Time-dependent Experimental Data Research Articles

Facile Synthesis of Polypyrrole-Decorated RGO-CuS Nanocomposite for Efficient Nickel Removal from Wastewater

Efficient wastewater treatment, particularly the removal of heavy metal ions, remains a challenging priority in environmental remediation. This study introduces a novel sandwich-structured nanocomposite, RGO-CuS-PPy, composed of reduced graphene oxide (RGO), copper sulfide (CuS), and polypyrrole (PPy), synthesized via a straightforward hydrothermal method. The unique combination of RGO, CuS, and PPy offers enhanced adsorption capacity for Ni(II) ions due to RGO’s high surface area and CuS’s active binding sites, supported by PPy’s structural stability contributions. This study is among the first to explore this specific nanocomposite architecture for Ni(II) removal, achieving an adsorption capacity of 166.67 mg/g and a high removal efficiency of 94.9% within 210 min for 55 mg/L of Ni(II) concentration at pH 6 and adsorbent dose of 3 mg/15 mL. The kinetic analysis shows the best fitted time-dependent experimental data with the pseudo-second-order model, indicating chemisorption. Isotherm studies confirmed the Langmuir model as the best fit, yielding a high monolayer adsorption capacity of 166.67 mg/g. Thermodynamic analysis shows the adsorption process was endothermic (ΔH° = 80.23 kJ/mol) and spontaneous (ΔG° ranging from −6.985 to −14.399 kJ/mol). Additionally, reusability tests using 0.1 M HCl for desorption demonstrated good reusability, emphasizing the RGO-CuS-PPy nanocomposite’s potential as a sustainable adsorbent for Ni(II) removal in wastewater treatment applications.

Combining wall interactions, fluid momentum balances and the Maxwell-Stefan equations for gas transport in porous media: An alternative approach

This paper presents a modelling framework for incorporating wall interactions into the Maxwell-Stefan equations for ideal gases in porous media. In contrast to already existing models in literature, such as the Dusty Gas, Binary Friction and Modified Binary Friction models, the framework makes use of N−1 (with N being the number of gas species) independent mass balances for the gas species in combination with a total fluid momentum balance. This approach has the advantage that already existing numerical schemes for fluid momentum balances, such as Darcy’s law or the Brinkman equations, can be used with only minor modifications. It also allows for separate initialisation of the velocity and pressure fields, something that is often beneficial when solving convection–diffusion equations numerically. The derived model is validated against both stationary and time-dependent experimental data from literature for binary Ar-He systems in porous media, using Knudsen diffusivities to define the wall friction terms.

A novel in situ sample environment setup for combined small angle x-ray scattering (SAXS), wide-angle x-ray scattering (WAXS), and Fourier transform infrared spectrometer (FTIR) simultaneous measurement.

Developing the synchrotron radiation experiment method based on combined technology offers more information on the formation mechanism of new materials and their physical and chemical properties. In this study, a new small-angle x-ray scattering/ wide-angle x-ray scattering/ Fourier-transform infrared spectroscopy (SAXS/WAXS/FTIR) combined setup was established. Using this combined SAXS/WAXS/FTIR setup, x-ray and FTIR signals can be obtained simultaneously from the same sample. The in situ sample cell was designed to couple two FTIR optical paths for the attenuated total reflection and transmission modes, which greatly saved the time of adjusting and aligning the external infrared light path when switching between the two modes with good accuracy. A transistor-transistor logic circuit was used to trigger the synchronous acquisition from the IR and x-ray detectors. A special sample stage is designed, allowing access by the IR and x-ray with temperature and pressure control. The newly developed, combined setup can be used to observe the evolution of the microstructure during the synthesis of composite materials in real-time at both the atomic and molecular levels. The crystallization of polyvinylidene fluoride (PVDF) at different temperatures was observed. The time-dependent experimental data demonstrated the success of the in situ SAXS, WAXS, and FTIR study of the structural evolution, which is feasible to track the dynamic processes.

BAYESIAN IDENTIFICATION OF PYROLYSIS MODEL PARAMETERS FOR THERMAL PROTECTION MATERIALS USING AN ADAPTIVE GRADIENT-INFORMED SAMPLING ALGORITHM WITH APPLICATION TO A MARS ATMOSPHERIC ENTRY

For space missions involving atmospheric entry, a thermal protection system is essential to shield the spacecraft and its payload from the severe aerothermal loads. Carbon/phenolic composite materials have gained renewed interest to serve as ablative thermal protection materials (TPMs). New experimental data relevant to the pyrolytic decomposition of the phenolic resin used in such carbon/phenolic composite TPMs have recently been published in the literature. In this paper, we infer from these new experimental data an uncertainty-quantified pyrolysis model. We adopt a Bayesian probabilistic approach to account for uncertainties in the model identification. We use an approximate likelihood function involving a weighted distance between the model predictions and the time-dependent experimental data. To sample from the posterior, we use a gradient-informed Markov chain Monte Carlo method, namely, a method based on an Ito stochastic differential equation, with an adaptive selection of the numerical parameters. To select the decomposition mechanisms to be represented in the pyrolysis model, we proceed by progressively increasing the complexity of the pyrolysis model until a satisfactory fit to the data is ultimately obtained. The pyrolysis model thus obtained involves six reactions and has 48 parameters. We demonstrate the use of the identified pyrolysis model in a numerical simulation of heat-shield surface recession in a Martian entry.

Alignment of highly resolved time-dependent experimental and simulated crash test data

We investigate for car and component crash tests the comparison of highly resolved experimental data with corresponding simulation data. Due to recent advances for optical measurement systems, one can nowadays obtain surface measurement data from a real crash experiment with high resolution in space and time. These advances call for new data processing methods that allow an alignment of this experimental data with numerical simulation results. We propose an approach based on a data representation stemming from a discrete Laplace–Beltrami operator, which allows such an alignment as well as a joint visual comparative analysis of both data sources. The method enables the identification of the best corresponding simulation among several numerical results, which also allows inferring physical quantities that cannot be measured in experiments. We evaluate the procedure on synthetic and real experimental data from two different crashworthiness setups.

Estimation of plasma properties using an extended Kalman filter with plasma global models

A physically-constrained extended Kalman filter (EKF) is applied to various zero-dimensional global models for the estimation of plasma properties using time-dependent experimental data such as the plasma density or ion flux. The capability of the EKF is demonstrated to estimate unknown system states simultaneously, such as reaction rate coefficients and the absorbed electron input power, which can be difficult, if not impossible, to measure experimentally. Global models accounting for pure argon reactions and argon-oxygen reactions are used in this work to demonstrate the ability of the filter to estimate dynamic and complex systems. The results obtained from the EKF plasma global model illustrate that model-data fusion techniques can be used to estimate plasma properties and processes for time-varying systems, such as pulsed discharges.

Magnetized chitosan nanocomposite as an effective adsorbent for the removal of methylene blue and malachite green dyes

Herein, a magnetically separable Fe3O4 decorated chitosan was facilely synthesized, systematically characterized, and subsequently employed as a versatile adsorbing material for the adsorption of malachite green and methylene blue dyes. The prepared adsorbent was characteristically examined through Fourier transform infra-red microscopy, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, X-ray diffraction, Brunauere-Emmette-Teller surface area analysis, thermogravimetric analysis, and vibrating-sample magnetometry techniques. The optimum process parameters for MB were observed to be 180 min of contact time, pH 7, and 1.2 g/L of adsorbent dose, and 210 min of contact time, pH 7, and adsorbent dose of 2 g/L was found to be for MG. The time-dependent experimental data were analyzed with different kinetic models, and pseudo-IInd-order was provided the best fit for the adsorption of both the dyes with a high value of the regression coefficient. The adsorption equilibrium data of both the dyes was best explained by Langmuir isotherm, and the maximum sorption capacity of MG and MB was found to be 55.86 and 76.34 mg/g, respectively. Thermodynamic analysis declared that the adsorption of MG and MB onto the Fe3O4 decorated chitosan was endothermic and spontaneous. Moreover, the adsorbent presented good reusability up to three successive ad-/de-sorption cycles, indicating that Fe3O4 decorated chitosan is a promising applicant for treating dye-containing wastewater.

Experimental Study of Gas/Liquid Diffusion in Porous Rocks and Bulk Fluids To Investigate the Effect of Rock-Matrix Hindrance

Summary The design of oil-recovery processes by gas injection or vapor solvent relies on the knowledge of diffusion coefficients to enable meaningful production predictions. However, laboratory measurements of diffusion coefficients are often performed on bulk fluids, without accountability for the hindrance caused by the pore-network structure and tortuosity of porous media. As such, our ability to predict effective diffusion coefficients in porous rocks is inadequate, and additional laboratory work is needed to investigate the impact of the medium itself on transport by diffusion. A vast number of studies focus on measurements of diffusion coefficients on simple binary systems and a few heavy-oil systems. This study proposes an experimental methodology, based on the pressure-decay technique, to measure diffusion of gas (methane) in crude oil within a porous rock. A diffusion experiment of gas into bulk oil (without porous medium) provides an upper-limit estimation of the gas/liquid-diffusion coefficient. Diffusion experiments using Indiana Limestone and Bakken Shale provide insight into different degrees of rock-matrix hindrance. Two analytical models and one numerical model were implemented to estimate the diffusion coefficients from time-dependent experimental pressure-decay data. These diffusion coefficients were found to be in agreement with literature on corresponding data, demonstrating the validity of the modeling approaches used. Results indicate considerable hindrance to diffusion in porous media relative to bulk oil and relate to the tortuosity of the rock matrix. The diffusion coefficient of methane in bulk oil was found to be 3.8×10−9 m2/s. In the limestone sample, this diffusion coefficient dropped by one order of magnitude, ranging between 1.5 and 6.5×10−10 m2/s, and decreased by another order of magnitude in the Bakken Shale sample to 2.0×10−11 m2/s. By comparing the influence of tortuosity with increasing the initial pressure, results show that tortuosity has a more-significant impact on the effective diffusion coefficient than the initial pressure.

Deep minima in the Coulomb-Born triply differential cross sections for ionization of helium by electron and positron impact

Previously, a deep minimum in the measurements of the triply differential cross section (TDCS) for electron-helium ionization at an incident energy of 64.6 eV was interpreted in terms of a vortex. We apply the Coulomb-Born (CB1) and modified CB1 approximations to this process at the same incident energy and obtain a deep minimum whose position is in reasonable accord with time-dependent close-coupling results and experimental data. We also obtain the deep minimum in the TDCS that was measured for an energy of 74.6 eV. For both incident energies, but at slightly different gun angles to those used experimentally, we obtain a very deep minimum in the TDCS that is related to a vortex in the velocity field associated with the CB1 transition matrix element. We determine for energies of 44.6 eV–79.6 eV the gun and polar angles for a deep minimum in the CB1 TDCS. We apply both approximations to positron-helium ionization. For an incident energy of 205.25 eV we find a deep minimum in the TDCS that is related to a vortex in the velocity field associated with the CB1 transition matrix element.

A 2D1/2 model for natural convection and solidification in a narrow enclosure

Efficient numerical models are derived for problems of natural convection and material solidification in a horizontal differentially heated slender cavity. These 2D1/2 models are obtained by averaging the equations of momentum, heat, and mass conservation along the transverse direction assuming both a constant temperature and a well defined velocity profile in this direction. Based on our former works, the transverse velocity profile is assumed to be either a Poiseuille profile (2Dp1/2 model), or Hartmann-type profiles featuring two boundary layers on the sides of a uniform bulk (2DH1/2 model). For this 2DH1/2 model, however, a parameter δ (giving the boundary layer thickness) has to be adjusted: optimal values have been found in a large range of the control parameters and expressed as a reliable fitted function of Gr. The ability of the model to reproduce 3D results in a 2D framework is investigated in a large range of the control parameters (Prandtl number Pr and Grashof number Gr); the validity domain of the model in this parameter space is also clarified and rigorously defined. A good precision is obtained for natural convection problems (intensity of the flow, temperature field) as well as for solid-liquid phase change problems (shape, position, and evolution of the front). A comparison with unpublished experimental data of solidification of pure tin is also conducted. The boundary conditions for the simulation are first defined after a post-treatment of the time-dependent experimental data in order for them to be representative of the experimental process despite a significant and time dependent thermal resistance between the walls of the crucible and the liquid. A very good agreement is observed between the 2DH1/2 model and the experimental measurements for this pure tin solidification experiment in the AFRODITE setup.

Study on the Accuracy of RANS Modelling of the Turbulent Flow Developed in a Kaplan Turbine Operated at BEP. Part 2 - Pressure Fluctuations

The aim of the paper is to investigate the limitations of unsteady Reynolds-averaged Navier-Stokes (RANS) simulations of the flow in an axial turbine. The study is focused on modelling the pressure pulsations monitored on the runner blades. The scanned blade geometry renders the meshing process more difficult. As the pressure monitor points are defined on the blade surface the simulation relies on the wall functions to capture the flow and the pressure oscillations. In addition to the classical turbulence models, a curvature correction model is evaluated aiming to better capture the rotating flow near curved, concave wall boundaries. Given the limitations of Reynolds-averaged Navier-Stokes models to predict pressure fluctuations, the Scale Adaptive Simulation-Shear Stress Transport (SAS-SST) turbulence model is employed as well. The considered test case is the Porjus U9, a Kaplan turbine model, for which pressure measurements are available in the rotating and stationary frames of reference. The simulations are validated against time-dependent experimental data. Despite the frequencies of the pressure fluctuations recorded on the runner blades being accurately captured, the amplitudes are considerably underestimated. All turbulence models estimate the correct mean wall pressure recovery coefficient in the upper part of the draft tube.

Effects of Piecewise Electric Field Operation on Sludge Dewatering: Phenomena and Mathematical Model

Electro-dewatering (EDW) is an energy-efficient method for sludge dewatering. In this study, effects of piecewise electric field operation on EDW were investigated by experiments and simulation. Operational parameters were studied mainly in terms of sludge resistance variation during electro-dewatering process, which were evaluated by linear sweep voltammetry (LSV) analysis. Simulation of the sludge cake electro-dewatering processes was developed and validated, based upon time-dependent experimental data of electric currents and filtrate weights. The modeling results were in good agreement with experiments. It was proved by experimental and modeling results that the piecewise operation has positive effects on key performances of EDW devices, that is, limited water content, space-time yield, and mass specific energy consumption.

Predictive simulation of non-steady-state transport of gases through rubbery polymer membranes

A multiscale, physically-based, reaction-diffusion kinetics model is developed for non-steady-state transport of simple gases through a rubbery polymer. Experimental data from the literature, new measurements of non-steady-state permeation and a molecular dynamics simulation of a gas-polymer sticking probability for a typical system are used to construct and validate the model framework. Using no adjustable parameters, the model successfully reproduces time-dependent experimental data for two distinct systems: (1) O2 quenching of a phosphorescent dye embedded in poly(n-butyl(amino) thionylphosphazene), and (2) O2, N2, CH4 and CO2 transport through poly(dimethyl siloxane). The calculations show that in the pre-steady-state regime, permeation is only correctly described if the sorbed gas concentration in the polymer is dynamically determined by the rise in pressure. The framework is used to predict selectivity targets for two applications involving rubbery membranes: CO2 capture from air and blocking of methane cross-over in an aged solar fuels device.

Time-Dependent Testing Evaluation and Modeling for Rubber Stopper Seal Performance.

Sufficient rubber stopper sealing performance throughout the entire sealed product life cycle is essential for maintaining container closure integrity in the parenteral packaging industry. However, prior publications have lacked systematic considerations for the time-dependent influence on sealing performance that results from the viscoelastic characteristics of the rubber stoppers. In this paper, we report results of an effort to study these effects by applying both compression stress relaxation testing and residual seal force testing for time-dependent experimental data collection. These experiments were followed by modeling fit calculations based on the Maxwell-Wiechert theory modified with the Kohlrausch-Williams-Watts stretched exponential function, resulting in a nonlinear, time-dependent sealing force model. By employing both testing evaluations and modeling calculations, an in-depth understanding of the time-dependent effects on rubber stopper sealing force was developed. Both testing and modeling data show good consistency, demonstrating that the sealing force decays exponentially over time and eventually levels off because of the viscoelastic nature of the rubber stoppers. The nonlinearity of stress relaxation derives from the viscoelastic characteristics of the rubber stoppers coupled with the large stopper compression deformation into restrained geometry conditions. The modeling fit with capability to handle actual testing data can be employed as a tool to calculate the compression stress relaxation and residual seal force throughout the entire sealed product life cycle. In addition to being time-dependent, stress relaxation is also experimentally shown to be temperature-dependent. The present work provides a new, integrated methodology framework and some fresh insights to the parenteral packaging industry for practically and proactively considering, designing, setting up, controlling, and managing stopper sealing performance throughout the entire sealed product life cycle.LAY ABSTRACT: Historical publications in the parenteral packaging industry have lacked systematic considerations for the time-dependent influence on the sealing performance that results from effects of viscoelastic characteristic of the rubber stoppers. This study applied compression stress relaxation testing and residual seal force testing for time-dependent experimental data collection. These experiments were followed by modeling fit calculations based on the Maxwell-Wiechert theory modified with the Kohlrausch-Williams-Watts stretched exponential function, resulting in a nonlinear, time-dependent sealing force model. Experimental and modeling data show good consistency, demonstrating that sealing force decays exponentially over time and eventually levels off. The nonlinearity of stress relaxation derives from the viscoelastic characteristics of the rubber stoppers coupled with the large stopper compression deformation into restrained geometry conditions. In addition to being time-dependent stress relaxation, it is also experimentally shown to be temperature-dependent. The present work provides a new, integrated methodology framework and some fresh insights to the industry for practically and proactively considering, designing, setting up, controlling, and managing of the stopper sealing performance throughout the entire sealed product life cycle.

Progress on ITER remote experimentation centre

Construction of ITER remote experimentation centre (REC) based on the broader approach (BA) activity of the joint program of Japan and Europe (EU) is progressing. In order to make the future experiments of ITER and JT-60SA effectively and efficiently implemented, development of a remote experiment system by using the Satellite Tokamak (JT-60SA) facilities was planned and the development of software for the remote experiment is ongoing, including the systems for the remote connection and the communication between the remote site and the on-site facility. The network system from REC in Rokkasho-site of Japan to the network in EU was established in collaboration with the National Institute of Informatics (NII). Effective data transfer method that is capable of fast transfer speeds in the gigabit range is investigated. Data transfer at the rate of several Gbps was successfully obtained between the institutes in Japan. The preliminary versions of the software for data analysis are developed, such as for visualization of time dependent experimental data and transport simulations, visualization of plasma boundary/equilibrium and spatial profiles of diagnostic data. The remote data access program and an integrated platform for Documentation and Experiment Management are also being developed. A remote experiment room in the Rokkasho-site in Japan was designed and the construction started. The function of REC will be tested and the total system will be demonstrated by the middle of 2017.

Experimental identification of diffusive coupling using 2D NMR.

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique.

Biodegradation Modeling of Nitrophenolic Pollutant in a Slurry Bubble Reactor

Biodegradation kinetics of 4-nitrophenol (PNP) in aqueous solution by a gram negative soil bacterium, Ralstoniaeutropha was firstly studied in a small scale batch reactor. The degradation of PNP was evaluated at initial PNP concentrations ranging from 3 mg/L to 14 mg/L. The rate of PNP consumption by the bacterium culture was modeled using Monod and Contois kinetics in batch condition. PNP degradation by adapted R. eutropha was well fitted to the Monod equation for the pollutant with initial concentration of 3-8 mg/L, whereas for PNP with initial concentration of 14 mg/L the experimental data were better fitted to the Contois kinetic model. The process of degradation of PNP was scaled up in a slurry bubble reactor with 250 ml working volume in presence of 0.75 L/min air flow rate. The derived kinetic model was validated by comparison the outlet time dependent experimental data of PNP concentration with the model in the slurry bioreactor and the results showed good agreement between experiments and the model.

Mistletoe leaves as a biosorbent for removal of Pb(II) and Cd(II) from aqueous solution

The adsorption of Pb(II) and Cd(II) ions onto the biosorbent from leaves of Ramus Loranthi, Scurrula Parasitica L., family Loranthaceae, commonly known as mistletoe or Tam gui in Vietnam, (henceforth to be referred as mistletoe leaves) was studied. The results showed that adsorption equilibrium was established in 150 min of contact time. The maximum adsorption for both metals obtained was at pH 5.5. The time-dependent experimental data of Pb(II) and Cd(II) adsorption process well fitted the pseudo-second-order model. The Redlich-Peterson, Toth, and Langmuir models were appropriate to describe the adsorption process, indicating the chemisorption process onto mistletoe leaves. The maximum adsorbent capacity was increased with an increase in temperature. It was found to be 44.8, 47.85, 49.1, and 50.07 mg/g for Cd(II) and 59.76, 63.25, 66.3, and 68.53 mg/g for Pb(II) at 303, 308, 313, and 318 K, respectively. The positive value of ΔH indicated the endothermic adsorption process. The high adsorption capacity for Pb(II) and Cd(II) obtained in this study shown that mistletoe leaves are a potential biosorbent for removal of these metals from wastewater and contaminated water.

Probing the growth mechanism of PbTe hopper-like crystal and ultra-long nanowires with rough surface synthesized through acetone-assisted solvothermal method

In this paper, uniform and massive PbTe hopper-like crystals with internal steps and ultra-long nanowires have been synthesized with acetone acting as a solvent and retarder. The as-obtained products were well investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM). A series of experiment conditions including reaction temperature, time, the ratio of solvent, have been performed in detail. Concentration of acetone, KOH and EDTA in the reaction mixture play a vital role for controllable structures and morphologies. Based on a series of the time-dependent experimental data, the possible growth mechanisms have been proposed to elucidate the formation of hopper-like crystals and nanowires with rough surface. This simple synthetic route may be extended to prepare other PbTe-based thermoelectric nanomaterials, such as AgPbmMTem+2 (M=Sb, Bi, La).

Understanding and Control of Dimethyl Sulfate in a Manufacturing Process: Kinetic Modeling of a Fischer Esterification Catalyzed by H2SO4

The formation and fate of monomethyl sulfate (MMS) and dimethyl sulfate (DMS) were studied by proton NMR for a sulfuric acid catalyzed esterification reaction in methanol. The kinetic rate constants for DMS and MMS were determined at 65 °C by fitting time-dependent experimental data to a model using DynoChem. In refluxing methanol, sulfuric acid was converted to monomethyl sulfate (MMS) in nearly quantitative yield within 45 min. Once formed, the MMS underwent a reversible esterification reaction to form DMS. Dimethylsulfate reacted with methanol to regenerate MMS and form dimethyl ether. A byproduct of the esterification reaction was water, which further consumed DMS through hydrolysis. On the basis of derived rate constants, in refluxing methanol, DMS would not be expected to exceed 4 ppm in the reaction mixture at equilibrium. In the presence of the carboxylic acid substrate, DMS was not detected in the reaction mixture. The reaction pathways of this system have been systematically investigated, and th...