Tailoring activated carbons for the development of specific adsorbents of gasoline vapors.
The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.
Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
J F
JF
Vivo-Vilches
E
E
Bailón-García
A F
AF
Pérez-Cadenas
F
F
Carrasco-Marín
F J
FJ
Maldonado-Hódar
D000327:Adsorption; D061808:Air Filters; D000393:Air Pollutants / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D004058:Diffusion; D052918:Environmental Restoration and Remediation; D004867:Equipment Design; D000431:Ethanol / Q000737:chemistry; D005740:Gases; D005742:Gasoline / Q000032:analysis*; D006358:Hot Temperature; D006878:Hydroxides / Q000737:chemistry; D009795:Octanes / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D016062:Porosity; D017680:Potassium Compounds / Q000737:chemistry; D013499:Surface Properties; D055549:Volatile Organic Compounds / Q000737:chemistry
D000393:Air Pollutants; D002264:Carboxylic Acids; D005740:Gases; D005742:Gasoline; D006878:Hydroxides; D009795:Octanes; D017680:Potassium Compounds; D055549:Volatile Organic Compounds; D000431:Ethanol; D002244:Carbon; D010100:Oxygen; C029943:potassium hydroxide; C026728:octane
Activated carbons; Breakthrough curves; Porosity; Surface chemistry; Thermal desorption; VOC adsorption