Adsorption Behavior Of Light Hydrocarbon VOCs On Activated Carbon

Activated carbon adsorption is widely used for removing Volatile Organic Compounds(VOCs)in the petrochemical industry.Three different types of activated carbon were used to adsorb n-C5 and n-C6.Various characterizations such as Brunner Emmet Teller(BET)measurements,X-ray diffraction(XRD),Fourier Transform Infrared Spectroscopy(FT-IR)are used to research the composition and structural characteristics of activated carbons.The dynamic adsorption behavior was researched as a function of various factors,such as gas hourly space velocity(GHSV),operation temperature and the concentration of VOCs.Results showed that granular coconut shell activated carbon(GCSAC),flake coconut shell activated carbon(FCSAC)and granular coal activated carbon(GCAC)are similar in composition,but different in specific surface area and total pore volume.FCSAC has larger micropore volume ratio.The adsorption capacity of the alkanes was not strong affected by the GHSV in the condition of low GHSV.However,GHSV has a great influence on the dynamic penetration capacity(DPC).The penetration and saturation time decrease,and the adsorption capacity decreases with the rising of temperature.Variation of VOCs concentration has a great effect on DPC,but not greatly impact on the dynamic saturation capacity(DSC).Then,the binary competitive adsorption behavior of n-C5 and n-C6 was studied.The effect of GHSV and the ratio of n-C5 to n-C6 on the binary competition process were investigated.In the binary competitive adsorption,n-C5 is a weak adsorbate which is easily replaced by the strong adsorbate n-C6.Compared with the single adsorption,DPC and DSC of n-C5 decreased significantly,and the DPC and DSC of n-C6 were not significantly changed.The decrease of GHSV resulted in a decrease of DSC of n-C5,and a slight increase of DSC of n-C6.The DPC of n-C5 and n-C6 were both slightly increased in the binary adsorption when the concentration of n-C6 was decreased.Finally,several regeneration methods of activated carbon were studied,including nitrogen purging,microwave regeneration and vacuum regeneration method.The vacuum regeneration method was found to have a better regeneration effect.The effects of temperature and regeneration time on regeneration were investigated experimentally.It was found that the recycle FCSAC regenerated under 200 ?,95 kPa vacuum for 2 hours has a good adsorption property.The regeneration rates of DPC and DSC of n-C5 were 50.07%and 69.60%,respectively.The recovered rates of DPC and DSC of n-C6 were 61.63%and 76.42%,respectively.The first order kinetics fitting of the adsorption data was performed.The adsorption rate constant of regenerative FCSAC was consistent with that of fresh FCSAC.After 5 times regeneration,the regeneration rate of DPC and DSC of n-C5 was 24.61%and 47.53%of the fresh active carbon,respectively.The regeneration rate of DPC and DSC of n-C6 was 20.07%and 54.96%,respectively.