Liquid Diffusion Coefficient Research Articles

Rapid measurement of liquid diffusion coefficients for different concentrations based on compound liquid-core cylindrical lenses and the finite element method.

Liquid diffusion coefficients are usually concentration-dependent (D(C)), and current methods for measuring the D(C) relationship suffer from long measurement times and large repetitive experimental workloads. This paper consequently proposes a new method for rapid measurement of D(C), which can eliminate the need to measure uncalibrated diffusion coefficients corresponding to concentration by comparing the theoretical concentration distribution of diffusion solution obtained by the finite element method and the experimental concentration distribution. The core diffusion and imaging setup is a compound liquid-core cylindrical lens, which can offer the advantages of high refractive index resolution and imaging quality, guaranteeing the accurate measurement concentration distribution. The D(C) relationship can be obtained by simply gathering an appropriate diffusion image in one experiment profiting from taking full use of the solution concentration spatiotemporal distribution information using the finite element molding fitting method, reducing the measurement time greatly from several days in traditional methods to within 2 hours, characterized by short measurement time, high measurement accuracy and small experimental workload. The D(C) relationship of NaCl solution at 25 °C was measured using this method, and the result was in accord with the instantaneous image method and the literature values.

Interplay of Kinetic and Thermodynamic Factors in the Stationary Composition of Vapor-Liquid-Solid IIIVxV1-x Nanowires.

Compositional control over vapor-liquid-solid III-V ternary nanowires based on group V intermix (VLS IIIVxV1-x NWs) is complicated by the presence of a catalyst droplet with extremely low and hence undetectable concentrations of group V atoms. The liquid-solid and vapor-solid distributions of IIIVxV1-x NWs at a given temperature are influenced by the kinetic parameters (supersaturation and diffusion coefficients in liquid, V/III flux ratio in vapor), temperature and thermodynamic constants. We analyze the interplay of the kinetic and thermodynamic factors influencing the compositions of VLS IIIVxV1-x NWs and derive a new vapor-solid distribution that contains only one parameter of liquid, the ratio of the diffusion coefficients of dissimilar group V atoms. The unknown concentrations of group V atoms in liquid have no influence on the NW composition at high enough levels of supersaturation in liquid. The simple analytic shape of this vapor-solid distribution is regulated by the total V/III flux ratio in vapor. Calculating the temperature-dependent desorption rates, we show that the purely kinetic regime of the liquid-solid growth occurs for VLS IIIVxV1-x NWs in a wide range of conditions. The model fits the data well on the vapor-solid distributions of VLS InPxAs1-x and GaPxAs1-x NWs and can be used for understanding and controlling the compositions of any VLS IIIVxV1-x NWs, as well as modeling the compositional profiles across NW heterostructures in different material systems.

Oxyfl uorinated polyethylene terephthalate for liquid storage containers

The effectiveness of surface modification of polyethylene terephthalate with a mixture of fluorine and oxygen to reduce the permeability to water and aqueous ethanol solutions has been studied. We obtained a decrease in the permeability coefficient of the modified fi lm for water and ethanol solutions, the degree of decrease in the permeability coefficient depends on the chemical composition of the liquid. Oxyfluorination leads to the production of a modified fi lm with an increased liquid diffusion coefficient compared to the original fi lm, which is associated with the formation of local defects which is confirmed by micrographs made with of an atomic force microscope and by measuring the surface roughness of the original and modified films.

Calculations of the diffusion coefficients in gases and liquids by the molecular dynamics method

In this paper the calculation results of the diffusion coefficients in gases and liquids by the method of molecular dynamics are presented. The modified intermolecular Lennard-Jones potential has been used. The diffusion coefficients dependences on temperature and density have been calculated. Using the diffusion coefficients dependence on temperature it has been found, that the collisional mechanism in rarefied and dense gases changed for the collective one in liquids. In the field of the thermodynamics parameters of two phase coexistence, drops of liquid occur in the vapour or bubbles occur in the liquid. The comparison of the experimental data with our calculations results in a satisfactory agreement.

Optimizing Mass Transfer in Multiphase Fermentation: The Role of Drag Models and Physical Conditions

Detailed knowledge of the flow characteristics, bubble movement, and mass transfer is a prerequisite for the proper design of multiphase bioreactors. Often, mechanistic spatiotemporal models and computational fluid dynamics, which intrinsically require computationally demanding analysis of local interfacial forces, are applied. Typically, such approaches use volumetric mass-transfer coefficient (kLa) models, which have demonstrated their predictive power in water systems. However, are the related results transferrable to multiphase fermentations with different physicochemical properties? This is crucial for the proper design of biotechnological processes. Accordingly, this study investigated a given set of mass transfer data to characterize the fermentation conditions. To prevent time-consuming simulations, computational efforts were reduced using a force balance stationary 0-dimension model. Therefore, a competing set of drag models covering different mechanistic assumptions could be evaluated. The simplified approach of disregarding fluid movement provided reliable results and outlined the need to identify the liquid diffusion coefficients in fermentation media. To predict the rising bubble velocities uB, the models considering the Morton number (Mo) showed superiority. The mass transfer coefficient kL was best described using the well-known Higbie approach. Taken together, the gas hold-up, specific surface area, and integral mass transfer could be accurately predicted.

The Preparation, Microstructure, and Wet Wear Properties of an Fe55-Based Welding Layer with the Co-Addition of 0.01 wt% CeO2 and 1.5 wt% SiC Particles Using the Plasma Beam Spraying Method

Severe erosion wear is found on valve spools, which threatens the safety and reliability of these units. The use of the plasma beam spraying surfacing method can significantly improve the corrosion resistance and sealing performance of hydraulic valve spools, reduce material waste, and reduce maintenance costs. The effects of the co-addition of CeO2 and SiC particles on the morphology, surface cracks, microstructure, precipitated phases, and wear property of plasma-beam-sprayed Fe55-based coatings on 1025 steel were investigated using OM, EDS, ultra-deep field microscopy, and a wet sand rubber wheel friction tester, respectively. The dendrite exhibited a directional growth pattern perpendicular to the substrate and the transitional states of the microstructure with the co-addition of CeO2 and SiC particles. CeO2 or SiC reduced the liquid phase diffusion coefficient DL of Cr and C and resulted in a decrease in the G/R ratio. The dendrites changed into equiaxed grains. The main phase composition of the Fe55 welding layer was Cr7C3, γ-Fe. The martensite in the surfacing layer and the carbides formed Cr7C3, which can improve the hardness of the surfacing layer. The grain boundaries consisted mainly of a reticular eutectic structure. The uniform distribution of the Cr7C3 hard phase in the Fe55+1.5 wt% SiC+0.01 wt% CeO2 resulted in a uniformly worn surface. The sub-wear mechanisms during the friction process were micro-ploughing and micro-cutting. The hardness and toughness of Fe55+1.5 wt% SiC+0.01 wt% CeO2 were well-matched, avoiding excessive micro-cutting and microplastic deformation. A low content of CeO2 could lead to the formation of equiaxed grain and effectively improve the uniformity of the microstructure. The wear-resistant layer of Fe55+1.5 wt% SiC+0.01 wt% CeO2 can effectively improve the service life and long-term sealing performance of the valve spools.

Investigation on interphase mass transfer coefficient of a deformable bubble with density contrast using phase-field lattice Boltzmann method

The gas–liquid mass transfer process with density contrast is modeled in this paper using a phase-field Lattice Boltzmann (LB) method. In this method, the phase-field model used to calculate the flow field and the continuous species transfer model used to calculate the concentration distribution are coupled by introducing the divergence condition of the velocity in the presence of mass transfer into the Allen-Cahn equation. For a deformable bubble rising in stagnant liquid, a two-dimensional parameter dependence study is conducted and the results indicate that an increase in initial diameter, as well as a decrease in liquid diffusion coefficient or liquid viscosity, can improve the steady-state value for the Sherwood number, whereas the distribution coefficient has a little impact on this steady-state value. Furthermore, a correlation originally proposed by Takemura and Yabe (1998) modified with a shape factor can be used to predict the steady-state Sherwood number in the numerical results.

The strategy of solid-liquid phase separation diffusion with DyH3 to approach a trade-off between properties and cost for sintered Nd-Fe-B magnets

Approach a trade-off between properties and cost for sintered Nd-Fe-B magnets in grain boundary diffusion (GBD) helps widen their application. In this study, we fabricated GBD Nd-Fe-B magnets via solid-liquid phase separation diffusion (SepD) with DyH3 nanopowder as the diffusion source. Investigations and comparisons with the traditional solid-liquid phase simultaneous diffusion (SimD) magnets were made regarding the liquid phase diffusion (LPD) temperature, magnetic characteristics, microstructures, diffusion coefficient, and domain morphology of SepD magnets. In addition, the cost was calculated and compared with TbH3 SepD magnets. It is determined that the optimal LPD temperature of DyH3 was 625 °C. Compared to the SimD magnet, Dy had a faster LPD rate in the SepD magnet, which leads to a deeper diffusion depth of 1200 µm. Consequently, the SepD magnet develops more core-shell structures. Additionally, SepD could prevent the development of anti-core-shell formations in the magnet's surface region. As a result, the SepD magnet had higher comprehensive magnetic properties and coercivity temperature stability. Impressively, compared to TbH3 SepD magnets, the cost of per kOe coercivity enhancement for per kilogram magnets of DyH3 SepD magnets can be reduced by more than 50 %.

Determination Method of Diffusion Coefficient in a Neat Redox-Active Ionic Liquid at a Microdisk Electrode in the Domains Ranging from the Steady-State to Potentiodynamic Near-Steady-State.

In redox-active ionic liquids (RAILs), either or both of the constituent ions are redox-active. Because of the high concentration of the ions, RAILs exhibit not only ion conduction but also electron conduction through the bimolecular electron self-exchange reaction. Because neat RAILs do not contain any supporting electrolyte, migration of the redox active ions results in enhancement or diminishment of the redox current at an electrode. To treat the migration effect for electrochemical analysis, a limiting current correction was theoretically derived by Oldham, Hyk, and Stojek (Oldham, K. J. Electroanal. Chem. 1992, 337, 91-126; Hyk, W.; Stojek, Z. Anal. Chem. 2002, 747, 4805-4813) for the steady-state voltammetry. Although steady-state voltammetry is a robust method in electrochemistry, the actual measurement is time-consuming and cannot be always made because of the instability of the electrochemical system. To overcome the problem, we propose the use of cyclic voltammetry to evaluate the diffusion coefficient of the redox-active ion that constitutes RAIL. The peak currents were analyzed by the purely diffusional framework of the Aoki-Matsuda-Osteryoung equation (Aoki, K.; Akimoto, K.; Tokuda, K.; Matsuda, H.; Osteryoung, J. J. Electroanal. Chem. 1984, 171, 219-230.) in the range from several mV s-1 to several ten mV s-1, and the migration correction to the near-steady-state limiting current was applied on the basis of the Oldham-Hyk-Stojek theory to scale the diffusion coefficient. As an example of RAILs, [FcC6ImC1][TFSI], which exhibits charge increase reaction with the same sign (S+ - e- ⇌ P2+), was used and the cyclic voltammograms were recorded at various sizes of the microdisk electrodes and various scan rates. The peak currents obeyed the Aoki-Matsuda-Osteryoung equation with the scaled diffusion coefficient, which has the same value as determined by the steady-state voltammogram. Our approach can be used to evaluate the diffusion coefficient of redox-active ions that constitute the RAIL with the charge increase reaction with the same sign.

Experimental study on hygrothermal properties of recycled aggregate concrete

Recycled aggregate concrete has great significance from the environmental protection perspective. However, the current research findings on its hygrothermal properties are sparse. In this study, the apparent density, thermal conductivity, mass moisture content, water vapor permeability coefficient, water absorption coefficient, and liquid water diffusion coefficient of recycled aggregate concrete were determined by experimental methods. The effect of temperature and humidity on thermal conductivity was also studied. Furthermore, the fitting relations of the thermal conductivity of recycled aggregate concrete with the two variables of temperature and relative humidity were presented. The isothermal moisture absorption curve and the fitting relationship of water vapor permeability coefficient with relative humidity were also developed. The results indicate that the thermal conductivity of the eight recycled concrete specimens in the dry state at 25°C ranges from 0.994 to 1.242 W/(m·K). The thermal conductivity increases with the increase in temperature. When the temperature rises from 25°C to 35°C, the thermal conductivity of recycled aggregate concrete increases by 3.8%–13.5%. With the increase of relative humidity, the thermal conductivity of recycled aggregate concrete shows an increasing trend, followed by a steady state, and finally the increasing trend, showing a cubic function relationship between them. When the relative humidity increases from 0% to 95%, the thermal conductivity increases by about 20%. The mass moisture content and the water vapor permeability coefficient increase with relative humidity. The results of this study can provide basic information for the study on the heat and moisture transfer of recycled aggregate concrete, and enhance the database of hygrothermal properties of building materials.

Parameter calculation and result storage for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy

Parameter calculation and result storage, as two necessary steps in phase-field simulation play an important role in ensuring the accuracy of simulation results. A strategy of parameter calculation and result storage is presented for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy under isothermal solidification. Based on the phase diagram and empirical formulas, key parameters of the phase-field model, such as equilibrium partition coefficient k, liquidus slope m, solutal diffusion coefficient in liquid D l, and solutal diffusion coefficient in solid D s, can be obtained. Both structured grid method and structured point method can be used to store simulation results, but using the latter method will reduce about 60% storage space and 37.5% storage time compared with the former. Finally, convergent simulation results of α-Mg dendrite growth are obtained and they are in good agreement with the experimental results about optical micrograph, which verify the accuracy of parameters and stability of storage method.

Evaporating Rayleigh–Bénard convection: prediction of interface temperature and global heat transfer modulation

We propose an analytical model to estimate the interface temperature $\varTheta _{\varGamma }$ and the Nusselt number $Nu$ for an evaporating two-layer Rayleigh–Bénard configuration in statistically stationary conditions. The model is based on three assumptions: (i) the Oberbeck–Boussinesq approximation can be applied to the liquid phase, while the gas thermophysical properties are generic functions of thermodynamic pressure, local temperature and vapour composition, (ii) the Grossmann–Lohse theory for thermal convection can be applied to the liquid and gas layers separately and (iii) the vapour content in the gas can be taken as the mean value at the gas–liquid interface. We validate this setting using direct numerical simulations in a parameter space composed of the Rayleigh number ( $10^6\leq Ra\leq 10^8$ ) and the temperature differential ( $0.05\leq \varepsilon \leq 0.20$ ), which modulates the variation of state variables in the gas layer. To better disentangle the variable property effects on $\varTheta _\varGamma$ and $Nu$ , simulations are performed in two conditions. First, we consider the case of uniform gas properties except for the gas density and gas–liquid diffusion coefficient. Second, we include the variation of specific heat capacity, dynamic viscosity and thermal conductivity using realistic equations of state. Irrespective of the employed setting, the proposed model agrees very well with the numerical simulations over the entire range of $Ra$ – $\varepsilon$ investigated.

Random Walks and Sticky Surfaces: Single-Molecule Measurements of Solute Diffusion in Ethanol/Water-Filled Anodic Alumina Nanopores

Nanoporous anodic aluminum oxide (AAO) membranes are now being explored for use in advanced chemical separations, including in the dehydration of biofuels such as ethanol. Optimization of membrane performance requires an in-depth understanding of how solvent mixtures and solutes behave under nanoconfinement. In this work, the diffusion of rhodamine B (RhB) dye through 10 and 20 nm AAO nanopores filled with a series of ethanol/water mixtures (0–33% water) is explored by fluorescence correlation spectroscopy (FCS). RhB was found to diffuse through the pores by two distinct mechanisms with mean diffusion coefficients, Df and Ds, reflecting fast and slow diffusive motions, respectively, with values that differ by nearly 2 orders of magnitude. Both Df and Ds increased with pore size and were significantly smaller than Db, the RhB diffusion coefficient in bulk liquid. Mean Df values follow a composition-dependent trend that closely mimics the viscosity dependence of Db. Additional slowing of fast RhB diffusion is attributed to both hydrodynamic drag and electrostatic interactions with the nanopore surface. The mean Ds values exhibit a different trend with increasing water content, revealing an increase in Ds and a decrease in the contributions of slow diffusion to the observed dynamics. The fluorescence time transient data used in the analysis show that the slow diffusion process is strongly hindered and likely involves frequent adsorption of RhB to the pore surfaces. These results provide new insights into the detailed molecular-level mechanisms of mass transport in nanoporous AAO membranes.

Calculation of diffusion coefficient of liquid less simple metals

Diffusion coefficient of liquid less simple metals has been studied using linear trajectory (LT) and small-step (SS) diffusion theories of liquid metals with Carnahan–Stirling (CS) approximation. Friction coefficients, the key ingredients of this study, are calculated using effective pair potentials, v(r), and static structure factors, S(q). For v(r), Brettonet–Silbert pseudopotential model has been chosen whereas for S(q), both variational modified hypernetted chain (VMHNC) integral equation and linearized Weeks–Chandler–Andersen (LWCA) perturbation theory have been employed. Calculated friction coefficients are found comparable to the available simulated data. Inclusion of CS approximation increases the value of friction coefficient obtained from hard part which dominates over rest of the coefficients. Applied LWCA theory provides slightly larger values of diffusion coefficients than those obtained from VMHNC. Comparing with literature values, calculated results suggest that the combination of LWCA theory along with LT and SS theories with CS approximation is excellent for calculation of diffusion coefficient.

Diffusion-limited C-rate: A criterion of rate performance for lithium-ion batteries

Rate performance is one of the important indexes of lithium-ion batteries. However, the discharge capacity would sometimes collapse after a critical C-rate, which is related to a classic concept termed the diffusion-limited C-rate (DLC). In this work, DLC is revisited using the Pseudo-Two-Dimensional model. The DLC analytical model is improved by incorporating the concentration-dependent liquid diffusion coefficient and shows good effectiveness compared with the simulation results. Subsequently, the impact of rate-limiting factors on the rate performance is examined to determine the effective scope of the proposed DLC model. Based on the adjustment of resistance ratios and time constant ratios of different kinetic processes, we find that the rate performance below DLC is hardly limited by electronic transports and charge transfer processes while the discharge capacity below DLC may be severely decayed if the solid-state diffusion in the electroactive particles is too slow. DLC helps identify the ‘knee’ on discharge capacity curves with discharge C-rate, which is a criterion of rate performance in some scenarios.

Effect of ion chelator on water sorption and transport behavior of unsaturated mortars with high volume fly ash and blast furnace slag

This paper investigated the effect of ion chelator on water dependency of water transport and fixation in mortars with high volume of fly ash (FA) and blast furnace slag (BFS). Ion chelator (CA) as a new type of crystalline admixture could improve self-healing performance of cementitious materials by crack-healing and pore filling. The porosity of mortar was measured by vacuum saturation and pore size distribution of mortar was tested by low-field nuclear magnetic resonance (LF NMR). The water sorption of mortar was evaluated by water vapor adsorption desorption balance. The water transport of mortar with and without crack was tested by capillary water absorption. Based on the experimental results, the water distribution of capillary water absorption in mortar was calculated. Results showed that the pore structure of mortar was improved evidently by CA, and the pores (>1μm) and the total porosity in mortar containing 50 %BFS were significantly reduced. CA had no obvious effect on the water vapor diffusion coefficient of mortar, but has a significant impact on the liquid water diffusion coefficient, especially in pure cement and containing 50 % BFS mortar. The total capillary water absorption and capillary absorption coefficient of mortars were reduced by CA, especially in pure cement and containing 50 % BFS mortar. The addition of CA decreased the water penetration in mortar, the reduction rates of water penetration depth in experimental groups (with CA) at 360 min were 12.4 % (100 %OPC), 6.0 % (30 %FA), 21.3 % (50 %BFS) and 10.8 % (16 %FA 24 %BFS) compared to control group (no CA). After curing for 42d, the normalized water absorption coefficients S” of cracked M100CA and M50BFS50CA were 55.1 % and 72.0 %, respectively. Ion chelator significantly improved internal pore structure and crack healing ability of the mortar containing 50 %BFS, and then delayed the water diffusion.

Measurement of the concentration- and temperature-dependent diffusion coefficient and activation energy via diffusion image analysis

Problems associated with obtaining measurements of the concentration- and temperature-dependent liquid diffusion coefficient, D(C, T), and the concentration-dependent diffusion activation energy, Ea(C), include large experimental workload and time consumption. To account for these, this paper introduces an optical method for rapidly measuring D(C, T) and Ea(C), based on the imagery of a liquid-core cylindrical lens (LCL) and numerical calculation. This method requires only one diffusion image obtained from the diffusion experiment, and D(C) is measured at a particular temperature. First, we measured the D(C) coefficients of glycerin solution at 288.0, 293.0, 298.0, 303.0, 308.0, 313.0, and 318.0 K. Then, the ray tracing theory was used to study the ray propagation law in the LCL composed of an inhomogeneous solution, which simulated the diffusion images of the entire experimental process and provided a method to verify the measured values of D(C). Finally, the law of diffusion activation energy varying with concentration was discussed based on the Arrhenius theory and the acquired values of D(C, T). This study further improves the measurement technology for D(C, T) and Ea(C) and provides an efficient methodology to build extensive D(C, T) and Ea(C) databases in the biochemical, medical, semiconductor, and environmental protection industries.

An improved method for measuring the concentration dependence of Fick diffusion coefficient based on Boltzmann equation and cylindrical liquid-core lenses

Liquid diffusion coefficient that depends on solution concentration (D(C))11D(C): Liquid diffusion coefficient that depends on solution concentration is an important basic data for calculating mass transfer rate and studying mass transfer process. To measure the D(C) of glucose aqueous solution, the spatial and temporal profiles of the experimental concentration (Cexpt(x,t)s)22Cexpt(x,t)s: Spatial and temporal profiles of the experimental concentration during diffusion process have been measured on the base of a combination liquid-core cylindrical lens. In theoretical analysis aspect, based on the analytical method proposed by Hall and the graphic method adopted by Matano and Sauer-Freise et al., Boltzmann-Matano (BM)33BM: Boltzmann-Matano semi-analytical method is proposed and used to solve the D(C) equation, the D(C) of glucose aqueous solution is calculated with the obtained Cexpt(x,t)s. In addition, using the Finite-Difference Time-Domain (FDTD)44FDTD: Finite-Difference Time-Domain method, the distribution functions of diffusion concentration (CFDTD(x,t)s)55CFDTD(x,t)s: Concentration profile calculated by FDTD method under different D(C) correlations are calculated and compared with the Cexpt(x,t)s. The results indicate that the BM semi-analytical method can be used to correctly measure the liquid diffusion coefficient, which has the advantages such as stable and reliable measurement results, high precision, fast speed, and it can avoid the error caused by determining the “Matano” plane. The profile calculated by FDTD method provides an effective verification for the correctness of the measured D(C) as comparing with the experimental profile.

Asymptotics and Summation of the Effective Properties of Suspensions, Simple Liquids and Composites

We review the problem of summation for a very short truncation of a power series by means of special resummation techniques inspired by the field-theoretical renormalization group. Effective viscosity (EV) of active and passive suspensions is studied by means of a special algebraic renormalization approach applied to the first and second-order expansions in volume fractions of particles. EV of the 2D and 3D passive suspensions is analysed by means of various self-similar approximants such as iterated roots, exponential approximants, super-exponential approximants and root approximants. General formulae for all concentrations are derived. A brief introduction to the rheology of micro-swimmers is given. Microscopic expressions for the intrinsic viscosity of the active system of puller-like microswimmers are obtained. Special attention is given to the problem of the calculation of the critical indices and amplitudes of the EV and to the sedimentation rate in the vicinity of known critical points. Critical indices are calculated from the short truncation by means of minimal difference and minimal derivative conditions on the fixed points imposed directly on the critical properties. Accurate expressions are presented for the non-local diffusion coefficient of a simple liquid in the vicinity of a critical point. Extensions and corrections to the celebrated Kawasaki formula are discussed. We also discuss the effective conductivity for the classical analog of graphene and calculate the effective critical index for superconductivity dependent on the concentration of vacancies. Finally, we discuss the effective conductivity of a random 3D composite and calculate the superconductivity critical index of a random 3D composite.

Optical measurement of concentration-dependent diffusion coefficient by tracing diffusion image width

ObjectiveRepeated experiments at different concentrations are necessary to measure the concentration-dependent liquid diffusion coefficient D(C), this process is arduous and time consuming using traditional methods. MethodsIn order to overcome the limitation, the self-designed liquid-core cylindrical lens were used as the diffusion cell and imaging element, considering one observed altitude on the focal plane of the self-designed liquid-core cylindrical lens, the variation in the diffusion image width reflects the experimental time-varying concentration profile Cez, t), D(C) over the whole concentration range was calculated by the comparison between calculated concentration profiles Cn(z, t)s and above experimental values by changing the observed altitudes. ResultThe D(C) of urea aqueous solution was measured with D(C) = 1.3872 × (1–0.0399 ×C-0.0031 ×C2-0.0002 ×C3) × 10−5 cm2/s, this is similar to literature values and verifiable via image simulations. Comparing with traditional measurement method, this approach requires one experiment and significantly reduces experimental workloads, further improving D(C) measurement technology.