Effective Diffusion Coefficient De Research Articles

Effect of process parameters on the extraction kinetics of Leptocarpha rivularis DC. in a packed bed extractor using supercritical carbon dioxide

The kinetics of supercritical extraction from L. rivularis stalks using CO2 were studied in terms of temperature (40−60ºC), pressure (18–30 MPa), specific CO2 consumption (30−50 kg/kg d.s.), and particle diameter (0.5−1.1 mm). The extraction yield was found to range from 17.30 to 27.23 g/kg d.s. The highest extraction yield was obtained at 40°C, 30 MPa, 30 kg CO2/kg d.s., and mean particle size of 0.5 mm. The yield increased with pressure and decreased with temperature and particle size (p≤0.05). The diffusion model based on Fick's 2nd law adequately described the cumulative extraction curves, using the effective diffusion coefficient (De) as the adjusted parameter, which ranged between 3.50 and 19.26×10−12 m2/s. The Biot number was estimated, indicating a prevalence of internal control to mass transfer resistance. Additionally, the “apparent solubility” was obtained from the initial slope of the cumulative extraction curves. The extraction yield correlated positively with apparent solubility (p≤0.05) and De coefficient (p≤0.05).

Study on the Adsorption of Trace Water in N-Methyl-pyrrolidone Solvents by A-Type Molecular Sieves.

N-Methyl-pyrrolidone (NMP) is an important coating solvent for the production of lithium batteries, and its water content will greatly affect the coating quality and energy density of lithium batteries, which needs to be reduced to 200 ppm. The current vacuum distillation technology suffers from high operating costs and high energy consumption, whereas the pervaporation technology only achieves solvent dehydration up to 99.5%. Therefore, it is of great significance to carry out the study of trace water removal from NMP solvents. In this paper, the A-type molecular sieve adsorption method was used to remove trace water from the NMP solvent, and the effects of molecular sieve type, particle size, adsorption temperature, feeding amount, and contact time on the dehydration performance of NMP system were first investigated. Adsorbed at 25 °C for 240 min at a feeding amount of 120 g/L, 3A molecular sieves were able to reduce the water content of the NMP solvent from 5000 to 140 ppm. Second, Langmuir and Freundlich equations were used to fit the static isothermal adsorption data, and the results showed a better correlation of the Langmuir equation. Then, the adsorption kinetics and diffusion mechanism were analyzed by the kinetic model and the Crank single-pore diffusion model. The R2 of the pseudo-first-order kinetic model was 0.9993, which was more suitable for describing the process of adsorption of water from the NMP solvent by 3A molecular sieves, and the effective diffusion coefficient De = 2.986 × 10-8 cm2/s was calculated for the Crank single-pore adsorption model, which proved water molecules on the 3A molecular sieve. The diffusion of water molecules on the inner surface of the pores is the controlling step of the adsorption process. Finally, the fixed-bed dynamic penetration curves were investigated to obtain the experimental data of fixed-bed adsorption, and the experimental data were fitted using the Thomas and Yoon-Nelson models, which showed that both models could describe the adsorption behavior of trace water in NMP solvents on 3A molecular sieves. This study provides a new idea for the removal of trace water in NMP systems, and a series of model fitting parameters provide basic data for industrial scale-up.

Simulation and Experimental Study of Solid-Liquid Extraction of Coal Tar Residue Based on Different Extractants.

Coal tar residue (CTR) is recognized as a hazardous industrial waste with a high carbon content and coal tar consisting mainly of toxic polycyclic aromatic hydrocarbons (PAHs). The coal tar in CTR can be deeply processed into high-value-added fuels and chemicals. Effective separation of coal tar and residue in CTR is a high-value-added utilization method for it. In this paper, ethyl acetate, ethanol, and n-hexane were chosen as extractants to study the extraction process of coal tar from CTR, considering the mass transfer in the liquid phase outside the CTR particles and the diffusion inside the CTR particles, and a mathematical model of the solid-liquid extraction process of CTR was established based on Fick's second law. First, the mass-transfer coefficients (kf) and effective diffusion coefficients (De) of ethyl acetate, ethanol, and n-hexane in solid-liquid extraction at 35 °C were determined to be 1.54 × 10-5 and 4.99 × 10-10 m2·s-1, 1.14 × 10-5 and 3.57 × 10-10 m2·s-1, and 1.01 × 10-5 and 3.48 × 10-10 m2·s-1, respectively. Furthermore, the simulated values obtained by the model also maintained a high degree of agreement with the experimental results, which indicates the high accuracy prediction of the model. Finally, the model was used to investigate the effects of the solvent-solid ratio, temperature, and stirring speed on the extraction rates with the three extractants. According to the analysis with gas chromatography-mass spectrometry (GC-MS), among the three solvents, n-hexane extracted the highest content of aliphatic hydrocarbons (ALHs), ethyl acetate extracted the highest content of oxygenated compounds (OCs), and ethanol extracted the highest content of aromatic hydrocarbons (ARHs). The model and experimental data can be used to provide accurate predictions for industrial utilization of CTR.

Diffusion of HTO, 36Cl and 22Na in the Mesozoic rocks of northern Switzerland: I. Effective diffusion coefficients and capacity factors across the heterogeneous sediment sequences

Argillaceous rocks are currently being examined worldwide as potential host rocks for repositories for radioactive waste and spent fuel due to their favourable characteristics such as the self-sealing ability or limited diffusive transport of fluids, solutes or gases. In this study, through-diffusion experiments focused on rock samples with different mineralogical compositions taken from deep boreholes in the Mesozoic rock sequence of northern Switzerland, to determine diffusion parameters of HTO, 36Cl− and 22Na+ perpendicular to the bedding plane. Both effective diffusion coefficients and accessible porosities were calculated from the data obtained. In the Opalinus Clay, the primary selected host rock of the repository, the effective diffusion coefficients (De) and accessible porosity values (ε) of the neutral species HTO within and across all study areas are relatively consistent (De = 8.8 ± 1.9 × 10−12 m2 s−1; ε = 0.12 ± 0.02), indicating that the material can be considered homogeneous in terms of diffusion properties. Importantly, the chemical composition of the pore water has no effect on the values of the effective diffusion coefficients of HTO. On the other hand, the rocks above and below the Opalinus Clay, up to the next aquifer, consist of tight sedimentary units (carbonates, siliciclastics including argillaceous rocks) with a wider range of diffusion coefficients, indicating a higher level of heterogeneity. The diffusion coefficients of anions, such as 36Cl−, tend to be smaller due to anion exclusion effects, while those of cations, such as 22Na+, tend to be larger due to surface enhanced diffusion. The extent of these effects is largely determined by the composition of the pore water, and – in the case of cations – by the extent of sorption which depends also on the sorption capacity – indicated by the cation exchange capacity - of the solid. As a result, variations in the effective diffusion coefficient of 36Cl− and 22Na+ can be observed firstly between different rock types (i.e. composition, fabric), and secondly between the different study areas due to differences in the chemical composition of the pore waters in contact with the solid phase.Based on the analysis of around 130 samples, it has been observed that the diffusion coefficients of the Mesozoic units in northern Switzerland exhibit a significant correlation with the total clay content of the rocks. These findings pave the way for the establishment of a diffusion database for the relevant elements under consideration in the Swiss radioactive waste programme and the Safety Case.

Resolving experimental biases in the interpretation of diffusion experiments with a user-friendly numerical reactive transport approach

The reactive transport code CrunchClay was used to derive effective diffusion coefficients (De), clay porosities (ε), and adsorption distribution coefficients (KD) from through-diffusion data while considering accurately the influence of unavoidable experimental biases on the estimation of these diffusion parameters. These effects include the presence of filters holding the solid sample in place, the variations in concentration gradients across the diffusion cell due to sampling events, the impact of tubing/dead volumes on the estimation of diffusive fluxes and sample porosity, and the effects of O-ring-filter setups on the delivery of solutions to the clay packing. Doing so, the direct modeling of the measurements of (radio)tracer concentrations in reservoirs is more accurate than that of data converted directly into diffusive fluxes. While the above-mentioned effects have already been described individually in the literature, a consistent modeling approach addressing all these issues at the same time has never been described nor made easily available to the community. A graphical user interface, CrunchEase, was created, which supports the user by automating the creation of input files, the running of simulations, and the extraction and comparison of data and simulation results. While a classical model considering an effective diffusion coefficient, a porosity and a solid/solution distribution coefficient (De–ε–KD) may be implemented in any reactive transport code, the development of CrunchEase makes it easy to apply by experimentalists without a background in reactive transport modeling. CrunchEase makes it also possible to transition more easily from a De–ε–KD modeling approach to a state-of-the-art process-based understanding modeling approach using the full capabilities of CrunchClay, which include surface complexation modeling and a multi-porosity description of the clay packing with charged diffuse layers.

Pulsed electric field using the needle–needle electrodes for improving the salt diffusion of pork brine salting

Pulsed electric field (PEF), as an emerging nonthermal processing technology, has attracted extensive attention and research in food processing. In the present study, PEF has been approved that has the potential to enhance salt diffusion in pork. In this study, pork lions were pretreated with PEF before being immersed in the brine (5% NaCl [w/w]) at 4°C to investigate the effect of needle-needle PEF pretreatment on pork brine salting. The changes in the weight, moisture, and salt content were detected during the salting process. The effective diffusion coefficient (De) and mass transfer kinetics were calculated.Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were subsequently used to analyze the microstructure of the pork and the secondary structure of myofibrillar proteins (MPs). The outcomes demonstrated that after brining for 8h with PEFpretreatment, the weight, moisture, and salt changes increased significantly. The central salt content achieved by 12h brining after PEF treatment (4.5kV) is equivalent to that achieved by brining for 20h without any treatment. The De was raised to 4.0×10-10 (PEF) from 3.1×10-10 (control).SEM and FTIR results revealed that PEF altered the microstructure of pork and the secondary structure of MP.Our study demonstrated that PEF generated by needle-needle electrodes could effectively promote salt diffusion and shorten salting processing.

Application of Response Surface Methodology for Optimization of the Biosorption Process from Copper-Containing Wastewater.

Copper-containing wastewater is a significant problem in the water industry. In this work, biosorption of copper ions on alginate beads have been considered as a promising solution. The effective diffusion coefficient De is the parameter describing the diffusion of copper ions in calcium alginate granules. Granules with a wide spectrum of alginate content from several to several dozen percent (0.6-20%) were tested. The granules with an alginate content of 20% were produced by a new method. The conductometric method was used to determine De. The study determined the De values depending on the process parameters (temperature and pH of copper solutions) and the alginate content in the granules. The RSM method was used to analyze the obtained results. The conducted research proved that all analyzed factors significantly affect the value of the diffusion coefficient (R2 = 0.98). The optimum operating conditions for biosorption of copper ions from CuCl2 salt, on alginate beads obtained by RSM were as follows: 0.57% of alginate content in the granules, temperature of 60.2 °C, and pH of 2. The maximum value of De was found to be 2.42·10-9 m2/s.

Modelo matemático para determinar a duração do processo de salgagem e a concentração de sal no peixe

Abstract The purpose of this scientific work is to build a diffusion model based on Fick's second law. The model is designed to determine the salting process duration and salt concentration in the fish muscle tissue (Atlantic herring). The method of photon correlation spectroscopy (PCS) by a certified Photocor FC correlator device was used. The device operating principle is based on Rayleigh radiation scattering, which allows us to directly determine the effective diffusion coefficients, taking into account all factors, without singling out a specific one. This research presents the spatiotemporal distributions of effective diffusion coefficients in a herring sample during brine salting. Formulas for calculating the salting duration and the average salt concentration in the thickness of fish muscle tissue are presented, and the time of reaching the sample center by salt and the average salt concentration in it were estimated. These parameters could be widely used for the finished product quality and the technical and economic indicators of production improvement. The average effective diffusion coefficient De through the sample thickness was used for calculation. The salting duration for a 30 mm thick herring sample with a saturated salt solution was 8.74 hours until the average salinity of the sample was 4.7%.

Temperature-Regulated Core Swelling and Asymmetric Shrinkage for Tunable Yolk@Shell Polydopamine@Mesoporous Silica Nanostructures.

Facile and controllable synthesis of functional yolk@shell structured nanospheres with a tunable inner core ('yolk') and mesoporous shell is highly desirable, yet it remains a great challenge. Herein, xx developed a strategy based on temperature-regulated swelling and restricted asymmetric shrinkage of polydopamine (PDA) nanospheres, combined with heterogeneous interface self-assembly growth. This method allows a simple and versatile preparation of PDA@mesoporous silica (MS) nanospheres exhibiting tunable yolk@shell architectures and shell pore sizes. Through reaction temperature-regulated swelling degree and confined shrinkage of PDA nanospheres, the volume ratio of the hollow cavity that the PDA core occupies can easily be tuned from ca. 2/3 to ca. 1/2, then to ca. 2/5, finally to ca. 1/3. Owing to the presence of PDA with excellent photothermal conversion capacity, the PDA@MS nanocomposites with asymmetric yolk distributions can become a colloidal nanomotor propelled by near-infrared (NIR) light. Noteworthily, the PDA@MS with half PDA yolk and microcracks in silica shell reaches 2.18 µm2 s-1 of effective diffusion coefficient (De) in the presence of 1.0 W cm-2 NIR light. This temperature-controlled swelling approach may provide new insight into the design and facile preparation of functional PDA-based yolk@shell structured nanocomposites for wide applications in biology and medicine.

Effects of Adding Different Proportions of H2 to the Simulated Hydrogen‐Rich Blast Furnace

AbstractThe volume‐fraction changes of CO2 and H2O after adding different proportions of H2 to the hydrogen‐rich blast furnace were simulated by thermodynamic calculations to evaluate the effects of H2 on coke gasification in a blast furnace. Thermodynamic calculations indicated that the H2O content in the mixed gas gradually increased with higher H2 content. The coke gasification kinetics effective diffusion coefficient De and interfacial reaction rate constant k+ of the coke gasification reaction improved with higher H2 content. In addition, the reactivity of cokes enhanced and the coke strength after reaction decreased with higher H2 content. Mercury porosimeter experiments demonstrated that the coke gasification reaction mainly occurred on the surface.

Investigation on the pollution release characteristics of subgrade base materials prepared by oil-based cutting thermal desorption residues.

The preparation of oil-based cutting thermal desorption residues into subgrade materials is one of the methods of their resource utilization. While the environmental safety for subgrade materials is lack of discussions. In this study, through the semi-dynamic leaching tests, the leaching characteristics of pollutants from residues subgrade materials under extremely acidic conditions were simulated. According to Fick's second law, combined with the effective diffusion coefficient (De), the risk of pollutant leaching and release in residue subgrade materials were evaluated. The concentrations of naphthalene, anthracene, benzo(a)anthracene, dibenzo(a,h)anthracene, Cd, and Zn met the requirements of class III water quality in the Chinese standard GB/T14848-2017. The release of naphthalene, anthracene, benzo(a)anthracene, dibenzo(a,h)anthracene, and Cd of leaching was dominated by diffusion. The release of benzo(a)pyrene and Zn of leaching was mainly dissolution. Hence, based on the investigation, the release law and characteristics of pollutants were explored when thermal desorption residues were applied as subgrade materials, which provided an important reference basis for the resource and utilization of oil-based cutting thermal desorption residues.

Conditioning of simulated cesium radionuclides in NaOH-activated fly ash-based geopolymers

The growing nuclear safety concerns call for better solutions than traditional Portland cement-based materials to retain radionuclides especially Cesium (Cs). This work explored engineering process development and characterization of low-cost sustainable NaOH-activated fly ash-based geopolymers (FA-GP) as a conditioning matrix for non-radioactive equivalent of Cs (133Cs+). The effects of processing parameters on the FA-GP microstructure, porosity, in-situ zeolite crystallization, and Cs immobilization performance (quantified as the Leachability Index LX) were investigated and compared with literature data. The immobilization of non-radioactive equivalent of Cs (133Cs+) in NaOH-activated FA-GP was investigated using factorial design of experiments. The Cs leachability index (LX) was evaluated according to ANSI/ANS-16.1. FA-GP were characterized using SEM, XRD, and N2 adsorption-desorption isotherms. The results revealed that the main factors influencing Cs immobilization were the curing temperature and the interaction between Cs dosage and curing temperature. LX ≥12 and effective diffusion coefficient De ≤10−12 cm2/s was obtained for FA-GP cured at 90 °C. The effective diffusivity was about 5–7 orders of magnitude lower than for the conventional Portland cement-based encapsulation materials. Enhanced immobilization of Cs (LX = 14.6, De = 2.5 × 10−15 cm2/s), not reported hitherto, was further achieved by in-situ pollucite (Cs,Na)2Al2Si4O12.2H2O crystallization within FA-GP via one-step synthesis route at 90 °C. In addition, leaching studies on powdered FA-GP demonstrated encouraging performance and reliability of FA-GP under extreme mechanical conditions. It therefore appears that FA-GP could be a promising nuclear waste immobilization material, especially for the waste containing high concentration of Cs.

Comparison of the intraparticle diffusion of DBT and 4,6-DMDBT in HDS over different mesostructured silica-based catalysts

Achieving ultradeep hydrodesulfurization (HDS) of diesel necessitates HDS catalyst optimization. Understanding the catalyst pore structure effects on the diffusion behavior of the organosulfur compound benefits the proper design of the HDS catalysts with maximized apparent reactivities. In the present study, we controllably synthesized three mesoporous silica-based catalysts (NiMo/Zr-SBA-15, FDU-12, and MCFs) with similar intrinsic reactivities (∼13 × 10-4 and ∼ 5 × 10-4 mol•g−1•h−1 for DBT and 4,6-DMDBT HDS) but different pore structures. The diffusion behaviors of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in pore channels were systematically investigated via the reaction kinetic method. The pore channel/cage sizes rather than the pore mouth/window sizes dominated the intraparticle diffusion. The effective diffusion coefficient (De) decreased in the order of NiMo/Zr-MCFs (19.7 cm2•s−1) > NiMo/Zr-FDU-12 (18.2 cm2•s−1) > NiMo/Zr-SBA-15 (8.2 cm2•s−1) for DBT, while NiMo/Zr-MCFs (7.4 cm2•s−1) > NiMo/Zr-FDU-12 (4.4 cm2•s−1) > NiMo/Zr-SBA-15 (4.2 cm2•s−1) for 4,6-DMDBT. The corresponding correlation with pore size suggested that the intraparticle diffusion resistance can be greatly relieved when the catalyst pore/cage size is > 25x larger than the molecule size of the organosulfur-containing compounds. The findings present fresh opportunities for designing silica-based HDS catalysts for efficient HDS reaction.

Mass transfer enhancement of tuna brining with different NaCl concentrations assisted by ultrasound

The influence of different NaCl concentrations (2.5, 5, 7.5 and 10% (w/w)) on the mass transfer kinetics of tuna during brining process with and without ultrasound assistance was evaluated. Results showed that an increase in NaCl concentration and the application of ultrasound accelerated the salt diffusion in the tuna muscle, and the highest yield was obtained in 5% brine concentration. Moreover, the kinetics parameters were significantly affected by the NaCl concentration and ultrasound application during brining. The values of the mass transfer kinetics parameters (k1, k2) for total and water weight changes decreased as NaCl concentration increased with and without ultrasound assistance during brining. In contrast, the higher the NaCl concentration, the higher the value of the salting kinetics parameters for salt weight changes. The application of ultrasound enhanced the salt effective diffusion coefficient (De) from 402.8% to 653.21% during the brining process, and the highest De was also found at 5% brine concentration. The application of ultrasound can improve the uniformity of salt distribution, enhance water holding capacity, reduce hardness and chewiness, but have no significant effect on color of tuna muscle.

Diffusion and Sorption Studies of Cs, Sr and Co in Intact Crystalline Rock

Three cationic tracers, Sr2+, Co2+ and Cs+ were tested with a modified electromigration device by applying 2V, 3V and 4V voltage gradients over an intact Grimsel granodiorite rock sample. An ideal plug-flow model and an advection-dispersion model were applied to analyze the breakthrough curves. Matrix characterization by C-14-PMMA autoradiography and scanning electron microscopy showed that in the centimeter scale of Grimsel granodiorite rock, the interconnected matrix porosity forms a well-connected network for diffusion. Micrometer-scale fissures are transecting biotite and chlorite minerals, indicating sorption of the studied cations. The ideal plug-flow model indicated that the effective diffusion coefficients (De values) for Sr2+, Co2+ and Cs+ tracer ions within the Grimsel granodiorite rock were 3.20 × 10−13 m2/s, 1.23 × 10−13 m2/s and 2.25 × 10−12 m2/s, respectively. De values were also derived from the advection-dispersion model, from which 2.86 × 10−13 m2/s, 1.35 × 10−13 m2/s and 2.26 × 10−12 m2/s were calculated. The diffusion speed for the tracers was in the sequence of Cs+ > Sr2+ > Co2+ that is in the same sequence as their diffusion in diluted water. The distribution coefficients (Kd values) calculated from the models covered the range of two magnitudes (from 10−7 m3/kg to 10−5 m3/kg). The result indicated that the sorption process of the studied elements did not reach equilibrium during the electromigration process, mainly due to the too much acceleration of the migration speed by the voltage gradients applied over the rock sample.

Multiple-perspective research on the spatial distribution of full-size aerobic granular sludge in wastewater treatment

With the further application of aerobic granular sludge (AGS), the granules specific morphological and structural assessment is more essential. Full-size AGS was evaluated from multiple-perspective of mass transfer performance, spatial structure and specific morphology. The results demonstrated that AGS with 2–3 mm particle size had the best performance in all aspects. Effective diffusion coefficient (De) values of ammonia nitrogen and oxygen for 2–3 mm AGS was 0.945 × 10−9 m2/s and 0.678 × 10−9 m2/s respectively, which was higher than other particle size. Pore distribution and specific surface area revealed the differences in full-size AGS. Excellent development of 2–3 mm AGS on mesopores and macropores provided a pathway for the diffusion of NH4+-N and O2. Its specific surface area was significantly higher than other granules, reaching 151.293 m2/g, which contributed to the adsorption of the substrate. Digital holographic microscopy (DHM) images were applied firstly to observe full-size AGS without staining, indicating the 2–3 mm AGS had the highest bacterial activity. Confocal laser scanning microscopy (CLSM) images showed a good distribution of extracellular polymeric substances (EPS) and cells in AGS. By optimizing the proportion of 2–3 mm AGS in all particles, the efficiency and stability of the AGS system is expected to be greatly improved.

Assessment of Clay Mineral Attenuation Capacity for Human Viral Pathogens

The current practice of curbing the ill effects associated with the open dumping of biomedical waste (BMW) solely relies on incineration. However, the incineration of BMW and plastic-based medical gear is associated with severe health hazards due to toxic emissions. Many countries are resorting to incineration at unpermitted locations and open dumping due to the enormous surge in the generated BMW during the ongoing pandemic times. Such improper practice of incineration of BMW incineration and open dumping leads to significant environmental pollution. Therefore, an alternative and environmentally sustainable disposal facility is essential to avoid the negative effects of BMW disposal. In this study, the effectiveness of compacted clay-based barrier systems was explored, for the first time, for the encapsulation of virus-contaminated BMW. The model parameters essential for designing such exclusive BMW containment facilities, namely effective diffusion coefficient (De) and retardation factor (Rd) for different clay minerals, were evaluated. The evaluation was based on the limited available batch sorption test and free solution diffusion test data for various hazardous pathogens. The model parameters were utilized to understand the attenuation of viral pathogens (SARS-CoV, poliovirus, and reovirus) and bacteriophages (MS2 and φx-174) in montmorillonite and kaolinite mineral barriers. The selected pathogens were chosen such that they represented SARS-CoV-2 in terms of its surface characteristics. The results from the present study revealed that a 2- to 3- mm thick exclusive clay-based barrier system was sufficient to contain the studied pathogens and SARS-CoV-2 for 50 years.

Comparison of Protein A affinity resins for twin-column continuous capture processes: Process performance and resin characteristics

Continuous chromatography is a promising technology for downstream processing of biopharmaceuticals. The operation of continuous processes is significantly different to batch-mode chromatography and needs comprehensive evaluation. In this work, the performances of four Protein A affinity resins were studied systematically for twin-column continuous capture processes. A model-based approach was used to evaluate the process performance (productivity and capacity utilization) under varying operation conditions, and the objective was to reveal the crucial resin properties for continuous capture. The trade-off between productivity and capacity utilization was found, and it is necessary to select appropriate resins for different feedstock and operation conditions. The capacity utilization heavily depends on mass transfer, and steep breakthrough curves are favorable for high capacity utilization. The productivity is determined by both equilibrium binding capacity and mass transfer, and the balance of feed amount and feed time is critical. Moreover, the influence of binding capacity and mass transfer on process productivity and parameter sensitivity with two important resin properties (equilibrium binding capacity qmax and effective pore diffusion coefficient De) were assessed by the model, and suitable resin parameter ranges for twin-column continuous capture were determined. The model-based approach is an effective and useful tool to evaluate the complex performance of different resins and guide the design of next-generation resins for continuous processes.

Effects of pulsed electric field pretreatment on mass transfer kinetics of pickled lotus root (Nelumbo nucifera Gaertn.)

This study investigated the mass transfer process, penetration of seasoning, texture and sensory quality of pickled lotus root slices with pulsed electric field (PEF) pretreatment and corresponding mechanisms. Samples were subjected to 10,000 pulses in 20s (0.5, 1.0 and 1.5 kV/cm), blanched in boiling water and then soaked in brine (3% dark soy sauce and 15% NaCl). PEF pretreatment significantly enhanced water loss and NaCl gain throughout the pickling process, and higher effective diffusion coefficient (De) of PEF-pretreated samples (PEF = 17.42 and Control = 9.51, 10^-7 m2/s) resulted in a shorter period to approach the theorical osmotic equilibrium of NaCl (0.12 w/w). Furthermore, better appearance, flavor and pickled degree of samples were also attributed to PEF pretreatment. The acquired results revealed that PEF can be used to pretreat foodstuffs before pickling processing considering its effects on improving mass transfer and potential for cost reduction.

Shrinkage, effective diffusion coefficient, surface transfer coefficients and their factors during solar drying of food products – A review

Drying of food materials leads to an increase in shelf-life and gives quality end products. Drying with solar energy is an economical and environmentally friendly method than other drying methods. The food products are dried using solar energy in different methods such as open sun drying, direct, indirect, mixed-mode and hybrid solar drying. There are some parameters such as shrinkage, effective diffusion coefficient (De), surface transfer coefficients, etc. majorly influence the solar drying of food products and these elements are extensively reviewed in this work. The shrinkage of food products affects the drying rate and quality of the food products as it involves surface cracking, volume, porosity and hardness changes. The De gives the moisture transfer rate in the food products during solar drying. The values of surface transfer coefficients including mass transfer coefficient (hm) and heat transfer coefficient (h) give the mass and heat transfer rate from the surface of the food product as these parameters are surface parameters. The parameters such as shrinkage, De, hm, and h of food products and their influencing factors need to be analyzed to understand more about the physics of the solar drying process. An extensive review is made on the factors of shrinkage, De, hm and h such as volume of water, moisture content, air temperature, air velocity, the thickness of product and geometry of food. The values of shrinkage, De, hm and h of different solar drying processes are tabulated and discussed. A brief review was performed on different mathematical models used to determine the values of shrinkage, De, hm, and h during solar drying of food products. The influencing factors such as moisture content, air temperature, velocity, thickness and geometry of the product on these three factors shrinkage, De, hm, and h were discussed. Important results and recommendations of this topic are mentioned at the final because it is an innovative review trial in the solar drying area.