Effect of liquid-phase O 3 oxidation of activated carbon on the adsorption of thiophene

Luoming Wu, Siddarth Sitamraju, Jing Xiao, Bing Liu, Zhong Li, Michael John Janik, Chunshan Song

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Abstract

In this work, a combined experimental and computational study is carried out to investigate the effect of O 3 oxidation of activated carbon (AC) in various types of aqueous media (alkaline, acidic and neutral aqueous solutions) on the adsorption of thiophene. A high surface area AC (BET surface area of 2880m 2 /g) is modified by ozone-oxidation in different aqueous media under ambient conditions. Experimental results show liquid phase ozone oxidation of AC introduces oxygen functional groups to the AC surface, resulting in enhanced adsorption capacity of thiophene. The impact of oxidation media on the adsorption capacity follows the order of NaOH>H 2 SO 4 >H 2 O, consistent with the order of the concentrations of oxygen functionalities introduced on the carbon surface. Computational results suggest that phenol and carboxyl groups on the surface lead to stronger thiophene adsorption than the bare (unfunctionalized) graphite surface, corroborating our experimental results. Additionally, the presence of bridging-oxygen functionalities on the carbon surface leads to extremely exothermic adsorption energies of thiophene, which can be attributed to sulfoxide formation and H-bonding interactions. DFT calculations suggest the adsorption strength of thiophene follows the order of bridging-O-functionalized (Ads E=-1.51eV)≫OH-functionalized (Ads E=-0.36eV)>COOH-functionalized (Ads E=-0.27eV)>bare graphite (Ads E=-0.26eV). The combined experimental and computational study provides direction for carbon surface functionalization for adsorptive desulfurization.

Original languageEnglish (US)
Pages (from-to)211-219
Number of pages9
JournalChemical Engineering Journal
Volume242
DOIs
StatePublished - Apr 15 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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