Band 21, Heft 6

The mixing uniformity plays a crucial role in a liquid-liquid two-phase chemical process. To quantify the uniformity of the liquid–liquid process, the specific surface area ratio is proposed and studied through computational fluid dynamics simulation. There is a scale effect in the liquid–liquid two phase chemical processing that the specific surface area ratio decreases to 7.01% when the diameter of the Y-like mixer increases from 1 mm to 10 mm. A millimeter-scale mixer with a fan-notched baffle structure was designed, and the baffle unit length, baffle tilt angle, baffle notch size and baffle thickness of the mixer were optimized. Compared with the 1 mm Y-like mixer, the specific surface area ratio of the 10 mm mixer with notched baffle structures increases to 2.5 times and the treatment capacity increases to 100 times. Additionally, experiment and simulation results prove that FNBS is considered to be a suitable structure for enhancing liquid-liquid two-phase. This study will provide a useful reference for the design of large-scale mixers applicable to liquid-liquid heterogeneous chemical processes.

In this study, the motion characteristics of bubbles in a vertical rectangular glass groove were investigated using image-processing techniques. A new metric (bubble offset) to evaluate the level of solution disturbance was proposed. The motion characteristics, such as the trajectory, bubble diameter, rise velocity, and coalescence, during the bubble rise were studied using different NaCl concentrations and airflow rates. The functional relationship of the bubble diameter and velocity with height was obtained by least-squares fitting (correlation coefficient R 2  ≥ 95%), and fits the power-law distribution. The results showed that the bubble motion characteristics were positively correlated with the airflow rate and negatively correlated with the NaCl concentration in the solution. The solution disturbance was closely related to the bubble offset, and the size of the bubble offset can be used to characterize the degree of the solution disturbance. The disturbance of the solution affects the bubble trajectory, rising velocity and coalescence. The bubble offset changed periodically with height, and its functional relationship was obtained. The accuracy of the functional relationship was verified using experimental data. The study of bubble motion characteristics is crucial for understanding phenomena such as heat and mass transfer and multiphase cooling.

In this work, the Supercritical AntiSolvent process has been used to generate micronized crystals of Retama raetam . The process was performed using ethanol and CO 2 as solvent and antisolvent, respectively. Recrystallization was made at various temperatures (30–50 °C) and pressures (8–12 MPa) using a constant flow rate of supercritical CO 2 (2 kg/h). We have been also varied the solution flow rate and its volume to identify conditions leading to spheroidal powder morphology. Size and morphology have been characterized by scanning electron microscopy and ImageJ software. The spraying of the supercritical solution directing the flow towards the precipitator results in the deposition of fine particles with uniform morphology at the bottom, and of a porous film adhering to the precipitator wall. For that reason, thermodynamic and hydrodynamic aspects are discussed so as to rationalize the powder and spongious film characteristics and provide a new way to control the SAS process applied to plant derivatives.

Catalysts play a vital role in petroleum and chemical reactions. Intensified concerns for cleaner air with strict environmental regulations on sulfur content in addition to meet economic requirements have generated significant interests for the development of more efficient and innovative oxidative catalysts recently. In this study, a novel homemade nano catalyst (manganese oxide (MnO 2 ) over tin (IV) oxide (SnO 2 )) was used for the first time as an effective catalyst in removing dibenzothiophene (DBT) from kerosene fuel using hydrogen peroxide (H 2 O 2 ) as oxidant in catalytic oxidative-extractive desulfurization process (OEDS). The catalyst was prepared by impregnation method with various amount of MnO 2 loaded on SnO 2 . The oxidation step was carried out at different operating parameters such as reaction temperature and reaction time in batch reactor. The extractive desulfurization step was performed by using acetonitrile as solvent under several operating conditions (agitation speed and mixing time). The activity of MnO 2 /SnO 2 catalyst in removing various sulfur compounds from kerosene fuel at the best operating conditions was investigated in this work. The results of the catalyst characterization proved that a high dispersion of MnO 2 over the SnO 2 was obtained. The experiments showed that the highest DBT and various sulfur compounds removal efficiency from kerosene fuel under the best operating conditions (oxidation: 5% MnO 2 /SnO 2 , reaction temperature of 75 °C, and reaction time of 100 min, extraction: acetonitrile, agitation speed of 900 rpm, and mixing time of 30 min) via the catalytic oxidative-extractive desulfurization process was 92.4 and 91.2%, respectively. Also, the MnO 2 /SnO 2 catalyst activity was studied after six consecutive oxidation cycles at the best operating conditions, and the catalyst prove satisfactory stability in terms of sulfur compounds removal. After that, the spent catalyst were regenerated by utilizing different solvents (methanol, ethanol and iso-octane), and the experimental data explained that iso-octane achieved highest regeneration efficiency.

Anaerobic co-digestion technology is widely used for biogas generation from organic wastes. In this study, co-digestion of petroleum oily sludge (POS) for biogas production in bench-scale anaerobic digesters at thermophilic conditions was investigated. The effects of inoculum type on the biogas production were considered. Three types of inoculums were examined individually for the co-digestion of POS which were; poultry manure, cattle manure, and cow dung. The results revealed that the biogas production from poultry manure, cattle manure, and cow dung exceeded its production from uninoculated POS by 64.6, 20.94 and 6.1% respectively. Effect of C/N on the co-digestion process was also considered in this study. Modified Gompertz model was applied to describe the kinetic of the co-digestion process. The predicted and experimental results of biogas generation were fitted well with coefficients of determination > 0.96 indicating appropriate conditions of the co-digestion process. Statistical analysis was performed to estimate if there were significant differences in terms of cumulative biogas yield. A significance level value of < 0.05 was obtained.

Polyvinyl alcohol (PVA), acrylic acid (AA), and β-cyclodextrin (β-CD) were used as monomers, and ammonium persulfate was used as an initiator. Orthogonal tests were optimized the experimental condition, and aqueous polymerization was used to prepare poly-β-cyclodextrin/polyvinyl alcohol/polyacrylic acid (β-CD/PVA/PAA) hydrogel. The samples were characterized by FT-IR (Fourier transform infrared), SEM (Scanning electron microscopy), and XRD (X-ray diffraction). β-CD/PVA/PAA hydrogel was analyzed, which influenced external environmental factors on the β-CD/PVA/PAA hydrogel adsorption performance, and the kinetic behavior of β-CD/PVA/PAA hydrogel on ciprofloxacin (CIP) adsorption was explored. The results concluded that the prepared β-CD/PVA/PAA hydrogel has a well-defined three-dimensional network structure. The decrease in the pH of the CIP solution and the adsorption temperature reduces the adsorption reaction of β-CD/PVA/PAA hydrogel on CIP. The kinetics of CIP adsorption by β-CD/PVA/PAA hydrogel confirmed the pseudo-second-order kinetic model ( R 2  > 0.997), the maximum equilibrium adsorption amounts is 372.12 mg/g, the removal rate reaches 74.42%. The adsorption process was mainly chemisorption, the adsorption isotherm fits the Freundlich adsorption isotherm model ( R 2  > 0.946), and the adsorption process was heterogeneous with multi-molecular layer adsorption. The adsorption process inclined more toward the adsorption of inhomogeneous multi-molecular layers. The β-CD/PVA/PAA hydrogel retained 80% adsorption properties after three adsorption-desorption under optimal conditions.

The deactivation of nickel catalysts in the dry reforming of methane (DRM) process has been one of the issues of interest to researchers. In this research, the effect of active phase and support promoter uses and synthesis method on synthesized Ni–Co/Al 2 O 3 –MgO nanocatalysts efficiency in wall coated microreactor on dry reforming of methane process studied. To determine the characteristics of the synthesized samples, XRD, BET, FESEM, and Ft-IR analyses have been performed. Analyses show that the use of ultrasound waves in the synthesis of catalysts improves the catalyst surface morphology so that about 82% of the particles of the synthesized sample are smaller than 100 nm and , increases the specific surface area to an average of 10%, and makes its structure smaller. Also, the total pore volume on the surface of the samples also shows a 10% increase. The use of promoters increases the catalyst activity and makes it more stable up to 18 h on stream. The use of a wall-coated microreactor improves heat transfer, easier access of reactants to active sites, no pressure drop, and higher activity than a conventional U-type fixed bed reactor. Nanocatalysts with Ni/Co = 5 and Al/Mg = 5 has shown the highest and most stable activity throughout the temperature range in the DRM process.

β-ammonium tetramolybdate [β-(NH 4 ) 2 Mo 4 O 13 ] is an important product of molybdenum metallurgy because of its uniform crystal structure and excellent thermal stability. The yield of molybdenum strip produced with β-(NH 4 ) 2 Mo 4 O 13 as raw material and various processing properties have been significantly improved. However, the crystallization process of β-(NH 4 ) 2 Mo 4 O 13 is very complex, including neutralization, polymerization, nucleation, and crystal growth stages, resulting in a variety of polymerization morphology. In this work, a concentric structure reactor was used to segment these stages with directional regulation of each stage. Residence time distribution (RTD) was used to evaluate the simulation of flow field characteristics in the concentric structure reactor. Determination of the influence of inlet-outlet positions, size and position of paddle, and baffle setting on the fluid behavior in a single tank suggested measures to improve the abnormal flow condition and reduce the dead zone volume fraction. In the concentric structure reactor, the dead zone volume fraction was only 2.36% when the clapboards were arranged alternately in an up-down design, using an inlet flow rate of 100 mL/min. β-(NH 4 ) 2 Mo 4 O 13 was prepared continuously by adding aqueous ammonia and product slurry for crystallization in the concentric structure reactor.

In recent years, research on the epoxidation of fatty acids has attracted a great deal of attention due to the increased need for eco-friendly epoxides generated from vegetable oils. The purpose of this research is to produce bio-lubricant from optimized epoxidized oleic acid by alcoholysis with methanol, tert-butyl alcohol, and ethanolamine. Epoxidation is carried out using in situ performic acid formation under a constant temperature of 60 °C where formic acid acts as an oxygen carrier and hydrogen peroxide acts as an oxygen donor. The determination of the optimum process parameters uses one factor at a time (OFAT) method and is based on the optimized process parameters until the maximum relative conversion to oxirane of 65% is achieved. The bio-lubricants are confirmed using the Fourier Transform Infrared (FTIR) analysis and the results show that the hydroxyl group is present at 3400 cm −1 of wavenumber. A kinetic modeling is performed using the MATLAB optimization tool. After 100 iterations, the reaction rate constant based on optimized epoxidized dated palm oil production were obtained as follows: k 11 = 0.4251 mol⋅L −1 ⋅min −1 , k 12 = 11.345 mol⋅L −1 ⋅min −1 , and k 2  = 0.6761 mol⋅L −1 ⋅min −1 .