Air Oxidized Activated Carbon Catalyst for Aerobic Oxidative Aromatizations of N-Heterocycles

A simple “reagent-free” thermal air treatment turns active carbon into a mildly oxidized material with an increased quinoidic content that catalytically dehydrogenates saturated N-heterocycles to the corresponding aromatic compounds. Additional...

The interaction of metallic ions onto activated carbon surface using computational chemistry software

Activated carbon was prepared from the seeds of aguaje palm ( Mauritia flexuosa L.f.) by a chemical activation with phosphoric acid. This activated carbon was used for adsorbing metal ions: Pb(II), Cd(II), and Cr(III). To understand the mechanism of adsorption of these heavy metals (Cr, Cd, and Pb), the activated carbon surface was oxidized with nitric acid (1 M) increasing the oxygenated surface groups showing an increasing in their adsorption capacities of these metals. The oxidized activated carbon slightly increased the maximum adsorption capacity to 5–7%. The order of adsorption for unoxidized and oxidized activated carbons was Pb> Cd> Cr. This experimental information was corroborated by molecular modeling program Hyperchem 8 based adsorption mainly on two factors: the electron density and orbitals—highest occupied molecular orbital and lowest unoccupied molecular orbital.Activated carbons were characterized by adsorption/desorption of N2, obtaining an increase of microporous surface area for oxidized activated carbon. An increase of surface acidity and a reduction of isoelectric points were observed in oxidized activated carbon. According to these results, the adsorption of metal ions is favored in contact with an oxidized activated carbon, which has more amount of phenolic and carboxylic functional groups. Similarly, decreasing the isoelectric point indicates that the surface has a higher negative charge. The surface information was corroborated by Hyperchem, which indicates that the surface of the oxidized activated carbon has a higher electron density, indicating a larger amount of electrons on its surface, which means the surface of oxidized activated carbon charges negatively and thereby attracts metal ions.

Toluene adsorption on porous Cu–BDC@OAC composite at various operating conditions: optimization by response surface methodology

The work presented here describes the synthesis of Cu–BDC MOF (BDC = 1,4-benzenedicarboxylate) based on oxidized activated carbon (microporous Cu–BDC@OAC composite) using an in situ method.

MODIFICATION OF OXIDIZED ACTIVATED CARBON SURFACE BY Fe AND Mn FOR ARSENIC REMOVAL FROM AQUEROUS SOLUTION

Carboxylate groups on oxidized activated carbon surface were transformed to the forms of Mn2+ and Fe3+ (signed as OAC-Mn and OAC-Fe respectively) through multi-step procedure. This modified activated carbon then was used as an adsorption material for arsenic removing from aqueous solution. Synthetic water containing As(III) and As(V) was used for study of arsenic adsorption capacities of OAC-Fe and OAC-Mn. The similar study had also been done with original granular activated carbon for comparison. The effects of modified metals onto oxidized activated carbon, metals doses and initial arsenic concentration on the removal of As(III), As(V) have been surveyed and discussed. Batch adsorption experiments were carried out with arsenic concentration in the range of 1 – 50 mg/l. Langmuir models were used for the adsorption isotherm screening. The results showed that both of OAC-Fe and OAC-Mn have good adsorption capacities for As(III) but OAC-Fe has a greater removal capacity for As(V) than OAC-Mn. OAC-Mn was identified as a good material for the of As(III) removal, because of its oxidation efficiency of As(III) to As(V) during adsorption process.