The Adsorption Characteristics and Mechanism of Pb(II) onto Corn Straw Biochar

2021 ◽  
Vol 15 (3) ◽  
pp. 287-295
Author(s):  
Liucheng Wang ◽  
Huanhuan Zhao ◽  
Xianglin Song ◽  
Yake Li ◽  
Dong Li
Keyword(s):  
Molecular Layer ◽  
Corn Straw ◽  
Adsorption Characteristics ◽  
Layer Adsorption ◽  
Adsorption Data ◽  
Renewable Material ◽  
Increasing Temperature ◽  
And Diffusion ◽  
Positive Effect ◽  
Single Molecular Layer

Heavy metal pollution has adversely affected the ecological environment. As an eco-friendly and renewable material, biochar has a positive effect on environmental restoration. For study the feasibility of removing lead using corn straw biochar, the adsorption characteristics and mechanism were studied. This work prepared corn straw biochar at 300 °C, and its surface properties were characterized. The adsorption kinetics, isotherm, thermodynamics were determined. The result indicated the mechanism belonged ion exchange and complexation, and the experiment were controlled by comprehensive process, which included reaction rate and diffusion. The Langmuir model had better fitting results for the adsorption data, which indicated that adsorption was chemical adsorption and single molecular layer adsorption, and the maximum adsorption amount of corn straw biochar at 25 °C, 35 °C and 45 °C were 81.63 mg/g, 83.89 mg/g and 89.21 mg/g respectively. The thermodynamic analysis showed that increasing temperature was helpful to adsorption, and the adsorption was spontaneous. The results can be used for comprehensive utilization of straw and treatment of lead pollution.

scholarly journals Adsorption Characteristics of New Coccine Dye on to Sludge Ash

2002 ◽  
Vol 20 (7) ◽  
pp. 669-681 ◽  
Author(s):  
Chih-Huang Weng
Keyword(s):  
Ionic Strength ◽  
Adsorption Energy ◽  
Dye Adsorption ◽  
Multilayer Adsorption ◽  
Sewage Sludge Ash ◽  
Adsorption Characteristics ◽  
Layer Adsorption ◽  
Decreasing Ph ◽  
Sludge Ash ◽  
Double Layer Thickness

The adsorption characteristics of an anionic azo dye (New Coccine) on to sewage sludge ash were studied. Results showed that the ash could remove the dye effectively from aqueous solution. The adsorption rate was fast and could be expressed by the modified Freundlich equation. It was found that pH is the most important parameter affecting the adsorption characteristics. The experimental data were correlated well to the non-linear multilayer adsorption isotherm. The ash adsorption capacities for the dye were in the range 3.25–5.70 mol/g and were affected by the pH, ionic strength and temperature. Decreasing pH, ionic strength and temperature increased the adsorption density. The effect of electrical double-layer thickness on the adsorption was discussed. Thermodynamic parameters indicated that the adsorption was an exothermic process. Values of the first-layer adsorption energy, ΔG10, ranged from −6.86 to −7.45 kcal/mol, suggesting that the adsorption could be considered as a physical process simultaneously enhanced by the electrostatic effect. The multilayer adsorption energy, ΔG20, ranged from −4.33 to −4.51 kcal/mol, suggesting that the adsorption was of the typical physical type. On the basis of the monolayer dye adsorption capacity, the specific surface area of the ash was calculated as 3.84–6.73 m2/g.

scholarly journals Solidification and superlubricity with molecular alkane films

2019 ◽  
Vol 116 (51) ◽  
pp. 25418-25423 ◽  
Author(s):  
Alexander M. Smith ◽  
James E. Hallett ◽  
Susan Perkin
Keyword(s):  
Solid Phase ◽  
Molecular Layer ◽  
Friction Coefficients ◽  
Model Studies ◽  
Surface Alignment ◽  
Hydrocarbon Films ◽  
Nanoscale Films ◽  
Alkane Films ◽  
And Control ◽  
Single Molecular Layer

Hydrocarbon films confined between smooth mica surfaces have long provided an experimental playground for model studies of structure and dynamics of confined liquids. However, fundamental questions regarding the phase behavior and shear properties in this simple system remain unsolved. With ultrasensitive resolution in film thickness and shear stress, and control over the crystallographic alignment of the confining surfaces, we here investigate the shear forces transmitted across nanoscale films of dodecane down to a single molecular layer. We resolve the conditions under which liquid–solid phase transitions occur and explain friction coefficients spanning several orders of magnitude. We find that commensurate surface alignment and presence of water at the interfaces each lead to moderate or high friction, whereas friction coefficients down toμ≈0.001are observed for a single molecular layer of dodecane trapped between crystallographically misaligned dry surfaces. This ultralow friction is attributed to sliding at the incommensurate interface between one of the mica surfaces and the laterally ordered solid molecular film, reconciling previous interpretations.

Powder x-ray diffraction of turbostratically stacked layer systems

1996 ◽  
Vol 11 (7) ◽  
pp. 1733-1738 ◽  
Author(s):  
D. Yang ◽  
R. F. Frindt
Keyword(s):  
Special Form ◽  
Molecular Layer ◽  
X Ray Diffraction ◽  
Layer System ◽  
X Ray ◽  
Debye Formula ◽  
Diffraction Patterns ◽  
Single Molecular Layer ◽  
Deposition Conditions

A special form of the Debye formula for calculating the powder x-ray diffraction of a turbostratically stacked layer system is derived, and calculated diffraction patterns for turbostratically stacked graphite and MoS2 layers are presented. Single-molecular-layer MoS2, prepared by exfoliation of lithium-intercalated MoS2 in water or alcohols, has been deposited on various supports, and x-ray diffraction patterns show that the restacking of the MoS2 layers can be perfectly turbostratic. The restacked MoS2 may or may not have water or organic bilayers between them, depending on the deposition conditions.

The remarkable activity and stability of a dye-sensitized single molecular layer MoS2ensemble for photocatalytic hydrogen production

2015 ◽  
Vol 51 (70) ◽  
pp. 13496-13499 ◽  
Author(s):  
Tiantian Jia ◽  
Molly M. J. Li ◽  
Lin Ye ◽  
Sam Wiseman ◽  
Guoliang Liu ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Binding Affinity ◽  
Molecular Layer ◽  
Single Layer ◽  
Eosin Y ◽  
Photocatalytic Hydrogen Production ◽  
Dye Sensitized ◽  
Strong Binding ◽  
Single Molecular Layer ◽  
Dye Molecule

Single layer MoS2synthesized by exfoliation with Li is demonstrated to take up the dye molecule, Eosin Y, with strong binding affinityviasulfur vacancies.

TEMPERATURE EFFECT ON THERMOMECHANICAL PROPERTIES OF BERYLLIUM CHALCOGENIDES BeS, BeSe AND BeTe

2006 ◽  
Vol 20 (01) ◽  
pp. 49-61 ◽  
Author(s):  
F. BENKABOU
Keyword(s):  
Elastic Constants ◽  
Dynamic Properties ◽  
Theoretical Calculations ◽  
Thermomechanical Properties ◽  
Structural Dynamic ◽  
Experimental Values ◽  
Beryllium Chalcogenides ◽  
Increasing Temperature ◽  
And Diffusion ◽  
Good Agreement

We have used the molecular-dynamic method for the calculation of the structural, dynamic and elastic properties of group BeS , BeSe and BeTe compounds for temperature ranging from 300 to 1200 K. Tersoff potential has been used to model the interaction between the groups II–VI compound atoms. The structural properties of cubic BeS , BeSe and BeTe have been calculated, and good agreement between the calculated and experimental values have been found. We have also predicted the elastic constants and diffusion coefficients of BeS , BeSe and BeTe . The values found compare very well with the theoretical results. For the temperature range under study, all elastic constants and dynamic properties show a softening with increasing temperature very similar to the theoretical calculations.

Vertical Positioning of Internal Molecular Scaffolding within a Single Molecular Layer

1998 ◽  
Vol 102 (47) ◽  
pp. 9550-9556 ◽  
Author(s):  
Henning Menzel ◽  
Mark D. Mowery ◽  
Mei Cai ◽  
Christine E. Evans
Keyword(s):  
Molecular Layer ◽  
Vertical Positioning ◽  
Single Molecular Layer

scholarly journals Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4990
Author(s):  
Petr Pokorný ◽  
Jiří Kolísko ◽  
David Čítek ◽  
Michaela Kostelecká
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Future Research ◽  
Ultra High Performance Concrete ◽  
Negative Effect ◽  
Laboratory Investigations ◽  
Increasing Temperature ◽  
Positive Effect

The study explores the effect of elevated temperatures on the bond strength between prestressing reinforcement and ultra-high performance concrete (UHPC). Laboratory investigations reveal that the changes in bond strength correspond well with the changes in compressive strength of UHPC and their correlation can be mathematically described. Exposition of specimens to temperatures up to 200 °C does not reduce bond strength as a negative effect of increasing temperature is outweighed by the positive effect of thermal increase on the reactivity of silica fume in UHPC mixture. Above 200 °C, bond strength significantly reduces; for instance, a decrease by about 70% is observed at 800 °C. The decreases in compressive and bond strengths for temperatures above 400 °C are related to the changes of phase composition of UHPC matrix (as revealed by X-ray powder diffraction) and the changes in microstructure including the increase of porosity (verified by mercury intrusion porosimetry and observation of confocal microscopy) and development cracks detected by scanning electron microscopy. Future research should investigate the effect of relaxation of prestressing reinforcement with increasing temperature on bond strength reduction by numerical modelling.

High-Temperature (up to 800 K) Operation of 6-kV 4H-SiC Junction Diodes

2006 ◽  
Vol 527-529 ◽  
pp. 1339-1342 ◽  
Author(s):  
Michael E. Levinshtein ◽  
Pavel A. Ivanov ◽  
Mykola S. Boltovets ◽  
Valentyn A. Krivutsa ◽  
John W. Palmour ◽  
...  
Keyword(s):  
Deep Level ◽  
Reverse Current ◽  
Differential Resistance ◽  
Base Resistance ◽  
Small Current ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Increasing Temperature ◽  
Surface Leakage ◽  
And Diffusion

Steady-state and transient characteristics of packaged 6-kV 4H-SiC junction diodes have been investigated in the temperature range Т = 300 – 773 К. Analysis of the forward current-voltage characteristics and reverse current recovery waveforms shows that the lifetimeτ of non-equilibrium carriers in the base of the diodes steadily increases with temperature across the entire temperature interval. The rise in τ and decrease in carrier mobilities and diffusion coefficients with increasing temperature nearly compensate each other as regards their effect on the differential resistance of the diode, Rd. As a result, Rd is virtually temperature independent. An appreciable modulation of the base resistance takes place at room temperature even at a relatively small current density j of 20 A/cm2. At T = 800 K and j = 20 A/cm2, a very deep level of the base modulation has been observed. The bulk reverse current is governed by carrier generation in the space-charge region via a trap with activation energy of 1.62 eV. The surface leakage current of packaged structures does not exceed 2×10-6 А at T = 773 K and a reverse bias of 300 V.

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