Direct synthesis of bi-modal porous structure MCM-41 and its application in CO2 capturing through amine-grafting

A bi-modal porous structure MCM-41 (BPS-MCM-41) was synthesized and functionalized by 3-[2-(2-Aminoethylamino)ethylamino]propyltrimethoxysilane (TRI); also, its performance in amine grafting and CO₂ capturing was compared with that of pore-expanded MCM-41 [1]. To create larger pores beside the mesoporous structure of MCM-41, carbon black nanoparticles were used as the solid template. Characterizing the BPS-MCM-41 using the BET and BJH techniques resulted in the surface reduction of 29.3 percent and volume increase of 68.46 percent. The pore size distribution showed two peaks: a narrow peak at 2.24 nm diameter, which belonged to micelles, and a wide one at about 50 nm due to the presence of used nanoparticles. The functionalization confirmed that BPS-MCM-41 is capable of accommodating a large quantity of amine groups. The CO₂ adsorption measurement indicated that internal volume of the adsorbent was a critical factor affecting the adsorption capacity of the amine grafted adsorbents.     

Investigation of well test behavior in gas condensate reservoir using single-phase pseudo-pressure function

Gas condensate reservoirs present complicated thermodynamic behavior when pressure falls below the dew point pressure, due to fluid dropout and change in the fluid composition. Condensate blockage in the near wellbore region reduces the well deliverability. Mixture composition change in the reservoir makes the interpretation of well tests in gas condensate reservoirs a serious challenge. In this study, at first the capillary number effect and Non-Darcy Flow on compositional simulation of gas condensate reservoirs were investigated and then well test analysis was carried out. The main objective of this work was to examine gas condensate well test analysis using single-phase gas pseudo-pressure and radial composite model assuming capillary number effect and Non-Darcy Flow. For this purpose some fluid samples were selected and results compared. Results indicate that estimation of reservoir properties below the dew point is in good agreement with actual input, particularly for lean fluid samples.     

Efficient loading and entrapment of tamoxifen in human serum albumin based nanoparticulate delivery system by a modified desolvation technique

Herein, the poorly water-soluble drug, Tamoxifen (Tmx), was loaded in the amphipathic matrix of human serum albumin (HSA) nanoparticles by a modified desolvation method. In order to enhance the drug loading (DL) and drug entrapment efficiency (DEE) (<2% and 10%, respectively), ultrasonication of Tmx-HSA mixture was performed prior to desolvation process. Tmx loading and entrapment efficiency were optimized by employment of the response surface methodology (RSM)-central composite design (CCD) of experiments. Under the optimum conditions of 1.59 mg Tmx/ml concentration, 7.76 pH and 5 h incubation of HSA-Tmx, the DL of 6.7% and DEE of 74% are achievable. Particles with the average size of 195 nm, zeta potential of −21 mV and polydispersity index of 0.09 were produced under these conditions. A more sustained Tmx release behavior was observed from polyethylene glycol (PEG) conjugated nanoparticles in comparison to the non-PEGylated ones. The short-term stability investigation showed no alteration in physicochemical properties of nanoparticles at 4 and 37 °C, but small increase in nanoparticles size was observed after three months of storage at room temperature. This is the first report for efficient production of a Tmx delivery system based on HSA nanoparticles.     

Use of a selective extractant-impregnated resin for removal of Pb(II) ion from waters and wastewaters: Kinetics,equilibrium and thermodynamic study

Adsorption of Pb(II) ion by a novel extractant-impregnated resin, EIR, was studied as a function of various experimental parameters using batch adsorption experiments. The new EIR was prepared by impregnating gallocyanine (GCN) onto Amberlite XAD-16 resin beads. The EIR was characterized by nitrogen analysis and SEM micrographs. The new EIR showed excellent selectivity factor values (α) for Pb(II) adsorption respect to other metal ions. The effects of some chemical and physical variables were evaluated and the optimum conditions were found for Pb(II) removal from aqueous solutions. The equilibrium adsorption isotherm was fitted with the Langmuir adsorption model. The maximum adsorption capacity (q_max) of EIR for Pb(II) ions was found to be 367.92 mg g⁻¹. The kinetic studies showed that the intra-particle diffusion is the rate-controlling step. Also, the intra-particle diffusion coefficients, D_ip values, were of the order of 10⁻¹² m² s⁻¹. The values of enthalpy (ΔH°) were positive, which confirms the endothermic nature of adsorption process. Also, the positive entropy changes (ΔS°) were showed that the randomness increased along with the adsorption process. In addition, the obtained negative values of Gibbs free energy (ΔG°) indicated feasible and spontaneous nature of the adsorption process at different temperatures. The new adsorbent was very stable so that it can be successfully used for many consecutive cycles without significant loss in its adsorption capacity.     

Highly efficient supported AlCl3-based cationic catalysts to produce polyα-olefin oil base stocks

The main aim of this research is to decrease the amount of AlCl₃ content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl₃ on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl₃ and TiCl₄ onto Al₂O₃, SiO₂, and mixed supports, that is, Al₂O₃/FeCl₃ and SiO₂/FeCl₃. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl₃; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al₂O₃ and SiO₂, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV⁴⁰ and KV¹⁰⁰). The viscosity index (VI) values, derived from KV⁴⁰ and KV¹⁰⁰, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by ¹H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures.     

Hydrodynamic and heat transfer properties of magnetic fluid in porous medium considering nanoparticle shapes and magnetic field-dependent viscosity

The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous medium. The nanofluid flow field is affected by a magnetic field perpendicular to the sheet. The dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic field. The continuity, linear momentum, angular momentum, and energy equations are first simplified using the order of magnitude technique that, along with the applied boundary conditions and the definition of the appropriate parameters, are transferred to the similarity space using the similarity analysis. Then the resulting equations are solved using the Runge–Kutta method.The distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was clarified. Increasing the Hartmann number, the vortex viscosity parameter, the magnetic parameter, the nanoparticle volume fraction, and the permeability parameter of the porous media increased the surface friction on the sheet. Increasing the vortex viscosity parameter, the magnetic parameter, and the volume fraction of the nanoparticles increases the Nusselt number.     

Microscopic and macroscopic atomization characteristics of a pressure-swirl atomizer,injecting a viscous fuel oil

Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean gas products such as hydrogen. Some entrained flow gasifiers operate with Heavy Fuel Oil(HFO) feedstock. In this application, HFO atomization is very important in determining the performance and efficiency of the gasifiers.The atomization characteristics of HFO(Mazut) discharging from a pressure-swirl atomizer(PSA) are studied for different pressures difference(Δp) and temperatures in the atmospheric ambient. The investigated parameters include atomizer mass flow rate( _m), discharge coefficient(CD), spray cone angle(θ), breakup length(Lb), the unstable wavelength of undulations on the liquid sheet(λs), global and local SMD(sauter mean diameter) and size distribution of droplets. The characteristics of Mazut sheet breakup are deduced from the shadowgraph technique. The experiments on Mazut film breakup were compared with the predictions obtained from the liquid film breakup model. Validity of the theory for predicting maximum unstable wavelength was investigated for HFO(as a highly viscous liquid). A modification on the formulation of maximum unstable wavelength was presented for HFO. SMD decreases by getting far from the atomizer. The measurement for SMD and θ were compared with the available correlations. The comparisons of the available correlations with the measurements of SMD andθ show a good agreement for Ballester and Varde correlations, respectively. The results show that the experimental sizing data could be presented by Rosin-Rammler distributions very well at different pressure difference and temperatures.     

Direct extraction of Mo(VI) from sulfate solution by synergistic extractants in the rotation column

Direct extraction of molybdenum from sulfate solution with synergistic extractants (mixture of D₂EHPA and TBP) was studied in the rotation column. The influence of extractant concentration and initial pH of aqueous phase was studied in the bench scale experiments. The outcomes demonstrated that the synergistic solvent extraction enhances the constancy of the extracted complexes for transfer into the organic phase. In the continuous experiments, the effect of different operating parameters such as speed of agitation, inlet solvent flow rate and inlet aqueous flow rate on the holdup, mean drop size, drop size distribution, slip and characteristic velocities and extraction percentage were examined. Modified correlations were proposed for prediction of hydrodynamic parameters with consideration of reaction extraction condition in the rotation column. Furthermore, these correlations were compared with the experimental data. According to the results, the direct extraction of Mo (VI) from aqueous solution and sulfuric media with extraction efficiency of 90.4% was obtained at higher rotor speed (240 r·min^-1 rpm) in this column.     

Mechanical and high velocity impact performance of a hybrid long carbon/glass fiber/polypropylene thermoplastic composite

This research explores mechanical and high velocity impact response of hybrid long carbon/glass fiber-reinforced polypropylene thermoplastic composites (HLFT) with different fiber lengths. The work examines three hybrid long fiber thermoplastic composites, i.e., 5, 10 and 20 mm. The HLFTs were prepared by a combination of extrusion and pultrusion processes and using a cross-head die. Tensile and Izod impact tests were carried out to evaluate the mechanical performance of each HLFT compound. A gas gun with a spherical projectile was used to conduct high velocity impact tests at three velocities of 144, 205 and 240 m/s. The results showed that internal mixing operation caused extensive reduction in fiber length of all three LFT lengths. Tensile strength, modulus and Izod impact test results were the indications of higher values with increase in HLFT length. Comparison of these results for the HLFT with that of corresponding glass/PP LFTs, adopted from earlier work by Shayan Asenjan et al. (J Compos Mater 53:353–360, 2019), showed better performance of HLFT. The high velocity impact results showed a steady higher impact performance with the increase in HFLT fiber length for all impact velocities tested. Comparison of HLFT high velocity impact performance revealed better results for all impact velocities tested with that of the corresponding glass/PP LFT composite.