Use Of External Magnetic Field Research Articles

Enhancing Electrocatalytic Activity through Tailored Charge and Spin Polarization in Molecules and Frameworks

Single-molecule and framework-based electrocatalysts are increasingly attractive in the field of electrocatalysis due to their precise atomic-level control and highly tunable properties, enabling the development of highly efficient and selective energy conversion processes. Tailoring charge and spin polarization within these structures presents a unique opportunity to significantly enhance catalytic activity, opening new avenues in developing efficient electrocatalytic systems. This presentation will outline methods our group has developed to synthesize and adjust charge and spin configurations in molecular and framework catalysts. We will explore a variety of pathways, including the design of single molecular catalysts with optimized spin states, the application of mesomeric and inductive effects for charge regulation, and the use of external magnetic fields and chirality to modulate spin polarization at the molecular level. Our findings indicate that such customization can accelerate the kinetics of spin-sensitive electrochemical reactions like oxygen electrocatalytic reactions. Furthermore, we will discuss how the inherent properties of the catalysts, particularly magnetic moments and spin-orbit interactions, play a crucial role in influencing catalytic performance in the presence of spin potentials. Hence, this presentation aims to provide an overview of our advanced strategies to reconfigure charge and spin states in framework and molecular catalysts, underscoring their potential to revolutionize electrochemical energy conversion technologies.

Spin-Hall conductivity and optical characteristics of noncentrosymmetric quantum spin Hall insulators: the case of PbBiI

Quantum spin Hall insulators have attracted significant attention in recent years. Understanding the optical properties and spin Hall effect in these materials is crucial for technological advancements. In this study, we present theoretical analyses to explore the optical properties, Berry curvature and spin Hall conductivity of pristine and perturbed PbBiI using the linear combination of atomic orbitals and the Kubo formula. The system is not centrosymmetric and it is hosting at the same time Rashba spin-splitting and quantized spin Hall conductivity. Our calculations reveal that the electronic structure can be modified using staggered exchange fields and electric fields, leading to changes in the optical properties. Additionally, the spin Berry curvature and spin Hall conductivity are investigated as a function of the energy and temperature. The results indicate that due to the small dynamical spin Hall conductivity, generating an ac spin current in the PbBiI requires the use of external magnetic fields or magnetic materials.

ЕЛЕКТРОХІМІЧНІ ПАРАМЕТАРИ МОДИФІКОВАНОГО АМОРФНОГО СПЛАВУ У ВОДНИХ РОЗЧИНАХ РІЗНОЇ ПРИРОДИ

Amorphous metal alloys (AMА) have high corrosion resistance, which can be significantly higher than that of stainless steels. Since ferromagnetic amorphous Fe-based alloys are widely used as soft magnetic materials, their operation is associated with the use of external magnetic fields. Such external influences can change, in particular, the corrosion resistance of amorphous materials. In addition to permanent, amorphous materials can be under the influence of variable magnetic fields. Preliminary exposure in magnetic fields, in particular, alternating ones, can be used to modify AMА. In this regard, electrochemical studies of AMА Fe80Si6B14 in various aggressive environments are appropriate. The search for optimal modes of modification to achieve the given physicochemical properties of the samples makes it possible to change their corrosion resistance. The features of the corrosion resistance of the ribbon amorphous alloy Fe80Si6B14, obtained by the method of ultra-fast cooling of the melt, were studied, for which the contact and external surfaces, which have different elemental composition and properties, are distinguished. Electrochemical studies of AMА electrodes in 0.5 M aqueous solutions of NaCl, НCl and NaОН were carried out by the method of chronopotentiometry and cyclic voltammetry using the Jaissle Potentiostat-Halvanostat IPM 88 PC-R potentiostat. The modification of samples of Fe80Si6B14 strip amorphous alloy was carried out by keeping them in an alternating magnetic field (frequency 50 Hz) for 0.5–3.0 hours. The corrosion resistance of the Fe80Si6B14 strip amorphous alloy modified by an alternating magnetic field in 0.5 M aqueous solutions of NaCl, NaOH and HCl was investigated by various electrochemical methods. It is shown that the corrosion resistance of the tape significantly depends on the duration of the modification and the nature of the aggressive environment. Higher corrosion resistance of Fe80Si6B14 samples modified by a variable magnetic field in 0.5 M aqueous HCl solution was established. The ribbon amorphous Fe80Si6B14 alloy shows exceptional durability to long-term modification in an alternating magnetic field with the subsequent stay of the samples in 0.5 M aqueous solutions of NaOH and HCl.

Demonstration of high-throughput magnetic hysteresis measurements based on spintronic THz emission

Spintronic terahertz (THz) emitters have been shown to be a cost-efficient source for use in time-domain THz spectroscopy. The use of external magnetic fields to control the polarity of the THz emission provides an opportunity to measure the magnetization of spintronic materials as well as shaping THz emission. Here, we demonstrate an efficient method of measuring magnetic hysteresis with material sensitivity and speed several orders of magnitude greater than typical magnetometry methods. In addition, we utilize the rapid control of material magnetization for lock-in detection in time-domain THz spectroscopy of spintronic emitters. The ability to rapidly control and measure the material magnetization on very small volumes provides an opportunity to study magnetic hetero-structures with sub-micron spatial resolution.

Magnetically Triggered Interplay of Capacitive and Diffusion Contributions for Boosted Supercapacitor Performance.

The chemistry involved in supercapacitors in terms of their mechanistic contributions leading to improved specific capacity will aid in easy commercialization. The main contributory factors in a supercapacitor are either capacitive (non-diffusion controlled) or ion-diffusion behavior, which results in enhanced charge-discharge characteristics of a supercapacitor reflected in its power density, whereas ion-diffusion behavior will lead to the enhanced energy density of a supercapacitor. In this context, the present article attempts to understand the use of external magnetic fields, leading to the interplay between capacitive and ion-diffusion behavior in a high-performance supercapacitor. The model system chosen in the present study, nickel cobalt copper carbonate hydroxide (NiCoCuCH), can effectively address the interplay between capacitive and ion diffusion contributions by varying total magnetic effects involving magnetic dilution. The magneto-enhancement of the electrodes nickel cobalt copper carbonate hydroxide (NiCoCuCH) and aluminum-doped nickel cobalt copper carbonate hydroxide (Al-NiCoCuCH) was demonstrated under the magnetic field from 0 to 250 mT. Both NiCoCuCH and Al-NiCoCuCH show dominant non-diffusion-controlled (capacitive) and diffusion-controlled behavior as a function of the applied external magnetic field. Under the influence of the external magnetic field, ferromagnetic coupling between metal-oxygen-metal centers via oxygen 2p orbitals enhances, leading to a facile redox pathway. To further control the charge-discharge behavior of the electrode via the interplay between diffusive and capacitive, a non-magnetic ion, Al3+, was doped into the bare metal carbonate hydroxide crystal lattice. The Al3+ ion not only alters the crystal symmetry but also restricts the alignment of the magnetic domains in the electrode, leading to a sluggish redox pathway, effectively increasing the capacitive contribution, and leading to improved charge-discharge characteristics at the expense of energy density. We have constructed an asymmetric device with the best-performing (110 mT) NiCoCuCH electrode as a positive electrode and activated carbon as a negative electrode. The NiCoCuCH/AC ASC device at 110 mT has the largest specific capacity (1100 C g-1 at 2 A g-1) at 110 mT, leading to a high energy density (250 W h kg-1) and a power density (1.7 kW kg-1) of the electrode.

Local symmetry breaking drives picosecond spin domain formation in polycrystalline halide perovskite films.

Photoinduced spin-charge interconversion in semiconductors with spin-orbit coupling could provide a route to optically addressable spintronics without the use of external magnetic fields. However, in structurally disordered polycrystalline semiconductors, which are being widely explored for device applications, the presence and role of spin-associated charge currents remains unclear. Here, using femtosecond circular-polarization-resolved pump-probe microscopy on polycrystalline halide perovskite thin films, we observe the photoinduced ultrafast formation of spin domains on the micrometre scale formed through lateral spin currents. Micrometre-scale variations in the intensity of optical second-harmonic generation and vertical piezoresponse suggest that the spin-domain formation is driven by the presence of strong local inversion symmetry breaking via structural disorder. We propose that this leads to spatially varying Rashba-like spin textures that drive spin-momentum-locked currents, leading to local spin accumulation. Ultrafast spin-domain formation in polycrystalline halide perovskite films provides an optically addressable platform for nanoscale spin-device physics.

A Framework for Simulation of Magnetic Soft Robots Using the Material Point Method

Simulation represents a key aspect in the development of robot systems. The ability to simulate behavior of real-world robots provides an environment where robot designs can be developed and control systems optimized. Due to the use of external magnetic fields for actuation, magnetic soft robots can be wirelessly controlled and are easily miniaturized. However, the relationship between magnetic soft materials and external sources of magnetic fields present significant complexities in modelling due to the relationship between material elasticity and magnetic wrench (forces and torques). In this work, we present a simulation framework for magnetic soft robots using the Material Point Method (MPM) which integrates hyper-elastic material models with the magnetic wrench induced under external fields. Compared to existing Finite Element Methods (FEM), the presented MPM based framework inherently models self-collision between areas of the model and can capture the effect of forces in non-homogeneous magnetic fields. We demonstrate the ability of the MPM framework to model the influence of magnetic wrench on magnetic soft robots, capture dynamic behavior of robots under time-varying magnetic fields, and provide an accurate representation of deformation when colliding with obstacles. We show the versatility of MPM framework by comparing simulations to a range of real-world magnetic soft robot designs previously presented in the literature.

Analytical modelling to study the magnetic field-assisted growth of graphene in the reactive plasma

A theoretical model has been developed to study the impact of a magnetic field on the growth of vertically aligned graphene sheets using plasma deposition techniques. The present model incorporates the dynamics of negatively charged electrons and positively charged ions and active neutral radicals of reactive gases in the complex plasma comprising Ar, C2H2, and H2 gases and deposition of these gaseous phase plasma species in the form of vertically aligned graphene sheets. The dynamics and deposition of the plasma particles can be controlled or enhanced by various process parameters and use of external magnetic field is one of the most promising way to enhance the deposition of species. In the present work, the growth of vertical graphene in a plasma environment has been studied with and without external magnetic field. The analytical simulations of the developed model revealed the significant enhancement in the growth of vertically aligned graphene sheets when magnetic field is applied in the plasma reactor. Our findings of the analytical simulations are in line with existing experimental observations.

Магнитная структура наночастиц Co-=SUB=-0.8-x-=/SUB=-Mn-=SUB=-x-=/SUB=-Zn-=SUB=-0.2-=/SUB=-Fe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- (x=0.6, 0.4 и 0.2) перспективных для биомедицинских применений

Magnetic nanoparticles (NP) of ferrite Co0.8-xMnxZn0.2Fe2O4 (x=0.6, 0.4 and 0.2) were synthesized by co-deposition. The structural, microstructural, magnetic and ultrathin properties of the obtained particles were investigated by X-ray diffraction and Mössbauer spectroscopy. The nanoparticle sizes calculated from radiographs at x=0.6, 0.4 and 0.2 are 15.2, 10.2 and 10.3 nm, respectively. The influence of the amount of Mn ions introduced on the properties of synthesized particles has been studied. The analysis of experimental Mossbauer spectra showed that the small size of the LF leads to a significant increase in the effects of dimensionality and the influence of the surface on the magnetic structure of the surface layer. The Mossbauer studies, for the first time without the use of external magnetic fields, on the example of MNCH spinel ferrites Co0.8-xMnxZn0.2Fe2O4, found that inside the particle the magnetic moments are ordered collinearly, whereas in the surface layer the moments are oriented at an angle to each other (beveled structure).

Fluorescent Single-Core and Multi-Core Nanoprobes as Cell Trackers and Magnetic Nanoheaters

Iron oxide magnetic nanoparticles (MNPs) have been widely studied due to their versatility for diagnosis, tracking (magnetic resonance imaging (MRI)) and therapeutic (magnetic hyperthermia and drug delivery) applications. In this work, iron oxide MNPs with different single-core (8–40 nm) and multi-core (140–200 nm) structures were synthesized and functionalized by organic and inorganic coating materials, highlighting their ability as magnetic nanotools to boost cell biotechnological procedures. Single core Fe3O4@PDA, Fe3O4@SiO2-FITC-SiO2 and Fe3O4@SiO2-RITC-SiO2 MNPs were functionalized with fluorescent components with emission at different wavelengths, 424 nm (polydopamine), 515 (fluorescein) and 583 nm (rhodamine), and their ability as transfection and imaging agents was explored with HeLa cells. Moreover, different multi-core iron oxide MNPs (Fe3O4@CS, Fe3O4@SiO2 and Fe3O4@Citrate) coated with organic (citrate and chitosan, CS) and inorganic (silica, SiO2) shells were tested as efficient nanoheaters for magnetic hyperthermia applications for mild thermal heating procedures as an alternative to simple structures based on single-core MNPs. This work highlights the multiple abilities offered by the synergy of the use of external magnetic fields applied on MNPs and their application in different biomedical approaches.

Magnetic stimulation of the angiogenic potential of mesenchymal stromal cells in vascular tissue engineering

ABSTRACT The growing prevalence of vascular diseases worldwide has emphasized the need for novel tissue-engineered options concerning the development of vascularized 3D constructs. This study reports, for the first time, the use of external magnetic fields to stimulate mesenchymal stromal cells (MSCs) to increase the production of vascular endothelial growth factor-A (VEGF-A). Polyvinylalcohol and gelatin-based scaffolds, containing iron oxide nanoparticles, were designed for optimal cell magnetic stimulation. While the application of static magnetic fields over 24 h did not impact on MSCs proliferation, viability and phenotypic identity, it significantly increased the production of VEGF-A and guided MSCs morphology and alignment. The ability to enhance MSCs angiogenic potential was demonstrated by the increase in the number of new vessels formed in the presence of MSCs conditioned media through in vitro and in vivo models. Ultimately, this study uncovers the potential to manipulate cellular processes through short-term magnetic stimulation.

Topological superconductivity in semiconductor–superconductor–magnetic-insulator heterostructures

Hybrid superconductor-semiconductor heterostructures are promising platforms for realizing topological superconductors and exploring Majorana bound states physics. Motivated by recent experimental progress, we theoretically study how magnetic insulators offer an alternative to the use of external magnetic fields for reaching the topological regime. We consider different setups, where: (1) the magnetic insulator induces an exchange field in the superconductor, which leads to a splitting in the semiconductor by proximity effect, and (2) the magnetic insulator acts as a spin-filter tunnel barrier between the superconductor and the semiconductor. We show that the spin splitting in the superconductor alone cannot induce a topological transition in the semiconductor. To overcome this limitation, we propose to use a spin-filter barrier that enhances the magnetic exchange and provides a mechanism for a topological phase transition. Moreover, the spin-dependent tunneling introduces a strong dependence on the band alignment, which can be crucial in quantum-confined systems. This mechanism opens up a route towards networks of topological wires with fewer constraints on device geometry compared to previous devices that require external magnetic fields.

Investigation of the Capabilities of Transverse Magnetic Field Controlled Laser-Induced Plasma Micro-Machining

Abstract Laser-induced plasma micro-machining (LIPMM) has proven a number of advantages in micro-machining due to reduced thermal defects, smaller heat-affected zones, and larger aspect ratios when compared with conventional laser ablation. The present work explores the use of external magnetic fields to further enhance process outcomes in LIPMM. Specifically, machining characteristics and outcomes including plasma intensity, attainable aspect ratios, and surface quality will be explored through a theoretical and experimental study in different classes of materials in a transverse magnetic field controlled LIPMM. First, process improvement mechanisms are illustrated in terms of plasma confinement and laser absorption in transverse magnetic fields. A magnetic field redistribution analysis is performed to reveal the differences in the achievable enhancements in machining characteristics in terms of material characteristics. Second, a set of single-factor experiments is conducted to investigate the effects of the strength and direction of the magnetic field on machining capabilities in magnetic and nonmagnetic materials (410, 304 stainless steels and silicon). The experimental results show that plasma intensity and aspect ratios can be significantly increased in the presence of transverse magnetic fields. The greatest influence on machining capability is achieved in a magnetic material. In this case, plasma intensity and aspect ratios were increased by about 176% and 160%, respectively, when compared with other materials with a magnetic field strength of 0.1 T and a magnetic field direction parallel to the processing direction. Finally, the morphology and cross-section profiles of micro-channels have been measured for verifying the impact on the surface quality of transverse magnetically controlled LIPMM.

A numerical study on heat transfer of a ferrofluid flow in a square cavity under simultaneous gravitational and magnetic convection

Thermomagnetic convection is based on the use of external magnetic fields to better control heat transfer fluxes in ferrofluids, finding important applications in engineering and many related areas. The improvement of such methods relies on fundamentally understanding the flow of ferrofluids under temperature gradients and external magnetic fields. However, the underlying physics of this phenomenon is very complex and not yet well characterized. The problem we analyze in this paper consists of a ferrofluid confined in a square cavity heated from the top and subjected to an external magnetic field applied in the horizontal direction. Differently from earlier investigations, this scenario leads to a clear competition between stabilizing gravitational forces and destabilizing magnetic forces; the unbalance between them drives the flow and dictates the mechanisms of heat transfer in the system. The problem is described by the equations of conservation of mass, momentum, and energy; both gravitational and magnetic effects are accounted for through the definition of the body force following the well-known Boussinesq approximation to express the ferrofluid’s density and magnetization as functions of temperature. The resulting set of fully coupled, nonlinear equations of the model is solved with a fully implicit finite element method. The results show that thermomagnetic convection increases convective heat transfer fluxes in the flow, but its net effects essentially depend on a complex balance among viscous, magnetic, and gravitational forces which determines the pattern of recirculation regions inside the cavity. There are two critical values associated with the external field’s intensity: the first marks the onset of thermomagnetic convection when the destabilizing magnetic effects become comparable to the stabilizing gravitational ones and the second corresponds to the external field’s strength that suffices to make the effects of gravity nearly negligible in the flow dynamics. The latter regime is dictated by a balance between viscous and magnetic forces only, and the corresponding numerical predictions agree notoriously well with a scaling analysis which suggests that $${\overline{\mathrm{Nu}}} \sim \mathrm{Ra}_\mathrm{m}^{1/4}$$, where $${\overline{\mathrm{Nu}}}$$ is the average Nusselt number at the isothermal walls and $$\mathrm{Ra}_\mathrm{m}$$ is the magnetic Rayleigh number, a dimensionless parameter associated with the intensity of the external field.

Magnetic Janus Particles for Static and Dynamic (Bio)Sensing

Magnetic Janus particles bring together the ability of Janus particles to perform two different functions at the same time in a single particle with magnetic properties enabling their remote manipulation, which allows headed movement and orientation. This article reviews the preparation procedures and applications in the (bio)sensing field of static and self-propelled magnetic Janus particles. The main progress in the fabrication procedures and the applicability of these particles are critically discussed, also giving some clues on challenges to be dealt with and future prospects. The promising characteristics of magnetic Janus particles in the (bio)sensing field, providing increased kinetics and sensitivity and decreased times of analysis derived from the use of external magnetic fields in their manipulation, allows foreseeing their great and exciting potential in the medical and environmental remediation fields.

Micromixing Efficiency of Particles in Heavy Metal Removal Processes under Various Inlet Conditions

Water quality problems are a persistent global issue since population growth has continually stressed hydrological resources. Heavy metals released into the environment from plating plants, mining, and alloy manufacturing pose a significant threat to the public health. A possible solution for water purification from heavy metals is to capture them by using nanoparticles in micromixers. In this method, conventionally heavy metal capture is achieved by effectively mixing two streams, a particle solution and the contaminated water, under the action of external magnetic fields. In the present study, we investigated the effective mixing of iron oxide nanoparticles and water without the use of external magnetic fields. For this reason, the mixing of particles and the contaminated water was studied for various inlet velocity ratios and inflow angles of the two streams using computational fluid dynamics techniques. The Navier-Stokes equations were solved for the water flow, the discrete motion of particles was evaluated by a Lagrangian method, while the flow of substances of the contaminated water was studied by a scalar transport equation. Results showed that as the velocity ratio between the inlet streams increased, the mixing of particles with the contaminated water was increased. Therefore, nanoparticles were more uniformly distributed in the duct and efficiently absorbed the substances of the contaminated water. On the other hand, the angle between two streams was found to play an insignificant role in the mixing process. Consequently, the results from this study could be used in the design of more compact and cost efficient micromixer devices.

Theory of the spin Hall effect in metal oxide structures

The spin Hall effect is considered a phenomenon in which a charge current is converted to a spin current due to the spin-orbit coupling (SOC). Recently, large values of the spin Hall angle (SHA), as the conversion efficiency between spin and charge currents, were observed in metal oxide structures in ferromagnetic/metal (FM/M) oxide bilayers, although their underlying mechanisms are ambiguous. The present study aims to analytically indicate that a mixed region of metal and oxide formed at the metal/oxide interface includes the surface oxide charge, which allows for introducing an SOC term in the electron Hamiltonian. Based on the results, the SHA increases by two orders of magnitude in a Cu/oxide thin film through the side jump and skew scattering mechanisms, reaching that of heavy metals. In addition, a comprehensive model is provided for the influence of oxidation on the SHA and spin-orbit torques (SOTs) in FM/M structures. We find that the magnitude of SOTs is greatly dependent on (i) the surface oxidation condition, (ii) the current flow path, and (iii) the electronic interface condition. The model represented in the present study is regarded as a promising model and prediction mechanism which explains recent observations. The findings can be implemented in generating spin current without any use of external magnetic fields and heavy metals in spintronic devices.

Investigation the influence of injection angle on electron acceleration in laser wake-field accelerator with the presence of external magnetic field

In this paper, the influence of initial momentum and the injection angle of electron in to the magnetized plasma in a laser wake-field accelerator have been studied.It has been seen that the use of external magnetic field in the opposite direction of laser pulse propagation leads to an increase in the wake-field amplitude and a decrease in laser pulse group velocity in comparison to the use of external magnetic field in same direction of laser pulse propagation or unmagnetized plasma case. The results show, the effect of initial momentum variation on the final energy gained by electron is lower in comparison with the effect of injection angle variation. It is observed when the injection angle is increased, the electron can stay more in acceleration phase and reach to more final energy. The maximum final energy of accelerated electron is about 2.5 GeV when the magnetic field is applied along the reverse direction. Also, the electron energy is increased with the increase of injection angle and lowest energy is related to the case of magnetic field applied along the reverse direction.

Visible Light Degradation of Naproxen by Enhanced Photocatalytic Activity of NiO and NiS, Scavenger Study and Focus on Catalyst Support and Magnetization.

This research was aimed to prepare a magnetically photocatalyst enabling to degrade pharmaceutical wastewater and detoxification of pollutant such as naproxen, by visible light irradiation. The nano-sized NiS and NiO photocatalysts exhibit higher reactivity than their microsized counterparts, but separation of the used photocatalyst from the degradation solution is hard and imperfect. To remove this difficulty, magnetic polypyrrole core-shell (Fe3 O4 @PPY) was synthesized and employed as catalyst support. The magnetization property of the synthesized photocatalysts measured by VSM technique indicated that the photocatalysts were sufficiently magnetized to be readily separated from degradation solution by use of external magnetic field. The DRS study showed that the band gap of the photocatalysts shifted to lower energy after immobilization on the support materials leading to higher degradation efficiency. The optimal efficiency was obtained with the catalysts loaded with 50% of NiO and 50% of NiS. The augmenting effect of H2 O2 and the inhibition influence of some organic and inorganic compounds on the degradation process were studied. Regeneration of the used photocatalyst was performed by heat treatment, and the catalyst treated at 400°C retained most of its initial capacity. The degradation capacity was kinetically fast, and the equilibrium was attained within 30min.

Neutral red separation property of ultrasmall-gluconic acid capped superparamagnetic iron oxide nanoclusters coprecipitated with goethite and hematite

Abstract The use of magnetic nanomaterials for the removal of toxic pollutants from water is currently gaining a considerable attention due to their low cost advantage and separation via the use of external magnetic field. However, for efficient functioning, these materials have to be structured in a way that will allow sufficient interaction with the pollutants within a shortest possible time. This can be achieved by employing very small sized nanomaterials such as nanoclusters which bear a very high surface energy and thus exhibit very rapid reactivity. In this report, ultrasmall-gluconic acid capped superparamagnetic iron oxide nanoclusters coprecipitated with goethite and hematite (USPIONCs-Goethem) were synthesized via a new cost-effective green approach and employed for the precipitation of neutral red from aqueous saline solution. The presence of goethite and hematite was verified using powder X-ray diffractiometry. The resulted magnetic- neutral red nanocomposite reassembled as sun-flowery-like nanostructure in the presence of an external magnetic field. A removal efficiency of about 92% was realized within a short time. This approach can be employed for the removal of other similar polyaromatic dyes bearing one or more lone-pair electron sites.