Experimental and Theoretical Study on the CH4 Adsorption by Granular and Microporous Activated Carbon

Adsorbed natural gas (ANG) by Granular Activated Carbon (GAC) has been widely investigated as an alternative to CNG and LNG technologies for storage and transportation of natural gas. In the present work, a theoretical and experimental study was conducted to accurately determine the amount of adsorption of CH4 by GAC. To carry out the experiments, the volumetric method was used up to 4 MPa at constant temperature of 298 K. Also, various adsorption isotherm models were used to model the experimental data collected from the experiments. The accuracy of the results              obtained from the adsorption isotherm models was compared and the values for the regressed parameters were reported. The results shows that the amount of CH4 adsorbed is dependent on the physical characteristics of activated carbons. Moreover, the Toth, two term TVFM and Sips isotherm models show good agreement with the experimental data

Controlling and characterising the deposits from polymer droplets containing microparticles and salt

It is very well known that as suspension droplets evaporate, a pinned contact line leads to strong outwards capillary flow resulting in a robust coffee ring-stain at the periphery of the droplet. Conversely tall pillars are deposited in the centre of the droplet when aqueous droplets of poly(ethylene oxide) evaporate following a boot-strapping process in which the contact line undergoes fast receding, driven by polymer precipitation. Here we map out the phase behaviour of a combined particle-polymer system, illustrating a range of final deposit shapes, from ring-stain to flat deposit to pillar. Deposit topologies are measured using profile images and stylus profilometery, and characterised using the skewness of the profile as a simple analytic method for quantifying the shapes: pillars produce positive skew, flat deposits have zero skew and ring-stains have a negative value. We also demonstrate that pillar formation can be disrupted using potassium sulphate salt solutions, which change the water from a good solvent to a thetapoint solvent, consequently reducing the size of the polymer coils. This inhibits polymer crystallisation, interfering with the bootstrap process and ultimately preventing pillars from forming. Again, the deposit shapes are quantified using the skew parameter

A modified MMM EOS for high-pressure PVT calculations of heavy hydrocarbons

A theoretical based cubic equation of state has been proposed (MMM EOS) by Mohsen-Nia (Mohsen-Nia et al., 1995) for calculation of pure fluid and mixture properties Z=(v+1.3191b)/(v−b)−a/[RT^(1.5)(v+b)]. In previous works, the superiority of the MMM has been shown over the vdW family of EOSs for PVT and VLE calculations. In this work, a new simple functional form for its attractive and repulsive parameters [a(T) and b(T)] is introduced. The proposed EOS is applied to vapor pressure and saturated density calculations of different pure fluids. Then, the proposed equation is used to calculate high-pressure PVT of heavy hydrocarbons. The performance of the proposed EOS for VLE calculations is examined against the corresponding experimental measurements for a number of binary mixtures and the results are compared with those obtained from the cubic EOSs frequently used for thermodynamic and fluid phase equilibrium calculations. The comparisons indicate the modified MMM EOS is quite suitable for property predictions of gas and liquid systems, especially for high-pressure PVT of heavy hydrocarbon systems of interest in the oil and gas industries

Human Serum Protein Adsorption onto Synthesis Nano-Hydroxyapatite

Adsorption of human serum proteins (Albumin and total protein) onto high purity synthesis nano-hydroxyapatite (HA), Ca_(10)(PO_4)_6(OH)_2, has been studied in a wide temperature range by UV–visible spectrophotometer. Adsorption isotherm is basically important to describe how solutes interactwith adsorbent, and is critical in optimizing the use of adsorbent. In the present study, the experimental results were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (DR) models to obtain the characteristic parameters of each model and square of the correlation coefficients (R^2). According to the results, the DR isotherm model had the best agreement with the experimental data. The effect of temperature on adsorption of human serum proteins (HSP) onto the synthesized nano-HA was studied. The experimental results indicated that temperature increase generally causes an increase in the adsorption of HSP onto the nano-HA. This is basically due to the effect of temperature on the HSP activity and its diffusion rate on HA surfaces

Measurement and modelling of static dielectric constants of aqueous solutions of methanol, ethanol and acetic acid at T = 293.15 K and 91.3 kPa

Static dielectric constants of aqueous solutions of methanol, ethanol and acetic acid at T = 293.15 K and 91.3 kPa were measured at weak electromagnetic field (≪0.001 V) and (≪60 Hz). The static dielectric measurements have been achieved by using the new set up presented in the previous work based on a low-pass filter. From the experimental data, excess dielectric constants, ɛE have been calculated and reported. An empirical polynomial equation was used for correlating the data of the dielectric constants for the aqueous solutions. In addition, the measured static dielectric constants data have been calculated on the basis of the empirical modification of the Kirkwood theory for multicomponent systems. According to the average absolute deviations obtained between experimental and calculated data, the calculated dielectric constants of aqueous solutions studied in this work are generally in good agreement with the experimental data

Characterization and non-isothermal crystallization behavior of biodegradable poly(ethylene sebacate)/SiO_2 nanocomposites

Poly(ethylene sebacate) (PESeb) and PESeb/silica nanocomposites (PESeb/SiO_2) were prepared by in situ polymerization from the direct esterification of ethylene glycol with sebacic acid in the presence of proper amounts of silica nanoparticles. The non-isothermal crystallization behavior of PESeb/SiO_2 nanocomposites has been studied using different theoretical equations such as Avrami, Ozawa and combined Avrami and Ozawa equations. It is found that the addition of nanoparticles of SiO_2 influenced the mechanism of nucleation and the growth of PESeb crystallites. Also, the nanocomposites show a higher Avrami value than the neat PESeb, implying a more complex crystallization configuration. Moreover, the combined Avrami and Ozawa equation can successfully describe the crystallization model under the non-isothermal crystallization. The crystallization activation energies, E_a, calculated from ‘‘Kissinger’s equation’’ have shown that the synthesized PESeb/SiO_2 nanocomposites have lower energy than the neat PESeb, reflecting the much lower energy barrier for the rapid heterogeneous nucleation

Magnetic cobalt-zinc ferrite/PVAc nanocomposite: synthesis and characterization

Metal oxide nanoparticles are the subject of current interest because of their unusual optical, electronic, and magnetic properties. In this work, cobalt zinc ferrite ( Co_(0.3)Zn_(0.7)Fe_2O_4 ) nanoparticles have been synthesized successfully through redox chemical reaction in aqueous solution. The synthesized Co_(0.3)Zn_(0.7)Fe_2O_4 nanoparticles have been used for the preparation of homogenous polyvinyl acetate-based nanocomposite ( Co_(0.3)Zn_(0.7)Fe_2O_4/PVAc ) via in situ emulsion polymerization method. Structural, morphological and magnetic properties of the products were determined and characterized in detail by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The XRD patterns of the Co_(0.3)Zn_(0.7)Fe_2O_4 confirmed that the formed nanoparticles are single crystalline. According to TEM micrographs, the synthesized Co_(0.3)Zn_(0.7)Fe_2O_4 nanoparticles had nano-needle morphology with an average particle size of 20 nm. The calculated coefficient of variation (CV) of nanoparticles diameters obtained by TEM micrographs was 16.77. The Co_(0.3)Zn_(0.7)Fe_2O_4 nanoparticles were dispersed almost uniformly in the polymer matrix as was proved by SEM technique. The magnetic parameters of the samples, such as saturation magnetization (M_s) and coercivity (H_c) were measured, as well. Magnetization measurements indicated that the saturation magnetization of synthesized Co_(0.3)Zn_(0.7)Fe_2O_4/PVAc nanocomposites was markedly less than that of Co_(0.3)Zn_(0.7)Fe_2O_4 magnetic nanoparticles. However, the nanocompoites exhibited super-paramagnetic behavior at room temperature under an applied magnetic field