Thermodynamic Parameters Of Sorption Research Articles

Chromatographic Method for Evaluation of Polymeric GC Stationary Phases Ageing Using the Novel Non-Cross-Linked Poly(3-(Tributoxysilyl)Tricyclononene-7) as the Model Stationary Phase.

The chromatographic properties and thermal stability are investigated for the polymeric stationary phase based on the norbornene polymer. It was shown that without additional cross-linking, poly(3-(tributoxysilyl)tricyclononene-7) demonstrates properties similar to liquid chromatographic stationary phases. It was also found to be more thermally stable than previously studied trimethylsilyl- and trimethoxysilyl- derivatives. The long-term heating at 170 °C resulted in an increase of mass transfer rate between stationary and mobile phases which could be observed as a decrease of parameter C of Van Deemter equation. This effect is rather unusual, as the polymeric stationary phases tend in decrease of the layer volume and porosity while ageing. Additionally, the values of thermodynamic parameters of sorption are calculated for the polymeric stationary phase: enthalpy of sorption varied −28 to −37 kJ/mol, entropy change was −41 to −51 J/mol K. The compensation curves were plotted for the alkanes, arenes, and alcohols, and the parameters of compensation plot were calculated, demonstrating the different sorption mechanisms both for hydrocarbons and oxygen-containing compounds, and different classes of organic compounds.

Some Theoretical Aspects of Tertiary Treatment of Water/Oil Emulsions by Adsorption and Coalescence Mechanisms: A Review

The massive increase in the volumes of oily contaminated produced waters associated with various industrial sectors has initiated considerable technological and scientific efforts related to the development of new cleaning strategies. The petrochemical industry (oil and gas production and processing) contributes to those volumes by approximately 340 billion barrels per year. The removal of emulsified oily components is a matter of particular interest because the high emulsion stability necessitates sophisticated technological approaches as well as a deep theoretical understanding of key mechanisms of oil/water separation. This review deals with the theoretical aspects of the treatment of emulsified oil/water mixtures and is particularly focused on tertiary treatment, which means the reduction of the oil content from 70–100 ppm to below 10 ppm, depending on national regulations for water discharge. The review concerns the mechanisms of oil/water separation and it covers the (i) adsorption isotherms, (ii) kinetics of adsorption, (iii) interfacial interactions between oil/water mixtures and solid surfaces, and (iv) oil/water separation techniques based on the wettability of solid/oil/water interfaces. The advantages and drawbacks of commonly used as well as newly proposed kinetic and adsorption models are reviewed, and their applicability for the characterization of oil/water separation is discussed. The lack of suitable adsorption isotherms that can be correctly applied for a description of oil adsorption at external and internal solid surfaces of both nonporous and porous structures is pointed out. The direct using of common isotherms, which were originally developed for gas adsorption, often leads to the incorrect data description because the adsorption of oily components at solid surfaces does not fit the assumptions from which these models were originally derived. Particularly, it results in problematic calculations of the thermodynamic parameters of sorption. The importance of nonlinear analysis of data is discussed, since recent studies have indicated that the error structure of experimental data is usually changed if the original nonlinear adsorption isotherms are transformed into their linearized forms. The comparison between the pseudo-first-order and pseudo-second-order kinetic models was performed. It was shown that the correlation between data and models strongly depends on the selection of data, particularly on the frequency of collected data in time scale. The wettability of solid surfaces by oil in air and under water is discussed, regarding the surface morphology of surfaces. We demonstrate that the combination of surface chemistry and topology strongly influences the separation of oil/water emulsions.

Sorption of rare earth coordination compounds

Rare earth elements (REEs) are valuable and strategically important in many high-technology areas, such as laser technology, pharmacy and metallurgy. The main methods of REE recovery are precipitation, extraction and sorption, in particular ion exchange using various sorbents, which allow to perform selective recovery and removal of associated components, as well as to separate rare earth metals with similar chemical properties.
 The paper examines recovery of ytterbium in the form of coordination compounds with Trilon B on weakly basic anion exchange resin D-403 from nitrate solutions. In order to estimate thermodynamic sorption parameters of ytterbium anionic complexes, ion exchange process was carried out from model solutions under constant ionic strength specified by NaNO3, optimal liquid to solid ratio, pH level, temperatures 298 and 343 K by variable concentrations method. Description of thermodynamic equilibrium was made using mass action law formulated for ion exchange equation and mathematically converted to linear form. Values of equilibrium constants, Gibbs free energy, enthalpy and entropy of the sorption process have been calculated. Basing on calculated values of Gibbs energy, a sorption series of complex REE ions with Trilon B was obtained over anion exchange resin D-403 from nitrate solutions at temperature 298 K. Sorption characteristics of anion exchange resin have been estimated: total capacity, limiting sorption of complex ions, total dynamic capacity and breakthrough dynamic capacity.

POTASSIUM ADSORPTION IN CALCAREOUS SOILS OF KURDISTAN REGION OF IRAQ

Sorption is one of the most chemical important processes, which determine nutrients availability in soil. Sorption isotherms provide sufficient information about soils sorption’s capacity, and it’s data can be used to determine thermodynamic sorption parameters. The aim of this studyis to evaluate the sorption of potassium onto some soils. An experiment was conducted with four calcareous soils of the Sulaimani province Kurdistan Region of Iraq by using the batch methods. 5g soil samples were equilibrated at 298±1 Kelvin with 50 ml of 0.01M CaCl2 containing 0 to 250 mg L-1 K as KCl. Suspensions were centrifuged, filtered, and concentration of K+ in the clear extract solution was determined. Amount of K+ sorbed by the soil was calculated from the difference between the initial and final concentration of K+ in the equilibrium solution. Sorption of K+ was evaluated using adsorption isotherms. The results showed that K+ sorption was described by linear, Langmuir, Freundlich, and Temkin equations. Langmuir equation gave a better fit of equilibrium K adsorption when it has a higher R2 and lowers SE. The data indicated that the maximum monolayer coverage capacity (b) from the Langmuir isotherm model ranged between (-113.63 to 2500) mg kg-1. The negative values of (b) for studied locations soils indicated to potassium release instead of adsorption. The Langmuir isotherm constant (KL) ranged from (-0.01 to 0.01) L mg-1. Maximum buffering capacity (MBC) is a capacity factor, which measures the ability of the soil to replenish K ion to soil solution that the ability of a soil to supply K to the soil solution. The value of MBC of the studied soils ranged from 0.453 to 23.75 mg kg-1.The sorption processes for the forth locations are favorable and spontaneous because the value of RL was an equal one.

Copper adsorption Behavior in some Calcareous Soils using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich Models

This study conducted to characterize copper adsorption behavior and determination sorption thermodynamic parameters in some calcareous soil from Sulaimani Governorate, Iraqi Kurdistan region. Copper adsorption studied in five calcareous soils includes (Sharazor, Qaradagh, Bazian, Mawat, and Surdash) varying in total calcium carbonate, organic matter and a cation exchange capacity of Sulaimani governorate in Iraqi - Kurdistan region. The adsorption isotherms of the Copper metal by the soil carried out using a batch method. One gram of each soil sample, in duplicate, was placed in plastic bottles and equilibrated with 50 ml of solution CaCl2 (0.01M), containing a series of Cu concentrations (0, 2.5, 5, 10, 20, and 40 mg Cu L-1) in the form of (CuSO4). The concentration of Cu determined in a solution using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The amount of Cu adsorbed by the sample determined by subtracting the equilibrium Cu concentration in the solution from the added Cu. The equilibrium isotherm data used to describe Cu adsorption in the five different soils using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm model. Freundlich model compared to the various models considered as the best model for describing copper adsorption at both temperatures (298 and 318oK) to describe the isotherm models in the studied soils depending on the highest value of the determination coefficient (R2), and the least value of root mean square error (RMSE), and Akaike information criterion (AIC).

The Stability Study of Thermodynamic Parameters of Sorption of Light Hydrocarbons on Poly [Trimethylsilyl (Propyn-1)] at Different Temperatures.

Chromatographic determination of the thermodynamic parameters of sorption for light hydrocarbons retention on a stationary phase based on poly [trimethylsilyl (propyn-1)] (PTMSP) was performed and the effect of column preheating at temperatures up to 260°C on the retention of analytes was investigated. It was shown that heating the column to 130°C does not affect the retention of the analytes. At temperatures above 130°C, the gradual decrease of the retention of analytes on PTMSP stationary phase is observed. The process is non-selective and proceeds at the same extent for all the studied hydrocarbons, regardless of the size and geometry of the molecule. Values of enthalpy and entropy of sorption of light hydrocarbons are determined for the original column and after its aging at 200°C. The enthalpy of sorption of the analytes at the PTMSP phase is practically independent on the heating temperature of the PTMSP phase, whereas the loss of entropy increases after heating. The increase of the entropy factor after the heating of the PTMSP stationary phase is associated with its aging and is confirmed by the construction of compensation functions for treated and untreated columns.

Sorption of Cu2+ and Zn2+ Ions by Humic Acids of Tundra Peat Gley Soils (Histic Reductaquic Cryosols)

Sorption properties of humic acid (HA) preparations extracted from the peaty horizon of peat gley tundra soil (Histic Reductaquic Cryosols) are characterized. The kinetic and thermodynamic sorption parameters of Cu2+ and Zn2+ ions by HAs are calculated. The sorption of the study heavy metal ions by HA preparations is estimated to be truly approximated by the pseudo-first-order response equation. The negative values of the Gibbs energy change at temperatures of 298.0 К and 314.3 К for Сu2+ (–26.2 and –24.5 kJ/mol, respectively) and Zn2+ ions (–22.2 and –22.0 kJ/mol, respectively) attest to the possibility of self-sorption of the study ions within the considered temperature range. Changes in the sorption enthalpy values (–33.1 kJ/mol for Cu2+ ions and –4.5 kJ/mol for Zn2+ ions) characterize both reactions as exothermal reactions. As the temperature rises, the sorption equilibrium constant for Сu2+ ions considerably decreases, whereas it does not change significantly for Zn2+ ions. The decreasing sorption equilibrium constants with the rise in temperature point to the equilibrium shift towards desorption. This is a characteristic feature of physical sorption that indicates possible existence of two fixation mechanisms of ions on the surface of HA preparations, namely, physical sorption and сhemisorption.

Determination of the Supramolecular Structure of Fluorocopolymer by Inverse Gas Chromatography

The molecular organization of ethylene copolymers with perfluorinated ethers is studied by inverse gas chromatography. The thermodynamic parameters of sorption of low-molecular-weight sorbates by the copolymers (the activity coefficient, partial molar mixing values) are calculated in a wide temperature range. Influence of the architecture of copolymer chains on the sorption parameters of their thin films is studied. It is shown that, despite the alternating distribution of monomers along copolymer macrochains, methylene groups form hydrocarbon clusters in a perfluorinated dispersion medium. The microheterogeneous structure of the studied copolymers is responsible for the permeability of copolymer thin films to low-molecular-weight liquid sorbates (both solvents and nonsolvents). It is suggested that the copolymers of this type are promising for use in the field of membrane technologies.

Adsorption and separation of terbium(III) and gadolinium(III) from aqueous nitrate medium using solid extractant

ABSTRACT A macroporous copolymer of styrene and divinylbenzene resin (TVEX-PHOR) was examined for adsorption of terbium(III) and gadolinium(III) from nitrate medium. Characterization of TVEX-PHOR before and after adsorption was investigated. Different factors affecting the sorption equilibrium were studied and a maximum separation value of 2.31 was reached at V/m = 0.3 L/g. Adsorption kinetics data indicated that the pseudo-second-order model is more applicable, while the isothermal data were found to be correlated with Freundlich model. The resin uptake capacity towards Tb(III) (24.93 mg/g) was more than that of Gd(III) (15.49 mg/g). Thermodynamic parameters of sorption indicated that the process was spontaneous and exothermic.

Gas Chromatography and Thermodynamic Characteristics of the Sorption of Model Sorbates on New Stationary Phases Based on Poly[oligo(ethylene glycol)diacrylates

The thermodynamic parameters of sorption of a test mixture of hydrocarbons on a new type of PEG-like stationary phases are determined from the temperature dependence of sorbate retention in the temperature range of 35–110°C. The determined entropy and enthalpy of sorption are close for all the studied stationary phases, despite the different ratios of ethylene glycol and acrylate moieties in the polymer’s phase structure. At the same time, the studied phases exhibit greatly different separation abilities, due apparently to the kinetic properties of the phases, as is indicated by differences in the efficiency of the columns with these phases and in the diffusion coefficients of sorbates on these phases.

Bisphenol A in the Yellow River: Sorption characteristics and influential factors

Sorption is an important means for pollutant migration in aquatic environments and an important mechanism of pollutant transfer and transformation. Thus, understanding the sorption/desorption of organic pollutants in an aquatic environment is vital to predicting pollutant fate. In this study, Bisphenol A (BPA) was selected as the target pollutant for an investigation of sorption characteristics on three sediments in the Lanzhou section of the Yellow River, with examination of sorption thermodynamic parameters and the effects of temperature, pH, and sediment particle size. Sorption is described well by the pseudo-second-order kinetic model, occurring at two stages, fast (0–6 h) and slow (6–16 h), with equilibrium reached within 16 h. The results suggested that the intraparticle diffusion was dominant in the sorption process. Sorption thermodynamics was nonlinear, fitting well with the Freundlich isotherm model. Physical sorption is the likely mechanism, combining the contributions of π–π interaction and hydrophobic interaction. Thermodynamic parameter analysis showed that Gibbs free energy, enthalpy, and entropy were less than zero, showing that it is spontaneous, exothermic, and chaos-decreasing. Among tested influence parameters, pH values, ionic strengths, temperatures, and particle sizes were found to considerably influence the sorption of BPA. Sorption capacity decreased as sediment particle size increased and as pH increased. Sorption capacity increased with increasing Ca2+ and decreased with increasing Na+. The results have important implications regarding the impact of sorption/desorption at different environmental factors and fate of BPA in Yellow River.

Influence of aging of poly[(trimethylsilyl)prop-1-yne] on the thermodynamics of sorption of light hydrocarbons

Changes in the properties of the poly[(trimethylsilyl)prop-1-yne] (PTMSP) film deposited on the walls of a quartz capillary under the action of high temperatures were studied by chromatographic methods. The change in the thermodynamic parameters of sorption of light hydrocarbons related to both physical aging of the PTMSP film and, possibly, its chemical destruction was examined.

Assessment of the Thermodynamic Properties of DL-p-Mentha-1,8-diene, 4-Isopropyl-1-Methylcyclohexene (DL-limonene) by Inverse Gas Chromatography (IGC).

Limonene is a colorless liquid hydrocarbon and had been investigated as a plasticizer for many plastics. Prediction of solubility between different materials is an advantage in many ways, one of the most convenient ways to know the compatibility of materials is to determine the degree of solubility of them in each other. The concept of "solubility parameter" can help practitioners in this way.In this study, inverse gas chromatography (IGC) method at infinite dilution was used for determination of the thermodynamic properties of DL-p-mentha-1,8-diene, 4-Isopropyl-1-methylcyclohexene (DL-limonene). The interaction between DL-limonene and 13 solvents were examined in the temperature range of 63-123°C through the assessment of the thermodynamic sorption parameters, the parameters of mixing at infinite dilution, the weight fraction activity coefficient and the Flory-Huggins interaction parameters. Additionally, the solubility parameter for DL-limonene and the temperature dependence of these parameters was investigated as well.Results show that there is a temperature dependence in solubility parameter, which increases by decreasing temperature. However, there were no specific dependence between interaction parameters and temperature, but chemical structure appeared to have a significant effect on them as well as on the type and strength of intermolecular interactions between DL-limonene and investigated solvents. The solubility parameter δ2 of DL-limonene determined to be 19.20 (J/cm3)0.5 at 25°C.

Study of the gadolinium sorption on the C100 ion-exchange resin for the development of the antineutrino detector targets

Adsorption of the gadolinium from H2O and HCl solutions on the ion-exchange resin C100 is investigated. The experiments were carried out by varying the acidity of the liquid phase, the amount of sorbent, and the temperature. The maximal sorption of the ions Gd3+ is observed from the solution 0–0.2 M HCl under optimal conditions, the sorption reaches more than 99.5%. Sorption of Gd3+ on C100 from H2O solution occurs most intensively during the first 3 min then for 30 min the system smoothly comes to equilibrium. The maximal sorption capacity of the resin C100 amounted to 1.2 ± 0.1 mmol g−1. The thermodynamic parameters of sorption: ΔG = − 24.20 kJ mol−1, ΔS = − 90.27 J mol−1 K−1, ∆H = − 50.93 kJ mol−1 were evaluated. It is shown that the sorption of gadolinium on the ion-exchange resin C100 is described by models of kinetically pseudo-first and pseudo-second order. It is established that the Gd3+ sorption on the C100 resin is reversible second order chemical reaction.

Sorption of humic substances on a weakly basic anion-exchange resin: Relationship with the adsorbate structure

Adsorption of a broad range of humic substances (HS) of different origins and fractional compositions on a macroporous weakly basic anion-exchange resin is studied. It is found that the nature of the HS has a substantial effect on both the efficiency of sorption and the mechanism of interaction with the adsorbent. The dependence of the determined thermodynamic parameters of sorption on the HS origin, composition, and structure is shown for a broad range of HS. It is concluded that the results can be used to predict the sorption properties of weakly basic anion-exchange resins with respect to HS of known origin and structural group composition.

Inverse gas chromatography study of polyvinylacetate-solvent and polyethylene-solvent systems

In this article, the thermodynamic behavior of polyvinylacetate (PVAc)–solvent, and polyethylene (PE)–solvent mixtures have been studied by determining the thermodynamic sorption parameters (enthalpy, entropy, and free energy), the mass-based solvent activity coefficients (Ω) and the Flory Huggins parameters (χ), by means of inverse gas chromatography (IGC) measurements. According to the Flory Huggins parameters of the PE–solvent mixtures, determined between 40 and 60°C the compatibility (the ability to interact with each other) of this polymer with the different types of solvents follows this order: dispersion solvents > polar solvents > association solvents. In the case of PVAc mixtures, the thermodynamic parameters were determined between 60 and 80°C, only for polar-type and association-type solvents due to, in the studied temperature range, the retention diagrams of dispersion solvents show that there are not bulk interactions. The Hildebrand solubility parameters of both polymers were also determined, according to Guillet procedure. The higher values of PVAc material (14.1 MPa0.5 for PE and 19.8 MPa0.5 for PVAc, at 60°C) are related to the strong interactions of vinyl acetate monomer. POLYM. ENG. SCI., 56:36–43, 2016. © 2015 Society of Plastics Engineers

GALLIUM SORPTION FROM ALKALINE SOLUTIONS OVER ANIONITES

Gallium sorption from alkaline solutions over various weak- and strong-basic anion-exchange resins under the dynamic conditions has been studied. The values of dynamic exchange capacity before breakthrough and full dynamic exchange capacity have been calculated. D-403 selective anion exchange resin has been selected. The gallate-ion sorption isotherm over D-403 weak-basic anion-exchange resin is described by Langmuir equation modified for ion-exchange equilibrium and the thermo-dynamic sorption parameters are determined. A method for determining gallium forms in alkaline solution is proposed. A series of anion sorption ability on the solid phase surface of D-403 anion exchange resin is presented.

Removal of crystal violet from water by magnetically modified activated carbon and nanomagnetic iron oxide.

Magnetically modified activated carbon, which synthesized by nanomagnetic iron oxide, was used for fast and effective removal of Crystal Violet from aqueous solutions. The scanning electron microscopy (SEM) images of nano-adsorbent showed that the average sizes of adsorbent are less than 100 nm. The various parameters, affecting on adsorption process, were examined including pH and temperature of dye solution, dose of adsorbent, and contact time. Then, thermodynamic parameters of sorption were calculated. Langmuir and Freundlich isotherms were used to fit the resulting data. Adsorption kinetics was consistent with a pseudo second order equation. Thermodynamic parameters of adsorption, ∆H0, and ∆S0 were calculated. Also, for further investigations, nano magnetic iron oxides was synthesized and used as adsorbent. Sorption capacities were depending on the temperature varied from 44.7 to 67.1 mg/g and from 12.7 to 16.5 mg/g for magnetically modified activated carbon and nanomagnetic iron oxide, respectively.

Eu (III) sorption from an aqueous solution onto SrTiO3 and surface complex behavior

Abstract The present work considers the interaction between Eu (III) in liquid phase and a sorbent solid material (SrTiO3). Certain materials are known strong complexion agents, including titanate; strontium titanate can be easily synthesized as a single-phase compound at a low temperature. Thus, the sorbent material SrTiO3 in the perovskite form was tested using 1 × 10−4 M Eu3+(NO3)2 solutions in a KNO3 0.5 M salt background. Both structural and thermodynamic studies were performed using the batch method. The sorption edge for Eu (III) on SrTiO3 was modeled using FITEQL 4.0v code and experimental sorption curves to calculate the europium surface complexation constants. The sorption edge was fitted with mono- and bidentate Eu3+(NO3)2+ surface complexes formed on the SrTiO3 surface. Below pH 6, bidentate surface complex was formed through two types of interactions (TiOH)2EuNO32+ (log K = 9.08 ± 0.02). However, at a pH values greater than 6, the immobilization process is associated with chemical precipitation due to surface europium hydroxyl and the carbonate species. The sorption thermodynamic parameters were thermodynamically quantified as a function of different system temperatures through applying the van’t Hoff modified equation; ΔH° = −31.30 kJ mol−1, ΔS° = −6.53 × 10−2 kJ mol−1 K−1, and ΔG° = −11.99 kJ mol−1. These results suggest that the Eu (III) sorption process onto SrTiO3 is exothermic and spontaneous.

Adsorption performance and mechanism for removal of Cd(II) from aqueous solutions by D001 cation-exchange resin

The adsorption and desorption properties of D001 resin for Cd(II) has been investigated. Batch studies were carried out with various pH, contact time, temperature and initial concentrations, and then column studies were conducted. The results showed that the optimal adsorption condition was at pH value of 3.0 in HAc-NaAc medium. The resin exhibited a high Cd(II) uptake of 185.8 mg/g at 298 K. The apparent activation energy Ea is 5.05 kJ/mol and the sorption thermodynamic parameters are ΔH = 21.1 kJ/mol, ΔS = 0.122 kJ/(mol K) and ΔG298K = -15.3 kJ/mol, which indicated that the adsorption process was spontaneous and endothermic. Compared with the Freundlich isotherm, the sorption of Cd(II) obeys the Langmuir isotherm better. The Thomas model was delineated here to predict the breakthrough curves based on the experimental column study data. Furthermore, the resin could be regenerated through the desorption of the Cd(II) anions using 1 mol/L HCl solution and could be reused to adsorb again. The infrared spectroscopic technique was undertaken. Compared with other absorbents, D001 resin was relatively low cost and was effective in removing Cd(II) ions.