Separation Process Research Articles

A Carrier Phase Ultrafiltration and Backflow Recovery Technique for Purification of Biological Macromolecules.

A simple carrier phase based ultrafiltration technique that is akin to liquid chromatography and is suitable for medium-to-large volume sample preparation in the laboratory is discussed in this paper. A membrane module was integrated with a liquid chromatography system in a "plug and play" mode for ease of sample handling, and recovery of species retained by the membrane. The sample injector and pump were used for feed injection and for driving ultrafiltration, while the sensors and detectors were used for real-time monitoring of the separation process. The concentration of retained species was enriched by utilizing controlled concentration polarization. The recovery of the retained and enriched species was enhanced by backflow of carrier phase through the membrane using appropriate combination of valves. The backflow of carrier phase also cleaned the membrane and limited the extent of membrane fouling. Proof-of-concept of the proposed technique was provided by conducting different types of protein ultrafiltration experiments. The technique was shown to be suitable for carrying out protein fractionation, desalting, buffer exchange and concentration enrichment. Adoption of this approach is likely to make ultrafiltration easier to use for non-specialized users in biological research laboratories. Other advantages include enhanced product recovery, significant reduction in the number of diavolumes of buffer needed for conducting desalting and buffer exchange, minimal membrane fouling and the potential for repeated use of the same module for multiple separation cycles.

A green bulk modification for imparting a green VIPS membrane with antifouling properties

BackgroundMembrane preparation and membrane modification processes have long involved the use of toxic solvents. The present work proposes to only use envrionmentally-friendly solvents for both the fabrication and the surface modification of hydrophobic microfiltration membranes. In addition, coating processes for membrane modification are essentially surface modification processes. However, spray-coating may be a suitable method for both surface and bulk modification. MethodsAfter dissolving poly(vinylidene fluoride) in dimethylsulfoxide, membranes were formed by the vapor-induced phase separation process, and then modified using an aqeous solution of an amphiphilic copolymer containing poly(ethylene glycol) methyl ether methacrylate units. Then, a variety of physicochemical techniques were employed to characterize the membrane structure and prove the effectiveness of the surface/bulk modification. Antifouling tests in static and dynamic conditions were conducted. Significant findingsIt is possible to reduce the water contact angle of the top surface of the membrane from 135° to 0° and that of the bottom surface from 126° to 0° within <10 s, indicating successful hydrophilization of the membrane on the one hand, and top-to-bottom modification, despite solely exposing the top surface to the spray, on the other hand. This conclusion was confirmed by deidcated surface chemistry analyses. Besides, the membranes maintained their original highly porous and symmetric structure with light effects on surface porosity and pore size following the spray-coating process. The drasting improvement of hydrophilicity resulted in effective mitigation of fibrinogen adsorption (reduced by 85 %) and Escherichia coli adhesion (reduced by 86 %). Fouling during cyclic filtration involving a bacterial suspension was also effectively reduced with a flux recovery ratio of 53 % (against 37 % for a commercial hydrophilic membrane) and an irreversible flux decline ratio of 47 % (against 63 % for a commercial hydrophilic membrane) in the conditions of the test.

Boosting the H2/CO2 and H2/N2 selectivities of a graphene oxide membrane by shrinking the membrane interlayer spacing via thermal treatment

Graphene oxide (GO) membranes have been widely studied and used for gas separation processes, but some structural changes are necessary to guarantee high membrane selectivities. The thermal reduction process stands out for reducing the interlayer channel size of the GO nanosheets to improve the molecular sieving mechanism. Herein, thermally annealed GO layers were deposited on the outer surface of porous alumina hollow fiber substrates and the produced composite membranes were tested for selective hydrogen (H2) separations. The influence of the thermal annealing process at different mild temperatures (80 and 160 °C) on the characteristics of the GO structure was investigated towards the improvement of the membrane efficiency for H2 separation. ATR-FTIR results confirmed the elimination of oxygenated groups, and XRD analyses showed the GO interlayer space decreased from 8.71 to 7.38 Å after the thermal annealing process at 160 °C. The GO thermally annealed membrane presented an H2 permeance of 2032.47 ± 101.69 GPU and an H2/N2 selectivity of 12.16 ± 0.30, which is 315% greater than the selectivity of the pristine GO membrane. Hence, the application of the thermal reduction method to produce GO membranes with greater selectivities is a viable alternative to deal with gas separation processes.

Anion-Exchange Membrane Oxygen Separator.

Anion-exchange membranes (AEMs), known for enabling the high conductivity of hydroxide anions through dense polymeric structures, are pivotal components in fuel cells, electrolyzers, and other important electrochemical systems. This paper unveils an unprecedented utilization of AEMs in an electrochemical oxygen separation process, a new technology able to generate enriched oxygen from an O2/N2 mixture using a small voltage input. We demonstrate a first-of-its-kind AEM-based electrochemical device that operates under mild conditions, is free of liquid electrolytes or sweep gases, and produces oxygen of over 96% purity. Additionally, we develop and apply a one-dimensional time-dependent and isothermal model, which accurately captures the unique operational dynamics of our device, demonstrates good agreement with the experimental data, and allows us to explore the device's potential capabilities. This novel technology has far-reaching applications in many industrial processes, medical oxygen therapy, and other diverse fields while reducing operational complexity and environmental impact, thereby paving the way for sustainable on-site oxygen generation.

Aerial Hybrid Adjustment of LiDAR Point Clouds, Frame Images, and Linear Pushbroom Images

In airborne surveying, light detection and ranging (LiDAR) strip adjustment and image bundle adjustment are customarily performed as separate processes. The bundle adjustment is usually conducted from frame images, while using linear pushbroom (LP) images in the bundle adjustment has been historically challenging due to the limited number of observations available to estimate the exterior image orientations. However, data from these three sensors conceptually provide information to estimate the same trajectory corrections, which is favorable for solving the problems of image depth estimation or the planimetric correction of LiDAR point clouds. Thus, our purpose with the presented study is to jointly estimate corrections to the trajectory and interior sensor states in a scalable hybrid adjustment between 3D LiDAR point clouds, 2D frame images, and 1D LP images. Trajectory preprocessing is performed before the low-frequency corrections are estimated for certain time steps in the following adjustment using cubic spline interpolation. Furthermore, the voxelization of the LiDAR data is used to robustly and efficiently form LiDAR observations and hybrid observations between the image tie-points and the LiDAR point cloud to be used in the adjustment. The method is successfully demonstrated with an experiment, showing the joint adjustment of data from the three different sensors using the same trajectory correction model with spline interpolation of the trajectory corrections. The results show that the choice of the trajectory segmentation time step is not critical. Furthermore, photogrammetric sub-pixel planimetric accuracy is achieved, and height accuracy on the order of mm is achieved for the LiDAR point cloud. This is the first time these three types of sensors with fundamentally different acquisition techniques have been integrated. The suggested methodology presents a joint adjustment of all sensor observations and lays the foundation for including additional sensors for kinematic mapping in the future.

Industry 4.0 Ready: Transforming STEM Laboratory Courses – Continuous Distillation as Example

AbstractLaboratory courses are key to science, technology, engineering, and mathematics (STEM) programs in higher education, but often lack the flexibility for distance learning and inclusiveness for all students. To address these challenges, TU Bergakademie Freiberg introduced remote laboratories not only for international degree programs and the “Disti4Study” application, which provides interactive visualization of industrial thermal separation processes. This paper focuses on the development and didactic challenges associated with the “Continuous Distillation Laboratory”. It illustrates how rethinking the technical and didactic frameworks of traditional laboratories can align with new learning objectives, such as those related to Industry 4.0, including the Internet of Things and data management.

Transport and clogging dynamics of flexible rods in pore constrictions.

The transport and clogging behavior of flexible particles in confined flows is a complex interplay between elastic and hydrodynamic forces and wall interactions. While the motion of non-spherical particles in unbounded flows is well understood, their behavior in confined spaces remains less explored. This study introduces a coupled computational fluid dynamics-discrete element method (CFD-DEM) approach to investigate the transport and clogging dynamics of flexible rod-shaped particles in confined pore constrictions. The spatio-temporal analysis reveals the influence of the rod's initial conditions and flexibility on its transport dynamics through a pore constriction. The simulation results demonstrate an increase in the lateral drift of the rod upon exiting the pore that can be scaled with channel height confinement. The clogging dynamics are explored based on hydrodynamic and mechanical forces, unveiling conditions for mechanical clogging through sieving. The developed method allows for the deconvolution of the forces that contribute to particle trajectories in confined flow, which is highly relevant in particle separation processes, fibrous-shaped virus filtration, biological flows, and related applications. The method is embedded into the open-source CFDEM framework, facilitating future extensions to explore multiple particle dynamics, intermolecular forces, external influences, and complex geometries.

Regulation of organic solar cells performance through external electric field: From charge transfer mechanisms to photovoltaic properties

In organic solar cells (OSCs), comprehending the charge transfer mechanism at D/A interfaces is crucial for photoinduced charge generation and enhancing power conversion efficiency (PCE). The charge transfer mechanism and photovoltaic performance of the parallel stacking interface configuration of the PTQ10 polymer donor and T2EH non-fullerene acceptor (NFA) are systematically studied at the microscopic scale. The analysis of the electron-hole distribution of the PTQ10/T2EH excited states revealed the presence of multiple charge excitation modes and charge transfer pathways. Using Marcus theory, we examine the charge separation rate (KCS) of PTQ10/T2EH under external electric field (Fext) modulation, and it is clarified that reorganization energy (λ) is the main factor that affects the KCS. Our results show that Fext has a positive impact on the photovoltaic properties of PTQ10/T2EH thin films, as evidenced by the modulation of the open circuit voltage (VOC), voltage loss (VLOSS) and fill factor (FF). Overall, this study provides valuable theoretical insights for Fext to accelerate the charge separation process and enhance photovoltaic efficiency.

Performance Test of Artificial Defoliating Broccoli Conveyor Line and Analysis of Defoliating Broccoli Inflorescences

There is a close relationship between stem and leaf biological characteristics of mature broccoli plants and defoliation technology. Morphological parameters such as the spread degree and diameter of cauliflower stem and leaf and the connection performance of cauliflower stem and leaf were studied. These experiments are helpful to the research of defoliation devices and methods for large-scale manual transportation lines. In this paper, according to the damage forms that may be suffered in the separation process of mature broccoli stems and leaves, “sunny” broccoli varieties were selected. Firstly, the mechanical properties of mature broccoli stems were obtained through different loading methods such as stretching, compression, shearing and bending. Secondly, the stress relaxation characteristics of broccoli were analyzed by static compression of broccoli flower balls. Finally, the separation method of broccoli stems and leaves was simulated by ANSYS. The simulation results showed that shear fracture was more suitable for stem and leaf separation of broccoli than tensile fracture. Then, aiming at the separation of stems and leaves of broccoli, an artificial broccoli assembly line was proposed to ensure the efficiency of leaf removal through man–machine cooperation. The dynamic characteristics of the belt of broccoli leaf removal line were studied to ensure the efficient and stable operation of the conveyor system of broccoli artificial leaf removal line.

Development of biomass aerogels with aligned channels: For continuous treatment of oily wastewater and solar-powered oil evaporation

A biomass CS/CNTs@MTMS (MCCS) aerogel with both aligned channel network, superhydrophobicity, and photothermal conversion ability was prepared by a green and facile strategy of directed freeze-drying and chemical vapor deposition using chitosan (CS), carbon nanotubes (CNTs), and methyltrimethoxysilane (MTMS) as the building materials. Capacity to adsorb a large variety of oils and organic solvents, with an adsorption capacity of up to 34–83 g/g. After 10 cycles, the adsorption capacity of MCCS remained at 94 % of the initial capacity, providing excellent reusability. In addition, due to its unique network of aligned channels, the MCCS can continuously separate oil and water, making it a sustainable oil–water separator. More interestingly, the MCCS aerogel has excellent photothermal conversion capabilities, and it was utilized to evaporate oil collected during the oil–water separation process using solar energy. This work provides an opportunity to design novel self-cleaning photothermally driven oil–water separation biomass materials with superhydrophobicity-strong lipophilicity.

Construction of a durable, halogen-free, and phosphorus-free flame retardant cotton fabric system with hydrophobic properties by phase separation and interface polymerization

Inspired by the synthesis of polyurethane, a multifunctional fabric with hydrophobic and long-lasting flame retardancy was prepared through the phase separation and interfacial reaction process between PEI (polyethyleneimine)/BX (borax) aqueous solution and isocyanate terminated polydimethylsiloxane (PDMS-NCO) in tetrahydrofuran solution. The limit oxygen index of the treated fabric increased from 18.0 % to 33.7 %, and the total heat release decreased by 34.2 %. The enhancement of flame retardant performance and thermal stability is attributed to the enhanced char-forming capacity. After 50 cycles of water washing, the cotton fabric can still pass the vertical flammability test because of the curing effect of PDMS-NCO on functional additives. Furthermore, SEM analysis revealed that the formation of nano-rough structures on the fibers was promoted by phase separation, thus leading an increased water contact angle of sample to 139°. The materials utilized in this modified process do not contain elements such as F, Cl, Br, and P, indicating its potential as an environmentally friendly methodology for fabric functionalization.

Planar Group Functionalization of Quasi-Discrete Pores in Metal-Organic Frameworks for Enhanced Isomeric Separation in Simulated Moving Bed Processes.

The efficient separation of 4-methyl-1-pentene (4MP1) from its structural isomers is crucial for industrial applications but remains challenging due to the similar physicochemical properties of these compounds. This study introduces a novel strategy using metal-organic frameworks (MOFs), specifically an engineered variant of ZIF-108, which demonstrates remarkable improvements in the thermodynamic and kinetic properties for 4MP1 separation. By substituting the methyl groups in ZIF-8 with planar nitro groups, we achieved a strategic resizing of the pore windows and cavity dimensions in ZIF-108. This adjustment not only enhanced the molecular affinity and selectivity toward 4MP1 but also facilitated a diffusion rate that is 164 times faster than that observed in ZIF-8. These properties significantly elevated the performance of ZIF-108 in simulated moving bed (SMB) processes, achieving up to 96.5% recovery of high-purity 4MP1, outperforming traditional adsorbents. Comprehensive characterization, including density functional theory (DFT) calculations and molecular dynamics (MD) simulations, provided insights into the interactions and the stability of the adsorption process. The findings suggest that the strategic modification of the pore architecture in MOFs holds significant potential for optimizing the separation processes of industrially relevant mixtures.

Microfluidic chip-assisted separation process and post-chip microalgae cultivation for carotenoid production

Microfluidic chip-assisted separation process and post-chip microalgae cultivation for carotenoid production

Variability of lead-zinc sulfide ore slurry rheological properties and its influence on flotation conditions

We investigated how the rheological characteristics of a flotation slurry change in response to variations in mineral species, slurry concentration, and particle size; slurry pH; and trap and rheological control reagent concentrations using slurries containing galena, sphalerite, quartz, and kaolinite. The results indicate that reducing particle size and increasing slurry concentration leads to varying degrees of increase in apparent viscosity and yield stress. At the same particle size, the slurry exhibits the following order of apparent viscosity and yield stress: kaolinite &gt; galena &gt; sphalerite &gt; quartz. In addition, as the slurry’s apparent viscosity and yield stress increase, the rheology decreases, creating progressively unfavorable conditions for the flotation of lead, zinc, and other target minerals. Furthermore, changes in pH have no significant effect on the slurry’s rheology when the slurry is comprised of vein minerals. Moreover, galena and sphalerite depict particle agglomeration in the slurry. Ultimately, the addition of sodium silicate as a rheological control reagent substantially enhances the slurry’s rheological properties. This results in a system where problematic minerals like kaolinite are more effectively dispersed, thereby promoting efficient lead-zinc mineral flotation. Regarding the flotation of lead sulfide and zinc minerals, the addition of kaolinite raises the apparent viscosity of the mixed slurry, hindering the flotation of the target minerals. Conversely, quartz lowers the apparent viscosity aiding the flotation separation process. Understanding the relationship between flotation conditions and the pulp’s rheological properties can provide valuable guidance for subsequent flotation tests.

苜蓿切断-气吹茎叶分离方法初步研究

The protein content of alfalfa leaves surpasses that of stems significantly, rendering harvested alfalfa following stems-leaves separation a valuable resource for livestock feed, thus ensuring the provision of high-quality raw materials for production. This study introduces a novel process for stems-leaves separation, alongside the establishment of a suspension velocity experiment rig aimed at investigating and determining the suspension velocity of alfalfa leaves, stems, and plants across various moisture levels. The relationship among various factors including different alfalfa components, the length of lateral branches, stem lengths, Moisture Content (MC), and suspension velocity was empirically derived through experimentation. In this study, the chopping and blowing method was proposed, where the alfalfa was cut into pieces according to a certain length, and then the alfalfa was blown apart by generating airflow through a fan. To comprehensively analyze the impact of airflow velocity and cutting length on the Separation Evaluation Index, a response surface mathematical model was developed. The empirical findings indicate optimal stems and leaves separation of alfalfa when the airflow velocity reaches 4.29556 m/s, paired with a cutting length of 33.7956 mm. Conclusively, this experiment validates the efficacy of the chopping and blowing separation method for alfalfa stems and leaves segregation, thereby offering valuable insights into alfalfa stems and leaves separation practices. The outcomes of this study hold significant reference value for the broader alfalfa agricultural domain.

Insights on the separation process of the diethyl carbonate plant obtained by ethanol and CO2

This paper presents the techno-economics insights of projects of diethyl carbonate (DEC) production from ethanol and CO2 in which the raw materials are proposed to be obtained from existing plants such as the bioethanol industry. The complete DEC plant was simulated using Aspen Plus®. The exothermic reaction system was modeled in multitubular PFR with CeO2 catalyst and dehydrating agent 2-cyanopyridine (2-CP), achieving an EtOH conversion of 86.04 % and a yield of DEC of 83.34 %. Three different configurations were evaluated in the DEC separation stage aiming to intensify the plant with the use of a sidestream distillation column and reactive distillation column. The integration of the DEC plant with ethanol and sugar biorefineries, offering lower-cost acquisition of raw materials, is the key to making the process economically profitable. The process has the potential to capture 0.088–0.204 kg CO2/kg DEC, demonstrating a promising pathway to extend the life cycle of renewable carbon.

A Remarkable Strategy to Hijack U(VI) from Mixed Metal Ion Solutions Using 1-Hydroxy-2-pyridone.

The present work envisages a chelation driven, facile, selective, and rapid method for uranium(VI) separation from a (U, Th) mixture using 1-hydroxy-2-pyridone (1,2-HOPO). Herein, U(VI) was selectively precipitated as the neutral [UO2(HOPO)2(H2O)]·nH2O (orange colored) complex while Th(IV) and other metal ions remained in the solution. The pH of the medium played a key role in facilitating the separation process.

Efficient continuous-flow separation and purification processes of 5-hydroxymethylfurfural

This study aimed to develop a green process for separating and purifying 5-hydroxymethylfurfural (5-HMF) that could accommodate various levels of 5-HMF production performance. The aim was to achieve a high purity level of 5-HMF exceeding 98%. The 5-HMF, initially containing high impurities, was produced from fructose in a multi-stage methyl isobutyl ketone/water fixed-bed reactor, achieving a 5-HMF selectivity of 53.2% and yield of 31.9%. This impure 5-HMF served as the feedstock for the proposed continuous purification system. The study integrated and evaluated various separation and purification technologies, including adsorption/desorption, solvent extraction, and distillation, to identify the most effective and practical approach. Optimization of process variables was conducted to enhance efficiency. Different techniques were required for purifying 5-HMF in both aqueous and organic phases. A two-stage microextraction process using methyl isobutyl ketone was identified as the most effective method for separating 5-HMF from the aqueous phase, achieving an extraction efficiency of 93.6% with a residence time of less than 2 min. Impurities in the organic phase were efficiently removed using a fixed-bed adsorber filled with Amberlyst 21 at 80 °C and 15 min. Subsequently, the solvent was removed through a one-stage distillation process. The sugar component in the solution was purified using activated carbon adsorption and could be recycled back into the production unit. The stability and reusability of the catalyst/adsorbent were also demonstrated. Furthermore, this research proposed an overall conceptual design for the 5-HMF production process, guiding further development of 5-HMF purification processes.

Modulation the carrier separation mechanism of CdS photoanode: From vacancy to crystal phase transformation

The photoelectrochemical (PEC) water splitting performance is conventionally limited by the process of photogenerated carrier separation and transport. This work provides an innovative strategy by combination of the spin-polarized electric field and homogeneous junction to address this critical issue. In this work, it finds that a spin-polarized electric field can be fabricated in the CdS photoanode with cubic phase by S vacancy intervention. Furthermore, after controlling the annealing temperature to reach 500 °C, cubic phase CdS photoanode translates to hexagonal phase by localized, forming a homogeneous junction CdS photoanode. By the synergy, the optimized CdS photoanode achieves a photocurrent density exceeding ∼5.0 mA/cm2 for hydrogen evolution under 100 mW/cm2 white light illumination, a 2.4-fold improvement over the performance of the unoptimized photoanodes. Thus, this work provides a novel method to regulation of the photogenerated carrier separation and transport processes for sulfur-based semiconductor photoelectrodes.

SPRi Biosensor for Simultaneous Determination of HIF-1α, Angiopoietin-2, and Interleukin-1β in Blood Plasma.

A new analytical method, based on SPRi biosensors, has been developed for the simultaneous determination of the pro-angiogenic factors HIF-1α, angiopoietin-2 (ANG-2), and interleukin-1β (IL-1β) in biological fluids. These proteins take part in the process of angiogenesis, i.e., the creation of new blood vessels, which is a key stage of cancer development and metastasis. A separate validation process was carried out for each individual compound, indicating that the method can also be used to study one selected protein. Low values of the limit of detection (LOD) and quantification (LOQ) indicate that the developed method enables the determination of very low concentrations, in the order of pg/mL. The LOD values obtained for HIF-1α, ANG-2, and IL-1β were 0.09, 0.01, and 0.01 pg/mL, respectively. The LOQ values were 0.27, 0.039, and 0.02 pg/mL, and the response ranges of the biosensor were 5.00-100.00, 1.00-20.00, and 1.00-15.00 pg/mL. Moreover, determining the appropriate validation parameters confirmed that the design offers high precision, accuracy, and sensitivity. To prove the usefulness of the biosensor in practice, determinations were made in plasma samples from a control group and from a study group consisting of patients with diagnosed bladder cancer. The preliminary results obtained indicate that this biosensor can be used for broader analyses of bladder cancer. Each of the potential biomarkers, HIF-1α, ANG-2, and IL-1β, produced higher concentrations in the study group than in the control group. These are preliminary studies that serve to develop hypotheses, and their confirmation requires the analysis of a larger number of samples. However, the constructed biosensor is characterized by its ease and speed of measurement, and the method does not require special preparation of samples. SPRi biosensors can be used as a sensitive and highly selective method for determining potential blood biomarkers, which in the future may become part of the routine diagnosis of cancers.