Novel cobalt–carbon@silica adsorbent

Abstract

Recently, carbon nanostructures are of high importance due to their unique characteristics and interesting applications. Pyrolysis of anthracene with cobalt complex Co(2,2′-bipy)Cl2(1), where (2,2′-bipy) is 2,2′-bipyridine, in the absence and presence of silica gave in high yield cobalt-carbon nanocomposite CoCNC (2) and CoCNC@SiO2(3) at 600 °C and 850 °C, respectively. They were characterized using SEM, TEM, PXRD, Raman and XPS. (3) and (2) contain core–shell cobalt(0)/cobalt oxide-graphite with or without silica support. PXRD indicates that (2) contains crystalline hexagonal α-Co and cubic β-Co phases while (3) contains only cubic β-Co phase and silica. The structure of (2) is 3D hierarchical carbon architecture wrapping spherical and elliptical cobalt nanoparticles. (3) consists of graphitized structures around cobalt nanoparticles embedded in the silica matrix. XPS reveals that the nanocomposites contain oxygen functional groups that enhance uptake of cationic dyes. CoCNC@SiO2(3) has higher capacity and thus is better adsorbent of Basic Violet 3 than CoCNC (2). The Langmuir adsorption capacity of (3) is 19.4 mg g−1 while column capacity is 12.55 mg g−1 at 25 °C. Freundlich isotherm and pseudo-second-order kinetic models fit well the adsorption data. Thermodynamics indicate that adsorption(3) is exothermic. Column regeneration was tested for three cycles and Yan et al. was found the best kinetic model.

Photodegradation of Congo Red by Modified P25-Titanium Dioxide with Cobalt-Carbon Supported on SiO2 Matrix, DFT Studies of Chemical Reactivity

“…TEM of CoC@SiO 2 show a graphitized structure around the cobalt nanoparticle embedded in the silica matrix. This was observed in CoC@SiO 2 -bipy (s1) [19] and CoHGC@SiO 2 [20]. CoC@SiO 2 -bipy (s1) showed a moderate BET surface area of 98 m 2 /g [19], while CoC@SiO 2phen should have a higher surface area, since CoHGC@SiO 2 showed 144.8 m 2 /g for BET surface area [20].…”

“…These types of structures can have high specific surface areas [18]. Co 2+ and Co 3+ ions appeared in XPS analysis of CoC@SiO 2 -bipy (s1) prepared from pyrolysis of cobalt bipyridine chloride [19] and XPS of CoHGC@SiO 2 prepared from cobalt phenanthroline sulfate complex [20] indicating that some cobalt atoms were oxidized to Co 3 O 4 . However, PXRD of these nanocomposites showed the presence of metallic cobalt (0).…”

Hierarchical Porous Carbon Cobalt Nanocomposites-Based Sensor for Fructose

“…Peak at 690 cm −1 was observed in Raman of HPC-Co and accompanied by two weaker peaks at ~ 510 cm −1 and ~ 480 cm −1 . This is characteristic of Raman active modes of micro-and nano-crystalline Co2O3 [30]. XPS analysis of HPC-Co nanocomposite confirms the existence of three elements with atomic percentage, cobalt Co 2p3/2 (3.99%), oxygen O 1s (24.83%) and carbon C 1s (71.18%), (Figure 8).…”

“…Peak at 690 cm −1 was observed in Raman of HPC-Co and accompanied by two weaker peaks at~510 cm −1 and~480 cm −1 . This is characteristic of Raman active modes of micro-and nano-crystalline Co 2 O 3 [30]. pore size distribution curve of (1) and (c) BJH pore size distribution curve of (2).…”

“…Recently, a simpler method was used to prepare metal/metal oxide carbon nanocomposites from one-step pyrolysis of cobalt and nickel complexes. It is interesting that these nanomaterials have wide application in water treatment [28][29][30][31], sensors [32] and electrochemical detection of organic molecules [21], electrocatalysis [33][34][35], and supercapacitor [36].…”