Modification Of Activated Carbons And Its Adsorption Capability For Toluene And Acetone

In recent years, due to the huge hazards in environment and human health, VOCs pollution causes for persons concern increasingly. Treatment methods of VOCs are also various, including absorption, adsorption, condensation, combustion and biochemical method, etc. Activated carbon adsorption is one of the most economical and mature method.Activated carbons were modified with three different acid and alkali solution. The physical structure and surface chemistry were characterized.One-component and two-component adsorption capability on activated carbons were measured which toluene and acetone were used as adsorbates. The results showed that adsorption capacity for toluene and acetone were improved on activated carbons modified with NaOH and NaHCO3, and the modification of HNO3 were directly opposite. Adsorption capacity for toluene was increased to maximum 153.3mg/g when activated carbons modified with 0.25mol/L NaOH. Saturated adsorption capacity for acetone was increased to maximum 132.6 mg/g when activated carbons modified with 0.25mol/L NaHCO3. The adsorption capacity for toluene was improved with increase of the basic group content, but it decreased with increase of acid groups content. Surface area, pore volume, pore size distribution and surface groups together determined the adsorption capacity of activated carbons. Competitive adsorption appeared of the two-component adsorption of toluene and acetone.Acetone which had been adsorbed could be replaced by toluene, it indicated that the adsorption capacity for toluene was stronger than that for acetone.The adsorption isotherms of toluene and acetone were measured on activated carbons of modification. The adsorption experimental data were processed by Langmuir and Freundlieh isotherm equations. The results showed that he adsorption process on activated carbons of toluene and acetone could be well described by these two equations, which indicated that the adsorption was monolayer adsorption and mainly adsorbed in microporous. Compared with unmodified activated carbons, modification of activated carbons could only change adsorption capacity for toluene and acetone but not the adsorption mechanism.The effect of inlet concentration and inlet flow and column bed height on adsorption capacity of activated carbons were studied. The results showed that adsorption time was shorter and adsorption capacity was increased with the increase of inlet concentration. Adsorption time was shorter and adsorption capacity was deceased with the increase of inlet flow. Changes of bed height had little effect on adsorption capacity, and which only can extended the adsorption time.