Cone Configuration Research Articles

Nonlinear Nonmodal Analysis of Hypersonic Flow over Blunt Cones

The linear amplification of modal disturbances that lead to boundary-layer transition in two-dimensional/axisymmetric hypersonic configurations is strongly reduced by the presence of a blunt nose tip, and the mechanisms underlying the low Mack’s second-mode N-factor values at the observed onset of transition over the cone frustum are currently unknown. Linear nonmodal analysis has shown that both planar and oblique traveling disturbances that peak within the entropy-layer experience appreciable energy amplification for moderate to large nose-tip bluntness. The present study extends the previous linear analysis by including the nonlinear effects. Specifically, the harmonic Navier–Stokes equations (HNSE) are solved with a fully implicit formulation and the Newton–Raphson method. The increased number of degrees of freedom for the nonlinear system presents difficulties for solution strategies based on direct solution of the linearized system. Such difficulties are overcome by using the generalized minimal residual method (GMRES) iterative method with a preconditioner corresponding to a simplified Jacobian without the cross-derivative terms. The HNSE solver is verified by comparing with nonlinear parabolized stability equation results for the nonlinear evolution of planar waves in an incompressible Blasius boundary layer and in a Mach 6 flow over a blunt cone. Finally, nonlinear nonmodal results are presented for planar traveling disturbances over a blunt cone configuration with reduced transition N factor as measured in wind-tunnel experiments. The nonmodal analysis demonstrates that entropy-layer disturbances generated close to the nose tip can seed the amplification of higher-frequency Mack’s second-mode instabilities farther downstream and hence can lead to a reduction in the transition N factor.

Biomechanical analysis of patient specific cone vs conventional stem in revision total knee arthroplasty

BackgroundIn revision total knee arthroplasty, addressing significant bone loss often involves the use of cemented or press-fit stems to ensure implant stability and long-term fixation. A possible alternative to stem was recently introduced utilizing custom-made porous metaphyseal cones, designed to reconstruct the missing tibial and femoral geometries. Early clinical and radiological assessments have shown promising results. The objective of this research was to biomechanically evaluate the performances of these custom-made cones.MethodsThe biomechanical study was conducted using a validated finite element model. The bone geometries of a patient (selected for their history of four knee revisions due to infection and periprosthetic fractures, followed by a successful treatment with custom-made 3D-printed metaphyseal cones) were employed for the study. On these bone models, different revision scenarios were simulated and examined biomechanically: (A) custom-made cementless metaphyseal cones; (B) cemented stems; (C) press-fit stems; (D) distal femoral reconstruction with press-fit stem. All the models were analyzed at 0 °and 90 °of flexion, under physiological load conditions simulating daily activities; stress distribution, average Von-Mises stresses and risk of fracture were then analyzed and compared among configurations.ResultsThe use of custom-made 3D-printed cones exhibited the most favorable stress distribution in both femoral and tibial bones. Tibial bone stress was evenly distributed in custom-made cone configurations, while stress concentration was observed in distal regions for the other scenarios. Additionally, custom-made cones displayed overall homogeneity and lower stress levels, potentially contributing to limit pain. Symmetrical stress distribution was observed between the lateral and medial proximal tibia in custom-made cone models, whereas other scenarios exhibited uneven stress, particularly in the anterior tibial bone.ConclusionsThe biomechanical analysis of porous custom-made metaphyseal cones in re-revision arthroplasties is in agreement with the positive clinical and radiological outcomes. These findings provide valuable insights into the potential benefits of using custom-made cones, which offer more uniform stress distribution and may contribute to improve patient outcomes in revision TKA procedures. Further studies in this direction are warranted to validate these biomechanical findings.

Aerodynamic characteristics of different configurations of mechanically deployable aerodynamic decelerator in subsonic region

AbstractThe deceleration effect of the deployable aerodynamic decelerator is not as good as a parachute in the subsonic region. This paper proposes a novel concept of using a parachute-like configuration (PLC) to enhance the deceleration performance of the mechanically deployable aerodynamic decelerator (MDAD) through structural transformation. The MDAD turned into the PLC from the sphere cone configuration (SCC) at Ma 0.8. The aerodynamic characteristics of the two configurations are analysed deeply. Compared to the SCC, the results show that the drag coefficient increases effectively, and the maximum increases is about 10% in the PLC. The airflow is altered by the MDAD configuration, which can affect the surface pressure and temperature. During the transformation process, the axial and normal force coefficients tend to stabilise. However, the static stability of the PLC deteriorates sharply compared to the SCC when the angle-of-attack exceeds 45°.

A novel morphing nose cone for underwater gliders: Performance analysis, parameter optimization, and driving mechanism design

As an autonomous underwater vehicle with low energy consumption, underwater glider has been widely applied to long-term ocean exploration missions. To better deal with complex working environments and various mission requirements, morphing underwater gliders are receiving increasing attention. This paper attempts to introduce the morphing nose cone that can achieve length and bending angle adjustments into the glider to improve its comprehensive performance. The performance indicators of the glider include energy utilization rate, static stability, and voyage velocity. Based on dynamic analysis and CFD simulation, performance evaluation models of a glider are established, and the effect of morphing nose cone configurations on the glider's hydrodynamic characteristics is discussed. Then, mathematical optimization models for morphing parameters of the nose cone are established, and they are solved by a multi-objective optimization algorithm and surrogate model technology. Especially, the diving and ascending motion processes of the glider are separately considered in the above optimization. Finally, the multi-objective optimization results are used for guiding the driving mechanism design of the morphing nose cone, and the principle prototype of a novel design scheme is manufactured to verify the feasibility. The research methods and results will provide new development direction for the morphing underwater glider technology.

The Hunt for Perpendicular Magnetic Field Measurements in Plasma

The one consistent technique for remotely estimating the magnetic field in plasma has been Faraday rotation. It is only sensitive to the portion of the vector parallel to the propagation path. We show how to remotely detect the portion of the vector that is perpendicular using a modified measurement. Isolating this electromagnetic propagation wave mode to measure the magnetic field enables us to (i) study more about the magnetic field vector in plasma, (ii) reduce error in total electron content measurements, and (iii) discover new magnetic field information from archived data sets. The Appleton–Hartree equation is used to verify a new approach to calculating the phase change to an electromagnetic wave propagating through a plasma at frequencies larger than the gyrofrequency, the cyclotron frequency, and the upper hybrid frequency. Focusing on the perpendicular propagation modes, the simplified equation for the integrated path effect from a perpendicular magnetic field is calculated. The direction of the perpendicular component is unknown, because the magnetic field is squared. Isolating the magnetic term in the equation with dual frequency waves is shown. We also show how to eliminate the magnetic field contribution to total electron content measurements with a similar approach. In combination with Faraday rotation, the degeneracy of the magnetic field vector direction is reduced to a cone configuration.

Station layout optimization for underwater acoustic positioning system based on combined cone configuration

The theoretical minimum of the geometric dilution of precision (GDOP) for target positioning cannot be achieved because of the coplanar constraint for underwater station configurations, and the conventional single-cone configuration leads to an infinite GDOP. Therefore, this study extends the single-cone configuration to the combined cone configuration. The proposed configuration is theoretically proven to be superimposable, rotatable, and GDOP-rotation-invariant. A criterion based on the global GDOP for underwater targets is constructed to address the problem of a single criterion for station layout optimization. However, traditional optimization algorithms are prone to local optimality and low convergence efficiency. Therefore, an improved adaptive particle swarm optimization (APSO) algorithm is proposed to optimize the configuration of the underwater acoustic positioning systems. Finally, it is verified that the proposed APSO can enhance the global optimality and improve the convergence efficiency of the algorithm. Combined with the measured data of the long baseline system, it is shown that the optimal combined cone configuration significantly reduces the global GDOP and improves the positioning accuracy compared with traditional configurations.

Transducer Resolution Effect on Pressure Fluctuations Beneath Hypersonic Turbulent Boundary Layers

The size of a pressure transducer is known to affect the accuracy of measurements of wall-pressure fluctuations beneath a turbulent boundary layer because of spatial averaging over the sensing area of the transducer. In this paper, the effect of finite transducer size is investigated by applying spatial averaging or wavenumber filters to a database of hypersonic wall pressure generated from a direct numerical simulation (DNS) that simulates the turbulent portion of the boundary layer over a sharp 7° half-angle cone at nominally Mach 8. A good comparison between the DNS and the experiment in the Sandia Hypersonic Wind Tunnel at Mach 8 is achieved after spatial averaging is applied to the DNS data over an area similar to the sensing area of the transducer. The study shows that a finite sensor size similar to that of the PCB132 transducer can cause significant attenuation in the root-mean-square and power spectral density (PSD) of wall-pressure fluctuations, and the attenuation effect is identical between cone and flat plate configurations at the same friction Reynolds number. The Corcos theory is found to successfully compensate for the attenuated high-frequency components of the wall-pressure PSD.

Drag reduction characteristics of recirculation flow at rocket base in an RBCC engine under ramjet/scramjet mode

To reduce the drag generated by the recirculation flow at the rocket base in a Rocket-Based Combined Cycle (RBCC) engine operating in the ramjet/scramjet mode, a novel annular rocket RBCC engine based on a central plug cone was proposed. The performance loss mechanism caused by the recirculation flow at the rocket base and the influence of the plug cone configuration on the thrust performance were studied. Results indicated that the recirculation flow at the rocket base extended through the entire combustor, which creates an extensive range of the “low-kinetic-energy zone” at the center and leads to an engine thrust loss. The plug cone serving as a surface structure had a restrictive effect on the internal flow of the engine, making it smoothly transit at the position of the large separation zone. The model RBCC engine could achieve a maximum thrust augmentation of 37.6% with a long plug cone that was twice diameter of the inner isolator. However, a shorter plug cone that was half diameter of the inner isolator proved less effective at reducing the recirculation flow for a supersonic flow and induced an undesirable flow fraction that diminished the thrust performance. Furthermore, the effectiveness of the plug cone increased with the flight Mach number, indicating that it could further broaden the operating speed range of the scramjet mode.

Geometry effects on energy selective focusing of laser-driven protons with open and closed hemisphere-cone targets

Relativistically intense laser light interacting with solid density targets can accelerate protons to multi-MeV energies via the target normal sheath acceleration process. The use of hollow hemisphere targets with a hollow conical region to focus protons of selected energies, for applications such as isochoric heating of matter and for the fast ignition approach to inertial confinement fusion, is explored for laser intensity Wcm−2. Specifically, the effects of having the cone tip open or closed is investigated experimentally and via a programme of scaled particle-in-cell simulations. The open cone configuration is found to result in proton focusing in the energy range of 9 to 24 MeV, and produce an annular profile for higher energy components, up to 55 MeV, while the spatial distribution of lower energy components remains unchanged. By contrast, for the closed cone case, the focusing effect is diminished by the fields present on the inner wall of the cone tip. Simulations reveal that strong electrostatic and magnetic fields present on the inner surfaces of the target induce the focusing effect with the open cone, but also result in proton divergence in the case of the closed cone. Additionally, the simulations demonstrate the possibility to tailor the cone geometry to select the energy range over which the focusing occurs.

Numerical investigation of oblique detonation waves on a truncated cone in hydrogen–air mixtures

Traditional methods of initiating oblique detonation waves (ODWs) using wedges and cones face a fundamental challenge in reconciling the need for rapid initiation with stable combustion, especially at low flight Mach numbers (Ma < 8). This study introduces an innovative initiation configuration involving a truncated cone. By utilizing Euler equations coupled with detailed hydrogen–air chemical reaction models, the wave dynamics induced by the truncated cone configuration are systematically explored. The findings reveal that the truncated cone configuration enables more rapid initiation of ODWs compared to conventional cones, while also preserving improved stability when contrasted with wedge. This behavior can be attributed to the planar flow characteristics in the post-shock field of truncated cone, generated by the upstream wedge-shaped shock, and the Taylor–Maccoll flow characteristics, caused by the downstream conical shock. Furthermore, the study delves into the initiation and morphological changes with respect to the inner radius and angle of the truncated cone. As inner radii or truncated cone angle increase, three initiation wave systems emerge: stable, oscillatory, and detached modes. Analysis of the dynamic variations in pressure and velocity within the induction zone highlights that the upstream oscillation originates from the flow velocity in the induction zone falling below the local Chapman–Jouguet velocity of normal detonation wave (NDW). However, the upstream region of the truncated cone exhibits more pronounced expansion effects, leading to momentum loss, and subsequently, the weakening and even vanishing of the NDW. This prompts the downstream oscillation of the initiation structure, instigating a cyclic oscillation pattern.

Seamless Parametrization with Cone and Partial Loop Control

We present a method for constructing seamless parametrization for surfaces of any genus that can handle any feasible cone configuration with any type of cones. The mapping is guaranteed to be locally injective, which is due to careful construction of a simple domain boundary polygon. The polygon’s complexity depends on the cones in the field, and it is independent of mesh geometry. The result is a small polygon that can be optimized prior to the interior mapping, which contributes to the robustness of the pipeline. For a surface of genus >0, non-contractible loops play an important role, and their holonomies significantly affect mapping quality. We enable holonomy prescription, where local injectivity is guaranteed. Our prescription, however, is limited and cannot handle all feasible holonomies due to monotonicity constraints that keep our polygon simple. Yet this work is an important step toward fully solving the holonomy prescription problem.

Numerical Simulation of Flow Field Over a Sharp-Tipped Double Cone at High Speed

The flowfield over a sharp-tipped double cone axisymmetric configuration is carried out by solving time dependent axisymmetric laminar compressible Navier-Stokes equations for freestream Mach number range of 2.0 - 6.0. The fluid dynamics equations are discretized in spatial coordinates using integral formulation in conjunction with finite volume method which reduces the governing equations to semi-discretized ordinary differential equations. Temporal integration is performed employing multistage Runge-Kutta time-stepping scheme. A local time step is used to achieve steady-state solution. The numerical computation is carried out on a mono-block with structured grids. The flowfield features over the sharp-tipped double cone configuration such as conical shock wave, separation region, separation and reattachment shock wave and bow shock wave in the cone region, expansion fan, and recirculation flow in the base region are well captured at Mach number 3 and 6 which are identical to the Edney VI type shock interaction. The velocity vector, Mach contours plots and variations of surface pressure coefficient along the sharp-tipped double cone configuration are analyzed at various Mach numbers. The fore-body aerodynamic drag is calculated employing computed pressure distribution. The paper presents the influence of the freestream Mach number on the flows with shock interactions over the sharp-tipped double cone geometry.

Synthesis of Imidazolium Cations Linked to Para-t-Butylcalix[4]arene Frameworks and Their Use as Synthons for Nickel-NHC Complexes Tethered to Calix[4]arenes.

A series of cationic p-tert-butylcalix[4]arenes, with side-arms that are functionalized with imidazolium groups, have been synthesized in good yields. The parent tetrahydroxy para-t-butyl-calix[4]arene was dialkylated at the phenolic hydrogen atoms using α,ω-dibromo-alkanes to yield bis(mono-brominated) alkoxy-chains of variable length. The brominated side-arms in these compounds were then further alkylated with substituted imidazoles (N-methylimidazole, N-(2,4,6-trimethyl-phenyl)imidazole, or N-(2,6-di-isopropylphenyl)imidazole) to yield a series of dicationic calixarenes with two imidazolium groups tethered, via different numbers of methylene spacers (n = 2-4), to the calixarene moiety. Related tetracationic compounds, which contain four imidazolium units linked to the calix[4]arene backbone, were also prepared. In all of these compounds, the NMR data show that the calixarenes adopted a cone configuration. All molecules were characterized by NMR spectroscopy and by MS studies. Single crystal X-ray diffraction studies were attempted on many mono-crystals of these cations, but significant disorder problems, partly caused by occluded solvent in the lattice, and lack of crystallinity resulting from partial solvent loss, precluded the good resolution of most X-ray structures. Eventually, good structural data were obtained from an unusually disordered single crystal of 5a, (1,3)-Cone-5,11,17,23-tetra-t-butyl-25,27-di-hydroxy-26,28-di-[2-(N-2,6-diisopropylphenyl-imidazolium)ethoxy]calix[4]arene dibromide and its presumed structure was confirmed. The structure revealed the presence of H-bonded interactions and some evidence of π-stacking. Some of these imidazolium salts were reacted with nickelocene to form the nickel N-heterocyclic carbene (NHC) complexes 7a-7d. A bis-carbene nickel complex 8 was also isolated and its structure was established by single crystal X-ray diffraction studies. The structure was disordered and not of high quality, but the structural data corroborated the spectroscopic data.

Unified stochastic particle simulation of polyatomic gas flows using SPARTACUS

Numerically simulating multiscale nonequilibrium gas flows that involve internal energy exchange is a challenging problem in engineering applications due to the complexity of the physical processes. The unified stochastic particle (USP) method, based on the Bhatnagar-Gross-Krook (BGK) model, is a promising approach for efficiently simulating multiscale flows. In this paper, we develop a USP method for polyatomic gases that can simulate hypersonic gas flows involving internal energy exchange across all flow regimes. This method is integrated into the open-source SPARTACUS solver, which was previously developed for monatomic gases. The newly developed USP method reassigns the velocity and internal energies of a subset of computational particles based on a precisely designed local target distribution function. A conservation algorithm is applied to ensure that the momentum and energy are conserved. To validate the accuracy and efficiency of the solver, we perform three benchmark cases, including flow past a two-dimensional cylinder, a three-dimensional 70° blunted cone, and an axisymmetric double cone configuration. The results demonstrate that SPARTACUS achieves excellent agreement with the reference results of DSMC and experimental data. Additionally, SPARTACUS provides significant computational efficiency advantages over the DSMC solver SPARTA, particularly in simulating three-dimensional gas flows.

Determination of Lu and Hf Mass Fractions and 176Hf/177Hf Ratios in Mafic‐Ultramafic Rock Reference Materials by Multi‐Collector Inductively Coupled Plasma‐Mass Spectrometry

Reported data for Lu, Hf mass fractions and 176Hf/177Hf isotopic ratios of mafic‐ultramafic rock reference materials (RMs) are rare at present, hampering the comparison of data quality between difference laboratories. Herein, we measured the Lu and Hf mass fractions and the 176Hf/177Hf isotopic ratios of ten mafic‐ultramafic rock RMs, including OKUM (komatiite), WPR‐1 (serpentinised peridotite), NIM‐N (norite), NIM‐P (pyroxenite), UB‐N (serpentinised peridotite), JP‐1 (peridotite), NIM‐D (dunite), MUH‐1 (serpentinised harzburgite), HARZ01 (harzburgite), DTS‐2b (dunite), which contain extremely low amounts of Lu and Hf (Lu, 2–150 ng g−1; Hf, 5–500 ng g−1). All measurements were conducted on a Neptune Plus multi‐collector inductively coupled plasma‐mass spectrometer employing an Aridus II desolvator inlet system and Jet sample/X skimmer cone configuration. The following RMs, OKUM, WPR‐1, UB‐N, JP‐1, NIM‐D, HARZ01 and DTS‐2b, have 176Hf/177Hf precision of less than 60 ppm (2s) at test portions of 0.06 to 0.3 g, and are good ultramafic RMs for Lu‐Hf systems. In contrast, significant Hf mass fraction and isotopic variability were observed in NIM‐N, NIM‐P and MUH‐1 at test portion masses of 0.1 to 0.3 g. Collectively, our study provides a new database that can be used by the geochemical community for evaluating the Lu‐Hf system of mafic‐ultramafic rocks.

Three-dimensional natural frequency investigation of bidirectional FG truncated thick hollow cone

PurposeThe authors examined the numerical natural frequency analysis of a 2D functionally graded (FG) truncated thick hollow cone using 3D elasticity theory.Design/methodology/approachThe material properties of the 2D-FGM (two dimensional-functionally graded materials) cone are graded along the radial and axial axes of the cone using a power–law distribution. The eigenvalue problem was solved using finite element analysis (FEA) employing graded hexahedral elements, and the verification of the finite element approach was assessed by comparing the current solution to earlier experimental studies.FindingsThe effects of semivertex angle, material distribution and the cone configuration on the natural frequencies have been analyzed. For various semivertex angles, thickness, length and power law exponents, many results in the form of natural frequencies and mode shapes are presented for the 2D-FGM cone. As a result, the effects of the given parameters were addressed, and the results were compared, demonstrating the direct efficiency of raising the power–law exponents and cone thickness on the rise of natural frequencies.Originality/valueFor the first time, the numerical natural frequency analysis of a 2D-FG truncated thick hollow truncated cone based on 3D equations of elasticity has been investigated. The material properties of the truncated cone have been distributed along two directions, which has not been considered before in any research for the truncated thick cone. The reason for using these innovative volume fraction functions is the lack of accurate coverage by functions that are available in the literature (Asemi et al., 2011; Babaei et al. 2021).

Study of flow of Buongiorno nanofluid in a conical gap between a cone and a disk

The cone–disk apparatus consists of a cone that touches the disk at its apex and is used in medical evices, viscosimeters, conical diffusers, etc. Theoretically, a three-dimensional flow of a nanofluid in a conical gap of a cone–disk apparatus is studied for four different physical configurations. Buongiorno nanofluid model, consisting of thermophoresis and Brownian diffusion mechanisms, is used to describe the convective heat transport of the nanofluid. The continuity equation, the Navier–Stokes momentum equation, the heat equation, and the conservation of nanoparticle volume fraction equation constitute the governing system for the flow of nanofluids. The Lie group approach is used to obtain self-similar equations. Solutions are computed for an appropriate rotational Reynolds number and four different gap angles to examine flow, mass, and heat transport features. The skin friction coefficients and torque are computed and analyzed. Multivariate nonlinear regression analysis is also performed. A co-rotating disk and cone configuration has been shown to produce less torque due to the increased centrifugal force. Of the four cone–disk apparatus configurations, the maximum heat/mass transport occurs for a rotating disk with a static cone for all selected gap angles, and the least drag in the radial direction is attained for a rotating cone with a static disk. In addition, there is a minimal drag along the tangential direction for the counter-rotating disk and cone configuration. Brownian diffusion and thermophoresis of the nanoparticles lead to a higher fluid temperature and, thus, lower Nusselt numbers are obtained.

High-Performance Solar Steam Generator Using Low-Cost Biomass Waste Photothermal Material and Engineering of the Structure.

In this work, high-performance, low-cost, environmentally friendly multilayered solar steam generation systems are fabricated by engineering the structure and using a biomass photothermal material. Remarkably, the biomass photothermal material is extracted from the pyrolysis waste of linseed (flax) grains. The introduced system desalinates water using solar energy as the renewable source of energy, and its light absorber is from the waste of a renewable source. The biomass waste powder possesses a mesoporous structure, providing high light absorption through photon scattering and its high surface area. Moreover, to harvest the incident light efficiently and manage the thermal energy generated, devices including light absorbers with cone and cubic configurations and different water manager layers are fabricated and compared to each other. To confirm the high performance of the introduced photothermal material, different systems comprising graphite, graphene oxide, and carbon nanotube light absorbers are also fabricated. Using a biomass light absorber combined with harvesting of the light in different directions (cone configuration), the system with a water evaporation rate of 1.59 kg/m2h corresponding to an efficiency of 92.9% is achieved. Furthermore, by depositing a thin layer of the transparent thermal superinsulator silica aerogel on the light absorber layer, the generated heat is localized and the heat losses are prevented, leading to a 7.5% enhancement of the water evaporation rate of the biomass system. The eco-friendly biomass-based system shows no significant change in its performance through operation for 40 desalination cycles of Persian Gulf water.

Study of fluid–thermal–structural interaction in high-temperature high-speed flow using multi-fidelity multi-variate surrogates

This study investigates the impact of the high-temperature effect, especially the real gas effect and chemical reactions, on hypersonic aerothermodynamic solutions of double cone and double wedge configurations, as well as the fluid–thermal–structural interaction of a double wedge configuration in hypersonic flow. First, a high-temperature computational fluid dynamics (CFD) code was benchmarked and correlated with experimental results, emphasizing the impact of high-temperature effects as well as turbulence modeling on heat flux prediction. Subsequently, the multi-fidelity multi-variate Gaussian process regression (M2GPR ) method for problems with high-dimensional outputs was developed to create an aerothermal surrogate model. The model achieves a balance between model accuracy and computational cost of sample generation, using the combination of a few high-fidelity samples and many low-fidelity samples. The numerical examples show that, using the M2GPR formulation, the required number of high-fidelity samples may be reduced by over 80% while maintaining an accuracy comparable to the high-fidelity CFD solvers. In addition, a geodesic-distance-based metric is developed to inform the choice of high-dimensional datasets of different fidelities for the M2GPR surrogate with improved accuracy. Finally, the aerothermal surrogate was applied to study the impact of the high-temperature effect on the aerothermoelastic response of a hypersonic skin panel, emphasizing the necessity of the accurate characterization of the localized heat flux for reasonable assessment of the response of a compliant structure in high-speed high-temperature flowfield.

A novel self-floating cyclodextrin-modified polymer for cationic dye removal: Preparation, adsorption behavior and mechanism

The separation and recycling processes of current cyclodextrin (CD)-based adsorbents are complicated. Thus, a novel composite based on a large surface area, porous, and self-floating tetrafluoroterephthalonitrile (TFN)-crosslinked CD polymer (FTFCD), was fabricated, characterized and applied to treat cationic dye pollutants. The characterization showed a porosity, good thermal stability, a stable crystal structure, and abundant functional groups on the prepared FTFCD, which had demonstrated great improvement on its adsorption capacity towards attention grabbing pollutants. The removal efficiency of the adsorbents for malachite green (MG) remained above 95% at pH 1 ∼ 10. In addition, the adsorbents were found to rapidly reach equilibrium governed by the pseudo-second-order kinetic model, and the maximum adsorption capacity of FTFCD was 1390.263 mg/g, as corroborated by the Langmuir isotherm model. While the phenolate groups of FTFCD found to electrostatically interacts with the MG strong cationic quaternary amine group, hydrogen-bonding was responsible for the hydroxyl group of FTFCD and the quaternary amine group binding. Meanwhile, the triangular cone configuration of MG makes it easy to be entrapped and absorbed in the hydrophobic cavity. Besides, after regeneration of exhausted FTFCD for five successive cycles, the MG removal efficiency still reached more than 80%. Thus, FTFCD could be applied as a potential alternative adsorbent for cationic dye removal owing to its excellent adsorption performance, convenient recycling, wide pH application, and environmental friendliness.