scholarly journals Evaluation of leaching behavior and immobilization of zinc in cement-based solidified products

2012 ◽  
Vol 66 (5) ◽  
pp. 781-786 ◽  
Author(s):  
Damir Barbir ◽  
Pero Dabic ◽  
Petar Krolo
Keyword(s):  
Diffusion Coefficients ◽  
Experimental Results ◽  
Leaching Test ◽  
Test Results ◽  
Zeolite A ◽  
Leaching Behavior ◽  
Zn Diffusion ◽  
Cumulative Release ◽  
Electroplating Sludge ◽  
And Diffusion

This study has examined leaching behavior of monolithic stabilized/solidified products contaminated with zinc by performing modified dynamic leaching test. The effectiveness of cement-based stabilization/solidification treatment was evaluated by determining the cumulative release of Zn and diffusion coefficients, De. The experimental results indicated that the cumulative release of Zn decreases as the addition of binder increases. The values of the Zn diffusion coefficients for all samples ranged from 1.210-8 to 1.1610-12 cm2 s-1. The samples with higher amounts of binder had lower De values. The test results showed that cement-based stabilization/solidification treatment was effective in immobilization of electroplating sludge and waste zeolite. A model developed by de Groot and van der Sloot was used to clarify the controlling mechanisms. The controlling leaching mechanism was found to be diffusion for samples with small amounts of waste material, and dissolution for higher waste contents.

Extended mixed-culture biofilms (MCB) model to describe integrated fixed film/activated sludge (IFAS) process behaviour

2009 ◽  
Vol 60 (12) ◽  
pp. 3233-3241 ◽  
Author(s):  
J. Albizuri ◽  
M. C. M. van Loosdrecht ◽  
L. Larrea
Keyword(s):  
Mixed Culture ◽  
Heterotrophic Bacteria ◽  
Experimental Results ◽  
Extended Model ◽  
Test Results ◽  
Competition For Space ◽  
Aerobic Reactor ◽  
Colloidal State ◽  
Attachment Coefficient ◽  
And Diffusion

This paper presents how, in a calibration process, different assumptions regarding the standard Mixed-Culture Biofilms (MCB) model were able to match the average results at a continuous Johannesburg pilot plant (comprising two aerobic reactors, AE1 and AE2), but failed to match the batch test results of either the rate of endogenous carbonaceous oxygen uptake (OUR) or the rate of nitrate production (NPR). Under the first assumption, where attachment and diffusion of particulate components were not used, the OUR in the biofilm of the first aerobic reactor (AE1) was too low due to the absence of slowly biodegradable COD (XS) attachment flux. In a second assumption, where high diffusion and attachment coefficients were used, the NPR in the biofilm of the AE1 reactor exceeded the experimental value due to the high attachment flux used for nitrifiers (XA) and the low competition for space from XS and heterotrophic bacteria (XH). The only way to match all the experimental results was through the use of a higher attachment coefficient for XS in the first reactor (AE1), but this was considered unreasonable. Hence, an extended model was developed where a colloidal state, which interacts at the same time with the flocs and the biofilm through attachment-detachment processes, is distinguished. This model allowed the experimental results to be matched, but using the same value for the attachment coefficients of all particulate components.

Effects of cyclic ageing on the tensile properties and diffusion coefficients of an epoxy-based adhesive

2021 ◽  
pp. 146442072199487
Author(s):  
JA da Costa ◽  
A Akhavan-Safar ◽  
EAS Marques ◽  
RJC Carbas ◽  
LFM da Silva
Keyword(s):  
Tensile Properties ◽  
Water Uptake ◽  
Diffusion Coefficients ◽  
Test Results ◽  
Adhesively Bonded ◽  
Maximum Water ◽  
Real Practice ◽  
And Diffusion ◽  
Maximum Water Content ◽  
Adhesively Bonded Structures

In real practice, adhesively bonded structures are usually exposed to cyclic environmental conditions. However, cyclic ageing processes are relatively unexplored. The aim of this study is to consider the effect of cyclic ageing on the rate of water uptake and the drying process in an epoxy-based adhesive. Fick’s law was considered to estimate the water diffusion coefficients for the ageing and the drying steps at different cycles. Different cyclic ageing times have been considered in the ageing procedure. Dogbone shape specimens were also manufactured and subjected to cyclic aging to investigate the tensile properties of the tested adhesive as a function of aging cycles. The gravimetric results showed that the rate of water uptake and drying is mainly a function of the level of water uptake of the first ageing cycle. Tensile test results showed that the maximum water content increases with each subsequent ageing cycle. It was also found that the Young’s modulus and the tensile strength of the adhesive decreased significantly after the initial ageing cycle, but all subsequent ageing cycles have considerably less influence on the mechanical properties of the adhesive.

PREDICTION OF THE TRANSPORT PROPERTIES OF SF6 WITH O2, CO2, CF4, N2 AND CH4 MIXTURES AT LOW DENSITY BY THE INVERSION METHOD (PART II)

2004 ◽  
Vol 03 (01) ◽  
pp. 69-90 ◽  
Author(s):  
BEHZAD HAGHIGHI ◽  
ALIREZA HASSANI DJAVANMARDI ◽  
MOHAMAD MEHDI PAPARI ◽  
MOHSEN NAJAFI
Keyword(s):  
Potential Energy ◽  
Diffusion Coefficients ◽  
Potential Energy Function ◽  
Model Potential ◽  
Inversion Method ◽  
Low Density ◽  
Initial Model ◽  
Lennard Jones ◽  
Inversion Procedure ◽  
And Diffusion

Viscosity and diffusion coefficients for five equimolar binary gas mixtures of SF 6 with O 2, CO 2, CF 4, N 2 and CH 4 gases are determined from the extended principle of corresponding states of viscosity by the inversion technique. The Lennard–Jones 12-6 (LJ 12-6) potential energy function is used as the initial model potential required by the technique. The obtained interaction potential energies from the inversion procedure reproduce viscosity within 1% and diffusion coefficients within 5%.

scholarly journals Boundary behavior and product-form stationary distributions of jump diffusions in the orthant with state-dependent reflections

2008 ◽  
Vol 40 (02) ◽  
pp. 529-547
Author(s):  
Francisco J. Piera ◽  
Ravi R. Mazumdar ◽  
Fabrice M. Guillemin
Keyword(s):  
Random Fields ◽  
Diffusion Coefficients ◽  
Boundary Behavior ◽  
Stationary Regime ◽  
Product Form ◽  
Local Times ◽  
Nonnegative Orthant ◽  
State Dependent ◽  
The Times ◽  
And Diffusion

In this paper we consider reflected diffusions with positive and negative jumps, constrained to lie in the nonnegative orthant of ℝ n . We allow for the drift and diffusion coefficients, as well as for the directions of reflection, to be random fields over time and space. We provide a boundary behavior characterization, generalizing known results in the nonrandom coefficients and constant directions of the reflection case. In particular, the regulator processes are related to semimartingale local times at the boundaries, and they are shown not to charge the times the process expends at the intersection of boundary faces. Using the boundary results, we extend the conditions for product-form distributions in the stationary regime to the case when the drift and diffusion coefficients, as well as the directions of reflection, are random fields over space.

scholarly journals The rate of evaporation of droplets. Evaporation and diffusion coefficients, and vapour pressures of dibutyl phthalate and butyl stearate

1946 ◽  
Vol 186 (1006) ◽  
pp. 368-390 ◽  
Keyword(s):  
Diffusion Coefficients ◽  
Atmospheric Pressure ◽  
Dibutyl Phthalate ◽  
Droplet Evaporation ◽  
Medium Size ◽  
Good Accordance ◽  
Butyl Stearate ◽  
Rate Of Evaporation ◽  
Low Pressures ◽  
And Diffusion

The rate of evaporation of drops of dibutyl phthalate and butyl stearate of radius approx. 0.5 mm. has been studied by means of a microbalance over a range of atmospheric pressures down to approx. 0*1 mm. of mercury. Wide departures from Langmuir’s evaporation formula were found to occur at these low pressures, but results are in good accordance with the theory of droplet evaporation advanced by Fuchs which hitherto has not been tested experimentally. This experimental verification of Fuch’s theory for droplets of medium size evaporating at low pressures shows that the theory can be applied to the evaporation of very small drops at atmospheric pressure. The vapour pressures of the above liquids have been measured by Knudsen’s method and the evaporation and diffusion coefficients calculated fro n the experimental data.

Aluminophosphate Glasses with High Sulfate Content

1994 ◽  
Vol 353 ◽  
Author(s):  
Sergey V. Stefanovsky ◽  
Igor A. Ivanov ◽  
Anatolii N. Gulin
Keyword(s):  
Diffusion Coefficients ◽  
Glass Structure ◽  
Chemical Durability ◽  
Electric Resistivity ◽  
Melting Points ◽  
Sulfate Content ◽  
Leach Rate ◽  
High Sulfate ◽  
Aluminophosphate Glasses ◽  
And Diffusion

AbstractTo immobilize a high sulfate radioactive wastes a system Na2O-A12O3-P2O5-SO3 has been chosen as one where glasses have a relatively low melting points and good chemical durability. Glasses within partial system 44 Na2O, 20 A12O3 (36-x) P2O5 x SO3 have been prepared at 1000 °C. A possibility of assimilation up to 12 mole % of SO3 has been established. The basic properties of sulfate-containing glasses as density, microhardness, thermal expansion coefficient, transformation and deformation temperatures, viscosity, electric resistivity, leach rate of ions and diffusion coefficients of 22Na, 35S, 90Sr and 137Cs have been measured. Glass structure by infrared and EPR spectroscopies has been investigated.

Experimental Study and Finite Analysis on Flexural Capacity of Laminated Glass

2011 ◽  
Vol 243-249 ◽  
pp. 258-262
Author(s):  
Jun Chen ◽  
Jia Lv ◽  
Qi Lin Zhang ◽  
Zhi Xiong Tao ◽  
Jun Chen
Keyword(s):  
Experimental Results ◽  
Laminated Glass ◽  
Test Results ◽  
Design Code ◽  
Flexural Capacity ◽  
Equivalent Thickness ◽  
High Rise ◽  
Safety Glass ◽  
Current Design ◽  
Good Agreement

Laminated glass has been increasing widely used in high rise buildings as a kind of safety glass in recent years. So we should analyze its material property. In this paper, we use flexural experiments and ANSYS program to analyze the main factors that affect the flexural capacity of the laminated glass. The test results show that the flexural capacity is closely related to film. And the ANSYS program had got good agreement with the experimental results. Comparison of experimental results with calculated ones indicates that the current design code will lead to conservative results and the equivalent thickness of laminated glasses provided in the code should be further discussed.

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