Thermodynamic evidences for the formation of tri-block copolymer/surfactant nanostructures in water

Adsorption of a dye on clay and sand. Use of cyclodextrins as solubility-enhancement agents.

Abstract Laboratory-scale studies were aimed at elucidating the physico-chemical aspects on the removal process of crystal violet (CV) from waters and solid substrates. The laponite clay (RD) and sand were chosen for the double aim at investigating them as CV adsorbents for water treatment and as substrates which mime the soil components. Sand is very effective in removing CV from waters. The cyclodextrins (CDs) were exploited as solubility-enhancement agents to remove CV from the solid substrates. They are powerful solvent media because they extract the CV from sand forming water-soluble CV/CD inclusion complexes and do not show affinity for sand. Optimum performance was shown by the modif…

Calorimetric and Volumetric Investigations of the Effect of the Hydrophobicity of the Surfactant on the Binding between (Ethylene oxide)13-(propylene oxide)30-(ethylene oxide)13 and Sodium Alkanoates in Aqueous Solutions

The enthalpy and the volume of transfer (DeltaY(t)) of the unassociated (ethylene oxide)(13)-(propylene oxide)(30)-(ethylene oxide)(13) (L64) from water to the aqueous sodium alkanoate solutions as functions of the surfactant concentrations (m(S)) were determined at 298 K. The surfactants studied are sodium hexanoate, sodium heptanoate, sodium octanoate, sodium undecanoate, and sodium dodecanoate. As a general feature, for the short alkyl chain surfactants, DeltaY(t) describes an S-shaped curve in the range of m(S) analyzed whereas for the more hydrophobic surfactants the DeltaY(t) vs m(S) trends exhibit maxima which appear at ms values very close to the critical micellar concentration in w…

Binding between (Ethylene Oxide)13−(Propylene Oxide)30−(Ethylene Oxide)13 and Sodium Decanoate. Volume, Enthalpy, and Heat Capacity Studies

Volume, enthalpy, and heat capacity of transfer (ΔYt) of (ethylene oxide)13−(propylene oxide)30−(ethylene oxide)13 (L64), at some concentrations, from water to the aqueous sodium decanoate (NaDec) solutions as functions of the surfactant concentration (mS) were determined at 298 K. The copolymer was studied in both the unassociated and associated forms. For a given L64 concentration (mC), the ΔYt vs mS profiles for the volume and the enthalpy are equal but different from that of the heat capacity because the latter contains also the relaxation terms. The experimental data were analyzed by assuming the distribution of L64 between the aqueous and the micellar phases and the shift of micelliza…

Thermodynamics of cyclodextrin-surfactant interactions. Volume Enthalpy and Heat Capacity Studies

Cyclodextrins as Solubility-Enhancement Agents for Contaminant Removal from Solid Substrates

IL RESTAURO DEL BOZZETTO SCULTOREO DEL CARRO DI SAN ROCCO DI PIETRO CONSAGRA. UNO STUDIO SUL COMPORTAMENTO CHIMICO-FISICO DI LEGANTI PITTORICI IMPIEGATI NELL’ARTE CONTEMPORANEA

Composite Aggregates of Tri-block Copolymers and Laponite in Aqueous Media. The Role Played by the Copolymer and their Ability to Solubilise Additives

Lead(II) ions adsorption onto amyloid particulates: An in depth study

The production of new cost-effective biocompatible sorbent sustainable materials, with natural origins, able to remove heavy metals from water resources is nowadays highly desirable in order to reduce pollution and increase clean water availability. In this context, self-assembled protein materials with amyloid structures seem to have a great potential as natural platform for a broader development of highly-tunable structures. In this work we show how protein particulates, a generic form of protein aggregates, with spherical micro sized shape can be used as adsorbents of Pb2+ ions from aqueous solution. The effect of pH, ionic medium, ionic strength and temperature of the metal ion solution…

Heat Capacity of Transfer of (Ethylene oxide)13-(propylene oxide)30-(ethylene oxide)13 from Water to the Aqueous Anionic Surfactant Solutions at 298 K. A Quantitative Treatment

Heat capacities of transfer (ACpt) of unimeric (ethylene oxide)(13)-(propylene oxide)(30)-(ethylene oxide)(13) from water to the aqueous surfactant solutions as functions of the surfactant concentrations (m(S)) were determined at 298 K. The surfactants investigated are sodium hexanoate, sodium heptanoate, sodium octanoate, sodium undecanoate, and sodium dodecanoate. For short alkyl chain surfactants, the profiles of the DeltaCp(t) versus ms curves show maxima and minima; for long alkyl chain surfactants, the maximum becomes sharper and moved to lower ms values whereas the minimum tends to disappear. These experimental trends are different from those of the enthalpy in agreement with the fac…

3D MICROSIZED PROTEIN AMYLOID PARTICULATES AS EFFECTIVE BIOADSORBERS FOR Pb2+ IONS

The production of new cost-effective biocompatible sorbent sustainable materials, with natural origins, able to remove heavy metals from water resources is nowadays highly desirable in order to reduce pollution and increase clean water availability. In this context, self-assembled protein materials with highly ordered amyloid structures, stabilised by H-bonds, seems to have a great potential as natural platform for a broader development of highly-tunable structures. By suitably varying solution conditions it is possible to tune aggregate size, surface area and morphologies as well as their physicochemical (hydrophobicity, hydrophilicity, swelling/deswelling properties) and mechanical proper…

A specific operative protocol set up during the restoration of the Grammichele's slate slab

Il cammino del sole, gli spazi del giorno. Piano urbanistico del comune di Grammichele (CT) su lastra di ardesia dipinta

Kinetic and equilibrium studies for uranyl removal from aqueous solution by adsorption onto alginate gel beads. DPV and ICP measurements

Effect of short homopolymer on structure and gelation of aqueous laponite dispersions

Aggregation of triblock copolymers in water induced by chlorinated oils

A thermodynamic study to evidence the alpha,omega-dichloroalkane/ block copolymer mixed aggregates formation: effect of the copolymer architecture.

Abstract The thermodynamics of α , ω -dichloroalkanes in aqueous solutions of (ethylene oxide)11(propylene oxide)16(ethylene oxide)11 (L35) and (propylene oxide)8(ethylene oxide)23(propylene oxide)8 (10R5) was determined at 298 and 305 K. Modeling the experimental data allowed to calculate the standard free energy ( Δ G D o / w ) and the volume ( Δ V D / w ) for the additive–copolymer mixed aggregates formation per additive molecule. Δ G D o / w for Cl2CH2 and Cl2(CH2)2 evidenced that the process is controlled by the forces exercising between the chlorine atoms and the OH groups of the copolymer micelles protruded into the aqueous phase. Cl2(CH2)3 experiences both the hydrophilic and hydrop…

Thermodynamics of Aqueous Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide)/Surfactant Mixtures. Effect of the Copolymer Molecular Weight and the Surfactant Alkyl Chain Length

A calorimetric study was performed to focus attention on the interactions between copolymers and anionic surfactants in aqueous solutions. Three aspects were analyzed: (1) the hydrophobicity of the surfactant, (2) the change of the copolymer molecular weight, and (3) the nature of the hydrophilicity of the copolymer. To this purpose, the family of sodium alkanoates (sodium octanoate through sodium dodecanoate) and the triblock copolymers EO76PO 29EO76 (F68), EO103PO39EO 103 and EO132PO50EO132 were investigated. Comparing F68 and EO13PO30EO13 (L64), previously studied by us, provided information on the effect of the copolymer hydrophilicity. The experimental data were analyzed by means of a …

Binding of Short Alkyl Chain Surfactants to the (Ethylene oxide)13−(Propylene oxide)30−(Ethylene oxide)13and (Ethylene oxide)75−(Propylene oxide)30−(Ethylene oxide)75Copolymers Studied by Microcalorimetry

The enthalpy of transfer (ΔHt) of neutral copolymers, at a fixed and low concentration ca. 10-3 mol kg-1, from water to the aqueous surfactant solutions as a function of the surfactant concentration (fSmS) was determined at 25 °C. The surfactants studied are sodium octanoate, sodium decanoate, N-octylpyridinium chloride (OPC), and N,N-dimethyloctylamine-N-oxide (ODAO). The copolymers are (ethylene oxide)13−(propylene oxide)30−(ethylene oxide)13 (L64) and (ethylene oxide)75−(propylene oxide)30−(ethylene oxide)75 (F68). The two copolymers show different hydrophilic−hydrophobic ratios, the larger being for F68. As a general feature, the shape of the ΔHt vs fSmS curve depends on the nature of t…

LEAD(II) AND CADMIUM(II) REMOVAL FROM AQUEOUS SOLUTIONS USING HAZELNUT AND ALMOND SHELLS SORBENT MATERIALS

Removal of toxic metal ions from natural and waste waters is of great importance for the health of living organisms and for environmental protection. Alternatively to the conventional chemical treatments, such as precipitation, reverse osmosis, etc, biosorption shows a growing interest for toxic metal ions removal from contaminated aqueous solutions. The sorption ability of every type of biomass towards metal ions depends on many variables that characterize the solution. Among these, the ionic strength (I) is one of the most important and cannot be neglected during an accurate adsorption study. For this reason and with the aim of quantitatively define the influence of I, here are reported t…

Thermodynamic Behavior of Non-Ionic Tri-block Copolymers in Water at Three Temperatures

Apparent molar volumes (V Φ) of aqueous solutions of some copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, were determined as functions of concentration at three temperatures. Viscosity measurements were also carried out on some of these systems. The effects studied include how the molecular architecture and the molecular weight affect the aggregation of the copolymer, keeping constant the EO/PO ratio. Modeling of the volumetric data yielded the partial molar volume of the copolymer in the standard (V°) and the aggregated (V M) states, as well as the equilibrium constant for micellization and the aggregation number. Analysis of the viscosity data supported the insigh…

Volumes of aqueous block copolymers based on poly(propylene oxides) and poly(ethylene oxides) in a large temperature range: A quantitative description

The focus of this paper was on a quantitative comprehension of temperature effect on the volumes of aqueous di-block and triblock copolymers, based on propylene oxide (PO) and ethylene oxide (EO) units. To this purpose, literature data dealing with (EO316PO94 + water) and (EO13PO30EO13 + water) mixtures were analyzed. The volume vs. temperature trends were rationalized on the basis of the (unimers + aggregate) equilibrium by taking into account the temperature effect on both the partial molar volumes of the unimeric and the aggregated copolymer as well as the equilibrium constant of micellization. The analysis extended to the expansibility allowed to quantify the contribution for the shift …

Gelation Dynamics of Laponite Hydrogels in Presence of Tri-block Copolymers and their Homopolymers: a Rheological and Dynamic Light Scattering Study

Incorporation of Nitropropane in Copolymer and Copolymer-Surfactant Aggregates. A Volume, Viscosity and Differential Scanning Calorimetry Study

Prodrug based on halloysite delivery systems to improve the antitumor ability of methotrexate in leukemia cell lines

The prodrug approach, as well as the development of specific systems able to deliver a chemotherapeutic agent in the target site, decreasing the side effects often associated with its administration, are still a challenging. In this context, both methotrexate drug molecules (MTX) and biotin ligand moieties, whose receptors are overexpressed on the surface of several cancer cells, were loaded on halloysite nanotubes (HNTs) to develop nanomaterial based on multifunctional and "smart" delivery systems. To highlight the crucial role played by biotin, carrier systems based on HNTs and MTX were also synthetized. In detail, several approaches were envisaged: i) a supramolecular interaction between…

Study and evaluation of nano-structured cellulose fibers as additive for restoration of historical mortars and plasters

Abstract UPM bio-fibrils are nano-structured cellulose fibers (nano-fibrils) produced by UPM Kymmene-Corporation, a Finnish company. This paper reports a preliminary study about nano-fibrils to determine their possible use for restoration of historical mortars and plasters. The aim of this study is to investigate the behavior of some mixtures added with nano-fibrils in their properties for conservative purposes. These mixtures reproduce the composition of historical mortars and plasters, made of natural hydraulic lime (NHL 3.5) and river sand. After 28 days of hardening, the properties of specimens with nano-fibrils were compared with untreated one to understand how nano-fibrils interact wi…

Effect of Block Copolymers and their Homopolymers on the Gelation Kinetics of Aqueous Laponite Dipsersions. Rheology and Dynamic Light Scattering Studies

Aqueous nonionic copolymer-functionalized laponite clay. A thermodynamic and spectrophotometric study to characterize its behavior toward an organic material.

The affinity of functionalized Laponite clay toward an organic material in the aqueous phase was explored. Functionalization was performed by using triblock copolymers based on ethylene oxide (EO) and propylene oxide (PO) units that are EO(11)PO(16)EO(11) (L35) and PO(8)EO(23)PO(8) (10R5). Phenol (PhOH) was chosen as organic compound, which represents a contaminant prototype. To this purpose, densities and enthalpies of mixing as well as PhOH UV-absorption spectra were determined. The enthalpy and the spectrophotometry revealed PhOH-Laponite interactions whereas the volume did not. It emerged that the area occupied by PhOH on the Laponite surface is equal to that computed from the partial m…

A specific operative protocol set up during the restoration of the Grammichele slate slab

This work deals with the conservation of a slate slab, representing the map of Grammichele, a small town in the hinterland of South Eastern Sicily. The slab was engraved and painted in 1693, just after the tremendous earthquake that distroyed most of the towns in that area. The conservation process is illustrated through three steps: i) archive research; ii) physical chemical analysis of constitutive materials and degradation products; iii) planning and carrying out of the restoration and conservation operations.

Temperature and Solvent effect on the Cyclodextrin-Triblock Copolymers Pseudo-Polyrotaxanes Formation

Laponite clay in homopolymer and tri-block copolymer matrices

Macromolecule/laponite nanomaterials were studied by DSC and X-ray diffraction techniques. The matrices are poly(ethylene) glycols at various molecular masses and poly(ethylene oxides)-poly(propylene oxides)-poly(ethylene oxides) tri-block copolymers. The latter were tuned by modulating the molecular masses, at constant hydrophilic/hydrophobic ratio, and the hydrophilicity. For all the investigated systems, the enthalpy of melting (ΔH m) is nearly constant up to a given composition thereafter it increases monotonically reaching the value of the pure macromolecule. We proposed a model to interpret the DSC data. Briefly, it was invoked a mechanism of interaction following which some segments …

Study for Designing Novel Gels to Clean an Aged Varnish on a Stone Painted Work of Art: DSC, FT-IR and Viscosity Analysis

A thermodynamic study to evidence interactions between tri-block copolymers and conventional surfactant

Enhancement of adsorption ability of calcium alginate gel beads towards Pd(II) ion. A kinetic and equilibrium study on hybrid Laponite and Montmorillonite–alginate gel beads

Abstract The adsorption ability of hybrid Montmorillonite and Laponite–calcium alginate gel beads towards Pd 2 + ion was studied in the pH range 2–4, in pure water and in aqueous NaCl solution at I = 0.01 mol L − 1 and T = 25 °C. The pseudo second order kinetic equation and the Langmuir and Freundlich isotherms were used to fit the kinetic and thermodynamic experimental data. A comparison of the results already published on the adsorption capacity of calcium alginate gel beads at the same experimental conditions was made. Enhancement of palladium(II) adsorption by alginate beads with the addition of the two clay minerals was obtained, with increments higher than 50% of Pd(II) ion recovered/…

Thermodynamic and Structural Characterization of Copolymer Functionalized Nanosized Particles

Aqueous Block Copolymer-Surfactant Aggregates: Tools to Solubilize Organic Compounds. Thermodynamic and Structural Investigations

Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn2+ at Different Ionic Strengths and Temperatures

The acid&ndash

Interactions of native and modified cyclodextrins with some biologically active pyridine derivatives.

Activated Biochar From Posidonia Oceanica. A New Adsorbent Material of Hydrocarbons from Wastewater

Environmental pollution by petroleum derivatives is a very current topic. In particular, low concentration of this kind of pollutants can seriously compromise the life of animals and plants of aquatic ecosystems (Yu, 2017). The current legislation provides that bilgewater, wastewater produced by boats, can be discharged directly into the sea only if the total hydrocarbon concentration not exceds 15 mg L-1. In this work, new activated carbons were tested as adsorbent materials of oil / hydrocarbons from wastewater. Moreover, an instrumental technique able to quickly measure the required low hydrocarbons concentration is also proposed. The new activated carbons were obtained from bio-oil prod…

Phenol in Aqueous Mixtures Composed by Pluronic Copolymer and Laponite Clay. A Calorimetric and Spectrophotometric Study

Aggregation of Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) Copolymers in Water at Some Temperatures. Volumetric and viscosimetric studies

Solubilisation of Chlorinated oils in triblock copolymers-surfactant mixed aggregates

HYDROCARBONS REMOVAL FROM BILGE WATER BY ADSORPTION ONTO ACTIVATED BIOCHAR FROM POSIDONIA OCEANICA

The normal operations carried out on the boats during navigation generate waste waters such as oily bilge water. The latter is the aqueous mixture of potential pollutants of different origins and types: oily fluids, lubricants and greases, cleaning fluids and other wastes that accumulate in the lower part of the vessel [1,2]. The current legislation provides that they can be discharge directly into the sea if the concentrations of some components are below the expected limits. In particular, with regard to oil / hydrocarbons contamination, the current regulatory limit is 15 mg L-1 of total hydrocarbons. The present work starts from a public/private partnership funded by a grant of the Minis…

Calorimetric, FT-IR and Viscosity Investigations to Designnovel Cleaning Agents for Removing Linseed Oil Based Varnish

Solubilization of Dichloroalkanes in Aqueous Tri-Block Copolymers Solutions. Thermodynamic and Structural Studies

A Volumetric and Calorimetric Study on Interactions Occurring Between Cyclodextrins and Nicotinic Acid in Aqueous Solution.

Sequestering ability of landfill leachate towards toxic metal ions

The great part of municipal solid wastes is worldwide stored in sanitary landfills. The interaction of organic and inorganic wastes with rainwater produces in the landfill a leachate of extremely variable composition. It depends on several variables such as the type of wastes, the age of landfill, the pH, the redox potential, etc [1-2]. Four are the recognized categories of pollutants in landfill leachate: inorganic macrocomponents, dissolved organic matter (DOM), heavy metals and xenobiotic organic compounds [3]. In particular, heavy metals (arsenic, cadmium, copper, lead, mercury, etc.) are usually present at concentration of few ppb and up to some ppm. A variable but consistent fraction …

Kinetics of Gelation of Aqueous Laponite Dispersions in the Presence of Tri-blockCopolymers and their Homopolymers. Rheological and Dynamic Light Scattering Studies

Cyclodextrin-Macromolecule Interactions. Volumetric and Calorimetric Investigations

Functionalized halloysite nanotubes for enhanced removal of lead(II) ions from aqueous solutions

In this study, environmental friendly halloysite nanotubes and their amino derivatives were used as adsorbent materials for lead(II) ions. The adsorption ability of both nanomaterials towards Pb2+ ions has been studied in NaClaq, at I = 0.1 mol L−1, in the pH range 3–6. Moreover, the effect of ionic strength on the adsorption process was evaluated at the pH of maximum efficiency of the adsorbent materials. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique to check the metal ion concentration in solution after contact with the two adsorbents. Different isotherm and kinetic equations were used to fit the experi…

Issues Related to the Restoration of Mirrors of the Wooden paliotto della chiesa del Santissimo Crocifisso all’Albergheria, Sicily (Italy)

ABSTRACTIn this work, the decision-making process involved in the restoration of the eighteenth century paliotto ligneo (wooden altar frontal) della chiesa del Santissimo Crocifisso all’Albergheria of Palermo is presented. Earlier research concerning mirror restoration was based on only a few case studies and the proposed techniques were not suitable for the artwork here. As a consequence, it was necessary to re-examine theories and protocols of modern restoration to plan an appropriate intervention of the altar frontal. Since in this artwork the role of mirrors is not to give back images, as usual, but rather to create special light effects and play of lights, this work aims to find an app…

Aqueous block copolymer-surfactant mixtures and their ability in solubilizing chlorinated organic compounds. A thermodynamic and SANS study.

Within the topic of surfactant enhanced solubilization of additives sparingly soluble in water, volumetric, solubility, conductivity, and small-angle neutron scattering (SANS) experiments on mixtures composed of alpha,omega-dichloroalkane, surfactant, copolymer, and water were carried out at 298 K. The triblock copolymers (ethylene oxide)132(propylene oxide)50(ethylene oxide)132 (F108) and (ethylene oxide)76(propylene oxide)29(ethylene oxide)76 (F68) were chosen to investigate the role of the molecular weight keeping constant the hydrophilic/hydrophobic ratio. The selected surfactants are sodium decanoate (NaDec) and decyltrimethylammonium bromide (DeTAB) with comparable hydrophobicity and …

Laponite Clay Dispersed in Polymeric Matrices. DSC and Structural Studies

Acid-base properties and sequestering abilities towards toxic metal ions of cyclodextrin-calixarene co-polymers

Smart materials with stimuli-responsive properties represent an interesting research area considering both their potential applications and the conceptual issues implied. They might be successfully employed in various fields, such as drug carrier/delivery devices to sensors, environment remediation, active packaging [1-2]. In this contest, we have recently synthesized various pH-responsive pre- and post-modified cyclodextrin-calixarene nanosponges (CyCaNSs) with 1,2,3-triazole linker units (ACNSs) able to vary their sequestering abilities towards organic and inorganic compounds. In particular, their adsorption properties were varied changing the molar ratio between the co-monomers, and the …

Oil solubilization in copolymer and copolymer covered laponite aqueous dispersion

Solubilization of an Organic Solute in Aqueous Solutions of Unimeric Block Copolymers and Their Mixtures with Monomeric Surfactant: Volume, Surface Tension, Differential Scanning Calorimetry, Viscosity, and Fluorescence Spectroscopy Studies

The ability of aqueous systems, formed by unimeric copolymers and their mixtures with a monomeric surfactant, in solubilizing large quantities of 1-nitropropane (PrNO2) was explored. The copolymers are F68 and L64, which differ for the hydrophilicity, and the surfactant is sodium dodecanoate. For a better understanding of the mechanism of solubilization, thermodynamic (volume and differential scanning calorimetry), spectroscopy (steady-state fluorescence), viscosity, and interfacial investigations were carried out. PrNO2 causes the micellization of the unimeric copolymer, and the required amount of PrNO2 depends on the composition, the copolymer nature, and the temperature. Large quantities…

Nanostructured systems functional to the recover and conservation of cultural heritage

Thermodynamics of adsorption of low and high molecular weight surfactants onto polystyrene nanoparticles

Polystyrene nanoparticles in the presence of (ethylene oxide)13(propylene oxide)30(ethylene oxide)13, N,N-dimethyloctylamine-N-oxide and their mixtures. A calorimetric and dynamic light scattering study

Polystyrene nanoparticles were synthesized by emulsion polymerization of styrene. They were functionalized using the conventional surfactant N,N-dimethyloctylamine-N-oxide (ODAO), the tri-block copolymer (ethylene oxide)13(propylene oxide)30(ethylene oxide)13 (L64) and their mixtures. To this purpose, dynamic light scattering and calorimetric experiments were carried out and provided information consistent to each other. The L64 adsorption is Langmuir-type in the copolymer dilute regime and generates complex structures at larger concentrations. In the region where ODAO is in the unimeric state, the adsorption process is cooperative leading to hemi-micelle formation at the polystyrene nanopa…

Mass Action Model Applied to the Thermodynamic Properties of Transfer of Nonionic Copolymers from Water to the Aqueous Surfactant Solutions

A thermodynamic model which enables the properties of aqueous copolymer/surfactant mixtures to be fit quantitatively was proposed. Namely, a relationship between the properties of transfer of the unassociated copolymer from water to the aqueous surfactant solutions (DeltaY(t)) and the surfactant concentration was derived. The model was based on the idea that AY, can be expressed in terms of the following contributions: (1) interaction between monomers of copolymer and surfactant, (2) displacement of the monomer-micelle equilibrium induced by the copolymer, (3) formation of the surfactant-copolymer aggregation complex, and (4) formation of the mixed micelles. Such a model was applied to most…

Solubilization of Nitropropane in Copolymer and Surfactant-Copolymer Aggregates

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide ( PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They …

Aggregates of Triblock Copolymers and Triblock Copolymer-Surfactant Functional to the Solubilization of Chlorinated Oils. A Thermodynamic Study

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica.

AbstractBilge waters are wastewaters produced on boats during navigation and usually contain hydrocarbons and oils. They cannot be directly released into the sea if not below a hydrocarbons concentration limit set by current legislation. Appropriate oil in water separator (OWS) systems can be installed on board boats to remove hydrocarbons from bilge water allowing their spillage into the sea. These systems may contain an adsorption step on a suitable adsorbent. Here, biochars produced from pyrolysis of dead Posidonia oceanica, pristine or chemically activated, have been tested as hydrocarbons adsorbents. Adsorption experiments with aqueous dispersions simulating bilge waters containing a m…

Thermodynamic Studies to Evidence Block Copolymer-Surfactant Interactions

Thermodynamics of Surfactant, Block Copolymer and Their Mixtures in Water: The Role of the Isothermal Calorimetry

The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van't Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van't Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the …

Tuning the Gelation of Aqueous Laponite Dispersions by means of Block Copolymers and their Homopolymers

Solid/liquid interface. Interaction between polystyrene nanoparticles and amphiphilic additives

Sustainable soy protein microsponges for efficient removal of lead (II) from aqueous environments

Protein-based materials recently emerged as good candidates for water cleaning applications, due to the large availability of the constituent material, their biocompatibility and the ease of preparation. In this work, new adsorbent biomaterials were created from Soy Protein Isolate (SPI) in aqueous solution using a simple environmentally friendly procedure. Protein microsponge-like structures were produced and characterized by means of spectroscopy and fluorescence microscopy methods. The efficiency of these structures in removing Pb2+ ions from aqueous solutions was evaluated by investigating the adsorption mechanisms. The molecular structure and, consequently, the physico-chemical propert…

A physico-chemical study to evidence nano-structured systems formed by triblock copolymers

Heat capacities and volumes of suspensions in the presence of surfactants

Abstract Density and heat capacity measurements of water–surfactant–silica ternary systems were carried out as functions of the silica and the surfactant concentrations at 298 K. From these properties, the apparent molar volume and heat capacity of the surfactant in a given water+silica mixture were evaluated. As well, the apparent specific volume and heat capacity of silica, at a given concentration, in the water+surfactant mixtures as functions of the surfactant concentration were calculated. Some surfactants (decyltrimethylammonium bromide, sodium octanoate, sodium decanoate, sodium dodecanoate, sodium decylsulfate, sodium perfluorooctanoate and N , N -dimethyldodecylamine- N -oxide) wer…

A Thermodynamic Model for the Properties of Transfer of Non-ionic Copolymers from water to the aqueous Surfactant Solution. Effect of the Copolymer Molecular Weight and the Surfactant Hydrophobicity

Experimental and robust modeling approach for lead(II) uptake by alginate gel beads: influence of the ionic strength and medium composition.

Abstract Systematic kinetic and equilibrium studies on the lead ions removal ability by Ca-alginate gel beads have been performed by varying several internal parameters, namely, number of gel beads, nature and composition of the ionic medium and pH, which allowed us to model a wastewater in order to closely reproduce the composition of a real sample. Moreover, the effects brought about the different ionic species present in the reacting medium have been evaluated. Differential Pulse Anodic Stripping Voltammetry (DP-ASV), has been systematically used to perform kinetic and equilibrium measurements over continuous time in a wide range of concentration. Kinetic and equilibrium data have been q…

Nanostructured Gels for the Conservation of a Slate Painted Work of Art

Solubilisation of chlorinated oils in triblock copolymers and triblock copolymer-surfactant mixed aggregates

Thermodynamic Characterization of Interactions of Cyclodextrins with Nicotinic Acid

The restoration of a painted stone work of art: study on altered protective layer

The Urban Map of the Grammichele City (Ct): Novel Gels Used for the Restoration of a Painted Stone Work Of Art

Triblock Copolymers/Laponite Nanostructures in Aqueous Media and their Solubilization Capability. Thermodynamic and Structural Study

Il paliotto architettonico ligneo del Museo Diocesano di Palermo. Studio e restauro

L'articolo pone l'attenzione su un buon numero di paliotti lignei della provincia di Messina, di Palermo e di Trapani, analizzando in particolare quello oggi conservato presso il Museo Diocesano di Palermo, proveniente dalla Chiesa del Santissimo Crocifisso all'Albergheria, da datare al primo quarto del Settecento, alla luce del recente restauro di cui si pubblicano i risultati. The article focuses on a number of wooden frontals of the province of Messina, Palermo and Trapani, analyzing in particular the one now at the Diocesan Museum of Palermo, from the Church of the Holy Cross at the Albergheria, dating from the first quarter of the eighteenth century, in the light of the recent restorat…

Calorimetric and Dynamic Light Scattering Characterization of Surfactant-Nanoparticle Interactions

Thermodynamic Evidence of Cyclodextrin−Micelle Interactions

The enthalpy of transfer (ΔHt) of hydroxypropyl-α-cyclodextrin (HP-α-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and β-cyclodextrin (β-CD) from water to the aqueous C6F13CO2Na and C7F15CO2Na solutions were determined in the pre- and post-micellar regions. The behavior of the macrocycles is system specific. Generally, the magnitude of the enthalpy is influenced by several factors:  (1) the alkyl chain length of the surfactant, (2) the cyclodextrin cavity and its alkylation, (3) the interactions between the free cyclodextrin and the free surfactant, (4) the host−guest equilibrium constant, (5) the host/guest stoichiometry, and (6) the micelle-cyclodextrin (free and/or complexed) interactions…

FUNCTIONALIZED HALLOYSITE NANOTUBES FOR ENHANCED REMOVAL OF Hg2+ IONS FROM AQUEOUS SOLUTIONS

AbstractWater is essential for humans, animals, and plants; pollutants, usually derived from anthropogenic activities, can have a serious effect on its quality. Heavy metals are significant pollutants and are often highly toxic to living organisms, even at very low concentrations. Among the numerous removal techniques proposed, adsorption onto suitable adsorbent materials is considered to be one of the most promising. The objective of the current study was to determine the effectiveness of halloysite nanotubes (HNT) functionalized with organic amino or thiol groups as adsorbent materials to decontaminate polluted waters, using the removal of Hg2+ ions, one of the most dangerous heavy metals…

Volumes and heat capacities of the aqueous sodium dodecanoate/sodium perfluorooctanoate mixtures in the presence of β-cyclodextrin

Apparent molar volumes (VΦ) and heat capacities (CΦ) of the sodium dodecanoate (NaL)/sodium perfluorooctanoate (NaPFO) mixtures in the water/β-cyclodextrin (β-CD) solvent as functions of the surfactant total molality (mt) were determined at 25°C. For a given surfactant mixture, VΦ decreases with mt to ca. 0.05 mol kg−1 thereafter it increases tending to a constant value. CΦ displays a behaviour opposite to VΦ. The mt values where the apparent molar properties exhibit extrema are nearly coincident with the critical micellar concentrations determined by conductivity. An equation correlating VΦ to mt was derived by assuming that the equilibria for the 1∶1 surfactant/cyclodextrin complex format…

Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.

The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strength range 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate …

A Calorimetric Investigation to Study the Effect of Polymers onto the Behaviour of Aqueous Laponite Concentrated Dispersions

Solubilization of an Organic Compound in Aqueous Solutions of Unimeric Block Copolymers and their Mixtures with Monomeric Surfactant. Volume, SANS, Surface Tension, DSC, Viscosity and Fluorescence Spectroscopy Studies

Volumetric and viscosimetric studies to probing the structure of nano-organized systems based on nonionic block copolymers at some temperatures

Thermodynamics of Micellization of Sodium Alkyl Sulfates in Water at High Temperature and Pressure

Apparent molar volumes VΦ,S were determined for sodium octyl, decyl, and dodecyl sulfates in water at 2 and 19 MPa from 25 to 130 °C. The shapes of VΦ,S vs the surfactant concentration curves depend on the surfactant alkyl chain, temperature and pressure. The standard partial molar volumes were calculated from data in the premicellar region whereas the partial molar volumes of the surfactant in the micellar phase were obtained from data in the postmicellar region. The partial molar expansibility and compressibility were evaluated from the dependence of the partial molar volume on temperature and pressure, respectively. Attention was focused to the expansibility and its pressure coefficient …

Aqueous Laponite Clay Dispersions in the Presence of Poly(ethylene oxide) or Poly(propylene oxide) Oligomers and their Triblock Copolymers

The effect of polyethylene oxide (PEO) or polypropylene oxide (PPO) oligomers of various molecular weight (Mw) as well as of triblock copolymers, based on PEO and PPO blocks, on aqueous laponite RD suspensions was studied with small-angle neutron scattering (SANS). The radius of gyration (RG) increases for low Mw whereas the opposite occurs for larger Mw. This behavior is explained on the-basis that an effective RG is given by two contributions: (1) the size of the particles coated with the polymer and (2) the interactions between the laponite RD particles which are attractive for small and repulsive for large polymers. The SANS curves in the whole Q-range are well described by a model of n…

A critical approach to the toxic metal ion removal by hazelnut and almond shells

The adsorption capacity of ground hazelnut (HS) and almond (AS) shells towards Pb(II) and Cd(II) has been studied at pH = 5, in NaNO3 and NaCl ionic media, in the ionic strength range 0.05-0.5 mol L-1. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry technique to check the amount of the metal ion removed by HS and AS materials. Different kinetic and equilibrium equations were used to fit experimental data and a statistical study was done to establish the suitable model for the data fitting. A speciation study of the metal ions in solution was also done in order to evaluate the influence of the ionic medium on the adsorption pr…

Volume and heat capacity studies to evidence interactions between cyclodextrins and nicotinic acid in water

Density and heat capacity of the water+cyclodextrin (CD), water+nicotinic acid (NA) and water+CD+NA mixtures were determined at 298.15 K. CDs with different cavity size and alkylation were selected. From the experimental data the apparent molar properties were calculated. Assuming the formation of inclusion complexes of 1:1 stoichiometry, these properties were modeled and provided the stability constants of CD/NA inclusion complexes and the corresponding property change. The binding of NA with the smallest sized alpha-cyclodextrin (alpha-CD) generates more stable complexes accompanied by the lower volume and the heat capacity changes. These results are in agreement with earlier proposed bin…

Characterization of the Cyclodextrin−Surfactant Interactions by Volume and Enthalpy

Volume and enthalpy of transfer of hydroxypropyl-α-cyclodextrin (HP-α-CD) and hydroxypropyl-γ-cyclodextrin (HP-γ-CD) from water to the aqueous solutions of sodium alkanoates (sodium hexanoate, sodium decanoate and sodium dodecanoate) were determined at 298 K. The cyclodextrin concentration was kept constant, and that of the surfactant was varied in order to analyze both the pre- and postmicellar regions. The experimental data in the premicellar region were consistent with the formation of 1:1 and 1:2 (1 cyclodextrin:2 surfactants) inclusion complexes, with the exception of the HP-α-CD/sodium dodecanoate system which presented only the 1:1 complexes. The mechanism of the 1:2 complexes format…

Solubilization of a,w-Dichloroalkanes in Block Copolymer Supramolecular Structures Formed in Aqueous Media. A Thermodynamic and Structural Study

Studi Termodinamici e Strutturali per la Solubilizzazione di alpha,omega-Dicloroalcani in Aggregati di Copolimeri Tri-Blocchi

Deadsorbimento di un Contaminante Organico all'Interfaccia Laponite/Acqua Indotto da Copolimeri a Blocchi