Diffusion Coefficient De Research Articles

Simulation Study of Xylitol-Mediated Effect on NaCl Diffusion Behavior in Cured Pork Tenderloin.

Polyhydroxy alcohol-mediated curing has great potential for producing low-salt cured meat products. This study investigated the mass transfer kinetics and the one-way diffusion simulation of sodium chloride (NaCl) during the curing process. Furthermore, Fick's second law determined the NaCl diffusion coefficient (De) of xylitol-mediated cured pork tenderloin. The results demonstrated that adding xylitol could reduce the De of NaCl. The De of NaCl, calculated using the one-way model, was 1.29 × 10-9 m2·s-1, 1.22 × 10-9 m2·s-1, 1.2 × 10-9 m2·s-1, and 1.15 × 10-9 m2·s-1 when the amount of xylitol added was 0%, 4%, 8%, and 12% (w/w), respectively. This result agrees with the predicted values from the power function time-varying model. Moreover, a three-dimensional simulating model of mass transfers constructed using COMSOL Multiphysics was developed to evaluate the NaCl diffusion in pork tenderloin during the curing process. This model has high accuracy and can be used to describe the diffusion of NaCl in curing. Overall, this study provided a foundation for NaCl diffusion and distribution during the curing process.

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%.

NIR light-propelled bullet-shaped carbon hollow nanomotors with controllable shell thickness for the enhanced dye removal.

Materials with asymmetric nanostructures have attracted tremendous research attention due to their unique structural characteristics, excellent physicochemical properties, and promising prospects. However, it is still difficult to design and fabricate bullet-shaped nanostructure due to its structural complexity. Herein, for the first time, we successfully constructed NIR light-propelled bullet-shaped hollow carbon nanomotors (BHCNs) with an open mouth on the bottom of nano-bullet for the enhanced dye removal, by employing bullet-shaped silica nanoparticles (B-SiO2 NPs) as a hard template. BHCNs were formed by the growth of polydopamine (PDA) layer on the heterogeneous surface of B-SiO2 NPs, followed by the carbonization of PDA and subsequent selective etching of SiO2. The shell thickness of BHCNs was able to be facilely controlled from ≈14 to 30nm by tuning the added amount of dopamine. The combination of streamlined bullet-shaped nanostructure with good photothermal conversion efficiency of carbon materials facilitated the generation of asymmetric thermal gradient field around itself, thus driving the motion of BHCNs by self-thermophoresis. Noteworthily, the diffusion coefficient (De) and velocity of BCHNs with shell thickness of 15nm (BHCNs-15) reached to 43.8μm⋅cm-2 and 11.4μm⋅s-1, respectively, under the illumination of 808nm NIR laser with the power density of 1.5 W⋅cm-2. The NIR laser propulsion caused BCHNs-15 to enhance the removal efficiency (53.4% vs. 25.4%) of methylene blue (MB) as a typical dye because the faster velocity could produce the higher micromixing role between carbon adsorbent and MB. Such a smart design of the streamlined nanomotors may provide a promising potential in environmental treatment, biomedical and biosensing applications.

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.

Synthesis and spark plasma sintering of solid-state matrices based on calcium silicate for 60Co immobilization

An effective sorption material for the immobilization of cobalt radionuclides into highly safe and reliable solid-state matrices is proposed. The resulting silicate sorbent СaSiO 3 had an amorphous mesoporous structure (A BET 53 m 2 /g) and a sorption capacity Co ions of 3.32 mmol/g. The physico-chemical characteristics of the СaCoSi 2 O 6 sample obtained after Co 2+ ions sorption were studied using XRD, N 2 and Ar adsorption-desorption, SEM-EDX and TG/DTA methods. Solid-state silicate matrices characterized by high density values (2.86–3.16 g/cm 3 ), compressive strength (150–637 MPa) and Vickers microhardness (1.80–5.25 GPa) were obtained by spark plasma sintering (SPS). The sample obtained at 1000 °C had the lowest values of Co 2+ ions leaching (R Co ~10 −7 g/(cm 2 ×day)) and diffusion coefficient (De 1.73 ×10 −17 cm 2 /s) from silicate matrices. Thus, the obtained СaCoSi 2 O 6 silicate matrices saturated with Co ions comply with the regulatory requirements of GOST R 50926–96 and ANSI/ANS 16.1 for 60 Co immobilization. • Amorphous CaSiO 3 with 3.32 mmol/g Co ions sorption capacity was prepared. • SPS method allowed to obtain the CaCoSi 2 O 6 matrices at 1000 °C for 2 min. • CaCoSi 2 O 6 solid-state matrices exclude Co 60 ions leaching and diffusion. • The characteristics of CaCoSi 2 O 6 matrices exceeded the GOST and ANSI/ANS 16.1 requirements.

Analytical methods for assessing retinal cell coupling using cut-loading

Electrical coupling between retinal neurons contributes to the functional complexity of visual circuits. "Cut-loading" methods allow simultaneous assessment of cell-coupling between multiple retinal cell-types, but existing analysis methods impede direct comparison with gold standard direct dye injection techniques. In the current study, we both improved an existing method and developed two new approaches to address observed limitations. Each method of analysis was applied to cut-loaded dark-adapted Guinea pig retinae (n = 29) to assess coupling strength in the axonless horizontal cell type ('a-type', aHCs). Method 1 was an improved version of the standard protocol and described the distance of dye-diffusion (space constant). Method 2 adjusted for the geometric path of dye-transfer through cut-loaded cells and extracted the rate of dye-transfer across gap-junctions in terms of the coupling coefficient (kj). Method 3 measured the diffusion coefficient (De) perpendicular to the cut-axis. Dye transfer was measured after one of five diffusion times (1-20 mins), or with a coupling inhibitor, meclofenamic acid (MFA) (50-500μM after 20 mins diffusion). The standard protocol fits an exponential decay function to the fluorescence profile of a specified retina layer but includes non-specific background fluorescence. This was improved by measuring the fluorescence of individual cell soma and excluding from the fit non-horizontal cells located at the cut-edge (p<0.001) (Method 1). The space constant (Method 1) increased with diffusion time (p<0.01), whereas Methods 2 (p = 0.54) and 3 (p = 0.63) produced consistent results across all diffusion times. Adjusting distance by the mean cell-cell spacing within each tissue reduced the incidence of outliers across all three methods. Method 1 was less sensitive to detecting changes induced by MFA than Methods 2 (p<0.01) and 3 (p<0.01). Although the standard protocol was easily improved (Method 1), Methods 2 and 3 proved more sensitive and generalisable; allowing for detailed assessment of the tracer kinetics between different populations of gap-junction linked cell networks and direct comparison to dye-injection techniques.

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.

Nanosized Janus AuNR-Pt Motor for Enhancing NIR-II Photoacoustic Imaging of Deep Tumor and Pt2+ Ion-Based Chemotherapy

Synthetic micro/nanomotors have great potential in deep tissue imaging and in vivo drug delivery because of their active motion ability. However, applying nanomotors with a size less than 100 nm to in vivo imaging and therapy is one of the core changes in this field. Herein, a nanosized hydrogen peroxide (H2O2)-driven Janus gold nanorod-platinum (JAuNR-Pt) nanomotor is developed for enhancing the second near-infrared region (NIR-II) photoacoustic (PA) imaging of deep tissues of tumors and for effective tumor treatment. The JAuNR-Pt nanomotor is prepared by depositing platinum (Pt) on one end of a gold nanorod with varying proportions of Pt shell coverage, including 10%, 25%, 50%, 75%, and 100%. The JAuNR-Pt nanomotor with Pt shell coverage proportions of 50% exhibits the highest diffusion coefficient (De), and it can rapidly move in the presence of H2O2. The self-propulsion of JAuNR-Pt nanomotor enhances cellular uptake, accelerates lysosomal escape, and facilitates continuous release of cytotoxic Pt2+ ions to the nucleus, causing DNA damage and cell apoptosis. The JAuNR-Pt nanomotor presents deep penetration and enhanced accumulation in tumors as well as high tumor treatment effect. Therefore, this work displays deep tumor imaging and an excellent antitumor effect, providing an effective tool for accurate diagnosis and treatment of diseases.

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.

Spectroscopy, Morphology, and Electrochemistry of Electrospun Polyamic Acid Nanofibers.

Polyamic acid (PAA) nanofibers produced by using the electrospinning method were fully characterized in terms of morphology and spectroscopy. A PAA nanofiber–modified screen-printed carbon electrode was applied to the detection of selected sulfonamides by following an electroanalytical protocol. The polyamic acid (PAA) nanofibers were characterized using Fourier transform infrared (FTIR) spectroscopy to study the integrity of polyamic acid functional groups as nanofibers by comparing them to chemically synthesized polyamic acid. A scanning electron microscope (SEM) was used to confirm the morphology of the produced nanofibers and 3D arrangement at the electrode interface. The Brunauer–Emmett–Teller (BET) method was used to determine the surface area of the nanofibers. Atomic force microscopy (AFM) was used to study the porosity and surface roughness of the nanofibers. Electrochemical evaluation based on diffusion-controlled kinetics was applied to determine the number of electrons transferred in the system, the surface concentration of the deposited PAA thin film (2.14 × 10−6 mol/cm2), and the diffusion coefficient (De) for the PAA nanofiber–modified screen-printed carbon electrode (9.43 × 10−7 cm−2/s). The reported LODs for sulfadiazine and sulfamethazine detection are consistent with requirements for trace-level monitoring by early warning diagnostic systems.

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+ &gt; Sr2+ &gt; 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.

Hydrothermal synthesis and spark plasma sintering of NaY zeolite as solid-state matrices for cesium-137 immobilization

Hydrothermal synthesis of NaY-type zeolite was carried out and the effect of temperature on the phase composition, crystal structure, textural characteristics, particle size and morphology, as well as sorption properties to Cs+ ions was studied. Solid-state matrices based on NaY zeolite the Faujasite structure containing 26.1 wt% cesium were obtained by spark plasma sintering (SPS) with high values of compressive strength (to 132.9 MPa) and Vickers microhardness to HV~ 698, Fracture toughness (K1c) ~ 1.26 MPa m1/2. The kinetics of ceramic matrices consolidation, phase composition and morphology using dilatometric studies, XRD, and SEM were studied. The thermogravimetric analysis shown the high thermal stability of the obtained samples up to 1300 °C. The high hydrolytic stability of CsAlSiO4 ceramic was proven (leaching rate of 2.33 ×10−8 g·cm−2·day−1 and cesium diffusion coefficient De 1.41 ×10−13), which exceeds the requirements of GOST R 50926–96 and ISO 6961:1982 for solid-state matrices.

Synthesis of amorphous KAlSi3O8 for cesium radionuclide immobilization into solid matrices using spark plasma sintering technique

An effective sorption material for cesium radionuclides immobilization in highly safe and reliable solid-state matrices was proposed. Prepared aluminosilicate (КAlSi3O8) adsorbent had amorphous mesoporous structure and Cs+ ions sorption capacity of ∼3.7 mmol/g. The physical-chemical characteristics of (Cs, К)AlSi3O8 sample saturated with Cs + ions were studied using XRD, FT-IR, SEM-EDX, and DTA-TG methods. Firstly, solid-state aluminosilicate matrices were obtained using spark plasma sintering (SPS) technology with high values of relative density (up to 99.9%), compressive strength (31.3–79.2 MPa), and Vickers microhardness (0.9–5.3 GPa). The sample obtained at 1000 °C had a low value of Cs+ leaching from matrices (RCs within the range of 10-7 g cm-2·day-1) and cesium diffusion coefficient (De 9.07 × 10-14 cm2/s). It was shown that prepared aluminosilicate cesium matrices comply with regulatory requirements of GOST R 50926-96 and ANSI/ANS 16.1.

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.