Preparation Of Activated Carobons From Cork By Chemical Activation With H₃PO₄

The activated carbon is a kind of sorbent with high-developed porosity, high adsorption capability, and is extensively used in every aspect of people's life such as industry, agriculture and national defence etc. Recently, the utilization of activated carbon as well as its specific beneficial properties are increased has boomed activated carbon development. In order to meet the market, many scholars work out many a variety of activated carbon. Cork is a specific carbonaceous material with honeycomb structure can been used to produce activated carbon.In this dissertation, the activated carbon is prepared by cork impregnated with H3PO4 and the effect of six experimental parameters, mass ratio, impregnant concentration, activation temperature, activation time, impregnated time, cork particle size, were studied. Base on these, the preferable technologic methods had been established. In addition, the atmosphere furnace used in the experiment is reconstructed from resistance furnace.The results are shown as follows:(1) Results indicate that activation temperature and activation time have significant influence on activated carbon adsorption performance, followed by mass ratio and impregnant concentration, and impregnated time as well as cork particle size has no significant influence.(2) It must be noted that activated carbon which is made from cork has a very low ash content (0.56% to 2.0%) compare with the literature data for the best commercial activated carbon (2%).(3) Mostly, the yield of activated carbon exceeds 30% which is also much higher than that prepared by physical and chemical activation.(4) The use of acid treatment of activated carbon can decrease the ash content as well as the yield. However, the iodine number adsorption and the methylene blue adsorption increase after the acid treatment.(5) The SEM images of activated carbon samples show that the cork structure is extensively modified. The surface of cork is changed, and the honeycomb structure of cork is destroyed. There are also pores on the activated carbon.(6) Experiment results show that the best technologic conditions of preparing activated carbon with cork are the mass ratio of 2.0:1, impregnant concentration of 25～35%, activation temperature of 350～400℃, activation time of 2～3 h, cork particle size of 24 mesh, impregnated time longer than two days. The activated carbon presented a yield of 34.8%, ash content of 0.6%, iodine number adsorption of 423.6 mg/g, methylene blue adsorption of 136.1 mg/g. It is also shown that cork is a good precursor and allows us to prepare activated carbons with mesoporosity well-developed. The activated carbon's methylene blue adsorption is much better than fist class activated carbon in the GB/T 13803.2—1999(135 mg/g).