scholarly journals New Concept for the Study of the Fluid Dynamics of Lithium Extraction Using Calix[4]arene Derivatives in T-Type Microreactor Systems

Separations ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Yehezkiel Steven Kurniawan ◽  
Ramachandra Rao Sathuluri ◽  
Keisuke Ohto ◽  
Wataru Iwasaki ◽  
Hidetaka Kawakita ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Length ◽  
Economic Value ◽  
Extraction Rate ◽  
Slow Kinetics ◽  
Kinetics Of ◽  
Area And Volume

Lithium extraction remains a challenge in the hydrometallurgy process due to its economic value and maldistribution sources. Employing calix[4]arene derivatives in solvent extraction techniques results in high selectivity and extraction capability, but a slow extraction rate. The slow kinetics of batch-wise extraction can be drastically accelerated by using a T-type microreactor system. Therefore, a combination of calix[4]arene and a microreactor system serves as an ideal platform for efficient lithium extraction. In this work, the fluid dynamics of lithium extraction using a monoacetic acid calix[4]arene derivative in a T-type microreactor system were studied. Increasing the O/A ratio increases the average length, surface area, and volume of the organic droplets, but decreases the specific surface area. In contrast, increasing the Reynolds number decreases the average length, surface area, and volume of the organic droplets, but increases the specific surface area. It was found that shorter diffusion distance, larger specific surface area, and faster vortex velocity were the factors that play the most pivotal roles in achieving great extraction rate enhancement in T-type microreactor systems compared to batch-wise systems. These findings represent an important new concept in the study of the fluid dynamics of lithium extraction using monoacetic acid calix[4]arene derivatives in T-type microreactor systems.

Study on the kinetics of process for obtaining cobalt nanopowder by hydrogen reduction under isothermal conditions

2021 ◽  
Vol 1 (1) ◽  
pp. 49-56
Author(s):  
Hieр Nguyen Tien
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

The kinetics of metallic cobalt nanopowder synthesizing by hydrogen reduction from Co(OH)2 nanopowder under isothermal conditions were studied. Co(OH)2 nanopowder was prepared in advance by chemical deposition from aqueous solutions of Co(NO3)2 cobalt nitrate (10 wt.%) and NaOH alkali (10 wt.%) at room temperature, pH = 9 under continuous stirring. The hydrogen reduction of Co(OH)2 nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 270 to 310 °C. The crystal structure and composition of powders was studied by X-ray phase analysis. The specific surface area of samples was measured using the BET method by low-temperature nitrogen adsorption. The average particle size of powders was determined by the measured specific surface area. Particles size characteristics and morphology were investigated by transmission and scanning electron microscopes. Kinetic parameters of Co(OH)2 hydrogen reduction under isothermal conditions were calculated using the Gray–Weddington model and Arrhenius equation. It was found that the rate constant of reduction at t = 310 °C is approximately 1.93 times higher than at 270 °C, so the process accelerates by 1.58 times for 40 min of reduction. The activation energy of cobalt nanopowder synthesizing from Co(OH)2 by hydrogen reduction is ~40 kJ/mol, which indicates a mixed reaction mode. It was shown that cobalt nanoparticles obtained by the hydrogen reduction of its hydroxide at 280 °C are aggregates of equiaxed particles up to 100 nm in size where individual particles are connected to several neighboring particles by contact isthmuses.

Preparation and Characterization of Microporous Hemp Stem-Based Activated Carbons

2013 ◽  
Vol 821-822 ◽  
pp. 1307-1312
Author(s):  
Xin Yu Cui ◽  
Jian Min Gao ◽  
Xin Min Hao ◽  
Jin Ju Sun ◽  
Tian Ma ◽  
...  
Keyword(s):  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Activated Carbons ◽  
Micropore Surface Area ◽  
Activating Agent ◽  
Micropore Size ◽  
Area And Volume

Activated carbons are prepared from hemp stem with KOH as activating agent under different ratio of KOH to carbon conditions. The BET(Brunauer Emmett and Teller) specific surface area of the hemp stem-based activated carbons first increases and then decreases with the increasing ratio of KOH to carbon. The specific surface area, micropore surface area and volume of the activated carbons reach a maximum of 1589.27m2/g 1420.52m2/g, 89% of the total area, 0.751m3/g at the ratio of 4.5:1. The micropore size distribution shows the activated carbons contain a large number of ultramicropore and supermicropore.

scholarly journals Adsorption and Photodegradation of Cationic and Anionic Dyes by TiO2-Chitosan Nanocomposite

2019 ◽  
Vol 19 (2) ◽  
pp. 441
Author(s):  
Imelda Fajriati ◽  
Mudasir Mudasir ◽  
Endang Tri Wahyuni
Keyword(s):  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Maximum Adsorption Capacity ◽  
Anionic Dyes ◽  
Anionic Dye ◽  
Reaction Constant ◽  
Kinetics Of

The adsorption and photodegradation of cationic and anionic dyes by TiO2-chitosan nanocomposites have been studied. This study investigated the specific surface area, pores volume, pores size of TiO2-Chitosan nanocomposite, and determination kinetics of the reaction on the adsorption and photodegradation process. The methods were carried out by mixing TiO2-nanocomposite into cationic and anionic dyes in various contact times and initial dye concentrations. The results showed that nanocomposite adsorption capacity increased with an increase in the amount of chitosan (TiO2/Chit 0.13) even though the specific surface area (SBET) was reduced. The results indicated that the adsorption on nanocomposite was influenced by the amount of -NH2 and -OH on the chitosan surface. The maximum adsorption capacity (qm) and the observed reaction constant (kObs) for MO were also known to be higher than MB, which means that the TiO2-chitosan nanocomposites could remove anionic dye more than cationic one.

POTASSIUM CARBONATE-TREATED PALM KERNEL SHELL ADSORBENT FOR CONGO RED REMOVAL FROM WATER

2015 ◽  
Vol 75 (1) ◽  
Author(s):  
Lee Lin Zhi ◽  
Muhammad Abbas Ahmad Zaini
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Potassium Carbonate ◽  
Congo Red ◽  
Palm Kernel ◽  
Surface Functional Groups ◽  
Palm Kernel Shell ◽  
Pseudo Second Order ◽  
Kinetics Of

This work was aimed to evaluate the adsorptive characteristics of potassium carbonate-treated palm kernel shell adsorbent for the removal of congo red from water. The adsorbent was characterized according to the specific surface area, surface morphology and surface functional groups. The bottle-point technique was employed to investigate the equilibrium uptake and the adsorption kinetics of congo red, and the removal mechanisms were proposed from the widely used isotherm and kinetics models. Results show that the specific surface area of adsorbent increased after the treatment rendering the maximum congo red uptake of 8.0 mg/g. The removal of congo red obeyed Langmuir isotherm and pseudo-second-order kinetics model suggesting the chemically-attributed homogeneous adsorption. Regeneration of congo red-loaded adsorbent by irradiated water showed a better regeneration efficiency of 82%. Palm kernel shell is a promising adsorbent candidate for congo red removal from water.

Preparation and Hydration Kinetics of Pure CaAl2O4

1991 ◽  
Vol 245 ◽  
Author(s):  
M. A. Gulgun ◽  
O. O. Popoola ◽  
I. Nettleship ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Single Phase ◽  
Hydration Kinetics ◽  
Phase Pure ◽  
Microscopy Techniques ◽  
Kinetics Of

ABSTRACTSingle phase, pure monocalcium aluminate (CaAl2O4) powders are chemically synthesized at temperatures as low as 900°C. The powders have a specific surface area of approximately 10 m2/g. The hydration kinetics of CaAl2O4 and the morphology of the hydrates are analyzed using electron microscopy techniques

scholarly journals Metal Foams as Novel Catalyst Support in Environmental Processes

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 587 ◽  
Author(s):  
Anna Gancarczyk ◽  
Katarzyna Sindera ◽  
Marzena Iwaniszyn ◽  
Marcin Piątek ◽  
Wojciech Macek ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mechanical Stability ◽  
Packed Bed ◽  
Metal Foams ◽  
High Porosity ◽  
Slow Kinetics

Metal foams are considered as promising catalyst carriers due to their high porosity, large specific surface area, and satisfactory thermal and mechanical stability. The study presents heat transfer and pressure drop experiments performed for seven foams of different pore densities made from diverse metals. Mass transfer characteristics are derived using the Chilton–Colburn analogy. It was found that the foams display much more intense heat/mass transfer than a monolith, comparable to packed bed. Next, the foams’ efficiencies have been compared, using 1D reactor modeling, in catalytic reactions displaying either slower (selective catalytic reduction of NOx) or faster kinetics (catalytic methane combustion). For the slow kinetics, the influence of carrier specific surface area at which catalyst can be deposited (i.e., catalyst amount) was decisive to achieve high process conversion and short reactor. For this case, monolith appears as the best choice assuming it’s the lowest pressure drop. For the fast reaction, the mass transfer becomes the limiting parameter, thus solid foams are the best solution.

scholarly journals Investigation of sintering kinetics of ZnO by observing reduction of the specific surface area

2007 ◽  
Vol 39 (3) ◽  
pp. 259-265 ◽  
Author(s):  
S. Stevanovic ◽  
V. Zeljkovic ◽  
N. Obradovic ◽  
N. Labus
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Arrhenius Equation ◽  
Sintering Process ◽  
Sintering Time ◽  
Activation Energy Of Sintering ◽  
Zno Powder ◽  
Parameter Values ◽  
Kinetics Of

Reduction of the specific surface area of porous ZnO during the sintering process was studied. ZnO powder was sintered at temperatures from 673 K to 1173 K. The decrease in the specific surface area was observed as a function of temperature and sintering time. Two different models were involved in order to define the appropriate parameters. The Arrhenius equation was used to give information on the activation energy of sintering. The LSE method was applied for determining optimum parameter values.

Sign in / Sign up

Export Citation Format

Share Document