Adsorption Dynamics Of VOCs On Activated Carbon Fixed Bed

Nowadays the speed of industry developing is increasing, and at the same time theemission of pollutants is also on the rise. Pollution governance is increasingly becoming thefocus of attention. VOCs as one of the main sources of air pollution, the harm is enormous.Organic waste gases released to the air not only pollute the environment, but also causedamages to the human body. So VOCs pollution control has become a hot topic of study. Atpresent, the adsorption technology is widely used in chemical, pharmaceutical, electronics,and other industries exhaust treatment, and also a variety of indoor air purification process,owing to convenient operation and simple process. Because of the wide range of diversenatures and wide range, the applications of VOCs in the industry are extensive. P-xylene isone of the most representative compositions of VOCs. A systematic study of adsorptionperformance on activated carbon for p-xylene and fixed bed adsorption dynamics was madein this article, and a foundation for industrial application was laid.P-xylene was selected as adsorbate system and granular activated carbon was selected asabsorbent material in this article. Dynamic gas-mixing and fixed beds were built, gaschromatography was used for the quantitative analysis of organic gas. The effects of theinitial concentration of the gas, volume flow rate, adsorption temperature, bed factors such aslength through the curve were investigated. The experimental results showed that, as theincreasing of the initial concentration, the breakthrough time is shorter, and the adsorptioncapacity of activated carbon also improved; the effects of gas flow on the shape ofbreakthrough curves were little, improving the gas flow properly, the breakthrough time isshorter and can increase the absorption capacity, but when the gas flow were too large, theabsorption capacity would reduce. As the temperature increases, the breakthrough time willbe shortened and also reduce the adsorption. The variation of temperature had no effects onthe shape of breakthrough curves and just made the breakthrough curves shift left and right.The dynamic model of fixed bed were studied. Invalid length of carbon fixed bed wascalculated by using the model of mass-transfer-district length. And the experiment data were fit by Yoon-Nelson model and Thomas model. The results showed that in condition that theinitial concentration and the gas flow were4.368mg/L and8L/min, the invalid length of fixedbed was1.103cm. The results also showed that the adsorption behavior of p-xylene onactivated carbon fixed bed was described by Yoon-Nelson model and Thomas model well.