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Adsorption isotherms of H2S, CO2, and CH4 on the Si-CHA zeolite were measured over pressure range of 0-190 kPa and temperatures of 298, 323, and 348 K. Acid gases adsorption isotherms on this type of zeolite are reported for the first time. The isotherms follow a typical Type-I shape according to the Brunauer classification. Both Langmuir and Toth isotherms describe well the adsorption isotherms of methane and acid gases over the experimental conditions tested. At room temperature and pressure of 100 kPa, the amount of CO2 adsorption for Si-CHA zeolite is 29 % greater than that reported elsewhere (van den Bergh et al. J Mem Sci 316:35-45 (2008); Surf Sci Catal 170:1021-1027 (2007)) for the... 

A fundamental chemical enhanced oil recovery (EOR) process is surfactant flooding in which the key mechanism is to reduce interfacial tension between oil and the displacing fluid and hence mobilizing the trapped oil. Surfactant loss by adsorption is one of the most important criteria that governs the economics of the surfactant flooding methods. In addition to this, detrimental effects and high price of currently used surfactants cause EOR process so expensive and unfeasible. This study is aimed to introduce a novel kind of plant based surfactant which is extracted from Zizyphus Spina-Christi tree. In addition, equilibrium adsorption behavior of this novel biosurfactant in aqueous solution... 

In this article, adsorption of p-xylene, m-xylene, o-xylene, and ethylbenzene on Na-BETA type zeolite in liquid phase at 15, 25, and 35 °C has been studied and the single adsorption isotherms have been obtained and reported. The Langmuir isotherm model was used to describe the experimental adsorption isotherm data. It was found that p-xylene is more strongly adsorbed component followed by ethylbenzene, m-xylene and o-xylene. This means that this adsorbent is selective for p-xylene. Using Langmuir isotherm model, the saturation adsorption capacities of the adsorbent were obtained as follows 143 mg/g for p-xylene, 105 mg/g for ethylbenzene, 83 mg/g for m-xylene, and 68 mg/g for o-xylene at 25... 

In this paper we report the results of classical molecular dynamics (MD) simulation of hexanoic acid adsorption on calcite (101-4) surface plane using Pavese and AMBER force fields for calcite and hexanoic acid, respectively. Pair correlation function, strictly suggests a well-structured adsorption. Density profile indicates the adsorption occurs through double-bonded O atom of the acid head group by direct interaction with Ca atom at calcite surface. Adsorption orientation of H and double-bonded O atoms was found to be as lock and key with respect to calcite surface Ca and O atoms, facilitating an effective adsorption. Adsorption time evolution indicates that O atom adsorption is... 

Magnetic nanocomposite hydrogels containing different amounts of graphene oxide were synthesized and characterized by FTIR, XRD, TGA, SEM, TEM, VSM and UV-vis spectroscopy. The prepared hydrogels were used as adsorbents for removal of a cationic dye, crystal violet, from water. The kinetics and isotherm of adsorption and the effect of different experimental conditions such as graphene oxide content, pH of the solution, contact time, adsorbent dosage and initial dye concentration on adsorption capacity were then investigated. Parameters related to kinetics and isotherm models were calculated and discussed. It was found that adsorption is well-described by pseudo-second-order kinetics and... 

We have used molecular dynamics simulation to investigate hydrophilic– hydrophobic interfaces between calcium chloride (CaCl2) aqueous solutions and normal hexane. The results demonstrate the increasing impact of salt concentration on the liquid–liquid interfacial tension, hence, negative adsorption of CaCl2 according to Gibbs adsorption isotherm. Moreover, we calculated the density profiles of hexane, water, and the counter ions. The results reveal an electrical double layer near the interface and the less affinity of calcium cations toward the interface than that of chloride anions. Orientation of water molecules at the studied concentrations may result in developing a positively charged... 

A new magnetic nano-adsorbent was synthesized via the radical polymerization of methyl acrylate on modified Fe3O4 nanoparticles, followed by its functionalization by amidation of the methyl ester groups using pentaethylenehexamine, to create active adsorption sites for removing anionic dyes from aqueous media. Physicochemical properties of the adsorbent were then characterized by SEM, TEM, XRD, FTIR, TGA and CHN analysis. The prepared nanocomposite was used as adsorbent for the removal of anionic dyes, naphthol green B and chromeazurol S, from aqueous solution and assessed in view of the kinetics and isotherm adsorption, and the effect of solution pH, contact time and initial dye... 

In this study, kinetics, equilibrium, and mechanisms of SDBS adsorption onto carbonate rock in presence/absence of alkaline/electrolyte, which is not well discussed in the available literature, is analyzed through batch experiments. Analysis of kinetic data showed that adsorption rate of SDBS onto carbonate is controlled by both boundary layer and intraparticle diffusion, also adsorption kinetics meets pseudo second-order model. The coefficient of kinetic model is a linear function of initial and equilibrium concentrations. The adsorption isotherm experiences four distinct regions, with a rising trend in the first regions until reaching to a maximum after which decreases slightly, as the... 

In this way, after experimental measurement of interfacial tension, different models including mono-exponential decay, dynamic adsorption models and empirical equation are used to correlate this time-dependent behavior of interfacial tension (IFT). During the modeling approach, the induction, adsorption, equilibrium, and meso-equilibrium times as well as diffusivity of surface active components known as natural surfactant including asphaltene and resin from crude oil to the interface are obtained. In addition, the surface excess concentration of surface active components at the interface and Gibbs adsorption isotherm are utilized to analyze the measured dynamic IFTs. Finally, the mechanisms... 

In this study, kinetics, equilibrium, and mechanisms of SDBS adsorption onto carbonate rock in presence/absence of alkaline/electrolyte, which is not well discussed in the available literature, is analyzed through batch experiments. Analysis of kinetic data showed that adsorption rate of SDBS onto carbonate is controlled by both boundary layer and intraparticle diffusion, also adsorption kinetics meets pseudo second-order model. The coefficient of kinetic model is a linear function of initial and equilibrium concentrations. The adsorption isotherm experiences four distinct regions, with a rising trend in the first regions until reaching to a maximum after which decreases slightly, as the... 

The 3A zeolites are excellent adsorbents for industrial-scale gas dehydration because of the low energy required for regeneration and ease of operation. A computational study of the dehydration of an industrial feed stream containing ethane and water was performed using an in-house code that included an appropriate equilibrium adsorption isotherm. The validated computational model was used to examine the impact of particle size on the process dynamics and the corresponding pressure drop. The water concentration along the adsorption column was also investigated. To increase the process capacity, the packed adsorption bed was divided into two distinct layers, which were operated with different... 

In this study, effectiveness of non-ionic block copolymers such as Lugalvan BNO12 and Triton X series (Triton X100 & Triton X405) has been reported for graphene dispersion in aqueous solutions. Stability of the aqueous graphene dispersions is investigated using UV–visible spectroscopy, Rheological, and Conductivity studies. Adsorption isotherms are constructed to determine the amount of polymers adsorbed on the surface of graphene by the spectroscopic analysis. Lugalvan BNO12 has been found to be adsorbed in higher amounts on the graphene surface compared to the Triton X series polymers. Thermogravimetric analysis (TGA) and Fourier Transform Infrared (FTIR) Spectroscopy investigations... 

In this paper, the pyrrolic nitrogen functional group's presence is investigated in the selective adsorption of CO2. The grand canonical Monte Carlo (GCMC), molecular dynamics (MD), and density functional theory (DFT) were used for this study's goal. GCMC was used to calculate adsorption isotherms, selectivity, and isosteric heats. MD was used to calculate the radial distribution function (RDF) and diffusion. Reactivity parameters, electrostatic potential (ESP), reduced density gradient (RDG), and independent gradient model (IGM) were calculated using DFT. Adsorption isotherms, selectivity, and isosteric heats demonstrated that the NH group caused the selective adsorption of CO2 among CH4,... 

Silica aerogel-multi wall carbon nanotube composites were synthesized successfully with a waterglass precursor and an ambient pressure drying method. Pure silica aerogels are so fragile that they cannot be used easily. Carbon nanotubes (MWCNT) were used as reinforcements to strengthen the mechanical properties of pure silica aerogels. Results show that inserting small amounts of MWCNT causes silica aerogels to monolith. By addition of MWCNT, monolith nanocomposites were produced with 800 m2/g surface area and a 140° contact angle. Results show that the silica aerogels and reinforced composites have an excellent adsorption property for the removal of organic pollutants from water. The average... 

Volatile organic compounds are a major cause of air pollution; therefore, VOCs are a serious fulmination for the environment. According to studies, adsorption processes have a high performance for the removal of pollutants that by selecting the proper absorbent, efficiency will be improved. In this work performance of two metal organic frameworks are studied so porous materials named MIL-101(Cr) and MIL-53(Fe) as an adsorbent for the removal of ethylbenzene have been synthesized hydrothermally. The materials were characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, adsorption of ethylbenzene, field emission scanning electron microscopy (FESEM),... 

Petroleum monoaromatics including benzene, toluene, ethylbenzene, and xylenes (BTEX) are among the notorious volatile organic compounds that contaminate water and soil. In this study, a surfactant- modified natural zeolite and its relevant granulated nanozeolites were evaluated as potential adsorbents for removal of petroleum monoaromatics from aqueous solutions. All experiments performed in batch mode at constant temperature of 20°C and pH of 6.8 for 48 h. The results revealed that the amount of BTEX uptake on granulated zeolites nanoparticles were remarkably higher than the parent micron size natural zeolite (in the order of four times). The isotherms data were analyzed using five models... 

GAC has been modified by loading of potassium nickel hexacyanoferrate (KNiCF) as a new adsorbent for cesium adsorption. The potassium nickel hexacyanoferrate-loaded granular activated carbon (KNiCF-GAC) was characterized using powder x-ray diffraction (XRD) and nitrogen adsorption-desorption isotherm data, infrared spectroscopy, and its cesium adsorption performance in aqueous solution was investigated. The effect of the various parameters such as initial pH value of the solution, contact time, temperature, and initial concentration of the cesium ion on the adsorption efficiencies of KNiCF-GAC have been studied systematically by batch experiments. The adsorption isotherm of KNiCF-GAC was... 

Removal of zirconium from its dilute aqueous solution using Aspergillus niger as a dried and living biomass was investigated. Through that, the effect of some operational parameters on biosorption, including pH, temperature, contact time, initial concentration of zirconium and dose of biomass, were studied. Based on the results, it was concluded that the uptake of zirconium by both dried and living biomasses is pH dependent, and maximum uptake was observed in pH = 3.1 for both biomasses. The maximum uptake capacity of the living biomass was obtained at 30°C. However, the biosorption of zirconium by dried biomass was not affected by temperature. The maximum uptake capacity for living and...