Preparation Of Super Finger Citron Residue Based Activated Carbon And Its Performance For CO₂Wet Storage

Super activated carbon is a type of porous material with high adsorption functions. Due to high surface area, high porosity and special surface properties of chemistry, it has been widely applied and extended in gas adsorption and storge fields.In the thesis, finger citron residue was used as raw material to prepare the finger citron residue based activated carbon of high surface area and high porosity by processes which including material pretreatment, carbonization, KOH impregnation and activation in the experiments. The effects of the conditions of material pretreatment, carbonization, weight ratio of KOH to precursor and activation on the iodine number, phenol and methylene blue of finger citron residue based activated carbon were studied in this paper. In the meantime, the structure of as-synthesized activated carbon was characterized by examinations with element analysis, N2adsorption isotherms, XRD, SEM and FTIR analyses, et al. Results shown the best conditions to prepare super activated carbon were pretreatment temperature120℃and time12h; carbonization temperature400℃and holding time2h; activation temperature850℃and time1h; temperature increase rate7℃·min-1and the weight ratio of KOH additives to the carbonized samples5:1. The finger citron residue based activated carbon obtained under these conditions had the pore volume1.60cm3·g-1, BET surface area2887m2·g-1, pore size distribution1.5-4nm, and the adsorbed amount of iodine1352mg·g-1, respectively.The adsorption ability for liquid or gas adsorbates is definitely important to evaluate the potential application of activated carbon. Phenol and methylene blue are usually considered as two typical kinds of water pollutants. The adsorption performances of these two pollutants of the activated carbon were studied in model water in this paper. As a result, the adsorbed amount of phenol and methylene blue were113mg·g-1and320mg·g-1when the initial concentrations of phenol and methylene blue were190mg·L-1and1.6g·L-1; the mass ratios of finger citron residue based activated carbon to the model water were1:625and1:200, respectively. Moreover, target to the serious environmental problem of green house gas CO2,the performance of CO2adsorption and storge was deeply invested in this paper. The CO2adsorption results have shown that the dry sample had a CO2adsorption capacity of19.21mmol9g-1at3℃and3.57MPa. The CO2adsorption uptake increased greatly when some amount of water was pre-adsorbed on the sample, which can be due to the formation of CO2hydrate in the pore spaces of the activated carbon. The maximum CO2adsorption capacity of wet sample was found to be29.02mmol·g-1at0℃and3.57MPa. The CO2hydrate formation enthalpy of finger citron residue based activated carbon was-55.27kJ·mol-1calculated from the Clausius-Clapeyron equation. This value is consistent with that reported previously for CO2hydrate formation in the literatures. This may be taken as confirmation that CO2hydrate is formed inside the pore spaces of the finger citron residue based activated carbon.Overall, this work confirms that finger citron residue was proved to be a promising precursor for super high surface area activated carbon and point to the potential application of finger citron residue based activated carbon in CO2adsorption and storage.