Complete Separation Research Articles

Experimental study on the flame merging and temperature profile produced by two pool fires beneath the curved ceiling

Compared to single-source fires in tunnels, double-source fires may exhibit more intricate flame merging behavior and higher flame burning rates due to their interaction, thereby escalating the risk of fire propagation within the tunnel. In this investigation, a 1:10 scale model of a horseshoe-shaped tunnel test site was deployed to conduct experiments on lateral double-source fires, scrutinizing flame merging behavior, probability prediction models, and temperature characteristics of tunnel ceiling smoke gas by varying the oil pool size and double-source spacing. Findings from the study suggest that flame merging behavior within the tunnel is contingent upon double-source spacing and heat release rate (HRR), manifesting in three distinct forms: complete merging, intermittent merging, and complete separation. Through the introduction of non-dimensional heat release rate and non-dimensional fire source spacing, a piecewise function has been devised to forecast the probability of flame merging for both fire types. Furthermore, a predictive model for the maximum temperature rise along the longitudinal centerline of a horseshoe tunnel was formulated, drawing from established theoretical frameworks.

Review of Recent Applications of Heat Pipe Heat Exchanger Use for Waste Heat Recovery

With the reduction in fossil fuels and growing concerns about global warming, energy has become one of the most important issues facing humanity. It is crucial to improve energy utilization efficiency and promote a low-carbon transition. In comparison with traditional heat exchangers, heat pipe heat exchangers indicate high compactness, a flexible arrangement, complete separation of hot and cold fluids, good isothermal operations, etc. As a result, heat pipe heat exchangers have attracted wide attention and application in various fields in recent years. This paper provides an overview of the application of heat pipe heat exchangers, with a focus on the application in waste heat recovery, and analyzes the opportunities and challenges of heat pipe heat exchanger applications based on existing publications.

Combination of a magnetic ionic liquid and magnetic particles for the determination of Pb(II) and Sn(IV) using electrothermal atomic absorption spectrometry

A procedure for the determination of traces of lead and tin by electrothermal atomic absorption spectrometry (ETAAS) after complexation with diethyl dithiophosphate and preconcentration by using a microextraction stage with a magnetic ionic liquid (MIL) supported by ferrite particles is presented. After complexation, the analytes are extracted into the ferrite-supported MIL, the solid particles acting as a carrier to facilitate the separation with a magnet. The analytes are released by treating with acetonitrile and the resulting liquid phase is sampled for the ETAAS measurement. The optimal experimental conditions such as pH, appropriate complexing agent, volumes and doses of all reagents used in the procedure are studied to achieve complete separation of both species. Enrichment factors of 195 and 165 and detection limits of 25 and 72 ng L−1 are obtained for Pb and Sn, respectively. The reliability of the procedure is checked by analyzing six certified reference materials and applied to water samples of different origin, the results being in addition confirmed by standard additions (recoveries 97 ± 7% in all cases).

CO2-triggered (3-aminopropyl)triethoxysilane-functionalized M-MOF-74 stabilized Pickering emulsions

Pickering emulsions with a stimulus response have been paid extensive concern due to their long-term stability and demulsification on-command. Metal-organic frameworks (MOFs) are expectable emulsifying agents to build Pickering emulsions based on their excellent properties such as high specific surface area, adjustable porosity and pore size. Herein, a novel kind of CO2-triggered Pickering emulsions formed by (3-aminopropyl)triethoxysilane (APTES)-functionalized M-MOF-74 (M-MOF-74-APTES, M = Zn, Cu or Mg) has been developed for the first time. It was found that even at the M-MOF-74-APTES amount of 0.5 wt%, the functionalized MOFs could still stabilize the n-hexane-watermixture to construct Pickering emulsions. The as-generated Pickering emulsions could be efficiently demulsified upon bubbling of CO2, resulting in complete separation of oil and water phases, but could be restored by subsequent N2 bubbling under homogenization. Mechanism study indicated that the acid-base reaction of CO2 with the amino group of M-MOF-74-APTES resulted in the creation of hydrophilic salts, which led to the lowering of particle wettability and broke the stability of the emulsion, causing demulsification of the Pickering emulsion. After removing CO2, the emulsion can be reconstructed by the reversible reaction. As an applied example, the Pickering emulsion has been availed as a micro-reaction system and M-MOF-74-APTES as a carrier of Pd(OAc)2 catalyst to realize the efficient combination of Suzuki-Miyaura reaction, product isolation and reuse of catalysts via alternate bubbling or removing of CO2.

Development of a DC-Biased AC-Stimulated Microfluidic Device for the Electrokinetic Separation of Bacterial and Yeast Cells.

Electrokinetic (EK) microsystems, which are capable of performing separations without the need for labeling analytes, are a rapidly growing area in microfluidics. The present work demonstrated three distinct binary microbial separations, computationally modeled and experimentally performed, in an insulator-based EK (iEK) system stimulated by DC-biased AC potentials. The separations had an increasing order of difficulty. First, a separation between cells of two distinct domains (Escherichia coli and Saccharomyces cerevisiae) was demonstrated. The second separation was for cells from the same domain but different species (Bacillus subtilis and Bacillus cereus). The last separation included cells from two closely related microbial strains of the same domain and the same species (two distinct S. cerevisiae strains). For each separation, a novel computational model, employing a continuous spatial and temporal function for predicting the particle velocity, was used to predict the retention time (tR,p) of each cell type, which aided the experimentation. All three cases resulted in separation resolution values Rs>1.5, indicating complete separation between the two cell species, with good reproducibility between the experimental repetitions (deviations < 6%) and good agreement (deviations < 18%) between the predicted tR,p and experimental (tR,e) retention time values. This study demonstrated the potential of DC-biased AC iEK systems for performing challenging microbial separations.

Hybrid Semiconductor Wafer Inspection Framework via Autonomous Data Annotation

Abstract In smart manufacturing, semiconductors play an indispensable role in collecting, processing, and analyzing data, ultimately enabling more agile and productive operations. Given the foundational importance of wafers, the purity of a wafer is essential to maintain the integrity of the overall semiconductor fabrication. This study proposes a novel automated visual inspection (AVI) framework for scrutinizing semiconductor wafers from scratch, capable of identifying defective wafers and pinpointing the location of defects through autonomous data annotation. Initially, this proposed methodology leveraged a texture analysis method known as gray-level co-occurrence matrix (GLCM) that categorized wafer images—captured via a stroboscopic imaging system—into distinct scenarios for high- and low-resolution wafer images. GLCM approaches further allowed for a complete separation of low-resolution wafer images into defective and normal wafer images, as well as the extraction of defect images from defective low-resolution wafer images, which were used for training a convolutional neural network (CNN) model. Consequently, the CNN model excelled in localizing defects on defective low-resolution wafer images, achieving an F1 score—the harmonic mean of precision and recall metrics—exceeding 90.1%. In high-resolution wafer images, a background subtraction technique represented defects as clusters of white points. The quantity of these white points determined the defectiveness and pinpointed locations of defects on high-resolution wafer images. Lastly, the CNN implementation further enhanced performance, robustness, and consistency irrespective of variations in the ratio of white point clusters. This technique demonstrated accuracy in localizing defects on high-resolution wafer images, yielding an F1 score greater than 99.3%.

Regional insights into Upper Palaeolithic territorial strategies and the factors of habitat choice in the territory of the Hungarian Central Mountains

The investigation into regional occurrence patterns contributes to a deeper understanding of Palaeolithic habitat exploitation. To explore this, geological, spatial, and environmental factors influencing the distribution of Upper Palaeolithic archaeological sites are studied in the Hungarian Central Mountains, focusing on Szeletian, Aurignacian, Gravettian, and Epigravettian cultures. The study employs a combination of spatial, statistical, classification analyses, and decision tests, including Kernel Density Estimation, Voronoi tessellation, the Dunn-Bonferroni test, Principal Component and Coordinate Analyses, Linear Discriminant Analysis, Random Forest Analysis, to examine the reasons behind the spatial distributions of archaeological sites by cultures. It was found that Szeletians inhabited higher elevation regions in the North Hungarian Mountains than Aurignacians. Voronoi tessellation shows that Gravettian and Epigravettian cultures exhibit a broader spread, with concentrations around the Danube Bend and southern foothills of the Mátra Mountains. Raw material distributions revealed that Szeletian sites are the closest to siliceous raw materials, while Aurignacian sites are the farthest. Principal component analysis reveals moderate separation in habitat selection and indicates that Aurignacians inhabited relatively warmer, less precipitous regions than Szeletians. Linear Discriminant Analysis indicates somewhat overlapping paleoenvironmental conditions in the case of Szeletian and Aurignacian sites; however, it shows the complete separation between Aurignacian and Gravettian sites. Random Forest Analysis results indicate that key separator factors between Szeletian and Aurignacian sites included topographical roughness, while daily energy expenditure and the mean temperature of the coldest quarter played the most crucial roles in separating Aurignacian and Gravettian, as well as Gravettian and Epigravettian sites.

An online fuzzy fraud detection framework for credit card transactions

Credit card transaction fraud is one of the challenging security concerns for financial firms globally. The continuously changing environment of fraud characteristics and the class imbalance and complete separation issues in fraud data create difficulties in accurately and efficiently predicting fraudulent transactions and implementing fraud detection systems in real-time. The study aims to develop a new real-time fraud detection framework that can efficiently be implemented online and address the issues caused by non-stationary changes in transaction and fraud characteristics, class imbalance, and complete separation. We propose a new approach to handle the impact of non-stationary changes in fraud transaction patterns. It enables efficiency in model training, given the sheer size of datasets. By implementing a robust fuzzy logistic regression model against class imbalance and separation problems, we address the challenge of having a very low rate of fraudulent transactions in the dataset and having separation issues due to specific characteristics of transactions. The analysis of the performance versus efficiency nexus of the proposed methodology reveals that the proposed framework shows strong performance results with specificity and sensitivity greater than 0.90 and Matthew’s correlation coefficient greater than 0.80 even on small sample sizes and produces highly accurate results in identifying fraudulent and non-fraudulent transactions with an accuracy greater than 0.99. Benchmarking with machine learning and other fraud detection approaches reveals that the proposed framework provides better detection performance while maintaining a higher rate of identifying non-fraudulent transactions than the alternative approaches. Improved classification performance leads to detecting fraudulent transactions with higher precision while avoiding misclassifying legitimate transfers, resulting in lower financial losses and improved customer satisfaction.

Integration of Indigenous Research Methodologies, Traditional Ecological Knowledge and molecular scatology in an assessment of mesocarnivore presence, diet and habitat use on Yurok Ancestral Lands.

Partnerships between Tribes and researchers in wildlife monitoring and application of Traditional Ecological Knowledge (TEK) have taken a variety of forms, and some scholars have noted a need for culturally sensitive approaches. Guided by Indigenous Research Methodologies, this research is coupled with Yurok TEK, or hlkelonah 'ue-megetohl ('to take care of the earth'), enabling an applied, culturally sensitive approach in partnership with the Yurok Tribe. We present results from a molecular scatology study of wildlife within the ancestral territory of the Yurok Tribe. Scats were collected opportunistically on road transects. All samples (N = 132) were analysed via DNA barcoding and results matched to documented 'Oohl 'we-toh (Yurok language) names to determine the depositor species (N = 8). Though there were four focal mesocarnivore species in our study, only bobcat (Chmuuek; Lynx rufus) and gray fox (Wergers; Urocyon cinereoargenteus) were detected as depositor species. Post hoc analyses were conducted to explore distribution, habitat use and selection in a use-availability context, and food habits of these two species. We found almost complete separation of bobcat and gray fox use of transects, as well as indication of partitioning of vegetation cover types and food. We demonstrate an integrated framework of Western and Indigenous sciences that allows the Indigenous researcher to transcend structured academic disciplinary boundaries. Our approach can be modified for partnerships between Tribes, agencies, academics and students for wildlife monitoring in broader geographic regions in various research applications.

Humanism during the COVID-19 pandemic: video call as a strategy to satisfy the communication needs of Intensive Care Unit patients and their family members.

Background: Patients affected by the COVID-19 pandemic required physical/social isolation due to the transmissibility of SARs CoV-2; those hospitalized in healthcare facilities often suffered loneliness due to a complete separation from their loved ones through visitor restrictions.(1) Human contact and movement were restricted to contain the spread of disease. When this kind of restriction must be employed, the “Guidance for Managing Ethical Issues in Infectious Disease Outbreaks”, states that it is necessary to provide people with “effective alternative communication strategies”. (2) Methods: This is an observational descriptive study that uses qualitative variables to analyze information obtained by virtual focus groups consisting of either medical professionals or family members of hospitalized patients in the ICU of the Eugenio Espejo Hospital (EEH) in Quito, Ecuador. Each video call allowed us to assess anonymous opinions concerning communication methods utilized during the delivery of daily clinical updates in the ICU. By focusing on a patient-and family-centered model, this study aims to minimize the impact of social isolation in hospitalized patients through the implementation of regular doctor-led video conference calls with family members, as well as video calls between the patient and family members when feasible.(1) Results: This study evaluates the increased satisfaction of family members and medical professionals with the implementation of video calls when compared to traditional telephone calls. A contrast between the time before implementing the telehealth team and the time afterward was observed in at least five positive characteristics: 1) the general telehealth experience, 2) the clarity of the messages, 3) the quality of care, 4) the sense of comfort, and 5) the improvement of communication. Conclusions: There was a positive effect on communication quality for both family members and medical professionals, increasing their satisfaction in terms of finding new methods to reduce the social isolation enforced by the current pandemic. Nevertheless, the future role of virtual communication remains undefined as we return to individualized face-to-face meetings.

Effect of Fractionation Columns on the Elution of Rare Earth Elements Recovered from Acid Mine Drainage

Rare earth elements (REE) can be found in expressive contents in different secondary sources, such as acid mine drainage (AMD). This work evaluated separation of light and heavy rare earth elements (REE) from an acid mine drainage (AMD) generated in a former uranium mine in Brazil by using ion exchange. This AMD presents pH 3.50, total REE content of 97 mg L−1 and 1.3 g L−1 of sulfate and was used in the REE loading experiments. Loading experiments were carried out in columns using a commercial strong acid cation (SAC) exchange resin. Elution was performed with 0.01 mol L−1 NH4EDTA in systems with one, two and three columns. Regarding the loading step, the resin presented a total loading capacity of 0.58 mmol g−1. The resin proved to be more selective for light REE with adsorption efficiency of 78% and 48% for heavy REE. Regarding elution, high efficiencies between 90 and 100% were achieved for REE. The final REE solution is approximately 10 times more concentrated in the liquor related to the acid mine water. Better fractionation results were achieved for the system with three columns. Although the complete separation of the REE into pure elements was not possible, two distinct fractions of heavy and light REE could be obtained, and La was completely separated from the other REE. In order to improve fractionation and separate the REE into individual ones, the concentrated fractions can proceed to subsequent ion exchange systems.

Influence of oligonucleotides structures for separation of diastereomers by capillary electrophoresis method using polyvinylpyrrolidone 1,300,000

In the field of oligonucleotides drug discovery, phosphorothioate (PS) modification has been recognized as an effective tool to overcome the nuclease digestion, and generates 2n of possible diastereomers, where n equals the number of PS linkages. However, it is also well known that differences in drug efficacy and toxicity are caused by differences in stereochemistry of oligonucleotides. Therefore, the development of a high-resolution analytical method that enables stereo discrimination of oligonucleotides is desired. Under this circumstance, capillary electrophoresis (CE) using polyvinylpyrrolidone (PVP) is considered as one of the useful tools for the separation analysis of diastereomers.In this study, we evaluated the several oligonucleotides with the structural diversities in order to understand the separation mechanism of the diastereomers by CE. Especially, five kinds of 2′-moieties were deeply examined by CE with PVP 1,300,000 polymer solution. We found that different trend of the peak shapes and the peak resolution were observed among these oligonucleotides. For example, the better peak resolution was observed in 6 mer PS3-DNA compared to the rigid structure of 6 mer PS3-LNA. As for this reason, the computational simulation revealed that difference of accessible surface area caused by the steric structure of thiophosphate in each oligonucleotide is one of the key attributes to explain the separation of the diastereomers. In addition, we achieved the separation of sixteen peak tops of the diastereomers in 6 mer PS4-DNA, and the complete separation of fifteen diastereomers in 6 mer PS4-RNA. These knowledge for the separation of the diastereomers by CE will be expected to the quality control of the oligonucleotide drugs.

Molecular dynamics simulations of Li+/Mg2+ separation using metal-organic frameworks

In this work, we investigate the extraction of Li+ from solutions containing Li+ and Mg2+ using metal-organic framework (MOF) membranes through molecular dynamics simulations (MD). Five MOFs with different pore sizes are studied. It is found that there is a critical pressure for MOFs with pore size smaller than 7.08 Å, below which Li + can be completely separated from Mg2+. This critical pressure increases as the pore size decreases. Under practical pressures (<50 MPa), MOFs with pore size around 6.5–7.0 Å are optimal for complete separation of Li+ and Mg2+. If high pressures can be reached, MOF with pore size of 5.48 Å appears to perform better because it ensures not only perfect separation but also a high flux of Li+. The hydration energy, potential of mean force, and density distribution of Li+ and Mg2+ are computed to explain the separation mechanisms.

Magnetic nanostructures with defined magnetic states fabricated by focused ion beam

A comparative analysis of the effects of Ga+-focused ion beam (FIB) on the magnetic properties of nanostructures was conducted in this study. It shows that the FIB cuts that cause the structures to switch from the initial vortex to the single-domain (“snake-like”) states do not require complete physical separation of the elements. Numerical simulations indicate that a remaining 3–5 nm or less magnetic material in a 20–30 nm thick permalloy layer can cause the switching. These results were partially confirmed experimentally, where grooves with a depth between 15–30 nm caused the switching. The addition of a titanium buffer layer significantly improves the accuracy and quality of the FIB cuts by reducing the amount of redeposited material.

Optimizing a radiochemical separation of 26Al from an acidic V-rich matrix

Sorption and desorption of Al(III) on a series of different extraction resins (LN, LN2, LN3, TK100, TK101, TK201) in acidic HNO3 media containing high concentrations of V(IV,V) was investigated. Static batch studies were conducted as a way of obtaining preliminary distribution coefficient (Kd) values that were further used to develop dynamic tests on real samples. It was shown that a complete separation and recovery of Al(III) from V(V) under acidic conditions (pH = 2) is possible by utilizing LN resin. Active “hot” dynamic studies with 26Al (≈10 Bq) as a radiotracer and real waste samples were conducted to further investigate and confirm the results of the inactive “cold” experiments. Utilizing this separation procedure, we have successfully removed all traces of 26Al (∼10−9 g) radiotracer from the bulk vanadium matrix.

Suppressed Ion Chromatographic Analysis of Anionic Macroelements in Nutmeg (Myristica fragrans) Diversity Specific to North Maluku

This study proposed an ion chromatography method for analyzing anionic macroelements (fluoride, chloride, nitrite, bromide, nitrate, sulfate, and phosphate), and applied it to nutmeg (&lt;em&gt;Myristica fragrans&lt;em&gt;)&lt;/em&gt;&lt;/em&gt; diversity to explore the potential of nutmeg as an electrolyte. The analysis method was based on a suppressed conductivity system that simultaneously analyzed the anionic macroelements on Metrohm Supp A 250/4.0 column using 8.0 mM sodium carbonate (Na&lt;sub&gt;2&lt;/sub&gt;CO&lt;sub&gt;3&lt;/sub&gt;) and 0.25 mM sodium bicarbonate (NaHCO&lt;sub&gt;3&lt;/sub&gt;) as a mixture eluent. Excellent peak resolution and completed separation were achieved within 18 min when the flow rate of the detector was 0.8 mL/min. The peak height with calibration curves at 2.5 ‒ 30.0 mg/L concentration ranges was obtained for all anionic macroelements. All collected nutmeg samples were specific to North Maluku. Based on the standard samples used, the analysis results revealed that only four anionic macroelements (chloride, nitrate, sulfate, and phosphate) were found in the nutmeg samples, and the concentration of each anion (e.g., chloride ion, and so) was different for each type of nutmeg. The highest total of anionic macroelements concentration was found in the &lt;em&gt;Myristica succedanea&lt;/em&gt; (1605.05 mg/kg) nutmeg sample,&lt;em&gt; &lt;/em&gt;while &lt;em&gt;Myristica specioga&lt;/em&gt; had the lowest (661.76 mg/kg). The method was validated regarding the detection limit (LOD) and reproducibility.

Liquid- liquid (Cyclohexanone: Cyclohexanol) separation using augmented tight nanofiltration membrane: A sustainable approach

Organic solvent nanofiltration (OSN) is an incipient technology in the field of organic liquid-liquid separation. The incomplete separations and complexity involved in these, forces many organic liquids to be released as effluents and the adverse effects of these on environment is enormous and irreparable. The work prominences on the complete separation of industrially significant cyclohexanone: cyclohexanol (keto-alcohol oil) and heptane: toluene mixtures. The separations of these above-mentioned organic liquid mixtures were carried out using the fabricated Lewis acid modified graphitic carbon nitride (Cu2O@g-C3N4) incorporated polyvinylidene difluoride (PVDF) composite membranes. These fabricated membranes showed a separation factor of 18.16 and flux of 1.62 Lm−2h−1 for cyclohexanone: cyclohexanol mixture and separation of heptane and toluene mixture (with heptane flux of 1.52 Lm−2h−1) showed a separation factor of 9.9. The selectivity and productivity are based on the polarity and size of the organic liquids. The role of Cu2O@g-C3N4 is influencing the pore size distribution, increased divergence from solubility parameters, polarity, solvent uptake and porosity of the composite membranes. The developed composite membranes are thus envisioned to be apt for a wide range of liquid-liquid separations due to its implicit nature.

Comprehensive investigation of recycled PVC powder.

This study constitutes a comprehensive investigation centred on comprehending the behaviour and characteristics of recycled polyvinyl chloride (PVC) powders. The overarching objective is to successfully conclude the initial research phase, during which PVC-coated fabric offcuts undergo a transformation into PVC powder while achieving complete separation from polyethylene terephthalate fibres. The study entails a qualitative description of the morphology of PVC powder particles, employing an optical microscope to distinguish the diverse shapes exhibited by these particles. The optical microscope observations of PVC powder reveal a distinct array of non-spherical particles characterized by flat, elongated shapes. These high-magnification images unveil the intricate morphological features of the particles, highlighting their irregular shapes. Subsequently, a quantitative analysis of PVC particle size distribution is performed, comparing results from optical microscopy with those obtained through mechanical sieving. The qualitative and quantitative findings obtained provide robust evidence supporting the correlation and confirm that most particles are smaller than 600 µm (93.6%) using an optical microscope and the sieving process (96.39%). The greatest fraction (83.44%) is in the size range between 200 and 600 µm. Assessing flowability, another significant aspect in the evaluation of powders, provides insights into its behaviour and interparticle interactions. The flowability results indicate a Compressibility Index of approximately 26.84%, which suggests poor flowability. This means that the powder is likely to encounter difficulties in flowing freely. This finding is in line with the Hausner ratio, which measures 1.37. This investigation of recycled PVC powder will offer insights into the potential applications and processing considerations of this powder. More concretely, the use of recycled PVC powder shows promise as a viable alternative to conventional PVC resin in plastisol formulations, offering the potential to maintain the properties of the final PVC product without adverse effects.

Influence of the Grid Inclination Angle on the Efficiency of Preliminary Separation of the Combed Heap

Introduction. A highly topical scientific and practical task is to justify the choice of the most advanced variant of the device for pre-separating the combed heap and to optimize its design. Aim of the Study. The study is aimed at testing the effect of the grid inclination angle on the effectiveness of pre-separating the combed heap. Materials and Methods. It is possible to minimize the separated grain flow into the threshing machine either by means of a feeder house grid bottom or by means of a horizontal separating device, located directly in front of the threshing drum. To select the optimal design of the separation device, there was planned and conducted a laboratory experiment. The study was carried out in two stages. In the first series of experiments, the elevator body was installed horizontally, and in the second series – at an angle of 45° to the horizon. The width of the grid bottom openings had four variations (6, 8, 10 and 12 mm), and the speed of the scraper conveyor was 3 m/s. A combed heap of the winter wheat variety Moskovskaya 56 was selected as the study object. The grain moisture was 12%. Results.According to the results of laboratory studies, it was found that with an increase in the width of the grid surface openings, the intensity of separating grain increases. The maximum device throughput (90%) corresponds to the horizontal position of the grid bottom of the experimental installation and the width of the openings b = 12 mm. Extrapolation of the separated grain decreasing graph indicates that to ensure complete separation of grain, the length of the separating grid should be at least L = 0.9 m. Discussion and Conclusion. The use of a horizontal separating grid allows increasing the device separation efficiency and reducing its metal content by 14–16%.

Effective decapsulation method for photovoltaic modules: Limonene-induced EVA controlled swelling under sonication and debonding mechanism analysis

Waste crystalline silicon (c-Si) solar cells are rich in metal resources. The detachment of ethylene-vinyl acetate (EVA) copolymer is a critical step in the recycling of end-of-life (EoL) c-Si photovoltaic (PV) modules, but a clean and high-efficiency adhesive removal method is absent. In this study, we presented a green solvent-based approach using limonene with ultrasound assistance for the efficient delamination of EVA from c-Si PV modules. By adjusting the concentration of limonene solution, the degree of swelling of EVA was effectively controlled, reducing the risk of battery damage caused by uneven swelling. The application of an ultrasonic physical field to the swelling system expedited the diffusion and penetration of the swelling agent between the EVA layers, while simultaneously supplying energy for the fracture of cross-linking bonds. Under the optimized laboratory-scale condition (70 °C, 0.5 h and 0.1 M limonene), complete separation of the glass and backsheet from the EVA bonding layer was achieved. The intact c-Si solar cells thus have the potential to be fully recovered in subsequent processes. FT-IR tests and density functional theory (DFT) simulations confirmed that under ultrasound conditions, limonene molecules selectively attacked crosslinking bridges and side chains of ethyl vinyl acetate in the EVA molecular chain. This induced the breakdown of the EVA crosslinked network structure, resulting in a reduction in adhesive strength and ultimately achieving interlayer separation in 20min. The findings of this study provide theoretical support and technical insights for the clean and efficient recycling of PV modules.