Initial stage of internal diffusion adsorption kinetics in adsorbents with a biporous structure

1975 ◽  
Vol 24 (10) ◽  
pp. 2259-2261
Author(s):  
P. P. Zolotarev ◽  
V. I. Ulin
Keyword(s):  
Adsorption Kinetics ◽  
Internal Diffusion ◽  
Initial Stage ◽  
Biporous Structure

Adsorption and Desorption of Cu / Zn Ions with Triethylenetetramine-Functionalized Adsorbents: Kinetics Study

2012 ◽  
Vol 209-211 ◽  
pp. 1999-2004
Author(s):  
Chang Kun Liu ◽  
Xu Xin Zhao ◽  
Hong Zhu ◽  
Xiao Fang Yue
Keyword(s):  
Adsorption Kinetics ◽  
Metal Ion ◽  
Single Species ◽  
Desorption Kinetics ◽  
Adsorption And Desorption ◽  
Diffusion Controlled ◽  
Initial Stage ◽  
And Performance ◽  
Two Stages ◽  
Zn Ions

Adsorption and desorption kinetics is critical in the efficiency and performance evaluation of the adsorbents. In this study, the adsorption and desorption kinetics of copper and/or zinc ions was investigated with the polyamine-functionalized adsorbents (P-TETA). The adsorption kinetics was studied in both single species system (when only one metal ion was present) and binary species system (when both metal ions were present). The adsorption kinetics in single species system was well fitted with two models at two stages for both Cu and Zn ions, indicating that the adsorption was diffusion-controlled at the initial stage and attachment-controlled at later stage. The adsorption kinetics in binary species system revealed the stronger coordination affinity of Cu ion with P-TETA than Zn ion. The desorption kinetics was well fitted with Elovich model for Cu ion desorption only, in both single and binary species system, with a higher desorption rate in single species system.

scholarly journals Study on the Adsorption of Methylene Blue from Dye Wastewater by Humulus Japonicus Leaves

2021 ◽  
Vol 236 ◽  
pp. 03028
Author(s):  
Zheng-gen Huang ◽  
Tao Wang ◽  
He-ying Yi ◽  
Xiao-bin Li
Keyword(s):  
Methylene Blue ◽  
Adsorption Kinetics ◽  
Adsorption Process ◽  
Adsorption Rate ◽  
Internal Diffusion ◽  
Blue Dye ◽  
Dye Wastewater ◽  
Membrane Diffusion ◽  
Isothermal Adsorption ◽  
Humulus Japonicus

This paper took the objective of preparing high-performance, low-cost biological adsorbent for printing and dyeing wastewater, and the adsorption experiment of dyestuff wastewater with high chromaticity and high biodegradability was studied. The Methylene Blue was adsorbed by the prepared Humulus Japonicus Leaves (HJ), the effects of adsorption time, pH, dosage of adsorbent, initial Methylene Blue concentration and temperature on the adsorption process were investigated, and the adsorption mechanism was described by adsorption isotherm, adsorption thermodynamics and adsorption kinetics, and the results showed that: when HJ was added 0.15g and ph was 7, the temperature was 30°C (303K), adsorption was carried out for 20min, simulated dye wastewater, adsorption efficiency of Methylene Blue of 100mg/l were excellent, adsorption rate reached up to 92%, the equilibrium adsorption rate was positively correlated with the initial concentration of CV dye. Humulus leaves adsorption CV Gibbs free energy of ΔG<0, ΔH>0, ΔS>0 showed spontaneous adsorption process, the adsorption process Methylene Blu was more suitable for the Freundlich isothermal adsorption equation, the adsorption kinetics accorded with the quasi two level kinetic model, the adsorption of the Methylene Blue dye molecule by the HJ was chemically adsorbed as the rate control step, the Methylene Blue molecule was mainly adsorbed on the surface of the Humulus leaves; the model of internal diffusion kinetics showed that there was membrane diffusion and internal diffusion of the HJ in the process of Methylene Blue adsorption. The experimental results showed that HJ as adsorbent can effectively remove Methylene Blue from dye wastewater, and the research results provide a new method and idea for biological treatment of dye wastewater.

New Oil-Absorbent Fiber Absorb the Oil of Water

2011 ◽  
Vol 255-260 ◽  
pp. 2860-2866 ◽  
Author(s):  
Mei Tao ◽  
Jin Tao Niu ◽  
Bao Dan Jin
Keyword(s):  
Adsorption Kinetics ◽  
Diffusion Rate ◽  
Suspension Polymerization ◽  
Mass Transfer Rate ◽  
Internal Diffusion ◽  
Order Kinetic ◽  
Absorption Model ◽  
Oily Wastewater ◽  
External Diffusion ◽  
Oil Absorbent

Experiment uses the Suspension Polymerization, under the dual oxidation-reduction system of H2O2-xanthate and H2O2-FeSO4 initiating, the lipophilic- monomer of BMA is grafted on the frame of cotton fiber which prepares oil-absorbent fiber. It has studied the adsorption kinetics, adsorption transfer and isothermal absorption model of the oil-absorbent fiber for the oily wastewater under 25°C. The result shows that the adsorption kinetics of the oil-absorbent fiber for the oily wastewater accords with pseudo second order kinetic model, it could get that the initial swelling rate is increase with stirring speed increasing from fitting. Particles internal diffusion model analyzing shows that the diffusion rate of external diffusion and particles internal diffusion are similar, increasing the stirring speed could increase the internal diffusion rate and external diffusion rate. Increasing the stirring speed could increase capacity mass transfer rate and it benefits to absorb. The absorbing of oil-absorbent fiber for oily wastewater accords with Langmuir and Freundlich isothermal absorption model.

Reaction couples of ceramic thin films prepared by CVD

1988 ◽  
Vol 46 ◽  
pp. 798-799
Author(s):  
D.W. Susnitzky ◽  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Thin Film ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Solid State Reactions ◽  
Spatial Distributions ◽  
Diffusion Couples ◽  
Kinetics Studies ◽  
Ceramic Thin Films ◽  
Initial Stage

Solid-state reactions have traditionally been studied in the form of diffusion couples. This ‘bulk’ approach has been modified, for the specific case of the reaction between NiO and Al2O3, by growing NiAl2O4 (spinel) from electron-transparent Al2O3 TEM foils which had been exposed to NiO vapor at 1415°C. This latter ‘thin-film’ approach has been used to characterize the initial stage of spinel formation and to produce clean phase boundaries since further TEM preparation is not required after the reaction is completed. The present study demonstrates that chemical-vapor deposition (CVD) can be used to deposit NiO particles, with controlled size and spatial distributions, onto Al2O3 TEM specimens. Chemical reactions do not occur during the deposition process, since CVD is a relatively low-temperature technique, and thus the NiO-Al2O3 interface can be characterized. Moreover, a series of annealing treatments can be performed on the same sample which allows both Ni0-NiAl2O4 and NiAl2O4-Al2O3 interfaces to be characterized and which therefore makes this technique amenable to kinetics studies of thin-film reactions.

Decoration technique and surface physics

1978 ◽  
Vol 36 (1) ◽  
pp. 436-437 ◽  
Author(s):  
H. Bethge
Keyword(s):  
Diffusion Path ◽  
Special Importance ◽  
Surface Physics ◽  
Step Structure ◽  
Initial Stage ◽  
Special Cases ◽  
Atomic Surface ◽  
The Mean ◽  
Bulk Structure ◽  
Decoration Technique

Besides the atomic surface structure, diverging in special cases with respect to the bulk structure, the real structure of a surface Is determined by the step structure. Using the decoration technique /1/ it is possible to image step structures having step heights down to a single lattice plane distance electron-microscopically. For a number of problems the knowledge of the monatomic step structures is important, because numerous problems of surface physics are directly connected with processes taking place at these steps, e.g. crystal growth or evaporation, sorption and nucleatlon as initial stage of overgrowth of thin films.To demonstrate the decoration technique by means of evaporation of heavy metals Fig. 1 from our former investigations shows the monatomic step structure of an evaporated NaCI crystal. of special Importance Is the detection of the movement of steps during the growth or evaporation of a crystal. From the velocity of a step fundamental quantities for the molecular processes can be determined, e.g. the mean free diffusion path of molecules.

Nucleation and initial growth of Pd2Si crystals on Si(111)

1993 ◽  
Vol 51 ◽  
pp. 844-845
Author(s):  
Xianghong Tong ◽  
Oliver Pohland ◽  
J. Murray Gibson
Keyword(s):  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Initial Growth ◽  
Surface And Interface ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Initial Stage ◽  
Effect Of Surface

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

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