Preparation And Its Adsoprtion Properties Of Activated Carbon From Stellera Chamaejasme L

In this thesis, high-efficiency activated carbon was prepared from biomass resorce, i.e. poisonous plant Stellera chamaejasme L, via one-step process using phosphoric acid solution as the activation agent. And the orthogonal experiment was designed to investigate the effects of activation agent concentration, the ratio of the raw material and phosphoric acid solution, the carbonization and activation time, and the activation temperature on the yield of the activated carbon as well as its adsorption capacities for iodine and methylene blue. The best conditions are as follows: the concentration of phosphoric acid solution was 50%, activation temperature was 400?, impregnation ratio was 1:4 g·ml-1, and time for activation was 60 min. Characteristics of the activated carbon prepared under this condition are as follows: the yield of the activated carbon is 57.41%, 1067mg·g-1 of iodine adsorption, 375mg·g-1 of methylene blue adsorption and 2.95% of ash content.The distribution of the pore size,total pore volume and the specific surface area of the Stellera chamaejasme L activated carbon were characterized by nitrogen adsorption-desorption measured by specific surface area and pore size analyzer, and based on the BJH and BET principles,the activated carbon prepared under the optimal condition has 1370 m2·g-1 of BET specific surface area, 3.18 nm of average pore diameter, and 87% of mesopores. The carbonation processes of Stellera chamaejasme L raw materials and Stellera chamaejasme L soaked in phosphoric acid were studied with TG analysis. The pore structural results, surface structure and surface functional groups of the Stellera chamaejasme L activated carbon were characterized by nitrogen adsorption-desorption, SEM, FT-IR, XRD and XPS, respectively.The static experimental method, concerning different conditions of the dosages of activated carbon, contact time, temperature, initial concentration and pH, was used to investigate the decoloration ability to the caramel solution and the removal efficiency to the phenol solution. The experiment result showed that the best decolorization level for caramel solution was 114% under the corresponding decolorization condition : the amount of activated carbon 1g·L-1, the adsorption time 30 min, the adsorption temperature 60 ? and the initial concentration 2g·L-1. In different initial concentration of phenol solution, the larger amount of activated carbon was added, the longer balanced adsorption time would be. When the pH was 3~8, Stellera chamaejasme L activated carbon had a relative large balanced adsorption amount to phenol solution. This adsorption amount would decrease when the pH of the phenol solution was larger than 8. The adsorption model of Stellera chamaejasme L activated carbon to the phenol solution accorded with Langmuir isotherm adsorption model. Based on Langmuir isotherm, the adsorption process belonged to molecular layer adsorption and the largest adsorption amount was 349.65 mg·g-1, and the adsorption dynamics followed secondary dynamics model. Based on the above results, the adsorption mechanism which reveals the structure-function relationship between activated carbon and adsorbate was discussed. This research provided theoretical guidance on the recycling use of Stellera chamaejasme L and the application of activated carbon.