Separation Process Research Articles

(Invited) Trials and Tribulations on Scaling Metal Recovery Technology from Lab to Market

PowerTech Water, Inc. d/b/a ElectraMet (ElectraMet) is a cleantech company founded in 2014 in Lexington, KY with the goal of applying carbon and electrochemistry to solve fundamental challenges in wastewater and process water applications. There exists a broad array of separation applications that could be tackled through electrochemical routes, and ElectraMet has worked on many of them.Early in ElectraMet’s history, focus was directed towards salt removal applications such as salt-free water softening, brackish water desalination, and ultra-pure water production. While some traction was found in these spaces, penetration of a new technology versus entrenched incumbents such as reverse osmosis and distillation made the sales process difficult. Limitations in what the technology could and could not do were also determined. Therefore, within the first few years of operation, focus shifted towards particular customer pain points, specifically metals separation applications. Problematic metals concentrations are present in drinking water, industrial effluents, and storm runoff, just to name a few. As a growing but still small business, it is important to choose a beachhead market where you can have the strongest value proposition, and electrochemical separations of metals offered a unique opportunity to solve challenges in the metals separation space. Therefore, considerable work has gone into developing these separation processes for specific metals and specific markets.In this talk, the early history of the company will be reviewed, including technology, funding, and market applications. The impact of strategic advisors and early successes will be discussed with regards to the direction of the company. Ultimately, product-market-fit and the strategies and struggles in building a small business will be presented. Efforts will be made to highlight possible pitfalls, roadblocks, and opportunities as seen through this particular journey.

Separation of Lithium over Magnesium, Sodium, and Calcium By Electrodialysis Using Commercial Membranes

Lithium is considered a critical raw material worldwide due to the growing market for electric vehicles. Due to the risk of supply interruption in the short and medium term, alternative sources of lithium are being explored for battery supply. Among these, salt-lake brines have become a key supply because their abundance represents about 59% of lithium resources 1. A secondary source in the medium term is the recycling of spent Li-ion batteries by hydrometallurgical processes 2,3. Together, recovering lithium from brine and recycling can supply the demand for transport electrification. Conventional lithium extraction techniques from both brine and battery recycling face the challenge of selective separation over contaminants and low extraction efficiencies 4,5.As an alternative, electrodialysis (ED) is an important selective separation technique with high selectivity, productivity, and less consumption of chemical reagents under energy consumption. This electrochemical membrane separation process uses an electric field inducing anion and cation transport across alternating anion and cation exchange membranes. While standard electrodialysis can be used to desalinate water and generate more concentrated brine), selective electrodialysis processes that up-concentrate a specific ion from a mixed salt solution are less developed. Our goal with this work is to evaluate the effect of common ions on lithium separation by ED using three different commercial membranes. The experiments were carried out in a 4-chamber reactor where the feed solutions consisted of equimolar chloride salts of lithium and either nickel (representing battery recycling), magnesium, sodium, or calcium (representing brine). Anolyte, receiving, and catholyte chambers (Figure 1) contained 1.0 M H2SO4.Here, we present the results in terms of cation permselectivity, productivity, and energy consumption using three different commercial membranes for the cation exchange membrane in the ED setup: a standard cation exchange membrane (CXM-200), a monovalent cation exchange membrane (CXP-S) and a nanofiltration membrane (NF-90). The performance of each membrane was tested under varying applied current densities to assess the impact of operating conditions on ion transport. Results have demonstrated monovalent cationic membranes are strongly selective for lithium over magnesium and nickel, achieving selectivity of 43 and 57, respectively. The increase in current density from 2.8mA/cm² to 11.5mA/cm² also increased the fluxes of lithium and co-ions by the monovalent membrane, consequently decreasing the selectivity from 56.7 to 2.4. In addition, nickel precipitates in the feed chamber as the current density increases from 2.8mA/cm² to 5.7mA/cm². We then translate these results into a process model for upscaling the ED reactor, considering the species transport rate through the reactor chambers and selectivity for lithium. Keywords: battery recycling; brine; electrochemical membrane separation; critical raw materials.Figure 1: ED reactor used for lithium selective separation by commercial membranes References (1) Fuentealba, D.; Flores-Fernández, C.; Troncoso, E.; Estay, H. Technological Tendencies for Lithium Production from Salt Lake Brines: Progress and Research Gaps to Move towards More Sustainable Processes. Resources Policy 2023, 83 (January). https://doi.org/10.1016/j.resourpol.2023.103572.(2) Guimarães, L. F.; Botelho Junior, A. B.; Espinosa, D. C. R. Sulfuric Acid Leaching of Metals from Waste Li-Ion Batteries without Using Reducing Agent. Miner Eng 2022, 183 (May), 107597. https://doi.org/10.1016/j.mineng.2022.107597.(3) Martins, L. S.; Rovani, S.; Botelho Junior, A. B.; Romano Espinosa, D. C. Sustainable Approach for Critical Metals Recovery through Hydrometallurgical Processing of Spent Batteries Using Organic Acids. Ind Eng Chem Res 2023. https://doi.org/10.1021/acs.iecr.3c03048.(4) Asadi Dalini, E.; Karimi, G.; Zandevakili, S. Treatment of Valuable Metals from Leaching Solution of Spent Lithium-Ion Batteries. Miner Eng 2021, 173 (September), 107226. https://doi.org/10.1016/j.mineng.2021.107226.(5) Xu, S.; Song, J.; Bi, Q.; Chen, Q.; Zhang, W. M.; Qian, Z.; Zhang, L.; Xu, S.; Tang, N.; He, T. Extraction of Lithium from Chinese Salt-Lake Brines by Membranes: Design and Practice. J Memb Sci 2021, 635 (May), 119441. https://doi.org/10.1016/j.memsci.2021.119441. Figure 1

(Invited) Selective Ammonia Separation Using Prussian Blue Analogues

Prussian blue analogues (PBAs) are a three-dimensional coordination polymer with iron and transition metals bridged with cyanide ligands, creating open-framework structures for hosting guest ions into interstitial sites. These sites can be occupied by cations via adsorption/desorption or intercalation/deintercalation, which has been widely utilized in developing separation processes and energy storage devices. Additionally, it has been well established that the size of the channel provides selectivity between monovalent cations based on their hydrated radii. Using these unique functionalities allows for selective ammonia recovery from wastewater. The feasibility of selective separation has been demonstrated using PBA-based electrodes that showed reversible and selective intercalation/deintercalation of NH4 + by cyclic operation. To enable continuous separation, we recently developed an electrochemically driven membrane process, where PBAs provided selective ion-conducting channels. An improved selectivity for NH4 + relative to Na+ was achieved using synthetic and domestic wastewaters, which was attributed to a thin layer of PBA created on the surface of a cation exchange membrane. These results collectively show that the use of PBAs for selective ammonia separation could lead to the development of efficient electrochemical processes for nutrient recovery.

Electrochemical Conversion of Bicarbonate Using Proton Exchange Membrane-Based Electrolyzer

Direct electrochemical conversion of captured carbon dioxide (CO2) is gaining interest as an efficient method for capturing and utilizing CO2, eliminating the need for energy-intensive CO2 separation process.[1] The integrated electrolyzer with bicarbonate feed operates on the principle of spontaneous reduction of CO2 released from bicarbonate within the electrolyzer. The key to the on-site decomposition of bicarbonate into CO2 is to acidify the bicarbonate within the electrolyzer through the deliberately generated pH gradient. Bipolar membrane has been extensively used to generate pH gradient and acidify the bicarbonate feed.[2] However, the high ionic resistivity of bipolar membrane and slow kinetic of water dissociation reaction can result in a high operation cell voltage.In this study, we demonstrate proton exchange membrane based-bicarbonate electrolyzer which produces carbon monoxide from bicarbonate feedstock with high CO production selectivity and low cell voltage that are comparable to the conventional gas fed CO2 electrolyzer. To achieve highly selective CO production selectivity, a nickel single atom catalyst (Ni SAC) where the atomically dispersed nickel active sites decorated on the nitrogen doped carbon was prepared and utilized. Ni-SAC showed high CO production selectivity even in bicarbonate feed electrolyzer. To further improve the performance of this integrated electrolyzer, significant attention was given to the optimization of electrode structures. Due to the complexity of the reaction environment within the integrated electrolzyer, the performance of the electrolyzer is heavily dependent on the porosity of electrodes and distribution of catalyst on the electrodes. By optimizing the fabrication of electrodes with Ni-SACs, the optimal catalyst coated electrode showed high CO production selectivity over 90% with current density of 100 mA/cm2 at low operating cell potential of 3 V.

Simulation of Magnetic Separation of Metal Ions in Aqueous Electrolytes

The magnetic separation of metal ions provides an alternative solution to traditional separation techniques such as pyrometallurgy, hydrometallurgy, biometallurgy or electrodialysis. Compared to traditional techniques that either use large amounts of chemicals (usually inorganic acids combined with reducing agent), produce large amounts of sludge as solid waste, consume a large amount of energy, or are difficult to separate ions of different charges [1], the magnetic separation of the metal ions can separate ions based on their magnetic susceptibility. This method is environmentally friendly [2] and consumes a small amount of energy (particularly when the system is designed using permanent magnets instead of electromagnets). The goal of this presentation is twofold. First, we derive the set of transport equations that need to be used to simulate the magnetic separation of metal ions in aqueous solutions. Then, we use these transport equations to simulate the magnetic separation process in various magnetic systems and predict the efficiency of magnetic separation of different systems.The mathematical model developed here is based on coupling the three-dimensional Navier-Stokes equations for flow transport with the drift (migration)-diffusion equations of ion transport [3] in the presence of magnetic field gradients. Both the drift-diffusion model and the Navier-Stokes equations include the magnetic force term as an additional driving force. By solving the entire system of equations self-consistently we analyze the effect of the diffusivity, concentration gradients, magnetic field gradients and fluid velocity over the capturing properties of the system. A detailed presentation of the mathematical model, underlying assumptions of the model, limiting cases, numerical implementation in three-dimensional structures, and simulations results will be presented at the meeting. In addition, we will present predictions for the magnetic separation of Li, Fe, Ni, Mn, and Co from the solution phase. Fortunately, these ions have significantly different magnetic susceptibility, which vary over more than 3 orders of magnitude, and which allows for the efficient extraction and separation of the elements from the solution and from each other.

Symmetry Breaking Charge Separation in Far-Red Absorbing Bisstyryl-Bodipy Dimers

Symmetry breaking charge transfer is one of the important photo-events occurring in photosynthetic reaction centers that is responsible for initiating electron transfer leading to a long-lived charge-separated state and has been successfully employed in light-to-electricity converting optoelectronic devices. Here, we report the synthesis of far-red absorbing and emitting BODIPY-dimer to undergo symmetry-breaking charge transfer leading to charge-separated states of appreciable lifetimes in polar solvents. Compared to its monomer analog, both steady-state and time-resolved fluorescence originating from the S1 state of the dimer revealed quenching which increased with an increase in solvent polarity. The electrostatic potential map from DFT and the time-dependent DFT calculations suggested the existence of a quadrupolar type charge transfer state in polar solvents, and the singlet excited state to be involved in the charge separation process. The electrochemically determined redox gap to be smaller than the energy of the S1 state supporting thermodynamic feasibility of the envisioned symmetry-breaking charge transfer and separation. The spectrum of the charge-separated state arrived from spectroelectrochemical studies, revealing diagnostic peaks helpful for transient spectral interpretation. Finally, ultrafast transient pump-probe spectroscopy provided conclusive evidence of diabatic charge separation in polar solvents by far-red pulsed laser light irradiation. The measured lifetime of the final charge-separated states was found to be 165 ps in dichlorobenzene, 140 ps in benzonitrile, and 43 ps in dimethyl sulfoxide, revealing their significance in light energy harvesting, especially from the less-explored far-red region.

DCE-Qnet: deep network quantification of dynamic contrast enhanced (DCE) MRI.

Quantification of dynamic contrast-enhanced (DCE)-MRI has the potential to provide valuable clinical information, but robust pharmacokinetic modeling remains a challenge for clinical adoption. A 7-layer neural network called DCE-Qnet was trained on simulated DCE-MRI signals derived from the Extended Tofts model with the Parker arterial input function. Network training incorporated B1 inhomogeneities to estimate perfusion (Ktrans, vp, ve), tissue T1 relaxation, proton density and bolus arrival time (BAT). The accuracy was tested in a digital phantom in comparison to a conventional nonlinear least-squares fitting (NLSQ). In vivo testing was conducted in ten healthy subjects. Regions of interest in the cervix and uterine myometrium were used to calculate the inter-subject variability. The clinical utility was demonstrated on a cervical cancer patient. Test-retest experiments were used to assess reproducibility of the parameter maps in the tumor. The DCE-Qnet reconstruction outperformed NLSQ in the phantom. The coefficient of variation (CV) in the healthy cervix varied between 5 and 51% depending on the parameter. Parameter values in the tumor agreed with previous studies despite differences in methodology. The CV in the tumor varied between 1 and 47%. The proposed approach provides comprehensive DCE-MRI quantification from a single acquisition. DCE-Qnet eliminates the need for separate T1 scan or BAT processing, leading to a reduction of 10 min per scan and more accurate quantification.

Optimization design of hydrocyclone with overflow slit structure based on experimental investigation and numerical simulation analysis

This study aims to address the issue of high energy consumption in the hydrocyclone separation process. By introducing a novel slotted overflow pipe structure and utilizing experimental and response surface optimization methods, the optimal parameters were determined. The research results indicate that the number of slots, slot angles, and positioning dimensions significantly influence the performance of the hydrocyclone separator. The optimal combination was found to be three layers of slots, a positioning dimension of 5.3 mm, and a slot angle of 58°. In a Φ100mm hydrocyclone separator, validated through multiple experiments, the separation efficiency increased by 0.26% and the pressure drop reduced by 24.88% under a flow rate of 900 ml/s. CFD simulation verified the reduction in internal flow field velocity and pressure drop due to the slotted structure. Therefore, this study provides an effective reference for designing efficient and low-energy hydrocyclone separators.

The series of L-lysine-derived gelators-modified multifunctional chromatography stationary phase for separation of chiral and achiral compounds

In this study, using chiral L-lysine as the molecular skeleton, three kinds of L-lysine-derived gelators (GBLB, GBLF and GFLF) were synthesized and then bonded to the surface of silica matrix (5 μm) by amide condensation to prepare a series of multifunctional chromatography stationary phases (GBLB-SiO2, GBLF-SiO2, and GFLF-SiO2) were prepared. The L-lysine-derived gelators not only possess chiral recognition ability, but also can spontaneously form oriented and ordered network structures in liquid medium through the interaction of non-covalent bonding forces such as hydrogen bonding, π-π stacking, and van der Waals forces. The comprehensive effect of multiple weak interaction sites enhances the molecular recognition ability and further improves the separation diversity of different types of compounds on stationary phases. The separation and evaluation of chiral compounds showed that benzoin, 1-phenyl-ethanol, 1-phenyl-propanol and 6-hydroxyflavanone could be separated in normal phase mode (NPLC). The separation of different types of non-chiral compounds, such as sulfonamides, nucleosides, nucleobases, polycyclic aromatic hydrocarbons (PAHs), anilines, and aromatic acids, were achieved in hydrophilic interaction/reversed-phase/ion-exchange mode (HILIC/RPLC/IEC), and the separation of polarized compounds could be performed under the condition of ultrapure water as the mobile phase, which has the typical retention characteristics of per aqueous liquid chromatography (PALC). The effects of organic solvent content, temperature, pH value, and buffer salt concentration on the retention and separation performance of the column were investigated. Comparison of the three prepared columns showed that the separation performance (such as aromatic selectivity) could be improved by increasing the types of functional groups on the surface of the stationary phase and the number of aromatic groups. In a word, the prepared stationary phase have multiple retention properties, can simultaneously separate chiral compounds and various types of achiral compounds. This work provides an idea for developing multifunctional liquid chromatography stationary phase materials, and further expands the application of gelators in separation science.

Catalytic Approaches to Tackle Mixed Plastic Waste Challenges: A Review.

Plastics are widely used materials in our daily lives and various industries due to their affordability and versatility. The massive production of plastic waste, however, has recently emerged as a pressing environmental concern across all media. To address this, emerging technologies are being explored for the sustainable valorization of postconsumer plastic wastes including thermochemical, physical, and catalytic processes aimed at transforming them into higher value-added products. However, the chemical recycling of mixed plastic wastes poses a formidable challenge due to the diverse array of monomers and catalyst systems involved, each employing distinct mechanisms. Complicating matters further is that contaminants reduce catalytic efficacy, requiring rigorous and labor-intensive separation and purification processes to extract individual plastic streams from practical plastic waste mixtures. Consequently, the majority of such mixtures often end up in incineration and landfills, perpetuating environmental and societal challenges, such as leachate, carbon dioxide emissions, and other air pollutants. This review will introduce current technical developments available for recycling practical plastic waste mixtures through catalytic processes. The current challenges in process performance, low selectivity of the desired products, and catalyst deactivation from the catalysis of plastic waste mixtures are also discussed. Promising approaches to overcome the problems are suggested in future research directions.

A sustainable mineral process for silicon and quartz recovery from quartz crucible waste ash via electrical separation

Driven by the explosive development of the photovoltaic (PV) industry, the treatment of the quartz crucible waste ash (QCWA) from monocrystalline silicon rod production must be considered to combat the shortage of silicon materials and promote sustainable development. In particular, the loss of grade 4 N high-purity silicon in QCWA is a frustrating fact for the silicon supply chain. In this work, an electrical separation process is proposed for the recovery of silicon and quartz from QCWA to realize waste resource reutilization. The charging processes and forces in the feed QCWA are first analyzed. Then, the electric field distribution during electrical separation is simulated to clarify the movement models of silicon and quartz particles and formulate reasonable electrical separation parameters. After systematic theoretical analysis, calculation, and simulation, electrical separation experiments were conducted. The results prove that the content of silicon in the concentrate and the corresponding content of quartz in the tailing respectively exceeded 93 % and 61 % under a particle size of 80 ∼ 120 mesh, a voltage of 40 kV, and a roll speed of 75 r/min. This work demonstrates that electrical separation is a sustainable process that could be recommended for silicon and quartz recovery from QCWA.

Tunable Wettability of a Dual-Faced Covalent Organic Framework Membrane for Enhanced Water Filtration.

Membrane technology plays a central role in advancing separation processes, particularly in water treatment. Covalent organic frameworks (COFs) have transformative potential in this field due to their adjustable structures and robustness. However, conventional COF membrane synthesis methods are often associated with challenges, such as time-consuming processes and limited control over surface properties. Our study demonstrates a rapid, microwave-assisted method to synthesize self-standing COF membranes within minutes. This approach allows control over the wettability of the surface and achieves superhydrophilic and near-hydrophobic properties. A thorough characterization of the membrane allows a detailed analysis of the membrane properties and the difference in wettability between its two faces. Microwave activation accelerates the self-assembly of the COF nanosheets, whereby the thickness of the membrane can be controlled by adjusting the time of the reaction. The superhydrophilic vapor side of the membrane results from -NH2 reactions with acetic acid, while the nearly hydrophobic dioxane side has terminal aldehyde groups. Leveraging the superhydrophilic face, water filtration at high water flux, complete oil removal, increased rejection with anionic dye size, and resistance to organic fouling were achieved. The TTA-DFP-COF membrane opens new avenues for research to address the urgent need for water purification, distinguished by its synthesis speed, simplicity, and superior separation capabilities.

Sedimentation dynamics of triply twisted Möbius bands: Geometry versus topology

We explore the sedimentation dynamics of triply twisted Möbius bands, each characterized by threefold rotational symmetry but distinguished by its construction and intrinsic geometrical properties. Three types of bands are considered: one with vanishing Gaussian curvature, constructed by isometrically deforming flat rectangular strips through bending without stretching; and two with negative Gaussian curvature, one being constructed by isometrically deforming helicoids. Experiment on these three types of bands, with a focus on varying aspect ratios, reveals a singular phenomenon: while the spin directions of bands not derived from helicoids spin in directions consistent with their inherent chirality, bands derived from helicoids exhibit an aspect-ratio-dependent spin, pointing to the existence of a critical aspect ratio at which geometric factors dominate over chiral influences. Supported by numerical simulations and a detailed analysis of the resistance tensors, we propose the unique response of bands derived from helicoids originates from a complex interaction among geometry, topology, and hydrodynamics. Two explanations are offered for the chiral transition observed in bands derived from helicoid. First, this transition may parallel the dynamics of superhelices, for which competing chiralities influence rotational behavior. Second, the unique geometrical properties of bands derived from helicoids, coupled with deviations between the rotation axis and the local symmetry axis, may underlie the observed aspect-ratio-dependent chiral transition. Our study underscores the significant role of geometrical and topological nuances in determining the behavior of chiral objects suspended in fluids. In addition to offering transformative potential across diverse fields, it promises advancements in mixing, separation processes, and innovative passive swimmers. Published by the American Physical Society 2024

Quantitative analysis of energy transfer and separation in vortex tubes: Factors and empirical insights

As a device with a simple structure for energy separation, the low efficiency of the vortex tube is the primary obstacle hindering its widespread application. No existing energy separation theory has gained wide acceptance due to inconsistencies with actual processes. Therefore, drawing on prior studies concerning the flow field, the formation process of flow distribution is presented. Then a quantitative analysis of the energy transfer and separation processes in vortex tubes driven by velocity gradient, temperature gradient, and pressure gradient is proposed. The viscous shear work, heat transfer, and turbulent heat transfer processes were analyzed separately. It was found that the main factors of vortex tube energy separation originated from the expansion of the inlet nozzle and the turbulent heat transfer process. At the same time, the viscous shear work and heat transfer processes also have a specific effect on the energy separation, in which the heat transfer process suppressed the energy separation effect of the vortex tube. In addition, its empirical results indicate that interactions among the turbulent heat transfer process, frictional dissipation, angular momentum conservation, and heat transfer should be considered in further studies.

The Allelopathy of the Invasive Plant Species Ludwigia decurrens against Rice and Paddy Weeds

Ludwigia decurrens Walter, belonging to the Onagraceae family, is native to southeastern and southcentral USA and has spread quickly, colonizing wetlands in South and Central America, East and South Asia and Africa. Ludwigia decurrens also infests rice paddy fields and causes serious damage to rice production. The phenomenon of allelopathy is often observed in invasive plant species and contributes to their invasive characteristics. However, no information has been made available on the allelopathy of L. decurrens against wetland species, including Oryza sativa (rice), or on its allelochemicals. Aqueous methanol extracts of whole L. decurrens plants showed allelopathic activity against O. sativa and paddy weeds, Echinochloa crus-galli and Monochoria vaginalis in an extract-concentration-dependent manner. Two allelochemicals, loliolide and dehydrololiolide, were isolated from the L. decurrens extracts through a bioassay-guided separation process using O. sativa as the test plant species. Loliolide and dehydrololiolide also suppressed the growth of O. sativa and E. crus-galli in a concentration-dependent manner. Thus, loliolide and dehydrololiolide may be involved in the allelopathy of L. decurrens and may provide a competitive advantage for L. decurrens due to their growth inhibitory activity. However, the inhibitory activity of loliolide was about 3-fold greater than that of dehydrololiolide. These investigations suggest the allelopathy of L. decurrens may play an important role in the invasion of the species into rice paddy fields and other wetlands. This is the first report on the allelopathy of L. decurrens against wetland species and the isolation and identification of the allelochemicals in L. decurrens.

Hydrodynamic Evaluation of a Filtering Hydrocyclone for Solid Particle/Water Separation.

A conventional hydrocyclones is a versatile equipment with a high processing capacity and low maintenance cost. Currently, several studies aim to alter the typical structure of the conventional hydrocyclone in order to modify its performance and purpose. For this, filtering hydrocyclones have emerged, where a porous membrane replaces the conic or cylindrical wall. During the operation of this equipment, in addition to the traditionally observed streams (feed, underflow, and overflow), there is a liquid stream resulting from the filtration process, commonly referred to as filtrate. This work proposes to numerically investigate the solid particle/liquid water separation process in a filtering hydrocyclone using the commercial software Ansys CFX® 15.0. The proposed mathematical model for the study considers three-dimensional, steady state and turbulent flow, using the Eulerian-Eulerian approach and the Shear Stress Transport (SST) turbulence model. This study presents and analyzes the volume fraction, velocity, and pressure fields, along with flowlines and velocity profiles. The results indicate that the proposed model effectively captures the fluid dynamic behavior within the filtering hydrocyclone, highlighting higher pressures near the porous membrane and a higher concentration of solid particles in the conical region, with water being more concentrated in the cylindrical part of the hydrocyclone. Additionally, the findings show that the volumetric flow rate of the filtrate significantly influences the internal flow dynamics, with conventional hydrocyclones demonstrating higher pressure gradients compared to the proposed filtering hydrocyclone.

Synthesis of eco-friendly bio-based coconut shell magnetic biochar for efficient bisphenol S sequestration in aqueous environment: green technology breakthrough

Water pollution has emerged as a critical global challenge, particularly the contamination of water bodies with persistent organic pollutants such as Bisphenol S (BPS), a known endocrine disruptor. This study presents the synthesis and application of eco-friendly bio-based coconut shell magnetic biochar (CSMB) for efficient sequestration of BPS from aqueous environments. Utilizing pyrolysis and co-precipitation techniques, the magnetic biochar was characterized through various methods including surface chemistry (pHpzc), electron dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) N2 adsorption-desorption, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). SEM revealed a porous structure with a high surface area, while FTIR confirmed the presence of functional groups essential for adsorption. X-ray diffraction (XRD) and VSM successfully incorporated magnetic nanoparticles, enhancing the separation process post-adsorption. The CSMB demonstrated a significant surface area of 373 m2 g−1, outperforming regular coconut shell biochar (CSB), with a BPS adsorption capacity of 43.5 mg/g compared to 26.7 mg/g for CSB. Batch adsorption tests assessed the impact of operational factors such as initial BPS concentration (8–150 ppm), contact time (30–150 min), temperature (298.15, 318.15, and 338.15 K), pH (3–11), and CSMB dosage (0.1–0.9 g). The results indicated optimal adsorption at pH 6 with a maximum capacity of 52.3 mg/g. Kinetic studies revealed that the pseudo-second-order model best described the adsorption process, while the Langmuir isotherm model provided an excellent fit for the adsorption data. The reusability of CSMB was validated over five cycles, with adsorption capacity decreasing slightly from 43.5 mg/g to approximately 41 mg/g, making it a sustainable and effective adsorbent for water treatment.

Разработка технологии получения безлактозного молока методом диафильтрации

Abstract. The purpose. The research is aimed at solving the problem related to the development of technology for producing an environmentally friendly product of animal origin – lactose-free milk. This will solve the problem of consumption of milk and dairy products by people who do not tolerate milk sugar for physiological reasons. Analyzing, on the basis of a literary review, the current state of the issue of lactose-free milk production, it can be concluded that existing technologies have certain disadvantages due to changes in the composition of the initial product, or the significant complexity of the technological chain. The proposed development is based on a method of milk diafiltration consisting of several repetitive cycles. The cycle consists in the separation of milk by the ultrafiltration process into permeate (aqueous lactose solution) and concentrate (proteins, fat, lactose residues). Then pure water is added to the concentrate in a volume equal to the volume of the discharged permeate. For a scientifically based approach to the development of the proposed technology, it is necessary to conduct a study of ultrafiltration separation of milk, obtain optimal operating parameters of the process, determine the change in permeability and selectivity of membranes from lactose concentration, consider the possibility of obtaining lactose-free milk with different mass fraction of fat, determine the number of cycles of the membrane diafiltration process. Research methods. The study of the process of ultrafiltration separation of milk was carried out in laboratory conditions on a membrane installation using organic and inorganic membranes. The experiments determined the main characteristics of ultrafiltration membranes – permeability and selectivity, with varying parameters (parameter range: P = 0.15…0.5 MPa, t = 35…65 °C). Results. Based on the experimental data obtained, by processing them and optimizing the parameters, optimal modes of the milk separation process by ultrafiltration were obtained. The following parameters are defined: the velocity of the product in the supramembrane space, the operating pressure of the separation process, its temperature. The preferred ultrafiltration membranes for the membrane-milk system have been selected. Scientific novelty. To develop a technology for producing lactose-free milk, for the first time a number of studies and experiments were carried out, such as changing the permeability and selectivity of membranes from the concentration of lactose, obtaining lactose-free milk with mass fraction of fat the number of cycles of the membrane diafiltration process was determined.

Strain-Induced Photocatalytic H2 Production over BiVO4 in Pure Water without Any Cocatalyst.

In this study, BiVO4 nanosheets (BiVO4-NS) were prepared by a facile hydrothermal method. It is found that sonication-induced strain can effectively promote the H2 production over BiVO4-NS in the presence of pure water without any cocatalysts. With the assistance of the sonication, the H2 production over BiVO4-NS is 1.344 mmol·g-1 after 3 h simulated sunlight irradiation, which is 24.8 times higher than that of BiVO4-NS without sonication (0.054 mmol·g-1). In addition, the products of water oxidation are determined to be hydroxyl radicals and hydrogen peroxide. Moreover, BiVO4-NS also shows obviously enhanced photoactivity than that of the commercially available BiVO4 nanoparticles (BiVO4-C). The improved photoactivity of BiVO4-NS is attributed to the effective charge separation and low charge transfer resistance. The underlying mechanism of sonication-promoted water splitting is investigated by a variety of controlled experiments. The results show that ultrasonic waves can produce obvious strain inside the sample, which results in lattice distortion of BiVO4. Therefore, the conduction band of BiVO4 is obviously negative shifted, which is beneficial for H2 production. In addition, the strain in BiVO4 also produces local polarization of the sample, which effectively promotes the charge transfer and separation process. It is hoped that our study could provide a new strategy for achieving efficient photocatalytic water splitting.

Analytical Computation of Hyper-Ellipsoidal Harmonics

The four-dimensional ellipsoid of an anisotropic hyper-structure corresponds to the four-dimensional sphere of an isotropic hyper-structure. In three dimensions, both theories for spherical and ellipsoidal harmonics have been developed by Laplace and Lamé, respectively. Nevertheless, in four dimensions, only the theory of hyper-spherical harmonics is hitherto known. This void in the literature is expected to be filled up by the present work. In fact, it is well known that the spectral decomposition of the Laplace equation in three-dimensional ellipsoidal geometry leads to the Lamé equation. This Lamé equation governs each one of the spectral functions corresponding to the three ellipsoidal coordinates, which, however, live in non-overlapping intervals. The analysis of the Lamé equation leads to four classes of Lamé functions, giving a total of 2n + 1 functions of degree n. In four dimensions, a much more elaborate procedure leads to similar results for the hyper-ellipsoidal structure. Actually, we demonstrate here that there are eight classes of the spectral hyper-Lamé equation and we provide a complete analysis for each one of them. The number of hyper-Lamé functions of degree n is (n + 1)2; that is, n2 more functions than the three-dimensional case. However, the main difficulty in the four-dimensional analysis concerns the evaluation of the three separation constants appearing during the separation process. One of them can be extracted from the corresponding theory of the hyper-sphero-conal system, but the other two constants are obtained via a much more complicated procedure than the three-dimensional case. In fact, the solution process exhibits specific nonlinearities of polynomial type, itemized for every class and every degree. An example of this procedure is demonstrated in detail in order to make the process clear. Finally, the hyper-ellipsoidal harmonics are given as the product of four identical hyper-Lamé functions, each one defined in its own domain, which are explicitly calculated and tabulated for every degree less than five.