Selective removal of dibenzothiophene from commercial diesel using manganese dioxide-modified activated carbon: a kinetic study
2015
Safieh, Kayed A Abu | Al-Degs, Yahya S. | Sunjuk, Mahmoud S. | Saleh, Abdullah I. | Al-Ghouti, Mohammad A.
With a total concentration of 7055 mg S/kg fᵤₑₗ, the content of organosulphur compounds (OSCs) in local diesel is 20 times higher than the regulated value. Analysis revealed that 30% of OSC is originated from dibenzothiophene (DBT). It is known that DBT is a hardly removable compound and selective adsorbents are often needed for its removal with low affinity for other diesel components. In this work, a selective adsorbent based on surface modification of activated carbon (AC) by MnO ₂ is prepared for DBT removal from diesel. The porous nature of AC enabled carrying large amounts of MnO ₂ particles to end up with a selective adsorber for DBT. The best performance was observed at a surface loading of 26.8% of Mn and DBT is favourably removed over mono- and diaromatics hydrocarbons in diesel. Adsorption kinetics of DBT is studied under a high initial concentration of 835–11,890 mg/kg and at a ratio of 11 cm ³/g (diesel:carbon). The results indicated a fast removal process after surface modification where 96% of the surface is occupied within 30 min of interaction. Kinetic data were best presented by reaction-based models with low prediction error sum of squares values 0.5–47.0, while, diffusion-based models showed limited application for modelling DBT adsorption. Accordingly, adsorption process is controlled by surface reactions and pore diffusion has a minor role in the overall process. The modified adsorbent is satisfactorily regenerated using n -hexane at 65°C.
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