Separate Solutions Research Articles

A novel (2+1)-dimensional Sawada-Kotera type system: multisoliton solution and variable separation solution

A novel (2+1)-dimensional Sawada-Kotera type system: multisoliton solution and variable separation solution

Pressure-driven membranes for advanced treatment of textile wastewater: Dye/salt fractionation, concentration, and cleaning strategies

Textile wastewater commonly contains various organic compounds and salt mixtures, potentially raising serious environmental and health concerns. Traditional treatment approaches are hindered by high salinity; consequently, membrane separation technologies have attracted increasing attention over the past few decades. Herein, four commercial pressure-driven membranes with molecular weight cut-off (MWCO) gradients were employed for the advanced treatment of different types of textile wastewater. Specifically, these membranes were initially subjected to a fractionation test toward the dye/salt mixtures, followed by deep concentration of the dye molecules. Using Congo red (CR), methyl blue (MB), NaCl, and Na2SO4 as representative dyes and salts, the results indicated that all membranes could effectively separate dye/salt mixtures and further conduct a deep concentration process toward the separated dye solutions. However, their efficiency and effectiveness largely depend on the membrane pore size and solution characteristics. For instance, membranes with lower MWCOs experience less fouling and shorter operation durations when treating CR-related solutions. All membranes showed improved fractionation efficiency toward MB/salt mixtures, requiring only approximately 10.2–42.9 % of the operation duration compared to CR-related solutions. The loose nanofiltration membrane proved superior to tight ultrafiltration membranes in both fractionation and concentration processes. Further research on cleaning methodologies demonstrated that both alkali and ethanol cleaning were influential in restoring the membrane performance. An appropriate ethanol/water concentration can effectively regenerate severely fouled membranes, achieving a high flux recovery ratio of ∼95 %. This study evaluated state-of-the-art pressure-driven membranes for textile wastewater treatment and guided cleaning strategies for optimal performance recovery.

Non-compatible fully [formula omitted] symmetric Davey–Stewartson system: Localized excitation and folded solitary wave

This paper studies a non-compatible fully PT symmetric Davey–Stewartson system which models the evolution of optical wave packet in nonlinear optics. “Non-compatible” means the first two equations of the system are inconsistent that do not need to comply with extra constraint like the compatible case. We employ the multi-linear variable separation approach to derive variable separation solution for this system. The obtained solutions contain four separated free functions, render enough freedom for us to generate diverse solitons. Firstly, we construct two kinds of localized excitations: lump-lattice and periodic-lattice structure. Secondly, we obtain four typical folded solitary waves, i.e. worm-dromion shaped, fin shaped and octopus shaped waves, by introducing suitable multi-valued functions. Lastly, we systematically analyze the interaction between two and three foldons, and give the classification of it. To our knowledge, this is the first time variable separation solution been reported in PT symmetric system. The basic idea of separating variables that used in this paper can be extended to other symmetric systems.

Inhibiting effects of humic acid on iron flocculation hindered As removal by electro-flocculation on air cathode iron anode

Activated carbon air cathode combined with iron anode oxidation-flocculation synergistic Arsenic (As) removal was a new groundwater purification technology with low energy consumption and high efficiency for groundwater with high As concentration. The presence of organic matter such as humic acid (HA) had ambiguous effects on formation of organic colloids in the system. The effects of the particle size distribution characteristics of these colloids on the formation characteristics of flocs and the efficiency of As purification was not clear. In this work, we used five different pore size alumina filter membranes to separate mixed phase solutions and studied the corresponding changes in iron and arsenic concentrations in the presence and absence of humic acid conditions. In the presence of HA, the arsenic concentration of < 0.05 µm particle size components was 1.01, 1.28, 3.07, 7.69, 2.85 and 1.24 times of that in the absence of HA. At the same time, the arsenic content in 0.05–0.1 µm and 0.1–0.45 µm particle size components was also higher than that in the system without HA, which revealed that the presence of HA hindered the flocculation behavior of As distribution to higher particle sizes in the early stage of the reaction. The presence of HA affected the flocculation rate of iron flocs from small to large particle size fractions and it had limited effect on the behavior of large-size flocs in adsorption of As. These results provide a theoretical basis for targeted, rapid, and low consumption synergistic removal of arsenic and organic compounds in high arsenic groundwater.

SYNTHESIS AND CHARACTERIZATION OF LOW-COST PLASTICIZED POLYMERIC MEMBRANES FOR SEPARATION OF BIVALENT CATIONS

Recently, polymer inclusion membranes (PIMs) have surfaced as a viable solution for selective transport and metallic ions separation. The efficiency of such membranes is subject to a number of factors, including the preparation method and relevant physico-chemical characteristics. In this paper, an improvement of a novel category of PIMs for performing ions separation is reported. The membranes were prepared using a mixture of two polymers: cellulose triacetate (CTA) and poly(methyl methacrylate) (PMMA), three different carriers, Aliquat 336 (basic), di-(2-ethylhexyl) phosphoric acid (D2EHPA) (acid) and tributyl phosphate (TBP) (neutral) and plasticized by dioctyle phthalate (DOP). All synthesized membranes were characterized using Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). A study of the transport of Co(II), Cu(II), Ni(II) and Pb(II) species using the synthesized membranes was conducted. Our results indicate that facilitated transport through PIMs is an effective way of solving the permanent problem of membrane stability.

Bio-carbon coil aerogels from tea waste: A sustainable solution for efficient oil-water separation

Discharging wastewater containing oils, fats, and organic solvents into water bodies poses a significant threat to the already limited freshwater resources. In recent years, three-dimensional (3D) porous adsorbent materials, such as aerogel materials, have gained attention for their high separation effectiveness in adsorption technology. However, the poor mechanical strength of existing aerogel materials limits their application in oil–water separation. To address this challenge, this study proposes to use carbon coils obtained from tea waste as a template for producing low-cost, ultra-light, elastic, and highly recyclable bio-carbon coil aerogels (BCCA). The BCCA, featuring high porosity and a hierarchical porous structure, demonstrated exceptional performance in oil–water separation applications. Specifically, it exhibited a high adsorption capacity for organic solutions (39 ∼ 117 g/g) and oils (32 ∼ 41 g/g), respectively, along with excellent selectivity, rapid adsorption time of approximately 30s, and good reuse capability, maintaining an adsorption efficiency of 85 %. These remarkable properties can be attributed to the exceptional hydrophobicity of the BCCA, with a contact angle of 134°, and the rapid capillary action facilitated by the helical network structure. The use of tea waste-derived carbon coils as a precursor for producing efficient and sustainable carbon coil aerogels presents a promising solution for environmental remediation, particularly in oil–water separation applications. This research addresses the issue of wastewater contamination and contributes to the utilization of tea waste, a readily available and abundant biomass resource, in the development of value-added materials for environmental sustainability.

Cost-effective separation of light fraction containing organic matter and charcoal material from agricultural soils using calcium chloride solution

ABSTRACT The weights of light fraction organic matter (LF) separated from soils using saturated CaCl2 solution (1.4 g cm−3) were compared to those separated using NaI solution (1.6 g cm−3 and 1.4 g cm−3) to examine the possibility of using CaCl2 solution for LF separation, to examine more cost-effective LF separation procedure. In terms of the recovery weight and carbon and nitrogen content, the LF characteristics of 19 samples of the plow layer or A horizon soils separated using CaCl2 solution were similar to those of LF separated using NaI solution (1.6 g cm−3), which is commonly used for LF analysis. These results suggest that CaCl2 solution could be used for LF analysis. The applicability of the CaCl2 separation procedure for the analysis of LF from soil containing charcoal material was further confirmed by examining another set of 16 samples of the plow layer. The recovery weights of LF from soil containing organic matter and charcoal material with CaCl2 solution were similar to those with sodium polytungstate (1.6 g cm−3), which is conventionally used not only for LF but also for charcoal material separation from soils.

A fully implicit edge/face centered discontinuous Galerkin / mixed finite element scheme for the advection-dispersion equation

Mixed Finite Element (MFE) method is a robust numerical technique for solving elliptic and parabolic partial differential equations (PDEs). However, MFE can generate solutions with strong unphysical oscillations and/or large numerical diffusion for hyperbolic type PDEs. For its part, Discontinuous Galerkin (DG) finite element method is well adapted to solve hyperbolic systems and can accurately reproduce solutions involving sharp fronts. Therefore, the combination of DG and MFE is a good strategy for solving hyperbolic/parabolic problems such as advection – diffusion/dispersion equations. The classical formulation of the two methods is based on operator and time splitting allowing for separate solutions to advection with an explicit scheme and to dispersion with an implicit scheme. However, this kind of approach has the following drawbacks: (i) it lacks efficiency, as two systems with different unknowns are solved at each time step, (ii) it induces errors generated by the splitting, (iii) it can be CPU wise-expensive because of the CFL constraint, and (iv) it cannot be employed for steady-state transport simulations.To overcome these difficulties, we develop in this work a fully implicit edge/face centered DG-MFE formulation where the two methods share the same unknowns. In this formulation, the DG method is developed on lumping regions associated with the mesh edges/faces instead of mesh elements. Thus, the traces of concentration at mesh edges/faces, which are the Degrees Of Freedom (DOF) of the hybrid-MFE, are also part of the DOFs of the DG. The temporal discretization is based on the Crank–Nicolson method for both advection and dispersion. Numerical tests are performed to validate the new scheme by comparison against an analytical solution and to show its ability to handle steady-state transport simulations.The procedure is developed for 2D triangular meshes but can easily be extended to other 2D and 3D shape elements.

Innovative valorization of EPS waste for oil/water separation using electrospinning and [Im, Br] ionic liquid

The aim of this study is to develop an innovative membrane for separating oil-water mixtures, based on Expanded polystyrene (EPS) waste collected from food and electronic packaging and functionalised by the ionic liquid 3-hexyl-1-methyl-1 H-imidazol-3-ium Bromide [Im,Br]. Different percentages of IL were added (1%, 3%, 6%, 12%). The surface chemistry, surface morphology, wettability and emulsion separation performance of the developed membranes were investigated in detail. The fiber diameter decreased considerably after the addition of the ionic (passing from 1,09 µm to 0442µm). Surface properties showed a transition from hydrophobic to super-hydrophobic properties, as demonstrated by water contact angles ranging from 116° to 154° degrees. These results demonstrate the successful functionalization of recycled EPS-based membranes by the addition of ionic liquid, leading to surfaces that are highly capable of repelling water. This research contributes to the advancement of sustainable solutions for oil-water separation during oil spill incidents, as well as recovering EPS waste.

Impact of urbanism on source separation systems: A life cycle assessment

This study aims to assess the effect of different urban configuration regarding the choice of wastewater management of the district with source separation systems. Understanding this link can guide researchers, and also urban actors, in order to choose the best source separation solution to implement in a specific urban configuration.For this purpose, an integrated modelling approach was used to model the district with different types of urban planning, the water resources recovery facility (WRRF) and create a life cycle inventory to carry out a life cycle assessment (LCA). Six different urban configurations were tested with three different source separation scenarios and compared with an advanced WRRF with high level of nutrients and organic matter recovery.This study concludes that urine source separation is beneficial compared to advanced WWRF for all the urban configurations. Sewer construction was identified as the main contributor to environmental impact for the low-density configuration (pavilions), limiting the benefits of source separation in this urban settlement. Blackwater separation with a decentralised treatment is only beneficial for high densely populated area. Treatment of blackwater and greywater for reuse, has greater impact than reference scenario, in all urban configurations, due to high energy consumption for greywater treatment. Future research should therefore explore technical solutions for limiting the energy consumption.

Single-Cell Liquid Biopsy of Lung Cancer: Ultra-Simplified Efficient Enrichment of Circulating Tumor Cells and Hand-Held Fluorometer Portable Testing.

Herein, we propose a paper-based laboratory via enzyme-free nucleic acid amplification and nanomaterial-assisted cation exchange reactions (CERs) assisted single-cell-level analysis (PLACS). This method allowed for the rapid detection of mucin 1 and trace circulating tumor cells (CTCs) in the peripheral blood of lung cancer patients. Initially, an independently developed method requiring one centrifuge, two reagents (lymphocyte separation solution and erythrocyte lysate), and a three-step, 45 min sample pretreatment was employed. The core of the detection approach consisted of two competitive selective identifications: copper sulfide nanoparticles (CuS NPs) to C-Ag+-C and Ag+, and dual quantum dots (QDs) to Cu2+ and CuS NPs. To facilitate multimodal point-of-care testing (POCT), we integrated solution visualization, test strip length reading, and a self-developed hand-held fluorometer readout. These methods were detectable down to ag/mL of mucin 1 concentration and the single-cell level. Forty-seven clinical samples were assayed by fluorometer, yielding 94% (30/32) sensitivity and 100% (15/15) specificity with an area under the curve (AUC) of 0.945. Nine and 15 samples were retested by a test strip and hand-held fluorometer, respectively, with an AUC of 0.95. All test results were consistent with the clinical imaging and the folate receptor (FR)-PCR kit findings, supporting its potential in early diagnosis and postoperative monitoring.

Biomolecules-mediated electrochemical signals of Cu2+: Y-DNA nanomachines enable homogeneous rapid one-step assay of lung cancer circulating tumor cells

This study presents a straightforward efficient technique for extracting circulating tumor cells (CTCs) and a rapid one-step electrochemical method (45 min) for detecting lung cancer A549 cells based on the specific recognition of mucin 1 using aptamers and the modulation of Cu2+ electrochemical signals by biomolecules. The CTCs separation and enrichment process can be completed within 45 min using lymphocyte separation solution (LSS), erythrocyte lysis solution (ELS), and three centrifugations. Besides, the influence of various biomolecules on Cu2+ electrochemical signals is comprehensively discussed, with DNA nanospheres selected as the medium. Three single-stranded DNA sequences were hybridized to form Y-shaped DNA (Y-DNA), creating DNA nanospheres. Upon specific capture of mucin 1 by the aptamer, most DNA nanospheres could form complexes with Cu2+ (DNA nanosphere-Cu2+), significantly reducing the concentration of free Cu2+. Our approach yielded the limit of detection (LOD) of 2 ag/mL for mucin 1 and 1 cell/mL for A549 cells. 39 clinical blood samples were used for further validation, yielding results closely correlated with pathological, computed tomography (CT) scan findings and folate receptor-polymerase chain reaction (FR-PCR) kits. The receiver operating characteristic (ROC) curve displayed an area under the curve (AUC) value of 0.960, demonstrating 100% specificity and 93.1% sensitivity for the assay. Taken together, our findings indicate that this straightforward and efficient pretreatment and rapid, highly sensitive electrochemical assay holds great promise for liquid biopsy-based tumor detection using CTCs.

Some Novel Fusion and Fission Phenomena for an Extended (2+1)-Dimensional Shallow Water Wave Equation

An extended (2+1)-dimensional shallow water wave (SWW) model which can describe the evolution of nonlinear shallow water wave propagation in two spatial and temporal coordinates, is systematically studied. The multi-linear variable separation approach is addressed to the extended (2+1)-dimensional SWW equation. The variable separation solution consisting of two arbitrary functions is obtained, by assumption, from a specific ansatz. By selecting these two arbitrary functions as the exponential and trigonometric forms, resonant dromion, lump, and solitoff solutions are derived. Meanwhile, some novel fission and fusion phenomena including the semifoldons, peakons, lump, dromions, and periodic waves are studied with graphical and analytical methods. The results can be used to enhance the variety of the dynamics of the nonlinear wave fields related by engineering and mathematical physics.

Design and evaluation of a microrectification platform using 3D printing

We present a microrectification platform to separate binary mixtures using 3D printed structures for enhanced mass transfer. Our approach (experiment and simulation) offers an effective solution for separation of liquids with close boiling points.

Unsupervised Temporal Correspondence Learning for Unified Video Object Removal.

Video object removal aims at erasing a target object in the entire video and filling holes with plausible contents, given an object mask in the first frame as input. Existing solutions mostly break down the task into (supervised) mask tracking and (self-supervised) video completion, and then separately tackle them with tailored designs. In this paper, we introduce a new setup, coined as unified video object removal, where mask tracking and completion are addressed within a unified framework. Despite introducing more challenges, the setup is promising for future practical usage. We embrace the observation that these two sub-tasks have strong inherent connections in terms of pixel-level temporal correspondence. Making full use of the connections could be beneficial considering the complexity of both algorithm and deployment. We propose a single network linking the two sub-tasks by inferring temporal correspondences across multiple frames, i.e., correspondences between valid-valid (V-V) pixel pairs for mask tracking and correspondences between valid-hole (V-H) pixel pairs for video completion. Thanks to the unified setup, the network can be learned end-to-end in a totally unsupervised fashion without any annotations. We demonstrate that our method can generate visually pleasing results and perform favorably against existing separate solutions in realistic test cases.

Potentiometric Monitoring of Iodide Ions Using a Highly Selective Iodide Sensor Based on AgI-Cu2S-Multi Walled Carbon Nano Tube Material

In this work, a new iodide selective sensor based on an AgI-Cu2S-Multiwalled carbonnanotube-Graphite-Paraffin oil composite material was described for highly selective potentiometric determination of iodide ions. To obtain the best potentiometric performance characteristics of the sensor, the sensor components was optimized and the sensor was formed by properly pressing of the optimized sensor components. The experimental results were showed that the most appropriate potentiometric response was achieved with the sensor materials containing a compositions of G:MWCNT:AgI:Cu2S:PO in the ratio 50:5:20:5:20 (% w/w). The developed sensor display a wide linear working range (1.0×10-5-1.0×10-1 molL-1) for iodide ions. In this linear working range, the Nernstian slope of the sensor was 51.5±1.0 mV and the correlation coefficient (R2) was determined as 0.9991. The sensor was of a very low response time (5s). The repeatability of the sensor potential response was very good and its response remained unchanged in the pH range of 6.0-9.0. The interference effect on the sensor response of different anionic species was tested by the separate solution method (SSM) and the sensor selectivity was quite good. The life time of the sensor was measured as 13 weeks and the sensor was successfully used as indicator sensor for the potentiometric titrations of iodide ions with silver nitrate solution. Additionally, the sensor was successfully applied for the direct detection of iodide ions in environmental water samples.

Production of gelatin fibrous mats using different nanofiber production methods for medical applications and comparison of their properties.

In the literature, there are studies on medical applications using different nanofiber production methods with natural polymers. However, each system has different fiber-forming capabilities. For this reason, in this study, we investigated the production of nanofibers from a biodegradable natural polymer, gelatin, using four separate nanofiber production methods, namely electrospinning (ES), electroblowing (EB), solution blowing (SB), and centrifugal spinning (CS). Our aim was to determine the most suitable fibrous web structure for medical applications and contribute to science in this respect. It was observed that the thinnest fibers (386 nm) and the heaviest mats (15.975 g m-2) were produced by the SB method as a result of using 10 wt.% gelatin solution with a total of 10 mL. With the ES and EB methods, tighter fabric structures were obtained than with the others due to the presence of electric fields. In the CS method, more and bead-free fibers were produced due to the increase in viscosity with a 12.5 wt.% gelatin solution. Moreover, with the concentration of 12.5 wt.%, the fiber diameters of SB and CS samples increased about 2-fold.

Life cycle assessment of fluorinated gas recovery from waste refrigerants through vacuum swing adsorption

The refrigeration industry is facing a challenge due to stricter regulations on the use of fluorinated gases (F-gases) with high Global Warming Potential (GWP). In many cases, the design of alternative refrigerants requires the recycling of low and moderate GWP compounds from existing refrigerant blends, but currently there is no a standardized technology available to recover them, and finally most gases are incinerated at the end of the equipment's life cycle. Recently, Vacuum Swing Adsorption (VSA) has been proposed as a possible solution for the complex separation of F-gas mixtures. The environmental sustainability of the recovery of R-32 from R-410A blend using a VSA process (circular economy scenario), was analysed through a life cycle assessment (LCA) approach, and it was compared to the conventional R-32 production (benchmark scenario). The results show that the VSA technology can achieve a 30.9% recovery of 97 mol% R-32 suitable for further reuse, with a reduction in the environmental loads ranging from 58 to 99% compared to industrial R-32 production. The carbon footprint of the recovery process is 4.81 kg CO2 equiv., while for the industrial production of R-32 is 10.9 kg CO2 equiv. This study proves that the development of adsorption-based technologies for F-gas recovery can improve the environmental impact of these compounds from a circular economy perspective.

Enhanced Desalination Performance Using Phosphate Buffer-Mediated Redox Reactions of Manganese Oxide Electrodes in a Multichannel System.

Water desalination mediated by electrochemical reactions to directly capture and release salt at electrode materials offers a low-voltage method for producing freshwater. Developing new system designs has allowed electrode materials to maximize their capacity for salt separation, especially when a multichannel system is used to introduce a separate electrode rinse solution. Here, we show that the use of an additive can provide a new strategy for improving electrode capacity and, hence desalination performance, which so far has been limited to increasing the electrolyte concentration. A custom-built, 2/2-channel flow cell divided by two cation exchange membranes and an anion exchange membrane was fed with 50 mM NaCl as the feed (two inner channels) and 0.5 M NaCl containing up to 0.1 M phosphate as the electrode rinse (two outer channels). Using manganese oxide electrodes with phosphate buffer-mediated redox reactions exhibited an improved desalination capacity of 68.0 ± 5.2 mg g-1 (0.55 mA cm-2) and a rate of 5.6 ± 1.3 mg g-1 min-1 (0.96 mA cm-2). The improvement was attributed to the buffer that served as a proton donor for promoting the H+ insertion reaction of amorphous or poorly crystalline MnO2. Additionally, the buffering capacity against acidification and the creation of insoluble manganese phosphate on the electrode surface prevented the dissolution of Mn2+, which could otherwise occur at the anode due to a decrease in the local pH upon H+ deinsertion. Thus, the use of manganese oxide electrodes coupled with phosphate provides a new strategy of increasing electrode capacity for water desalination.

Стан підтримки малого та середнього підприємництва на регіональному рівні

The entrepreneurial environment in Ukraine is beginning to emerge under the influence of the shock of the transition period associated with the mass release of workers and employees, the collapse of the financial system, the lack of national currency, and, consequently, the lack of funds for people’s livelihood. The article raises a range of issues related to the dilemma of “state support – self-regulation” of entrepreneurial structures, which, despite their constant presence on the policy agenda, find separate solutions at different stages of societal development. The paper notes that the differences in regional development have also affected the state of the entrepreneurial environment at the regional level and the set of measures to support small and medium-sized enterprises (SMEs). The article analyzes SME support programs at the level of the Poltava region and highlights their positive and negative aspects. It is concluded that the regional SME support programs’ positive results are due to factors such as linking financial assistance to the number of jobs created and cooperation of the city SME representatives with NGOs, Poltava City Council, and PROMIS project representation in the region. Attention is paid to the activity of the Regional Fund for Entrepreneurship Support, reflecting the specifics of the economy of the Poltava region. The necessity of new approaches to improve the state support of small and medium-sized enterprises, considering the war risks, conditions of post-war recovery, and the limited state budget, was substantiated. In this context, it is recommended to strengthen the capacity of entrepreneurship through the self-organization of entrepreneurs by creating business associations. It is noted that the associations already registered during the study are actively cooperating with state institutions to improve the conditions for their own economic activity. The proposals and conclusions formulated in the article can be helpful for regional public authorities in forming and implementing SME support policy, as well as individual programs to support and stimulate SME development. Keywords: support, small and medium entrepreneurship, public authorities, program, development, interaction.