Preparation And Regeneration Of Novel Activated Carbon Composite Adsorbents With High Thermal Conductivity

The removal of volatile organic compounds (VOCs) prior to their emission into theatmosphere is a serious challenge in environmental protection. One of reliable methods torevover VOCs for reuse is by adsorption with porous adsorbents, whileactivated carbons arethe most widely used materials, but limited by a lack of regenerative ability.Microwave irradiation produces efficient interal heating by direct coupling of microwaveenergy with molecules, which can be employed as a high-efficiency and low-cost regenerationmethod. However, over heating and even burning will happen during microwave regenerationof the traditional activated carbon, due to the temperature gradientand uniform heat transfer inadsorbent beds, which deriven from the low thermal conductivity of the traditional activatedcarbon. Therefore, development of novel activated carbons with high thermal conductivity isnot only the key point to enhance the regenerative ability of activated carbons, but also ofgreat significance to the microwave regeneration technology.In this paper, a novel activated carbon with high heat thermal conductivity was developedby modification of activated carbon with silicon carbide, and the effects of synthesisparameters, such as activation temperature, activation time, SiC/activated carbon ratio, on thetexture of the SiC/activated carbon composite has been scientificly investigated.And themixed activated carbon with20%silicon carbide (SiC-AC-20) not onlyretained high surfacearea and large pore volume, but also advantaged by its thermal conductivity three times higherthan commercial activated carbon.The adsoption of typical VOCs (toluene) on high heat thermal conductivity activatedcarbon (SiC-AC-20), homemade conventional activated carbon (AC) and commercialactivated carbon (SY-6) was compared, and benefited by its high specific surface area,SiC-AC-20presented a high adsorption capacity of toluene (45.95mg/g), which was close thevalue of SY-6(47.45mg/g).The desorption of toluene from high heat thermal conductivity activated carbon(SiC-AC-20), homemade conventional activated carbon (AC) and commercial activated carbon (SY-6) revealed that the activation energy for desorption of toluene from SiC-AC-20was lowest among three kinds of activated carbons in both cases of conventional heating andmicrowave regeneration. Moreover, activation energy for desorption in microwaveregeneration was much lower than in conventional heating regeneration.After multiple microwave regeneration (five times), high heat thermal conductivityactivated carbon(SiC-AC-20) still presented considerable adsorption capacity of toluene,which was superior to the commercial activated carbon (SY-6). This work not only improvesthe regenerative ability of activated carbons, but also promotes the development ofmicrowave regeneration technology.