Study On Preparation Of Flowers And Leaves Based Activated Carbon Materials And Their Adsorption Behaviors

With the prosperous development of social economy, although convenience and comfort daily life bring for us, but our ecosystem is damaged seriously at the same time. Recently, especially the aquatic ecosystem is suffering severe pollution. Activated carbon?AC?, a kind of adsorbent with high specific surface area and excellent adsorption performance, is often used to deal with industrial wastewater. Owing to high cost, its preparation and application have been limited. This paper devotes to prepare the cheap and non-toxic biomass activated carbon, and its application in water treatment. In order to reduce the cost of the raw material and to ensure its abundance, it has been found that AC could be prepared from residues of food industry and biomass wastes. Not only this can avoid the resource waste, but also alleviate the environment pollution. Namely, use the natural biomass wastes?paulownia flowers and ginkgo leaves? as precursor, activated carbon materials with high adsorption performance are prepared, and by further modification, magnetic activated carbon materials are also prepared. Meanwhile, the resulting carbon materials are used to deal with the water pollution which include heavy dye, metal ions and phosphate. The main contents of this paper include the following sections:First, start with how to prepare biomass activated carbon with high specific surface area, we discuss the influence factors of the preparation?the selection of raw materials and activator, impregnation ratio and activation temperature and so on?, kinetic model, isotherm model and the tendency in the future research.Second, to use pretreated paulownia flowers?PF? and ginkgo leaves?GL? as raw materials, PFAC and GLC were prepared by one step carbonization-activation method. The structure and characterization were analyzed by FT-IR, XPS, BET, SEM, TEM and TG. Based on the above results, the pore-forming mechanisms were introduced and discussed in detail. The results showed that the resulting activated carbon materials with hierarchical pores, and posses high specific surface area.Third, adopt methylene blue and phenol as adsorbate models, the studies of the adsorption activity were investigated. The results showed that the MB?300 mg/L? and phenol?50 mg/L? removal ratio of PFAC reach 99.97 % and 99.46 %, respectively. After treatment, effluent could meet the national discharged standards. The equilibrium data of PFAC were fitted with Langmuir isotherm models well, belong to monolayer adsorption. The MB?600 mg/L? removal ratio of GLC reaches 99.87 %, the maximum adsorption capacity is 599.27 mg/g. After treatment, effluent could meet the national discharged standards. The equilibrium data of GLC was fitted with Freundlich isotherm models well, belong to heterogeneous adsorption. The kinetic studies of PFAC and GLC showed that the pseudo second-order rate equation could fit the experimental data well, chemical adsorption play a dominant role.Fourth, to use the prepared ginkgo leaves based activated carbon?GLC? as raw materials, ginkgo leaves based magnetic activated carbon?MG? was prepared by co-precipitation method. The structure and characterization were analyzed by FT-IR, BET, SEM, TG. The results showed that the resulting activated carbon with high adsorption performance and magnetic performance.Fifth, adopt Cu²⁺ and phosphate as adsorbate models, the adsorption activity study of MG was investigated. The results showed that Cu²⁺ and phosphate removal ratio of MG reach 97.72 % and 98.53 %, respectively. After treatment, effluent could meet the national discharged standards. The equilibrium data of MG were fitted with Freundlich isotherm models well, belong to heterogeneous adsorption. The kinetic studies showed that the pseudo second-order rate equation could fit the experimental data well, chemical adsorption play a dominant role.In summary, the biomass wastes were employed as a precursors to prepare three kinds of carbon materials. The prepared carbon materials have high specific surface area and good adsorption performance, and are effective and low-cost adsorbents in water pollution control.