نشریه پژوهش های کاربردی مهندسی شیمی - پلیمر
سال پنجم شماره 1 (پیاپی 15، بهار 1400)

Plant fibrous suspensions require electrostatically cationic polymers to provide proper and strong structures during papermaking. The charge bearing naturally and synthetically polymers (Polyelectrolytes), are considered as the most chemicals used in cellulosic products mills, due to improvement in the fibrous suspension and network properties. For this, cationic acrylamide polymer (CPAM) and anionic nano cellulose (ANC) were added individually and in combination forms into the fibrous suspension recycled from brown packaging papers. Compared to the blank sample without any the polymeric additive, the polymeric contained suspensions and networks revealed improvements in fibrous suspension properties; i.e., retention, freeness and the solid materials loss during the network formation; and in the fibrous dried network, include density, tensile and burst strengths. Individually application of each CPAM and ANC increased the suspension retention (productivity) as 8% and 2%, resp. Fibrous suspension freeness and loss materials content continuously increased and decreased up to 47%, respectively that could provide significant technologically and economically benefits. Paper density (+5%), tensile (+17%) and burst (+27%) properties improved drastically compared to the blank. But, tear strength of fibrous network decreased (-4%) which could be attributed to the network higher fines contents and retention, originated from the acrylamide polyelectrolyte flocculation effect. Individually application of ANC also enhanced suspension retention, network density, tensile and burst strengths and declined network tear strength with lesser suspension freeness and loss. Anionic nature, high specific surface area and huge hydrogen bonding potential of ANC are the main reasons of the obtained results. ANC post addition to CPAM contained suspension resulted in tear reduction, but higher suspension retention and freeness, together with higher density, tensile and burst strength of cellulosic network.

Research subject: Mazut is widely used in petrochemical, power, and marine industries. The use of these fuels, in addition to causing widespread air and sea pollution in the country, has also led to severe international penalties, rising costs, and corrosion of equipment. Therefore, the use of mazut fuel with sulfur compounds of up to 0.5% in the world, as a refining mazut fuel at the origin (in refineries) and taking into account all aspects, is more important. There are limited industrial methods for the hydrotreating of mazut (Due to the heavy oil cut and the complexity of sulfur compounds in it), the most common of which is hydrogen desulfurization (HDS). Research approach: The goal of this research, The simulation and economic evaluation of the hydrotreating plant from Mazut fuel with a capacity of 13.75 million barrels per year. The simulation of this process was performed in Aspen HYSYS petroleum refinery software. In this simulation, the effect of effective operating parameters such as pressure, hydrogen to mazut ratio, and finally catalyst consumption on the removal of sulfur compounds, production of by-products, net production costs, and total investment costs are investigated. Main Results The results showed that for the hydrotreating process of this mazut with sulfur compounds 3.5%, total capital investment is 308.9 million US$ and the net production cost of treated mazut fuel is estimated to be 114.5 million US$ per year. Also, economic sensitivity analysis showed that the operating parameter of the hydrogen to mazut ratio had the greatest effect on increasing the total capital investment and net production cost, which should be minimized as much as possible.

Breast cancer is one of the most common cancer in the world with the highest mortality rate in women. Chemotherapy is the typical therapy for the cancer. However, it has side effects due to damage to healthy cells. Targeted drug delivery by nano carriers to the cancerous cells reduces the toxic side effects on normal cells. Serum albumin is a widely used drug carrier because of its availability, ease of preparation, and binding ability to various ligands. Attachment of iron oxide nanoparticles to albumin can control their distribution by applying an external magnetic field.

In this study, albumin nanoparticles attached to superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized and loaded with 5-Fluorouracil (5-FU) anticancer drug by using the desolvation technique. The produced nanoparticles were characterized in terms of size, surface charge, and drug entrapment, by dynamic light scattering (DLS) and UV-Vis spectrophotometry. The cytotoxic effects of 5FU-loaded magnetic albumin nanoparticles and free 5FU on MCF7 cells were evaluated with the MTT assay. The internalization of nanoparticles in MCF-7 cells was confirmed by Prussian blue staining. In the end, the effects of nanoparticles on cell cycle and apoptosis were evaluated by flow cytometry using propidium iodide.

The mean particle size and zeta potential of 5FU loaded albumin nanoparticles and albumin magnetic nanoparticles were 220 nm, -25.8 mV, and 221 nm, -28 mV respectively. Drug entrapment efficiency and drug loading efficiency were also, 20%, 1%, and 15.8%, and 0.06% for albumin nanoparticles and magnetic albumin nanoparticles in turn. The drug-loaded magnetic albumin nanoparticles showed higher cytotoxicity than the free drug on MCF-7 cells. The flow cytometry cell cycle analysis showed more cytotoxicity of albumin nanoparticles in comparison with other groups. According to these results, it can be said that 5-FU loaded magnetic albumin nanoparticles were more effective and deserve further studies in the cancer treatment.

The aim of this research was the investigation on kinetic of curing reaction of polyurethane binder based on hydroxyl terminated polybutadiene (HTPB). This reaction is of particular interest in advanced polyurethane composite materials.

HTPB diol was dynamically cured using differential scanning calorimetery (DSC) at different heating rates (5, 10, 20 and 40° C/min) with curing agents of Toluene Diisocyanate (TDI) and Isophorone Diisocyanate (IPDI) in presence and absence of Dibutyltin Dilaurate (DBTDL) catalyst. Kinetic parameters were calculated using Kissinger, Ozawa and isoconversion models. Urethane formation and viscosity build-up during cure reaction was studied by Fourier Transform Infrared Spectroscopy (FT-IR) and rotational visocmetery (RV) methods.

Results showed that activation energy, enthalpy, progress and the rate of reaction were influenced by type of curing agent and the presence of catalyst. Kinetic models showed activation energy was reduced about 1 kJ/mol at each 0.05 unit increase in the degree of cure. The activation energy of HTPB-TDI-DBTDL binder system versus degree of cure was reduced slower in comparison to HTPB-IPDI-DBTDL binder system. Decrease in activation energy at degrees of cure higher than 90% was intensified as probable diffusion of low molecular weight molecules into polymer chains. Enthalpy of reaction in HTPB-TDI-DBTDL binder system at heating rates of higher than 10° C/min was independent of heating rate, whereas in HTPB-IPDI-DBTDL binder system the enthalpy of reaction is highly dependent on heating rate. Chemorheological results showed that rate of curing reaction for binder systems are in the order of HTPB-TDI-DBTDL>HTPB-IPDI-DBTDL>HTPB-TDI.

Leaching and recovery parameters controlling the releasing of selenium from Sar-Cheshmeh copper anode slimes are studied and determined.

Copper anode slimes is produced during the production of cathodic copper at the bottom of electrolyte cells, which is composed of insoluble anode components in the electrolyte. The copper anode slimes are made up of those components of the anodes, which are not soluble in the electrolyte. They contain varying quantities of precious metals like gold, silver, selenium and tellurium, and other precious metals in the anodic copper. They are being extracted as a by-product in the copper production process. Due to the fact that the main source of selenium is sulfur deposits such as copper and nickel. Copper anodic slimes is currently the only source of selenium in the world. In this study, the extraction of selenium from anodic copper slimes has been feasible. To do this, acid leaching has been used. Copper anodic sludge is the raw material for the production of more than 90% of the world selenium and is the main source of selenium production.[1-3]

In this paper, the effect of operational parameters such as acid concentration, temperature, process time and liquid to solid ratio on selenium recovery through copper slimes leaching was investigated. The optimum conditions of batch leaching For maximum selenium extraction from anodic copper slimes are attained at 3 mol L-1 of HNO3 concentration, 0.01 (W/V) solid to liquid ratio for 60 min contact time at 70 º C. Under the optimized conditions, the selenium leaching efficiency was 99%. The thermodynamic data showed positive values of both ΔH and ΔS which indicates that the leaching process is indeed endothermic and random while the obtained negative values of ΔG show that selenium dissolution process is spontaneous in nature.

Nanomaterials are substances that, because of their size, can easily penetrate small pores and apply their impact. Nanofluids can allow appropriate wettability change in the reservoir rock, therefore, an accurate understanding of the behavioral mechanisms of these nanofluids is important in changing the wettability. This is because if there is no proper understanding of these mechanisms, they may exhibit the opposite behavior and cause damage to the reservoir. In previous research, CuO / TiO2 / PAM nanocomposite was synthesized and mechanistically introduced.

In this study, in continuation of the previous study, the behavioral and mechanism study has been investigated in a more accurate and documented manner, and spectral absorption tests, chemical flooding, and relative permeability diagrams confirm the effectiveness of enhanced oil recovery results of this nanocomposite. In carbonate rocks due to the positive surface charge of the rock and the negative charge of the nanocomposite, adsorption of nanomaterials in a double electrode layer state has been suggested as the dominant mechanism of wettability change. In sandstone rocks due to the charge coincidence of rock surface and nanomaterials which are both negative, the mechanism of disjoining pressure was the dominant mechanism of wettability change. To prove the abovementioned behaviors 200 ppm concentration of nanofluid was analyzed by spectroscopy method of adsorption analysis to validate the attraction forces of the nanocomposite with carbonate rocks and repulsion forces with sandstones.

Dynamic chemical flood tests were performed to confirm the effectiveness of this material in increasing oil production and showed 8.5% and 6.35% increase in oil production for carbonate and sandstone lithologies, respectively. Relative permeability diagrams showed an intersection point in the carbonate system with a 10% increase in water saturation and an intersection point in the sandstone system with a 12% increase in water saturation and the behavioral effect of the material at the studied concentrations.

With the rapid development of science and technology, cerium and cerium oxide are widely used in various fields, including in the manufacture of aluminum, aluminum alloys, some steels and in permanent magnets, catalysts, Polishing powder, Glass, Cinema, and Ceramic Technology. Solvent extraction is one of the effective techniques for extraction, separation, and purification of cerium.

The extraction of cerium (IV) from sulfuric acid solutions using Cyanex 921 in kerosene was investigated. The different parameters affecting the extraction process of cerium(IV) such as pH of aqueous solutions , reagent, metal ion concentration, contact time as well as temperature, are separately investigated. Experiments in the pH range of 0.5 to 5.5, at 25±1 oC , using Cyanx 921 in the concentration range of 0.06 to 0.4 mol L-1, and a mixture of Cyanx 921 and D2EHPA was performed in different ratios.

From the temperature study, the extraction reaction for Ce (IV) was found to be exothermic in nature. The results indicated that the effective extraction of cerium(IV) from sulfuric acid solutions cannot be achieved in a single equilibration because the solubility of Cyanex 921 in aliphatic diluents is limited at ambient temperature. To rectify this issue, the possibility of using a synergistic mixture of Cyanex 921 and D2EHPA as extractant system to recover cerium(IV) from sulfuric acid solutions was investigated. Mixtures of Cyanex 921 and D2EHPA resulted in synergistic extraction of cerium (IV) from sulfuric acid solutions. The results indicated that, under experimental conditions, the maximum synergistic coefficient was obtained at the molar ratio of (0.6M D2EHPA / 0.2 M Cyanex 921) 3.0, and cerium(IV) was extracted into organic phase in the form of Ce(SO4)(HSO4)2. Cyanex 921.

Well-designed plastic foams, with respect to their cell density and cell size, open-or-close cells, and the cell uniformity, compared to their counterpart unfoamed plastic parts, beside of having the advantages of less material consumption, dimensional stability, better processability, and a higher surface quality, they can have superior mechanical and physical properties, including strength to weight, impact strength, thermal and dielectric properties. The temperature distribution in the different zones of the extruder, the qualities and quantities of the nanoparticle additives and their dispersion in the polymer matrix can have significant effect on the mechanical properties of the produced foams by the extruder.

In this study, using an extruder, MA-g-polypropylene microcellular foams, containing 3, 7 and 9 wt% of nano-clay particles, were produced under three temperature arrangements on the extruder and the material and the processing effects on the mechanical properties were investigated.  

The result of this investigation shows that adding of nanoclay improves the mechanical properties of MA-g-PP.s foams. As an example, the results show that the sample with 7 wt% of surface modified nanoclay, owns about 10% higher impact toughness compared to the samples produced without nanoclay. Also for the same samples a rise of about 5% was recorded in Young modulus. The microstructural studies of the produced foams by scanning electron microscope (SEM) show that adding of nanoclay can result on more foam uniformity and smaller cell size. In this study, the smallest average cell size (87.5 μm) and the lowest density (0.3 g/cm3) were recorded for a sample with 7wt% nanoclay.