Journal of Iranian Chemical Engineering (Farsi Edition)
Year:2024 | Volume:23 | Issue:133|Papers Count:9

The removal of carbon dioxide due to environmental problems is still of great interest to researchers. In this study, simulation of carbon dioxide removal by absorption four amine base solvents including; monoethanolamine (MEA), diethanolamine (DEA), methyl diethanolamine (MDEA) and aminomethylpropanol (AMP) in a polypropylene hollow fiber membrane reactor is investigated. A comparative study for solvents by multi-physics Comsol software based on fluid dynamics (CFD) calculations is performed. The results showed that the best adsorption rate was obtained by MEA solvent with 88% CO2 absorption rate. The absorption of carbon dioxide by each amine-based solvents in the references is investigated separately. The simulation results are validated separately for each solvent. An acceptable consistency is obtaned between the present simulation data and the results of others given refrences. Finally, as a result of this study, it is shown that the present simulation is powerfully provided suitable and alternative data for carbon dioxide removal by each four traditional amine-based solvents in compare with the available experimental data.

Due to its resistance to flame and chemicals, PVC has been widely used as an electrical insulation material for wires and outer sheathing of cables. During normal operation, underground power cables are subjected to various stresses such as exposure to heat, humidity, and mechanical stress, which lead to changes in insulation properties and deterioration over time. Polymer nanodielectric materials refer to polymer nanocomposites that have several weight fractions of inorganic particles with nanometer dimensions. Dispersing these tiny nanoparticles with polymeric materials resulted in significant improvements in both dielectric and thermal properties, which in turn makes polymer nanocomposites the most popular term in the dielectric community. To optimize these novel properties, the dispersion of nanoparticles within polymeric matrices should be enhanced, and this can be achieved by chemical functionalization of nanoparticles surfaces using silanes or polyalcohol as coupling agents. This functionalization will result in changing the chemistry of nanoparticles to be compatible with that of polymers, and to reduce their agglomeration within polymer matrix. In the present study, the results of the researchers' studies on the dielectric properties such as relative electrical permeability, dielectric loss and mechanical properties such as tensile strength and modulus of elasticity of PVC used in insulation of wires and cables due to the introduction of metal oxide nanoparticles and some of their important results have been discussed.

A molecular dynamic simulation study of n-heptane hydro conversion over bifunctional Pt/MSU catalyst have been accomplished. Investigating morphology and topology of catalyst structure, the performance of catalyst through diffusing feed as particles, passing through pores and connecting channels have been analyzed. Furthermore, product selectivity and other specific structural properties in the range of 573-723K and atmospheric pressure have been assessed from diffusion and kinetic point of view. The result of diffusion illustrates that the MSD of n-alkanes has incremental trend with temperature. Maximum MSD for monobranched (MB) and multibranched (MTB) isomers are 45000 and 25000A2 respectively. Diffusion coefficient for MB, MTB and methane are 91.8, 54.3 and 457m2/s. From kinetic simulation, the feed conversion, pairwise lateral interaction according to DFT calculation and Morse potential function are achieved and the source of cracked and isomer products have been specified.

In this research, polystyrene-poly (ethylene glycol)-polystyrene (PS-b-PEG-b-PS) amphiphilic triblock copolymer was synthesized by atom transfer radical polymerization (ATRP) method. The results of FTIR and NMR analyses were confirmed the successful synthesis of the presented triblock copolymer. The experiments of hydrate inhibition performanc testing were carried out in the presence of methane gas using rocking-cell reactor at initial pressure of 68 bar and 1.5oC, respectively. The potential kinetic inhibitory effect of synthesized PS-b-PEG-b-PS copolymer was investigated at the conectrations of 0.05 and 0.1 wt% and compared with the similar data of commercial inhibitors including polyvinylpyrrolidone (PVP) and Luvicap EG as a polyvinylcaprolactam (PVCap)-based kinetic inhibitor from BASF. The obtained results showed that the synthesized PS-b-PEG-b-PS at concentration of 0.1% wt had about 92% inhibitory performance, while PVP as a commercial inhibitor had up to 84% inhibitory performance. Furthermore, the rate of gas consumption in the presence of the synthesized PS-b-PEG-b-PS was decreased about 6 times compared to Luvicap EG and 2 times less than to PVP one. The synthesized amphiphilic triblock PS-b-PEG-b-PS copolymer by ATRP method could be introduced as a new potential kinetic gas hydrate inhibitor. 

The aim of this research is creating a mesoporous structure in the MFI zeolite membrane layer and increase the pores diameter in order to increase the water permeability. The mesoporous structure was created by adding carbon black to the synthesis solution of the membrane in the in-situ hydrothermal method. The X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Berner-Emmett-Taylor (BET) and nitrogen gas permeability tests were used to characterize and the water permeation test was used to investigate the performance. The results showed the successful synthesis of the MFI zeolite membrane layer with proper crystallinity on the α-alumina support with the thickness of about 15 µm and the pore size between 4.5-20 nm, so that the largest amount of meso-pores had a diameter of 7.4 nm. The diameter of the pores has increased by 10 times compared to the synthesis without the presence of carbon black. The results of the water permeation test showed that increasing the the pores diameter using carbon black could increase the water flux of the membrane (26 L/m2.hr) up to 14-75 times compared to microporous membranes (0.35-1.74 L/m2.hr). Investigating the water flux of the membrane for water containing dissolved solids showed that the water flux of the mesoporous membrane (12 L/m2.hr) is still higher than the microporous membranes after 2 hr.

Spectral conversion of light and production of more useful photons for the photosynthesis process increases the growth of photosynthetic microorganisms including microalgae. Many researches have been done in this field, but due to the geometry of the cultivation system, the location of the light source, the failure to return photons into the system, etc., an accurate assessment of the effect of the spectral conversion on the growth of microalgae has not been provided. In this research, the effect of spectral conversion on the growth rate of microalgae Chlorella sp. has been evaluated using a more accurate method than other studies. For this purpose, a white LED lamp was placed inside a double-walled transparent tube as a light source, and the space between the walls was filled with Rhodamine 6G solution as a spectral converter. The whole above system was placed in the middle of a culture flask, in order to distribute the light homogeneously. In addition, the outer surface of the culture flask was covered with aluminum foil in order to minimize the photons leaving the flask and returning them inside. The results showed that in this method, the biomass productivity of Chlorella sp. microalgae increased up to 220%. The amount of this increase in more light intensity has been significantly less. In addition, the amount of light photons used in biomass production also increased up to 4 times

In order to improve the photocatalytic properties of TiO2 nanoparticles synthesized by sol-gel method, surface modification was conducted by iron using an impregnation-ultrasound method. XRD, FE-SEM, EDX and FTIR analysis showed Fe3+ ions doped in TiO2 nanoparticles with anatase nanocrystalline structure. Based on the UV-vis DRS results, the presence of iron in the TiO2 structure caused the light absorption to extend to the visible region and reduced the band gap of nanoparticles to 2.93 eV. The activity of TiO2 and Fe-TiO2 nanoparticles in the photocatalytic degradation of direct blue 71 (DB71) dye was investigated under visible light irradiation. Dye degradation reached 90.3% after 180 minutes of irradiation using Fe-TiO2, which indicates the high activity of nanophotocatalyst under visible light irradiation. The main reasons for increasing the photocatalytic activity of Fe-TiO2 are reduction of crystalline size, creation of new energy levels, high absorption of visible light and appropriate charge transfer. A mechanism for the effect of iron on the performance of Fe-TiO2 was presented. Degradation reaction kinetics and stability of Fe-TiO2 nanophotocatalyst were investigated.

Removal of antibiotics from water resources is essential for their harmful effects on living organisms. In this work, a polymeric membrane based on polyvinylidene fluoride deposited by cellulose loaded with Magnesium oxide nanoparticles (PVDF /Cellulose/MgO) has been prepared. The prepared membrane was characterized using FESEM, XRD, AFM, and contact angle measurement. The efficiency of the prepared membranes as an adsorbent for removing amoxicillin as a model pollutant was investigated. The effect of pH, amoxicillin concentration, and the time on the removal of amoxicillin was studied. The results showed that with a decrease in pH, a reduction in the initial concentration of amoxicillin, and an increase in time, the percentage of amoxicillin removal increases, and the maximum percentage of amoxicillin removal was obtained at about 85% at 200 mg/liter of amoxicillin, pH = 3, and 100 min. The kinetic of amoxicillin removal using PVDF/Cellulose/MgO membrane was also investigated. These results confirmed that PVDF/Cellulose/MgO membrane would be a potential adsorbent for removing amoxicillin from contaminated water.

One of the most concernative challenges of the current century is the disposal of waste tires; recycling them by devulcanization can be a solution to environmental problems. To find the relationship between the screw configuration and the properties of the samples, some new elements with different angles and shears were designed, and installed on the extruder. Then, 15 rubber samples were devulcanized by the extruder and Physical-mechanical tests were performed on them. To determine what process conditions will cause favorable mechanical properties in samples. During the tests, it was determined that temperature will be the most influential parameter in the devulcanization process. It was found that the highest percentage of devulcanization occurs at lower temperatures and medium and high shear rates. In this condition, the weight fraction of sol will be at its maximum value, which increases the processability of the samples. While increasing the temperature and decreasing the cutting rate cause a negative effect on the process. Among the investigated properties; the changes in abrasion and resilience were independent of screw configuration.