Study On The Modification Of Activated Carbon And Its Adsorption Capacity Of VOCs

In this paper,modification of activated carbon through microwave,electric direct heating,sodium hydroxide and nitric acid were studied,and the adsorption capacity of toluene and butanone on modified activated carbon were carried on at the same time.Study of modification of activated carnon by microwave shows that surface acidic functional groups of activated carbon decreases and alkalescent functional groups and iodine adsorption value of activated carbon increase with the increase of modification temperature,at the same time,more open channels in activated carbon are observed. Comparision of activated carbon modified with unmodified indicates that the adsorption capacity of modified activated carbon is larger than the original,and the largest increase is 28.3%and 32.9%for the MW850,and longer time to reach saturation adsorption, while the adsorption of MW450 and MW650 is to some tune,but they are larger than the original quality.Direct electric heating experiments of modified activated carbon adsorption show that modification of the temperature the higher,the acid content of activated carbon surface functional groups containing lower,alkalescent functional group and the iodine adsorption value increase,and significantly more open pore.Saturated adsorption capacity OF EH850 to toluene and butanone is the largest(249mg/gAC and 240mg/gAC respectively),while the adsorption capacity of EH650 and EH450 have very small difference.Modification by sodium hydroxide results in the change of surface oxygen functional group,and the concentration of sodium hydroxide is the dominant factor of change.Experimental results indicate that the higher of the concentration,the fewer of oxygen acidic functional group,while the proportion of oxygen-containing basic functional groups bigger and polarity increasing;Below the concentration of 10%,the modified activated carbon adsorption capacity of toluene is enhanced,but adsorption capacity gradually weakened with the increased concentration.When the concentration above 10%,the adsorption capacity of the modified activated carbon is lower than the original.The oxygen functional group content of acid-base in activated carbon surface change with the different concentrations of nitrate after modification by nitric acid. Results show that saturation adsorption capacity of midifies activated carbon to toluene and butanone decrease with the increase of nitric acid concentration,for toluene, with largest decrease more than 50%and saturation time 2.3h,shortening more than 1.5h than the original,while forbutanone,with the largest decrease about 52%,saturation time 2.4h,shortening 1.6h than the original.