Dried hybrid imogolite nanotubes as solids with a changeable surface area: an insight into textural properties based on the correlation between nitrogen gas adsorption, immersion calorimetry into water, and small angle X-ray scattering.

Powdered samples of three imogolite materials with an inner surface covered with Si-CH groups (hybrid IMO-CH) were prepared by ambient drying at 323 K, freeze drying, and spray drying. Reliable estimates of the intra-tube (), inter-tube (), and inter-bundle () specific surface areas of these samples were inferred from a model-guided correlation between the results of measurements by small angle X-ray scattering (SAXS), nitrogen gas adsorption, and immersion calorimetry into water. Since the SAXS studies indicated no significant deformations of IMO-CH nanotubes upon drying, further studies by gaseous N adsorption at 77 K indicated the intra-tube and inter-bundle specific surface areas as being only accessible to this adsorbate.

Renewing Interest in Zeolites as Adsorbents for Capture of Cationic Dyes from Aqueous and Ethanolic Solutions: A Simulation-Based Insight into the Efficiency of Dye Adsorption in View of Wastewater Treatment and Valorization of Post-Sorption Materials.

The impact of solvents on the efficiency of cationic dye adsorption from a solution onto protonated Faujasite-type zeolite (FAU-Y) was investigated in the prospect of supporting potential applications in wastewater treatment or in the preparation of building blocks for optical devices. The adsorption isotherms were experimentally determined for methylene blue (MB) and auramine O (AO) from single-component solutions in water and in ethanol. The limiting dye uptake (saturation capacity) was evaluated for each adsorption system, and it decreased in the order of MB-water > AO-water > AO-ethanol > MB-ethanol.

Influence of the Nanotube Morphology and Intercalated Species on the Sorption Properties of Hybrid Layered Vanadium Oxides: Application for Cesium Removal from Aqueous Streams.

The present paper examines the impact that the nanotube morphology and organic or inorganic intercalated species may have on the cesium sorption by layered vanadium oxides prepared with the use of hexadecylamine as a structure-directing agent. The hybrid material represented by a chemical formula of (VO)(VO)(CHN)(HO) was achieved through accelerated microwave-assisted synthesis carefully optimized to ensure the best compromise between the scroll-like morphology and the hydrophobic character. To enhance its dispersibility in water, this sample was subsequently modified by progressive replacement of the CHN units by NH cations.

Impact of Structural Functionalization, Pore Size, and Presence of Extra-Framework Ions on the Capture of Gaseous I by MOF Materials.

A computational approach is used on MOF materials to predict the structures showing the best performances for I adsorption as a function of the functionalization, the pore size, the presence of the compensating ions, and the flexibility on which to base future improvements in selected materials in view of their targeted application. Such an approach can be generalized for the adsorption of other gases or vapors. Following the results from the simulations, it was evidenced that the maximum capacity of I adsorption by MOF solids with longer organic moieties and larger pores could exceed that of previously tested materials.

A Critical Review of Solid Materials for Low-Temperature Thermochemical Storage of Solar Energy Based on Solid-Vapour Adsorption in View of Space Heating Uses.

The present report deals with low-temperature thermochemical storage for space heating, which is based on the principles of vapour adsorption onto solid adsorbents. With the aim of obtaining comprehensive information on the rationalized selection of adsorbents for heat storage in open sorption systems operating in the moist-air flow mode, various materials reported up to now in the literature are reviewed by referring strictly to the possible mechanisms of water vapour adsorption, as well as practical aspects of their preparation or their application under particular operating conditions. It seems reasonable to suggest that, on the basis of the current state-of-the-art, the adsorption phenomenon may be rather exploited in the auxiliary heating systems, which provide additional heat during winter's coldest days.

Microwave-assisted hydrothermal synthesis of manganate nanoflowers for selective retention of strontium.

An alternative microwave-assisted hydrothermal route for the preparation of manganate nanoflowers under basic conditions has been proposed in view of potential uses in selective retention of strontium from multicomponent aqueous streams. Based on the combination of such characterization techniques as Scanning and Transmission Electronic Microscopy, X-ray photoelectron spectroscopy, and X-ray Diffraction, as well as taking advantage of the computer-aided structure simulation, homogeneous nanoflower morphology possessing a layered structure and K compensating cations was evidenced as corresponding to the KMnO chemical formula. The nanoflower sample was subsequently tested for the selective adsorption of strontium and cesium by measuring the individual adsorption isotherms from single-solute and multicomponent aqueous solutions.

The effect of chelating anions on the retention of Co(II) by γ-alumina from aqueous solutions under the unadjusted pH condition of supported catalyst preparation.

This study analyzes the effect of the addition of acetate, citrate, and nitrilotriacetate anions on the retention of Co(II) cations by the γ-alumina surface in view of the preparation of alumina supported cobalt catalysts. The emphasis was placed on the way the Co(II) species attach to the solid surface when adsorbed from aqueous solutions under the unadjusted pH condition. The individual adsorption isotherms onto γ-AlO support for cobalt and a given ligand were determined by following the solution depletion method in single-solute and bi-solute systems.

Recent developments in nanostructured inorganic materials for sorption of cesium and strontium: Synthesis and shaping, sorption capacity, mechanisms, and selectivity-A review.

Liquid wastes containing non-ferrous heavy metal ions and some radionuclides, Cs and Sr in particular, represent one of the most dangerous sources of environmental contamination. The remediation of wastewater containing such pollutants continue to be among the biggest challenges of Sustainable Development and Environmental Safety. Sorption-based technologies have proven their efficiency also in reducing the radionuclide content in aqueous streams to low-level residual activity, with the concomitant decrease in the amount of ultimate solid waste generated.

On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution.

Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium.

What are the main contributions to the total enthalpy of displacement accompanying the adsorption of some multivalent metals at the silica-electrolyte interface?

The integral molar enthalpies of displacement, Δdplh, accompanying adsorption of Mg(II), Ca(II), Sr(II), Ba(II), Cd(II), Co(II), Zn(II), and Eu(III) cations from aqueous solutions of metal nitrate onto Spherosil XO75LS at 298K were determined based on the combination of liquid flow calorimetry and classical adsorption for two degrees of surface coverage: 0.035μmolm(-2) and 0.08μmolm(-2), in the presence of 0.

Driving force for the hydration of the swelling clays: case of montmorillonites saturated with alkaline-earth cations.

Important structural modifications occur in swelling clays upon water adsorption. The multi-scale evolution of the swelling clay structure is usually evidenced by various experimental techniques. However, the driving force behind such phenomena is still not thoroughly understood.

Bulk hydrolysis and solid-liquid sorption of heavy metals in multi-component aqueous suspensions containing porous inorganic solids: are these mechanisms competitive or cooperative?

Fundamental aspects of the removal of heavy metals from aqueous streams under conditions of competition among the various species have been studied between pH 3 and 9 on Spherosil XO75LS, ordered mesoporous MCM-41 and MCF silicas, as well as a MCF sample grafted with (3-aminopropyl)methoxydimethylsilane (AMPS-MCF). Cd(II), Co(II), Pb(II), or Sr(II) nitrate solutions were used to determine the percentage of metal uptake by each solid at 298 K as a function of the pH of the equilibrium solution, at an initial metal concentration of 0.0001 mol L(-1) and the ionic strength being fixed with 0.

Benzalkonium chloride and sulfamethoxazole adsorption onto natural clinoptilolite: effect of time, ionic strength, pH and temperature.

The influence of different physical factors on the adsorption of the cationic surfactant benzalkonium chloride (BC) and the model drug sulfamethoxazole by a purified natural clinoptilolite (NZ) has been studied in order to employ zeolite-surfactant-drug composites as drug deliverer. It has been demonstrated that the adsorption of BC and sulfamethoxazole onto NZ depends of the time, the temperature, the ionic strength and the pH of the aqueous medium. The optimal conditions for the preparation of the zeolite-surfactant and zeolite-surfactant-drug composite materials are established.

Competitive interactions between components in surfactant-cosurfactant-additive systems.

Complex interactions of phenol (PhOH), heptanol (HeOH) and heptanoic acid (HeOIC) with micellar aggregates of hexadecyltrimethylammonium bromide (HTAB) in aqueous solutions at surfactant concentrations close to the CMC, HeOH or HeOIC content of 0.5 mmol kg(-1), and phenol molality of 1, 5, or 10 mmol kg(-1) have been investigated at 303 K by means of (1)H NMR spectroscopy, titration calorimetry and solution conductimetry. The analysis of the composition-dependence of the (1)H chemical shifts assigned to selected protons in the surfactant and additive units revealed the location of PhOH both within the hydrophobic micelle core and in the vicinity of the quaternary ammonium groups, the phenol penetration being somewhat deeper in the presence of HeOIC.

Adsolubilization of drugs onto natural clinoptilolite modified by adsorption of cationic surfactants.

The combined adsorption onto purified natural clinoptilolite (NZ) of the cationic surfactant benzalkonium chloride (BC) and the model drugs metronidazole and sulfamethoxazole has been studied in order to design systems for the storage and release of drugs. The equilibrium adsorption of benzyldimethylalkylammonium chloride surfactants with hydrocarbon chain lengths corresponding to 12, 14 and 16 carbon atoms (BC12, BC14 and BC16) onto NZ from aqueous solutions was compared to that of BC. The effect of exchangeable cations on the NZ structure and that of acid-base pre-treatment of NZ on the adsorption capacity of BC was evaluated.

Competitive solubilization of phenol by cationic surfactant micelles in the range of low additive and surfactant concentrations.

Competitive interactions of phenol (PhOH) with micellar aggregates of hexadecyltrimethylammonium bromide (HTAB) against 1-butanol (BuOH) in aqueous solutions at surfactant concentrations close to the critical micelle concentration (CMC), BuOH concentration of 0.5 mmol kg(-1), and phenol contents of 1, 5, or 10 mmol kg(-1) have been investigated at 303 K by means of (1)H NMR spectroscopy, titration calorimetry, and solution conductimetry. The solubilization loci for phenol were deduced from the composition-dependence of the (1)H chemical shifts assigned to various protons in the surfactant and additive units.

Contribution of 1H NMR to the investigation of the adsorption of cationic Gemini surfactants with oligooxyethylene spacer group onto silica.

The present study aims to investigate the behavior of a series of cationic Gemini surfactants with a hydrophilic spacer at liquid-gas and solid-liquid interfaces, with particular emphasis on the effect of spacer length. Gemini surfactants containing two quaternary ammonium groups bound by an ethylene oxide spacer chain, referred to as 12-EO(x)-12 with x = 1,3,7 and 12 were synthesized. Surface tension measurements were used to show that the hydrophilic spacer with oxyethylene moieties was not fully extended at the air-water interface.

Interactions of phenol with cationic micelles of hexadecyltrimethylammonium bromide studied by titration calorimetry, conductimetry, and 1H NMR in the range of low additive and surfactant concentrations.

Interactions of phenol (PhOH) with micellar aggregates of hexadecyltrimethylammonium bromide (HTAB) in aqueous solutions at surfactant concentrations close to the CMC and phenol contents of 1, 5, or 10 mmol kg(-1) have been investigated at 303 K by means of titration calorimetry, solution conductimetry, and (1)H NMR spectroscopy. Estimates of the main thermodynamic parameters related to HTAB micellization were made for PhOH/HTAB/H(2)O systems based on the specific conductivity measurements and calorimetric determination of the cumulative enthalpy of dilution as functions of the surfactant concentration at a fixed additive content. The combined analysis of the results obtained in H(2)O solutions pointed to the preferential location of PhOH in the outer micelle parts by an enthalpy-driven mechanism.

Copper-containing monodisperse mesoporous silica nanospheres by a smart one-step approach.

Copper-containing mesoporous silica spheres of size in the colloidal range with perfect conservation of pore-ordering, shape and monodispersity and high intra-pore metal dispersion were prepared via a new one-step synthesis and functionalisation route.