Authors:K. Shang, Y. Yang, J. Guo, W. Lu, F. Liu, and W. Wang
The extraction of cobalt by Winsor II microemulsion system was studied. In the bis (2-ethylhexyl) sulfosuccinate sodium salt
(AOT)/n-pentanol/n-heptane/NaCl system, AOT was used as a anionic surfactant to form microemulsion in n-heptane, n-pentanol was injected in the microemulsion as a cosurfactant. Co(II) was found to be extracted into the microemulsion phase
due to ion pair formation such as Co2+(R–SO3−)Cl. The influence of different parameters such as the volume ratio of aqueous phase to microemulsion, surfactant concentration,
pH of the feed solutions, cosurfactant concentration as well as temperature on the extraction yield (E%) were investigated. The results showed that it was possible to extract 95% of cobalt by the AOT Winsor II microemulsion.
Authors:Yuelun Wang, Bo Hou, Jiangang Chen, and Yuhan Sun
The Fischer–Tropsch (FT) synthesis is a process of hydrocarbon production from carbon monoxide and hydrogen. Cobalt-supported catalysts are currently preferred over Fe-based systems due to their superior
throughout the organic matrix. The resin is then calcined to produce the desired oxides [ 22 ].
Cerium ammonium nitrate, (NH 4 ) 2 Ce(NO 3 ) 6 , copper nitrate, Cu(NO 3 ) 2 ·3H 2 O, and cobalt nitrate, Co(NO 3 ) 2 ·6H 2 O, were used as precursors. The
To study the sorption behavior of Co(II) on soil and soil components such as birnessite, humic acid (HA) and their mixture,
a series of experiment were conducted using the batch equilibrium technique on parameters such as equilibrium time, ionic
strength, solution pH, and temperature. The soil samples collected from location near radioactive waste repository in Korea
were used and birnessite was synthesized using a method by McKenzie for experiment. The experimental results indicate that
Co sorption on soil, birnessite and soil with birnessite are strongly affected by the pH of solution. Typical for metal sorption
to soils, the fraction of Co adsorbed increased as a function of pH at the experimental conditions. For sorption isotherm,
the Freundlich equation provides a good fit for sorption on soil and soil with birnessite. Adsorption of HA on birnessite
decreased with increase of pH, with a sharp decrease at pH 5–6. From Co sorption experiment in a ternary system of Co, birnessite,
and HA, the presence of HA enhanced Co adsorption at pH below 6.5 and reduced the Co sorption at the intermediate and high
Authors:Yuelun Wang, Bo Hou, Debao Li, Jiangang Chen, and Yuhan Sun
Fischer–Tropsch synthesis (FTS) is a part of gas-to-liquids (GTL) technology, which produces clean fuels from natural gas. Cobalt-based FTS catalysts are usually preferred for the synthesis of long-chain paraffins
Raney metal type catalysts are prepared by leaching the reactive material out from alloys of catalytically active transition metals such as nickel, cobalt, iron, copper and a reactive material such as aluminum with
, the potential commercial cobalt catalysts are typically composed of four components: Co metal, a small amount of a second metal, oxide promoters (alkali, rare earth, and/or transition metal oxide such as ZrO 2 ) and supports (silica, alumina or titania
Sorption of Co on bentonite has been studied by using a batch technique. Distribution coefficients (Kd) were determined for the bentonite-cobalt solution system as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Radushkevich equations. Thermodynamic parameters for the sorption system have been determined at three different temperatures. The positive value of the heat of sorption,
H0=22.08 kJ/mol at 298 K shows that the sorption of cobalt on bentonite is endothermic, where as the negative value of the free energy of sorption,
G0=–10.75 kJ/mol at 298 K shows the spontaneity of the process.
G0 becomes more negative with an increase in temperature which shows that the sorption process is more favourable at higher temperatures. The mean free energyE
7.7 kJ/mol for sorption of cobalt on bentonite shows that ion-exchange is the predominant mode of sorption in the concentration range of the metal studied i.e. 0.01 to 0.3 mol/dm3. The presence of some complementary cations depress the sorption of cobalt on bentonite in the order of K+>Ca2+>Mg2+>Na+. Some organic complexing agents and natural ligands also affect the sorption of cobalt. The desorption studies with ground water at low cobalt loadings on bentonite show that about 97% metal is irreversibly sorbed.
Radiolysis of aqueous solution of di and trivalent cobalt with 1:2 (bis) carboxymethylaminodiethyltetraacetic acid (EGTA)
was investigated, both in absence and in presence of oxygen. A radiolytic mechanism has been proposed. It has been shown that
the degradation at the ligand of the chelate is due to OH only.
synthesis and characterization of cobalt(0) nanoclusters stabilized by HPO 4 2− or poly(acrylic acid), PAA, as well as their use as catalysts in hydrogen generation from the hydrolysis of sodium borohydride (NaBH 4 ). The HPO 4 2− ion was preferred as an