effect. The removal efficiency of 50 ppm Ni‐EDTA by MoS2/CuS+PMS process and Ni‐citrate by MoS2/CuS process reached 99.7 % and 100 % for 20 min treatment, respectively. The excellent performance of MoS2/CuS+PMS process for heavy metal complexes removal is attributed to two ways: oxidative degradation and catalytic decomplexation. Oxidative degradation is to degrade complexing agent into small molecules through.SO4− produced by PMS activated directly by the synergy between MoS2, CuS and Ni‐EDTA. Catalytic decomplexation is to replace Ni2+ in Ni‐EDTA by the metal active sites of MoS2/CuS to release Ni2+ and remove it. These two degradation pathways make the MoS2/CuS+PMS process has excellent removal efficiency. In addition, the MoS2/CuS+PMS process eliminates the dependence of the Fenton reaction on iron‐based reagents and avoids the production of iron sludge precipitation. These findings provide new insights for the development of metal sulfide activating PMS to treat complexation plating effluents. [ABSTRACT FROM AUTHOR]

The complexation reactions of nickel (II) with 2-hydroxythiophenol and its derivatives (2,5- dihydroxythiophenol, 2-hydroxy-5-chlorothiophenol, 2-hydroxy-5-bromothiophenol, and 2-hydroxy-5- iodothiophenol) in the presence of hydrophobic amines were studied by spectrophotometric methods. Aniline and N, N-dimethylaniline were used as hydrophobic amines. It found that mixed-ligand complexes (MLC) are formed in a weakly acidic medium (pH 2.3-8.0). The maximum in the light absorption spectrum of the complexes is observed at λ = 620-650 nm. The molar coefficients of light absorption are (4.1-4.3)×104 . The best extractants were chloroform, dichloroethane and carbon tetrachloride. With a single extraction with chloroform, 97.8-98.4% of nickel is extracted in the form of MLC. Based on the data obtained, photometric methods for the determination of nickel in various objects were developed. [ABSTRACT FROM AUTHOR]

The supramolecular interaction between Uridine (UR) and β-cyclodextrin (β-CD) has been investigated in liquid, solid, and virtual state. Noncovalent interaction between UR and β-CD in aqueous medium was confirmed by using absorption, fluorescence emission, and time-resolved fluorescence spectroscopy. The solid inclusion complex was prepared using physical mixing, kneading method, and coprecipitation method and it was characterized using FT-IR, SEM, powder X-ray diffraction patterns TG/DSC, and 1H NMR techniques. The stoichiometric ratio of the inclusion complex was found to be 1:1 and the binding constant of the inclusion complex at 303 K were determined using Benesi–Hildebrand plot. The changed in the Gibbs free energy for the complexation reaction was determined and it was found that the complexation process was spontaneous. As the changes in the chemical shift, values of the UR have been observed after the formation of an inclusion complex. The inclusion process is virtually evident by molecular docking studies using the patch-dock server. As the biological application of this complexation, the cytotoxic activity has also been successfully tested against breast cancer cell line which exposed at different concentration for 74 h. [ABSTRACT FROM AUTHOR]

All-atom molecular dynamics simulations can provide insight into the properties of polymeric gene-delivery carriers by elucidating their interactions and detailed binding patterns with nucleic acids. However, to explore nanoparticle formation through complexation of these polymers and nucleic acids and study their behavior at experimentally relevant time and length scales, a reliable coarse-grained model is needed. Here, we systematically develop such a model for the complexation of small interfering RNA (siRNA) and grafted polyethyleneimine copolymers, a promising candidate for siRNA delivery. We compare the predictions of this model with all-atom simulations and demonstrate that it is capable of reproducing detailed binding patterns, charge characteristics, and water release kinetics. Since the coarse-grained model accelerates the simulations by one to two orders of magnitude, it will make it possible to quantitatively investigate nanoparticle formation involving multiple siRNA molecules and cationic copolymers. [ABSTRACT FROM AUTHOR]

Complexation behavior of oppositely charged polyelectrolytes in a solution is investigated using a combination of computer simulations and experiments, focusing on the influence of polyelectrolyte charge distributions along the chains on the structure of the polyelectrolyte complexes. The simulations are performed using Monte Carlo with the replica-exchange algorithm for three model systems where each system is composed of a mixture of two types of oppositely charged model polyelectrolyte chains (EGEG)5/(KGKG)5, (EEGG)5/(KKGG)5, and (EEGG)5/(KGKG)5, in a solution including explicit solvent molecules. Among the three model systems, only the charge distributions along the chains are not identical. Thermodynamic quantities are calculated as a function of temperature (or ionic strength), and the microscopic structures of complexes are examined. It is found that the three systems have different transition temperatures, and form complexes with different sizes, structures, and densities at a given temperature. Complex microscopic structures with an alternating arrangement of one monolayer of E/K monomers and one monolayer of G monomers, with one bilayer of E and K monomers and one bilayer of G monomers, and with a mixture of monolayer and bilayer of E/K monomers in a box shape and a trilayer of G monomers inside the box are obtained for the three mixture systems, respectively. The experiments are carried out for three systems where each is composed of a mixture of two types of oppositely charged peptide chains. Each peptide chain is composed of Lysine (K) and glycine (G) or glutamate (E) and G, in solution, and the chain length and amino acid sequences, and hence the charge distribution, are precisely controlled, and all of them are identical with those for the corresponding model chain. The complexation behavior and complex structures are characterized through laser light scattering and atomic force microscopy measurements. The order of the apparent weight-averaged molar mass and the order of density of complexes observed from the three experimental systems are qualitatively in agreement with those predicted from the simulations. [ABSTRACT FROM AUTHOR]

NMR diffusometry has been gaining wide popularity in various areas of applied chemistry for investigating diffusion and complexation processes in solid and aqueous phases. To date, the application of this method to study aggregation phenomena proceeding beyond the dimer stage of assembly has been restricted by the need for a priori knowledge of the aggregates' shape, commonly difficult to know in practice. We describe here a comprehensive analysis of aggregation parameter-dependency on the type and shape selected for modeling assembly processes, and report for the first time a shape-independent model (designated the SHIM approach), which may be used as an alternative in cases when information on aggregates' shapes is unavailable. The model can be used for determining equilibrium aggregation parameters from self-diffusion NMR data including equilibrium self-association constant and changes in enthalpy, ΔH, and entropy, ΔS. [ABSTRACT FROM AUTHOR]

The release of potentially toxic metals, such as copper (Cu), into the water column is of concern during polymetallic nodule mining. The bioavailability and thus toxicity of Cu is strongly influenced by its speciation which is dominated by organic ligand (L) complexation in seawater, with L-complexes being considered less bioavailable than free Cu2+. The presence of CuL-complexes in deep-sea sediments has, however, not been systematically studied in the context of deep-sea mining. We thus analyzed the Cu-binding L concentration ([L]) in deep-sea pore waters of two polymetallic nodule provinces in the Pacific Ocean, the Peru Basin and the Clarion-Clipperton-Zone, using competitive ligand equilibration–adsorptive stripping voltammetry. The pore-water dissolved Cu concentration ([dCu]) ranged from 3 to 96 nM, generally exceeding bottom water concentrations (4–44 nM). Based on fitting results from ProMCC and Excel, Cu was predominantly complexed by L (3–313 nM) in bottom waters and undisturbed pore waters. We conclude that processes like deep-sea mining are unlikely to cause a release of toxic Cu2+ concentrations ([Cu2+]) to the seawater as > 99% Cu was organically complexed in pore waters and the [Cu2+] was < 6 pM for 8 of 9 samples. Moreover, the excess of L found especially in shallow pore waters implied that even with a Cu release through mining activities, Cu2+ likely remains beneath toxic thresholds. [ABSTRACT FROM AUTHOR]

Allicin, a chemical found in functional foods, has a variety of beneficial bioactivities but the unpleasent odor and unstability hinder its applications. Isolating products from cyclodextrin (CD) complexation, using β‐CD and its derivatives, is usually a time and energy‐consuming process. Herein, a high‐efficiency and eco‐friendly preparation method of an inclusion (allicin@α‐CD) formed by allicin and α‐CD was designed, which turned liquid allicin into crystal particles with high‐speed stirring (10,000 r/min) at 25°C for 10 min in water. In vivo and in vitro masking evaluations showed that the inclusion particles could decrease the unpleasant odor of allicin. Molecular docking and experimental characterization results illustrated that the main reason of odor masking was due to the disulfide and thiocarbonyl groups of allicin being partially encapsulated by the cavity of α‐CD. Compared with the physical mixture, the stability of allicin in allicin@α‐CD at 60°C for 10 days was 33‐fold improved. Overall, this efficient strategy of inclusion provided a promising approach for the industrialization of allicin‐related formulations. Practical Application: In this study, an environmentally friendly method of α‐CD inclusion without the use of organic reagents was designed to solidify and stabilize allicin, which effectively masked the unpleasant odor and taste of allicin. It has contributed greatly to improving the compliance of consumers and provided a new and effective approach to broaden the application of allicin. [ABSTRACT FROM AUTHOR]

AlH3(PPh3)2 was synthesized as a stable solid being the first known 1 : 2 alane arylphosphane adduct. Although only weakly intra‐molecularly coordinated, it displays as a molecular crystal significant inertness against atmospheric humidity and oxygen due to strong steric screening of the alane unit. The compound readily dissociates PPh3 in solution allowing for its use as a Lewis acidic reducing agent. These features lead to an easy to store, easy to use reducing agent that may enable the quantitative investigation of aluminum hydride chemistry including reduction, complexation and hydroalumination reactions. The structure contains two non‐equivalent penta‐coordinated aluminum centers that despite long Al−P distances of ca. 2.7 Å display unusually high quadrupolar coupling constants CQ of 25.1 and 26.5 in 27Al solid state NMR measurements. The product was also tested as a reducing agent on a small set of selected compounds with various functional groups. [ABSTRACT FROM AUTHOR]

The effect of temperature on the chloride binding capacity (CBC) of cementitious materials was investigated. A reactive transport model including thermodynamic equilibrium, kinetic control and surface complexation was applied to investigate this effect. The surface complexation model was completed by introduction of the equilibrium constant of calcium silicate hydrate (C–S–H) complexation reactions at different temperatures (5, 21 and 35°C). In order to validate the developed numerical model, the results were compared with experimental data obtained from the literature. Good agreement was found between the numerical and experimental CBCs. The effect of temperature on the CBC of cementitious materials was evaluated and is discussed in this paper. The van 't Hoff equation of C–S–H surface complexation reactions (SCRs) and variation of the standard thermodynamic properties of the SCR (ΔrHT0 (kJ/K) and ΔrST00) at the reference temperature of T0 = 25°C and p0 = 1·1013 × 105 Pa are also presented. [ABSTRACT FROM AUTHOR]

BACKGROUND At present, various kinds of hydrogel adsorbents are applied to the treatment of heavy metal ions in wastewater. In this work, we focused on the adsorption of cadmium [Cd(II)] and copper [Cu(II)] onto microspheres of a novel thermosensitive hydrogel (NH2‐SA/PNIPA, aminated sodium alginate/poly‐N‐isopropyl acrylamide), studied the effect of temperature on the phase transition of the hydrogel in detail, and discussed the influence on the adsorption behavior of metal ions in the hydrogel. RESULTS: The NH2‐SA/PNIPA exhibited a higher adsorption efficiency under the conditions of interfering monovalent cationic and neutral pH. The adsorption capacities based on the Langmuir model were 57.2 mg g–1 for Cu(II) and 100.5 mg g–1 for Cd(II) at 20 °C, respectively. Higher temperature facilitated the adsorption process and also led to the volume shrinkage and hydrophobicity of NH2‐SA/PNIPA. The metal ions had different hydration and hence different adsorption capacities, of 56.7 mg g–1 for Cu(II) and 88.6 mg g–1 for Cd(II) at 40 °C. The results of diffusion behavior analysis showed that the diffusion coefficients were ≈1 × 10−11 m2 s–1. The adsorption performance of NH2‐SA/PNIPA hardly decreased even after five cycles. In addition, the adsorption process was controlled mainly by the complexation reaction. CONCLUSION: The novel hydrogel microspheres overcame the deficiency of conventional adsorbents and possessed high diffusibility. This work provides a theoretical basis and empirical evidence for enhancement of adsorbents for removing heavy metals in wastewater. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

This review describes synthetic concepts and breakthroughs in 1,4-diphosphinine and related P-bridged bis(NHCs) chemistry, covering the last four decades, starting from monocyclic 1,4-dihydro-1,4-diphosphinines in the early 80s to the most recent and promising achievements of tricyclic 1,4-dihydro-1,4-diphosphinines and tricyclic 1,4-diphosphinines. Theoretical aspects are presented for 1,4-dihydro- and 1,4-diphosphinines considering HOMO LUMO situations as well as the degree of aromaticity. Moreover, fundamental characteristics of analytical data of these compounds are highlighted with special focus on substituent effects, structural aspects and trends of electrophilicity. The two P-centers and the heterocyclic rings of 1,4-dihydro- and 1,4-diphosphinines constitute a broad platform for substitution, reduction/oxidation, alkylation, complexation and cycloaddition reactions, i.e., a comprehensive compilation of reactivity aspects is presented. Furthermore, very recent developments in the synthesis and reactivity of tricyclic PV/V- and PIII/III-bridged bis(imidazole-2-ylidenes) will be discussed together with new perspectives derived from an antiaromatic middle ring. In total, our intention is to show new frontiers, i.e., new synthetic paths, thus creating novel opportunities for potential applications in molecular and materials chemistry. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to evaluate de influence of protein–sugar complexation on the stability and functionality of C-reactive protein, after exposure to constant high temperatures, in order to develop highly stable positive controls for in-vitro diagnostic tests. C-reactive protein is a plasmatic protein used as a biomarker for the diagnosis of a series of health problems such as ulcerative colitis, cardiovascular diseases, metabolic syndrome, due to its essential role in the evolution of chronic inflammation. The sugar–protein interaction was investigated using steady state and time resolved fluorescence. The results revealed that there are more than two classes of tryptophan, with different degree of accessibility for the quencher molecule. Our study also revealed that sugar–protein complexes have superior thermostability, especially after gamma irradiation at 2 kGy, the protein being stable and functional even after 22 days exposure to 40 °C. [ABSTRACT FROM AUTHOR]

Introduction: Galling insects manipulate the development of their host plants. Galls are rich in secondary metabolites, such as phenolic compounds and terpenes. Caryocar brasiliense acts as a host of galling insects. Few studies report the impacts of this plant-insect interaction on the species' morphology, physiology, and secondary metabolism. Objective: The purpose of this study was to verify if there is a correlation between the levels of total phenols and flavonoids in C. brasiliense leaf extracts and environmental variables, such as temperature and precipitation, throughout the year, and to evaluate how galling insects can interfere in this seasonality. Methods: Ethanol extracts from leaves were obtained by soxhlet extraction. The main classes of secondary metabolites were detected by phytochemical prospecting. The levels of total phenols and flavonoids were quantified by the Folin-Dennis tests and complexation reaction with aluminum chloride, respectively. Pearson 's correlation coefficient shows that the levels of phenols and flavonoids were correlated with the average monthly maximum temperatures and precipitation accumulation, respectively, recorded in Gurupi - Tocantins. Results and Discussion: Phytochemical prospecting indicated flavonoids, saponins, tannins, triterpenes, steroids, and alkaloids in both extracts. In C. brasiliense, the samples of healthy leaves suffered a greater variation in the levels of phenols (68.39±2.3 to 279.34±3.1 mg GAE g-1 extract) and flavonoids (164.06± 3.0 at 269.03±3.6 mg QE g-1 extract) compared to leaf samples with galls. A strong positive correlation was found between the contents of total phenols and maximum temperatures and a strong negative correlation with precipitation through Pearson's correlation. Conclusions: The variations observed in the levels of phenols and flavonoids in the extracts of C. brasiliense seem to be related to abiotic factors and the herbivory promoted by the galling insect. [ABSTRACT FROM AUTHOR]

Rhenium is an important emerging metal material. The scarcity of reserves and the difficulty in separation and enrichment have always been important reasons restricting its industrial application. In this work, aminated SBA-15 is used as substrate for the crosslinking reaction to prepare a type of Schiff base-containing mesoporous dioxide silica material (GA-MMA-0.2 N-SS) for high selectively recovering Re(VII) in aqueous solution. The results show that the using amount of APTES is small in the modification process of the adsorbent material, and the modified adsorbent still maintains the orderly mesoporous structure. The adsorption capacity of GA-MMA-0.2 N-SS for Re(VII) up to 198.77 mg·g−1 under pH 1.5, and it can still reach more than 97% after 4 elution cycles. Adsorption mechanism study indicated that the complex reaction between N atoms and ReO 4 - is the main adsorption mechanism of Re(VII) on GA-MMA-0.2 N-SS. This study provided a new adsorbent based schiff base and ordered mesoporous silica for the separation of Re(VII) from mixed solution, which also provides new ideas for the design of adsorbents in the future. [Display omitted] • Highly ordered Schiff base functionalized silica was prepared by post-grafting. • GA-MMA-0.2 N-SS was prepared by a small amount of organic modifiers. • Complexation reaction between Schiff base and ReO 4 - occurred in adsorption process. • GA-MMA-0.2 N-SS exhibit satisfactory adsorption capacity, stability and selectivity. [ABSTRACT FROM AUTHOR]

The sensitivity of electrochemical (EC) sensors has been improved through the development of multiple approaches. However, the majority of EC sensors were limited in their practical application by high costs or tedious procedures. Herein, based on ethylenediaminetetraacetic acid (EDTA)-Pb2+ complexation reaction, a facile and affordable immunosensor was designed. Pb2+-magnesium silicate hydrate was served as the sensing substrate. The immunorecognition process was carried out in the Eppendorf tube, and antibody-functionalized Pb2+-polydopamine was utilized as immunoprobe. In the tube, the quantitative and appropriate excess of EDTA was introduced to complex with Pb2+ on the immunoprobes. The remaining EDTA was added to the sensing substrate surface to coordinate with some Pb2+ in it. This leaded to the reduction of the EC signal of Pb2+, which was related to the antigen concentration. Using prostate-specific antigen as the model analyte, the sensitive detection was realized with a low limit of detection (30.49 fg mL−1). Remarkably, the assay results were available within 24 min, sensibly faster than the most existing EC sensors. [Display omitted] • Pb2+-magnesium silicate hydrate was served as the sensing substrate. • Pb2+-polydopamine was utilized as support for immunoprobe. • EDTA-Pb2+ coordination reaction was applied to improve the sensitivity of the sensor. [ABSTRACT FROM AUTHOR]

In this study, the optimal geopolymers (OGP) with excellent compressive strength and immobilization ratio are prepared by steel slag (SS), fly ash (FA), and desulfurized gypsum (DG) to immobilize Pb and Cd in the sediment. D-optimal mixing design model and Design-Expert software were used to optimized the preparation of OPG. XRD, SEM/EDS, XPS and CT were used to reveal the immobilization mechanism. Results indicated that the optimal mass ratio of SS、FA and DG is 0.604, 0.296 and 0. 100. The compressive strength of the OGP after curing 3d and 7d was 3.45 MPa and 4.90 MPa, respectively. And the immobilization rates of Pb and Cd were 99.65 % and 37.80 %, respectively. The main phase of OGP was amorphous aluminosilicate, mullite, calcium sulfate, hematite, calcium silicate hydrates and srebrodlskite. Among them, the amorphous aluminosilicate played a key role in the immobilization of Pb and Cd. The specific immobilization mechanism of Pb and Cd was concluded: (1) Cd was immobilized in OGP by ion exchange, precipitation and complexation reaction, while (2) Pb was controlled by lattice immobilization and complexation reaction. (3) the new crystalline phase containing Pb and Cd was existed by the form of amorphous phase in OGP. • A novel geopolymer with excellent compressive strength and Pb/Cd immobilization efficiency is developed. • Cd is immobilized in OGP by ion exchange, precipitation and complexation reaction. • Pb is immobilized in OGP by lattice immobilization and complexation reaction. [ABSTRACT FROM AUTHOR]

Uranium (U) pollution in soil resulted by human activities is a critical environmental issue. Goethite and humic acid (HA), as predominant soil constituents, significantly influence the migration and transformation of uranium in soil, but effects of combining them together on the sequestration and immobilization of U at different mineralization condition are still rare. To simulate the ability of different combinations of HA and goethite to limit the migration of uranium (VI) in the soil environment, the humic acid-modified goethite (OPHG, TSHG) were synthesized by one-pot and two steps synthesis methods in this study. After modified by HA, the specific surface area of materials increased from 29.67 m2/g to 121.53 m2/g and 39.89 m2/g respectively. The effects of dosage, contact time, pH, initial concentration and temperature on the removal of U(VI) by goethite and modified goethite were investigated. The results showed the maximum difference of them reached 41.59% and 15.69 mg/g for reaction 60 min at pH=4.5. The equilibrium adsorption data fit to the pseudo-second-order kinetics and Langmuir models, and the maximum adsorption capacities increased from 64.63 mg/g to 92.04 mg/g. The analyses results indicated that OPHG remove U(VI) mainly through the formation of ≡ FeO UO 2 OH between Fe−O and uranyl ions, as well as the complexation of carboxyl and hydroxyl groups on HA molecules with uranium to form the HA-Goethite-U(VI) ternary complexes FeOHAUO 2. These results are benefited for understanding the effects of HA and goethite on immobilization uranium in soil and would be used to predict and remediate the polluted soil. [Display omitted] • Synthesized modified goethite in different ways to simulate the combination of humic acid and goethite in soil (OPHG, TSHG). • OPHG presented better removal efficiency than goethite and TSHG for the increased specific surface area. • The mechanism of uranium capture by modified goethite is mainly through the surface complexation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] The study explores the interactions between 5,10,15,20-tetra(N-methylpyridyl)porphyrin (H 2 P) and sodium dodecyl sulfate (SDS) at concentrations below the critical micelle concentration (CMC) in aqueous solutions employing spectrophotometric and fluorescence methods. The composition and structure of the complexes involved in the association of H 2 P with premicellar SDS aggregates of varying compositions denoted as [ H 2 P -5·SDS], [ H 2 P -10·SDS] and [ H 2 P -20·SDS] were characterized using mass spectrometry, DOSY, and 1D NOESY techniques. Possible reasons for the decrease in the intensity of absorption and emission of porphyrin in micellar aggregates of SDS compared to porphyrin in an aqueous environment are analyzed. The research has revealed that SDS can act as both a catalyst and an inhibitor, depending on its concentration in the reaction of complexation of H 2 P with metal cations (Co2+). The spectrophotometric approach examined interaction processes between 5,10,15,20-tetra(N-methylpyridyl)porphyrinate Co(III) and premicellar SDS aggregates, which proceed similarly to the processes with the porphyrin ligand. The study demonstrated the impact of premicellar aggregates on the binding capacity of Co(III) porphyrinate with electron-donating molecules using imidazole as an illustrative example. [ABSTRACT FROM AUTHOR]

[Display omitted] • BODIPYs are promising fluorophores in classical fluorescent probes in cation recognition. • Chromo-fluorogenic BODIPY probes have been developed for the detection of s , p -, d - or f -element ions. • The action of chemosensors was based on various mechanisms, such as PET, ICT, FRET and others. • The reaction of probe with metal ions results in fluorescent "Off-On" or "On-Off" responses. • Multianalyte BODIPY-probes for the detection of multiple metal ions are tested simultaneously. Content assessment of metal ions (analytes) in solutions, industrial waters and natural objects is one of the most important tasks in biochemistry, medicine, ecology and various industries. To solve this problem, new types of highly sensitive and selective analytical probes are being developed. The most promising areas of analytical control are based on the bright coloristic and fluorescent responses of the complexation reactions of the probe with the analyte. Various classes of fluorescent dyes have been successfully used to obtain such probes. Among them, BODIPY fluorophores are of particular interest due to the manifestation of intense spectral-luminescent and other practically significant properties. The review focuses on advances in the development of chromo-fluorogenic BODIPY probes containing various receptor fragments selective for cations of individual s- , p -, d - or f -elements. Probes work by various mechanisms, such as photo induced electron transfer (PET), internal charge transfer (ICT), fluorescence resonance energy transfer (FRET) and others. Ultimately, the reaction of the probe with the analyte results in significant fluorescent "Off-On" or "On-Off" responses. The review contains several sections in which fluorescent BODIPY probes were divided into groups of detectable s- , p -, d - and f -elements. The spectral properties of BODIPY probes, their chromo-fluorogenic, including ratiometric, responses when binding to the analyte being determined in solutions, the binding efficiency, as well as the selectivity of determining the analyte are discussed. In addition, in many cases the possibility of practical use of probes for the analysis of metal ions in aqueous, aqueous-organic media, and cells was shown. [ABSTRACT FROM AUTHOR]

Cemented paste backfill (CPB) is used as a support and filler material in underground mines. In underground conditions, before mine closure and flooding, surface and groundwaters with variable quality are in contact with CPB material, which may result in the leaching of harmful substances from the CPB. In this study, we used actual mine water from a gold mine to flush CPB in a laboratory test to simulate underground conditions and the environmental influence of CPB on groundwaters more realistically than before. Different CPB materials were treated with mine water in columns for nine months. The columns were drained and filled with new mine water batches four times during the experiment to simulate intermittent flushing underground. The dissolved elemental content, major cations, pH and oxidation-reduction potential (ORP) of the waters were measured, and the chemical results were analysed by performing geochemical modelling with the widely used geochemical code PHREEQC. X-ray tomography was also used to examine the internal structure of the CPB specimens. The results demonstrated that calcium and sulphate present in CPB parent materials leached into the mine water, which might cause a deterioration of CPB. In contrast, the concentrations of dissolved As, Sb and Ni decreased in the mine water when it was in contact with CPB materials. However, arsenic started to be re-released from the materials at the end of the nine-month experimental period. The geochemical modelling suggests that the removal of metals/metalloids from the mine water was driven by the surface complexation reactions on originally present and/or freshly precipitated metal (hydr)oxide minerals. A longer and modified testing period is needed to thoroughly examine the conditions under which these adsorbed elements start to release over time. • Column tests to study the interaction between mine water and cemented paste backfill. • Removal of dissolved As, Sb and Ni from mine water during experiments. • Ca, SO 4 2− and Mo were released from CPB materials to mine water. • Metal(loid)s removal mainly resulted from surface complexation reactions. • High release of Ca might deteriorate the internal structure of CPB. [ABSTRACT FROM AUTHOR]

Tc-99 has drawn widespread concern because of its long half-life, high fission yield and high mobility in research of radioactive waste disposal and environmental remediation. TcO 4 − through-diffusion experiments in Opalinus Clay (OPA) were performed under air and under argon No noticeable Tc-breakthrough was observed for over one year while the total Tc concentration in the source reservoir was steadily decreasing under both air and argon atmosphere. The total Tc activity distribution in the clay sample along the diffusion direction was obtained by slicing the OPA clay samples retrieved from the diffusion cells, using the abrasive peeling technique. In the case of diffusion under air atmosphere, almost no Tc was measured in that part of the sample close to source reservoir, while much more Tc was measured under argon atmosphere. A reasonable explanation for this observation is that the reductive retention of Tc plays a significant role during transport. A reactive transport model was constructed to simulate the diffusion process whereby the diffusion of Tc was coupled with redox reactions. Even though reduction of TcO 4 − by aqueous Fe2+ is thermodynamically feasible, it was not observed in the experiment. Furthermore, Fe2+ associated with solid phase was demonstrated to be more active than aqueous Fe2+. Therefore, surface complexation redox reaction was proposed. Dissolution rate of pyrite, equilibrium constant and diffusion coefficient of TcO 4 − were considered as possible factors controlling the redox reaction. Modeling results showed that TcO 4 − diffused into the clay and was partially reduced into surface complexed Tc(IV) by pyrite. When TcO 4 − transported under air atmosphere, O 2 competitively consumed Fe2+ and pyrite, resulting in no Tc immobilization in the related zone. [Display omitted] • 99Tc diffusive mobility in Opalinus clay was investigated. • No 99Tc was observed to diffuse through the 1 cm clay after more than one year. • A reactive transport model coupling diffusion processes and redox reactions with surface complexed Fe was proposed. [ABSTRACT FROM AUTHOR]

Zoogloea sp. MFQ7 achieved excellent denitrification of 91.71% at ferrous to manganous ratio (Fe/Mn) of 3:7, pH of 6.5, nitrate concentration of 25 mg L−1 and carbon to nitrogen ratio of 1.5. As the Fe/Mn ratio increasd, the efficiency of nitrate removal gradually decreased, indicating that strain MFQ7 had a higher affinity for Mn2+ than Fe2+. In situ generated biogenic Fe–Mn oxides (BFMO) contained many iron-manganese oxides (MnO 2 , Mn 3 O 4 , FeO(OH), Fe 2 O 3 , and Fe 3 O 4) as well as reactive functional groups, which play an significant part in tetracycline (TC) and cadmium (Cd2+) adsorption. The adsorption of TC and Cd2+ by BFMO can better fit the pseudo-second-order and Langmuir models. In addition, multiple characterization results of before and after adsorption indicated that the removal mechanism of BFMO on TC and Cd2+ was probably surface complexation adsorption and redox reactions. [Display omitted] • Strain MFQ7 exhibited excellent denitrification with ferrous and manganous. • Different ferrous to manganous ratios had a large effect on denitrification. • Bioprecipitation were mainly consist of MnO 2 , Mn 3 O 4 , FeO(OH), Fe 2 O 3 , and Fe 3 O 4. • The adsorption mechanism was probably surface complexation and redox reactions. [ABSTRACT FROM AUTHOR]

In this study, Ti 3 C 2 T x was synthesized from Ti 3 AlC 2 by HF 40% and 12 M LiF + 9 M HCL in 24 hr at temperatures of 313.15 and 333.15 K. Morphology, structure, and functional groups were investigated by the XRD, SEM, EDS, and BET analyses. Under the conditions of thorium (IV) concentration of 150 mg.l−1, pH ∼ 3, temperature of 298.15 K, and contact time of 540 min, the adsorption uptake of thorium (IV) with Ti 3 C 2 T x -HF and Ti 3 C 2 T x -HF in situ was 148 and 346 mg.g−1, respectively. The 3-fold adsorption of Ti 3 C 2 T x -HF in situ was because of the larger interlayer spacing, the larger number of hydroxyl functional groups, and the larger surface area due to the synthesis with 12 M LiF + 9 M HCL. Modification of Ti 3 C 2 T x with phosphate groups was done to increase the adsorption capacity of thorium (IV). The results showed that the adsorption process of thorium (IV) with pristine and modified Ti 3 C 2 T x followed pseudo-second-order kinetics and Freundlich model heterogeneous isotherm. Thermodynamic data revealed that the adsorption process was endothermic. Examining the adsorption mechanism indicated that electrostatic reactions and inner-sphere complexation were the dominant mechanisms of the process. [Display omitted] • Synthesis strategies of Ti 3 C 2 T x MXene are introduced. • The mechanism leading to the excellent adsorption performance of Ti 3 C 2 (OH) x and Ti 3 C 2 (OH) x -KH 2 PO 4 MXene is presented. • The effect of pH, temperature, background ions, dose and contact time on the adsorption of thorium was investigated. • The behaviour of Ti 3 C 2 (OH) x and Ti 3 C 2 (OH) x -KH 2 PO 4 MXene for adsorption and desorption of thorium is discussed. • The selectivity of Ti 3 C 2 (OH) x -KH 2 PO 4 was investigated in the presence of Ce3+, Gd3+, Dy(III) and Sr cations. [ABSTRACT FROM AUTHOR]

Fluoroquinolone antibiotics (FQs) form complex pollutants when they coexist with metal ions or oxides in water. These complexes alter the physicochemical properties and ecotoxicological effects of all of these three components, posing significant challenges to water treatment processes and drinking water safety. Previous studies have primarily focused on individual pollutants with little research on complex pollutants as a whole. This study summarizes the research status of complex pollutants in water environments. First, the occurrence of complex pollutants in the water was recorded. Second, the interaction mechanisms between FQs and metal ions/oxides are summarized. Complex pollution by FQs and metal ions mainly occurs through chelation reactions, whereas FQs and metal oxides are prone to adsorption and oxidation reactions. In this regard, the functional groups of FQs influence the reaction by modifying the electron transfer ability and steric hindrance, altering the reaction intensity owing to the differences in electron affinity and steric hindrance effects. Metal oxides affect complex pollution formation through differences in adsorption and oxidation capabilities. Subsequently, the effect of complex pollutants on the removal of FQs, metal ions, and metal oxides was evaluated. In particular, complex pollution affects the oxidative removal of FQs by modifying the oxidation pathways and influencing the efficiency of oxidants. In addition, complex pollution affects the photodegradation of FQs by modifying FQs' activity, electron capture, and reaction activation energy. Finally, the toxicological effects of the complex pollution were assessed to provide valuable insights into the prevention and treatment of complex pollution processes. [Display omitted] • Complexes of FQs and metal oxides/metal ions were widely detected in water. • The reaction between FQs and metal ions was complexation reaction. • FQs and metal oxides were prone to adsorption and oxidation reactions. • Impact of complexes on the removal of FQs and metal oxides/metal ions were evaluated. [ABSTRACT FROM AUTHOR]

Nitrogen-grafting through the addition of glycine (Gly) was performed on a metal- phenolic network (MPN) of copper (Cu2+) and gallic acid (GA) to increase its adsorption capacity. Herein, we reported a one-step synthesis method of MPN, which was developed according to the metal–ligand complexation principle. The nitrogen grafted CuGA (Ng-CuGA) MPN was obtained by reacting Cu2+, GA, and Gly in an aqueous solution at a molar ratio of 1:1:1 and a pH of 8. Several physicochemical measurements, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N2 sorption, X-ray diffraction (XRD), and thermal gravimetry analysis (TGA), were done on Ng-CuGA to elucidate its characteristics. The analysis revealed that the Ng-CuGA has non-uniform spherical shaped morphology with a pore volume of 0.56 cc/g, a pore size of 23.25 nm, and thermal stability up to 205 °C. The applicational potential of the Ng-CuGA was determined based on its adsorption capacity against methylene blue (MB). The Ng-CuGA was able to adsorb 190.81 mg MB per g adsorbent at a pH of 6 and temperature of 30 °C, which is 1.53 times higher than the non-grafted CuGA. Detailed assessment of Ng-CuGA adsorption properties revealed their pH- and temperature-dependent nature. The adsorption capacity and affinity were found to decrease at a higher temperature, demonstrating the exothermic adsorption behavior. [ABSTRACT FROM AUTHOR]

Pb(II) leakage from batteries, dyes, construction materials, and gasoline threaten human health and environmental safety, and suitable adsorption materials are vitally important for Pb(II) removal. Bone char is an outstanding adsorbent material for water treatment, and the effectiveness in Pb(II) removing need to be verified. In this paper, the transport characteristics of Pb(II) in columns filled with a sand and bone char mixture were studied at the laboratory scale, and the influences of the initial concentration, column height, inlet flow rate, and competing ion Cu(II) on Pb(II) adsorption and transport were analyzed. The Thomas and Dose-Response models were used to predict the test results, and the mechanisms of Pb(II) adsorption on bone char were investigated. The results showed that the adsorption capacity of the bone char increased with increasing column height and decreased with increasing initial Pb(II) concentration, flow rate, and Cu(II) concentration. The maximum adsorption capacity reached 38.466 mg/g and the saturation rate was 95.8% at an initial Pb(II) concentration of 200 mg/L, inlet flow rate of 4 mL/min, and column height of 30 cm. In the competitive binary system, the higher the Cu(II) concentration was, the greater the decreases in the breakthrough and termination times, and the faster the decrease in the Pb(II) adsorption capacity of the bone char. The predicted results of the Dose-Response model agreed well with the experimental results and were significantly better than those of the Thomas model. The main mechanisms of Pb(II) adsorption on bone char include a surface complexation reaction and the decomposition-replacement-precipitation of calcium hydroxyapatite (CaHA). Based on selectivity, sensitivity, and cost analyses, it can be concluded that bone char is a potential adsorbent for Pb(II)-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

The pit stability product of 316L stainless steel (SS) under a salt film was examined by experimental techniques, analytical methods, and numerical modeling. Both analytical and numerical results suggested that electromigration had a measurable contribution to the dissolution current during stable pit growth under a salt film, preventing the use of the 1D Fick's law of diffusion to obtain the pit stability product under such conditions. Moreover, the numerical results indicated that migration contributed to almost 2/3 of the mass transport limiting current. Although the diffusion coefficient of metal cations decreased with an increasing concentration inside the pit, it could be replaced by a constant diffusion coefficient, defined as an equivalent diffusion coefficient. When the complexation reaction was cconsidered, the modeling results agreed with the experimental data, indicating that a 4.2 M FeCl2 could be used as a simplified pit-like electrolyte to estimate the pit stability product under a salt film for 316L SS. [ABSTRACT FROM AUTHOR]

Phytoplankton growth in the open ocean is critical to carbon fixation and often limited by low iron concentrations. Owing to its low solubility, phytoplankton employ ligands for iron uptake; therefore, ligand binding characterization is important. Herein, a micro immiscible liquid/liquid interface was employed with four ligands through an electrochemically induced facilitated ion-transfer process. Ligands 1,10-phenathroline (phen), 1-nitroso-2-naphthol (N2N), 2-(2-thiazolylazo)-p-cresol (TAC), and salicylaldoxime (SAL), where tested using established facilitated ion-transfer thermodynamics combined with differential pulse voltammetry. Three metal ion/ligand binding stoichiometries were observed for Fe2+:phen, whereas only one was observed with Fe2+ with SAL, N2N, and TAC. Overall binding constants were calculated such that binding strengths can be ranked highest to lowest as phen>N2N>TAC>SAL. Additionally, the formal ion transfer for Fe2+ (0.66 V) for an aqueous/1,2-dichloroethane interface was also determined. [ABSTRACT FROM AUTHOR]

Transition metals such as Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) have been reacted with gibberellic acid (HGA) to give novel complexes, and those have been characterized by physical, spectral and analytical methods. The plant hormone gibberellate acts as a deprotonated bidentate ligand in the complexation reaction with central metal ions in the ratio 1 : 2 (Mn+ : GA). The complexes [M(GA)2(H2O)2], where [M = Mn(II), Co(II), and Ni(II)] form octahedral structures, while [M(GA)2] complexes [M = Zn(II), Cd(II), and Hg(II)] display four-coordination geometry. The octahedral structures of Cr(III) and Fe(III) complexes are characterized by the general formula [M(GA)2(H2O)(Cl)]. Computational study carried out has determined possible interactions of the complexes with COVID-19 (6LU7). [ABSTRACT FROM AUTHOR]

The paper sludge conditioning effects of waste polyester textile fibers as skeleton builders combined with ferric chloride (FeCl3) were evaluated and the sludge dewatering mechanism was explored. The catalytic effect of Fe-rich sludge biochar (Fe-SB) on enhancing sludge dewaterability was evaluated. Results showed the combined fiber-FeCl3 conditioning significantly promoted the sludge dewaterability compared with conditioner alone, leading to a 77.5% decrease in specific filtration resistance and a 68.9% increase in net yield. The decrease of extracellular polymeric substances (EPS) contents showed that the EPS were difficult to extract and sludge floc strength was enhanced as a result of chemical reactions such as complexation processes and charge neutralization. Hence, the enhancement of sludge dewaterability was primarily due to the sludge cake with a porous and incompressible structure formed by fiber and FeCl3, and the rigidity structure of fiber. Moreover, the Fe-SB prepared by fiber-FeCl3 conditioning sludge could effectively activate persulfate to enhance the sludge dewaterability, with water content of dewatered sludge decreasing by 14.6%. The Fe-SB had dual functions of the heterogeneous catalyst of persulfate and skeleton builder. This study presents a sludge recycling method that combined physicochemical conditioning and sludge biochar materials prepared by pyrolysis. [ABSTRACT FROM AUTHOR]

Copper(II) complexation of the [B10H10]2– anion has been studied in the presence of 2,2′-bipyridyl (bipy) in organic solvents. The reaction between CuCl, bipy, and (Et3NH)[Ag[B10H10]] in DMF leads to copper(II) complex [Cu2(bipy)4(µ-CO3)][B10H10]·2DMF·H2O. The copper complexation reaction has been performed under the redox conditions Cu(I) → Cu(II) in the presence of silver(I) compounds. When [Cu2(bipy)4(µ-CO3)][B10H10]·2DMF·H2O has been heated in DMSO, the monosubstituted derivative [2-B10H9OH]2– has been isolated as complex [Cu2(bipy)4(µ-CO3)][2-B10H10O0.17]·2DMSO·H2O consisting of the [B10H10]2– anion and its monosubstituted derivative [2-B10H9OH]2– cocrystallized in the 0.83:0.17 ratio. The metal-promoted process of exopolyhedral substitution of terminal hydrogen atoms in the [B10H10]2¬ anion in the presence of Cu(II) compounds has been discussed. Complexes synthesized have been studied by elemental analysis, IR, 1H and 11B NMR spectroscopy; the X-ray diffraction studies were performed for [Cu2(bipy)4(µ-CO3)][B10H10]·2DMF·H2O and [Cu2(bipy)4(µ-CO3)][2-B10H10O0.17]·2DMSO·H2O. [ABSTRACT FROM AUTHOR]

A quartz crystal adsorbent coated with 5,10,15,20-tetrakis(4-methylphenyl) porphyrin was used to examine the complexation phenomenon of three metallic ions [aluminum(III), iron(III) and indium(III)]. The aim is to select the appropriate adsorbate for metalloporphyrin fabrication. The equilibrium adsorption isotherms of tetrakis(4-methylphenyl) porphyrin were performed at four temperatures (from 300 to 330 K) through the quartz crystal microbalance (QCM) method. Subsequently, the experimental data were analyzed in order to develop a thorough explanation of the complexation mechanisms. The experimental results indicated that the aluminum(III) chloride is the adequate material for metalloporphyrin application. Theoretical investigation was established through physics adsorption models in order to analyze the experimental isotherms. The AlCl3 isotherms were modeled via a single-layer adsorption model which is developed using the ideal gas law. Whereas, the FeCl3 isotherms were interpreted via a single-layer adsorption which includes the lateral interactions parameters (real gas law), indicating the lowest stability of the formed iron-porphyrin complex. The participation of the chloride ions in the double-layers adsorption of InCl3 was interpreted via layer by layer formulation. Interestingly, the physicochemical investigation of the three adopted models indicated that the tetrakis(4-methylphenyl) porphyrin adsorption was an endothermic process and that the aluminum(III) chloride can be recommended for an industrial application because it presents the highest adsorption energy (chemical bonds with porphyrins). [ABSTRACT FROM AUTHOR]

This study investigated the influence of tartaric acid (TA) on the early hydration of NaOH-activated ground-granulated blast-furnace slag (GGBS) paste. Early hydration process of the paste with or without TA was characterized by the hydration heat using an isothermal calorimeter. In addition, inductively coupled plasma spectroscopy, X-ray diffraction, Fourier transform IR spectroscopy and scanning electron microscopy analyses were used as auxiliary tests. The results reveal that TA has a significant retarding effect on the hydration of NaOH-activated GGBS paste, finally leading to the initial setting time increasing with increasing TA. The complexation reaction of Al rather than Ca is the main reason for the observed retardation effect. The Al-complexed carboxylate salts formed by the complexation reaction of Al inhibit the depolymerization of the Si–Al phase, which leads to extend the time for SiO32− and Al3+ to reach the saturation point in pore solution. And it subsequently delays the crystallization and nucleation of the main hydration products. However, TA has a little effect on the hydration products of NaOH-activated GGBS paste. The application of TA maintains the variety of main crystal products and the constant structure of gel products. The gel product still remains C–(A)–S–H with a primarily Q2 structure. Therefore, TA is an effective retarder for the NaOH-activated GGBS system. [ABSTRACT FROM AUTHOR]

• MBC@APTES-PAMAM exhibited higher adsorption capacity for the removal of Cu(II). • The maximum Cu(II) adsorption capacity of MBC@APTES-PAMAM was 251.81 mg/g. • External impact factors such as pH, competing ions, surfactant and humic acid greatly influenced Cu(II) adsorption process. • The adsorption mechanism of MBC@APTES-PAMAM for Cu(II) was elucidated. Cu (II) is one of the most harmful heavy metals in the environment, due to the hazardous effects to aquatic organisms, plants, animals, and human beings. In this work, a novel modified magnetic biochar (MBC@APTES-PAMAM) was prepared by PAMAM dendrimer for the removal of Cu (II). The analysis of structural properties identically demonstrated that the abundant -NH 2 groups were successfully loaded onto magnetic biochar surfaces. The sorption kinetics process of Cu (II) onto MBC@APTES-PAMAM was better fitted by the pseudo-second-order model. Langmuir isotherm model was better described for Cu (II) sorption process. MBC@APTES-PAMAM showed outstanding performances on Cu (II) removal, and the maximal adsorption amount was 251.81 mg/g. Adsorption experiment indicated that MBC@APTES-PAMAM had a higher Cu (II) removal efficiency under the pH range from 2 to 8. The adsorption capacity of Cu (II) onto MBC@APTES-PAMAM was decreased in the presence of competing ions. The existence of surfactant and humic acid had great influences on Cu (II) adsorption process. The Cu (II) adsorption mechanism was connected to the -NH 2 by complexation reaction, due to the increased electrostatic attraction and bridging influences. In addition, MBC@APTES-PAMAM also exhibited comparable removal performances for COD (70.82%), TN (71.10%), TP (100%), NH 3 N (55.03%) and Cu (II) (99.68%) in the practical treatment of landfill leachate. Overall, MBC@APTES-PAMAM is a green, low-cost, and high efficiency adsorbent for Cu (II) removal. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, the manganese oxide (HMO) modified from low-grade pyrolusite by the NaOH molten roasting and washing processes was used as a low-cost and efficient adsorbent for toxic metal removal. The HMO showed excellent selective sorption and regeneration for Pb2+. Furthermore, the equilibrium adsorption isotherm was well-fitted by Langmuir models. The adsorption process was described by the pseudo-secondary kinetics. Characterization results of X-ray diffraction, energy-dispersive X-ray spectroscopy, infrared, and X-ray photoelectron spectroscopy showed that Pb2+ adsorption by HMO mainly depended on complexation reaction between hydroxyl groups on the surface and Pb2+ from aqueous solution. [ABSTRACT FROM AUTHOR]

The quadratic autocatalytic reaction forms a key step in a number of chemical reaction systems, and traveling waves are observed in such systems. In this study, we investigate the effect of complexation reactions on traveling waves in the quadratic autocatalytic reaction system. More precisely, under the assumption that the complexation reaction is fast relative to the autocatalytic reaction, we show that the governing system is reduced to a two-component reaction-diffusion system with density-dependent diffusivity. Further, the numerical evidence suggests that for some parameter values, a traveling wave solution of this reduced two-component system is nonlinearly selected. This is contrast to that associated with the quadratic autocatalytic reaction (without complexation reactions). [ABSTRACT FROM AUTHOR]