نشریه پژوهش های کاربردی مهندسی شیمی - پلیمر
سال ششم شماره 1 (پیاپی 19، بهار 1401)

In recent years, toner-based printers have found many applications for ease of use, economical, high speed and quality. Therefore, many attempts have been made to produce toner by various methods such as suspension polymerization and emulsion aggregation. But in all these methods, despite the proper color properties and particle size, the reaction conversion is low.

In the present study, in situ emulsion polymerization method based on styrene and butyl acrylate monomers in the presence of carbon black has been used to produce toner with a conversion above 75%. In this regard, the effect of polymerization reaction temperature and stirrer speed on conversion at different times, particle size and particle size distribution, thermal and color properties of the final product were investigated. Color measurement was performed to evaluate the color characteristics. Also, the microstructure of the synthesized toners was evaluated using scanning electron microscopy.

The results show that in situ emulsion polymerization method while having the proper conversion of the reaction in the range of 75-90% is well able to create the suitable color characteristics and particle size distribution for the toner. All toners produced had a particle size distribution and a spherical shape that was unaffected by the reaction temperature and stirrer speed. By increasing the polymerization temperature from 70℃ to 80℃, resulted in a higher conversion, but the increase in stirrer speed had a dual effect on the conversion. Sticking of spherical particles with each other was observed by increasing the temperature to 90℃. The sudden addition of a monomers to the reaction media and using batch process resulted in the observation of two glass transition temperatures. This type of toner synthesis can be a guide for future research to produce toner with the highest conversion.

Because of the rising global demand for propylene, various extensive studies and research have been done in order to develop alternative ways that are both more energy-efficient and require less energy. In this research, CuBTC is used as a manganese catalyst base in the oxidative dehydrogenation of propane to produce propylene. The wet impregnation method is used to manufacture the catalysts.

Wet impregnation is used to prepare the catalysts, which is a step in the manufacturing process. Analyses such as FTIR, XRD, BET, SEM, and EDX are used to examine and describe catalysts that have been created. On the basis of the central composition method, we have investigated the impacts of reaction temperature, manganese loading percentage, oxygen-to-propylene ratio, and their interactions on the synthesis of propylene in this study. The central composite method's input parameters include manganese concentrations ranging from 1 to 5 percent, a propane-to-oxygen ratio ranging from 1 to 3 percent, and a temperature ranging from 140 to 280 degrees Celsius.

After that, it is shown that the projected models for propane conversion, propylene selectivity, and oxidative dehydrogenation efficiency percentage are about 95 percent based on reactor testing and evaluation of the Design-Expert software results. It was possible to improve the efficiency of the oxidation dehydration process by 4.9 percent by using a conversion percentage of 28.38 percent, a selectivity of 18.14 percent at 278 degrees Celsius, a metal oxide loading of 3.74 percent, and propane to oxygen ratio of 1.5 percent. When laboratory data were compared to predicted data, the correlation coefficient was 93% in favor of the laboratory data.

Oil extracted from the underground oil reservoirs contains heavy hydrocarbons.Heavy hydrocarbons include waxes,asphalts and resins that can appear as solids in compounds,which waxes are of particular importance.Changes in factors such as temperature,pressure,compounds of light components in petroleum compounds,etc.Cause the formation of solid paraffin wax deposits in these compounds.The wax precipitate formed mainly contains paraffins,naphthenes and to a lesser extent aromatics.The formation of these sediments in the first stage can block the underground pores, reduce their permeability and reduce the efficiency of oil extraction.In the next stages,the formation of deposits will lead to many problems. For example,it can clog pipes and increase flow resistance, resulting in a drop in flow pressure and,in addition to increasing the power required to pump fluid, cause premature depreciation of the facility.The issue of wax sediment formation and the factors affecting it have been discussed by researchers for many years and different methods have been studied to control it.In this project,by examining 1 nanoparticle of SiO2,as chemical inhibitor, acceptable results were obtained in reducing the wax appearance temperature(WAT).First,using differential scanning calorimetry analysis,a temperature of 250C was obtained for the crude oil cloud point.Then,by adding nanoparticles in different concentrations,this temperature was significantly reduced for different amounts of nanoparticles.Analysis of polarized optical microscopy also shows the change in structure of wax crystals to a disk like after the addition of nanoparticles. To investigate the flow behavior of crude oil,the apparent viscosity parameter was used at shear rates of 0.01,0.1 and 1 rpm and higher and lower temperatures of WAT temperature.Then,using wax deposition of oil samples by two analyzes of X-ray diffraction(XRD) and scanning electron microscopy(FESEM) with EDAX additive to study the dispersion of nanoparticles in wax deposits and changes resulting from the addition of nanoparticles in depositions was paid.In this regard,according to X-ray diffraction analysis,it was found that the nanoparticles had no chemical interaction with wax molecules,but was a confirmation of the results obtained in the analysis of differential scanning calorimetric analysis.The layered structure of the wax precipitate by adding nanoparticles to a fine-grained structure was also one of the results of scanning electron microscopy analysis.

Solar energy is a renewable resource that is abundant and can solve many problems of energy shortage. In order to use solar energy to desalinate water and produce high quality steam, one of the cheap and commercially proposed structures is floating solar steam generation system. In this system, water is transferred to the surface of the system in a controlled manner and is converted to steam using the heat generated in the photothermal layer. There are generally four main challenges in solar steam generation systems. These challenges include managing and preventing heat loss, structural strength, managing and transferring water within the structure, absorbing light and converting light into heat.

In this paper, floating multilayer solar steam generation systems were fabricated in which porous polyurethane foam was used as the substrate and thermal insulation layer. Moreover, felt was used as the water-transfer layer. Photothermal materials including graphite, gold, and mixtures of graphite and gold were used as the light-absorbing layers to produce high-quality steam. Also, in order to determine the water evaporation rate and the efficiency of the systems, the amount of changes in water mass and system temperature has been measured.

Among the different solar steam generation systems studied, the system made of graphite-gold mixture absorber is able to produce steam at a rate of 1.257 kg.m-2.h-1. This rate is equivalent to an efficiency of about 82%. To evaluate the performance of the systems in more real situation, they were tested using seawater. As resulted, the rate of evaporation of seawater by the graphite-gold mixture system is 1.201 Kg.m-2.h-1 and its efficiency is 78.4%.

This study demonstrates a synthetic strategy for the preparation of porous SiO2 for adsorption applications using natural and waste materials from rice husks which are functionalized with polymer dendrimer molecules and surface amino groups as the source of biosilica and were investigated to remove divalent cadmium ions from aqueous solutions.

Porous silica nanoparticles with a mean diameter of 45 nm were successfully fabricated from rice husk (RH) biomass via a multistep method. During the first step, sodium silicate is extracted from rice husks. Then, cetyltrimethylammonium bromide, HCl, and acetic acid were added to the sodium silicate solution, and the resulting mixture was sonicated. After the hydrothermal reaction, the collected samples were calcinated to obtain silica nanoparticles. These synthetic nanoparticles were identified using various techniques such as Fourier-transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, nitrogen adsorption-desorption analysis and dynamic light scattering analysis. Then, the adsorption kinetics and the effects of synthetic nanoadsorbents dosage on the removal of divalent cadmium ions were investigated. The effect of contact time on cadmium adsorption and recyclability of adsorbent was also investigated.

The results show that there is no significant reduction in the performance and activity of this nanosorbent in the adsorption of metal ions after 6 times of recycling and reuse. The excellent performance of this nanosorbent in the removal of metal ions is due to its high porosity, active surface amine groups and high surface-to-volume ratio.

In this study, Thiourea-functionalized super-paramagnetic nanoparticles were used as a heterogeneous catalyst in the Petasis-Borono Mannich reaction.
Research approach: In the first stage of this study, Fe3O4@SiO2 nanoparticles were synthesized as spherical core-shell nanoparticles such that Fe3O4 particles were considered as the core. Then in the next step, the characteristics of surface functional groups, crystal structure, magnetic properties, size and surface appearance of nanoparticles and the process of functionalizing the structure in layers, using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) were examined, identified and analyzed. Then, to evaluate the efficiency of the structure, it was used as a catalyst in the Borono-Mannich reaction of potassium potash. Infrared spectroscopy (FT-IR) and hydrogen nuclear magnetic resonance spectroscopy (HNMR) were used to investigate the structure of the products.

The IR spectroscopy results showed that the peaks appearing in 568 cm-1 and 670 cm-1 were related to iron-oxygen bond, the peaks in 1092 and 800-950 cm-1 were related to silicon-oxygen bond, which indicates the formation of silicon layer on nanomagnetic particles and the validity of the reaction products. The results also showed that the amount of saturated magnetite in about 23 emu/g increased with increasing complex ligand. X-ray diffraction analysis showed that the index peaks of (2θ= 21.25˚, 37.29˚, 43.73˚, 52.56˚, 65.09˚, 69.73˚, 76.81˚) were realized and for certainty of the formation of the desired magnetic nanoparticles in crystalline phase were used. The results of SEM analysis showed the structure of nanoparticles in a spherical shape and EDX analysis confirmed the presence of elements in the structure which included sulfur. Also, the thermogravimetric analysis index showed approximately 7% decomposition coefficient. The first, second and third decomposition were observed 1% by weight (60°C), 5% by weight (200 to 300°C) and 1% by weight (350 to 700° C), respectively. The highest yield of 68% was measured with 40 mg catalyst in acetonitrile. The structure of thiourea was properly stabilized in a magnetic nanocatalyst.