Band 22, Heft 4

Chloride molten salt systems are widely used as electrolytes for molten salt electrolysis because of their relatively low eutectic temperatures and good thermal stability, but there is a serious lack of data on the thermophysical properties of chloride molten salts at elevated temperatures, whereas the nature of the electrolyte is very important for the electrolysis process. In this paper, the variation of the microstructure and thermophysical properties of the binary mixed LiCl–CaCl 2 molten salt system with temperature and composition is calculated using molecular dynamics (MD) simulations based on the BMH potential. The microscopic conformations observed in LiCl–CaCl 2 molten salts are mainly irregular, distorted tetrahedra and octahedra, which dynamically coexist, as analyzed by the radial distribution function, coordination number and angular distribution function. In addition, the effects of temperature and composition on the density, ionic self-diffusion coefficient, shear viscosity, and ionic conductivity of the molten salts were investigated, and the relationships of the thermophysical properties of LiCl–CaCl 2 molten salts with temperature and composition were obtained, which provide fundamental thermophysical data for the molten salt electrolytes.

Due to the substantial volume of waste produced and the potential for high-value bioactive compounds to be extracted from potato peel, the valorization of industrial waste of potato processing industry is the subject of this research. The study presents an innovative technique for efficient extraction of 4-hydroxybenzoic acid (P-HBA), a valuable bioactive molecule, from potato peel extract by utilizing molecularly imprinted chitosan beads (MICB). The MICB was synthesized using environmentally benign cross-linkers such as Tetraethyl orthosilicate (TEOS), Sodium triphosphate (STPP), while P-HBA was is used as a template. The MICB was investigated using FTIR, SEM, and EDAX. Adsorption studies were conducted to optimize parameters like adsorbent dose, solution concentration, time and pH. A recovery rate of 95.07 % is recorded from a synthetic P-HBA solution when measured by HPLC while from the actual potato processing industrial effluent the same is 40 %. The adsorption capacity of MICB is 67.5 mg g −1 and specific binding capacity is 20.62 mg g −1 which remained unchanged for six consecutive cycle reuse. This is the first study to report uptake of a bioactive molecule from actual potato processing industry waste.

The hydrodynamic and stirring characteristics of gas-slag-copper matte three-phase in side-blowing melt pool melting were numerically simulated using a combination of the volume of fluid (VOF) model in computational fluid dynamics and the realizable k - ε turbulence model. The study obtained macroscopic flow and gas-liquid two-phase distribution information of the flow field in the melting process. It also examined the effects of isokinetic blowing and nonlinear blowing on the fluid velocity, penetration depth, gas content, and turbulent eddy volume of the flow field, and compared the results. The results indicate that, for the same total gas volume, constant velocity blowing (CVS) inadequately agitates the molten pool, resulting in a large stirring dead zone within the flow field. In contrast, nonlinear blowing enhances the fluid velocity overall. Specifically, sinusoidal variable speed blowing (SWS) and rectangular variable speed blowing (RWS) reduce the stirring dead zone area by 79  and 73.5 %, respectively. This is attributed to the increase in maximum penetration depth and slag phase gas content, as well as the decrease in gas escape during nonlinear blowing. The vortex volume over the total calculated time for the three conditions is enhanced by 6.7  and 1.1 % for SWS and RWS, respectively. Additionally, the turbulent kinetic energy of the fluids is increased by 18.7  and 17 %, respectively.

A shell-and-tube Methanol Steam Reformer (MSR) system was designed for diesel engines. The effects of structural and operational parameters of the spiral baffles in the methanol reformer on heat transfer and hydrogen production performance were investigated. Additionally, a multi-objective optimization using response surface methodology was conducted to study the interactive effects of spacing and thickness, as well as liquid hourly space velocity and steam–methanol ratio, on the methanol conversion rate, hydrogen concentration and hydrogen production. The results indicated that reducing the baffle spacing and increasing the baffle thickness further improved heat transfer efficiency. Optimal conditions were achieved at a spacing of 30 mm and a thickness of 2 mm, resulting in a methanol conversion rate of 64.2 %. Increasing the steam–methanol ratio from 0.5 to 2 increased the methanol conversion rate from 50.6 % to 79.7 %, with a subsequent decrease in hydrogen concentration. Increasing the liquid hourly space velocity from 635 h −1 to 1905 h −1 significantly reduced the methanol conversion rate from 94.5 % to 64.2 %, but the hydrogen production increased from 0.111 mol/s to 0.228 mol/s. Optimization results indicate that the liquid hourly space velocity and steam–methanol ratio have a greater influence on the hydrogen production efficiency of the methanol reformer.

Cyclodextrins (CDs), due to its unique ‘outer hydrophilic and inner hydrophobic’ structure, can be used as excellent carriers to protect active aroma compounds. The hydrodynamic conditions in the reactor substantially influence the characteristics of the cyclodextrin inclusions. Based on this, this study investigated the effects of the impeller type and the rotational speed on the characteristics of the inclusion complexes, meanwhile the corresponding scale-up process was also investigated. Results showed that the pitched blade turbine was the optimum impeller due to better axial flow performance. The average particle size, polydispersity index (PDI), loading capacity and the major aroma concentration of the inclusion complexes prepared at 5 and 120 L reactors did not have significant difference compared to the inclusion complexes prepared at 0.5 L reactor under conditions of geometry similarity and constant power per unit volume, which verified the feasibility of the scale-up rule of the encapsulation process.

This study explores and analyzes the mixing efficiency of five innovative micromixers, each featuring serpentine microchannels, through comprehensive experimentation. The mixing experiments were conducted on micromixers with distinct shapes: backward arrow, loop, square, circular, and box waves, all equipped with backward arrow-shaped inlets, using the Villermaux–Dushman protocol. The assessment of mixing performance was carried out across a range of Reynolds numbers (Re) from 100 to 700, accompanied by varying pressure drop measurements. The efficiency of mixing was determined using ultraviolet spectrophotometry to measure the absorbance values and times for mixed fluids from the five micromixers. At Re values greater than 100, the mixing performance ranked as follows: Square-wave > Circular-wave > Box-wave > Loop-wave > Backward Arrow-shaped micromixers. Factors such as repeated perturbations, the presence of crests and troughs, the angle of the channels, and the split and recombination effects played significant roles in these outcomes. With increasing Re from 100 to 700, we observed progressive and consistent results across all microchannels. Remarkably, at a broad range of Reynolds numbers, the five micromixers demonstrated superior mixing performance compared to designs based on unbalanced split and collisions, achieving an impressive mixing efficiency of over 93 %, while keeping the pressure drop under 80 kPa. This pressure drop range is suitable for a variety of lab-on-a-chip and micro-total analysis systems. Furthermore, the experimental results show that the mixing performance of microfluidic systems can be improved by incorporating the presented design method of microchannel shapes, especially the Square-wave.

To increase the specific surface area of corn starch and remove the anion contaminant in water, STP-OGG-DD, which is composed of porous corn starch (Stp), methylpropenoxyethyl trimethyl ammonium chloride (DMC) and dimethyldiallyl ammonium chloride (DMDAAC), was prepared and used for the flocculation of humic acid (HA). In this preparation, ferrous sulfate and hydrogen peroxide act as initiators for free radicals that attract cationic monomers to gather on starch chains. The effects of reaction time, reaction temperature, dosage of cationic monomer, and initiator on the reaction performance were investigated. The results showed that the conversion rate of starch monomer was 97.69 %, the grafting rate was 96.47 %, and the grafting efficiency was 95.85 %. Stp-OG-DD was characterized by scanning electron microscopy, and its structure was characterized by X-ray diffraction and infrared spectroscopy. In the flocculation test. The flocculation effect of 30 mg/L flocculants with different grafting rates on 30 mg/L humic acid was investigated, and the relationship between the two was studied. The results showed that the flocculant with a high starch grafting rate had a better removal effect on humic acid and was positively correlated. Different from the traditional gelatinization method, the enzymatic hydrolysis method is used to pretreat starch, which not only saves energy but also enlarges the specific surface area of molecules. In addition, adding two cationic monomers improved the grafting effect of starch. DMC and DMDAAC could be polymerized alternately onto the starch backbone, providing long molecular chains and abundant positive charge for enzymatic hydrolysis of starch molecular chains. In addition to exploring the grafting of samples under reaction conditions, flocculants prepared under different conditions were used to flocculate 30 mg/L humic acid to further determine the role of grafting rate in the removal effect.

Vegetable oils are rich in unsaturated bonds that can be converted to epoxidized oleic acid. They are considered sustainable, renewable, and also environmentally friendly. To date, there is a paucity of studies on production of dihydroxystearic acid (DHSA) using an eco-friendly ion exchange resin as it is not fully utilised. As a result, the aim of this study is to elucidate the mechanism of ring-opening by hydrolysis for the production of DHSA using amberlite IR-120H as a catalyst. The process of epoxidizing oleic acid involved the in situ generation of performic acid, which was then used to convert oleic acid into epoxidized oleic acid. This performic acid was created by combining formic acid, serving as the oxygen carrier, with hydrogen peroxide, acting as the oxygen donor. Under optimal conditions, the maximum relative conversion of oleic acid to oxirane was attained, with up to 85 %. Overall, DHSA with a high hydroxyl value (182 mg KOH/g), was successfully produced from oleic acid using in situ hydrolysis of epoxidized oleic acid.

CaCl 2 molten salt, as a common electrolyte in the process of molten salt electrolysis, has a high decomposition potential and a strong ability to bind O 2− . So the study of the structure and properties of CaCl 2 is significant for the molten salt electrolysis. In this paper, molecular dynamics simulations (MD) method was used to investigate the variation rule of the local structure and physicochemical properties of CaCl 2 molten salt with temperature. The results show that the temperature has less effect on the heterozygous ion pairs and more effect on the homozygous ion pair. With the increase of temperature, the interaction between ion pairs is weakened, the coordination number decreases, the local structure changes a little, and the structural configuration tends to be an irregular octahedral structure with vacancies. The calculated self-diffusion coefficients, viscosities, and ionic conductivities are consistent well with the reality, but there is a significant error in densities due to the strong polarization effect of Ca 2+ compared to the reality. The local structure directly determines the thermodynamic properties of the molten salts. This study promotes the basic theoretical research on alkaline earth metal-containing molten salts and is an important reference for the study of molten salt electrolysis process.

Self-similarity impeller (SS impeller) was applied to enlarge the cavern region for the mixing of pseudoplastic fluid. The mixing characteristics of pseudoplastic fluid in an SS impeller stirred tank were explored by employing experimental and numerical simulation. The results indicated that the utilization of SS impeller resulted in significant improvement in the largest Lyapunov exponent of mixing system, as well as reduced mixing time and decreased mixing efficiency number compared with pitched-blade impeller (PB impeller) operating at an equivalent power consumption per unit volume. A reduction in power consumption was obtained through the application of self-similar configuration for the impeller blades. Meanwhile, SS impeller could enhance the fluidity of pseudoplastic fluid, minimize the stagnation regions, and enlarge the cavern region. This phenomenon was even more pronounced as the increase in self-similar iteration number of SS impeller. It was found that the design of self-similar structure for impeller blades could expand the cavern region and enhance the mixing efficiency for the mixing of pseudoplastic fluid, particularly as the self-similar iteration number increased.

This article develops a method for determining the areas of attraction of trajectories by stable points of dynamic equilibrium. This method is based on determining a line separating these areas. In the case of n -fold equilibrium states, there are a maximum of ( n  + 1)/2 regions of attraction. This is the maximum number of stable states. It may also happen that none of the states are stable and then there will not be any area of attraction. The number of all states n is odd. In the case of single stable states, we are dealing with one unlimited region of attraction. In the case of three-fold equilibrium states, two of which are stable, there are two regions of attraction, etc. In this study, the case of three-fold dynamic equilibrium states of a chemical tank reactor is considered.