Preparation And Adsorption Properties Of Jute-based Activated Carbons

Activated carbons are excellent adsorption materials with highly developed inner porous structure and high specific surface area. Thus they have been widely used in various fields such as air purification, solvent recovery, wastewater treatment, catalyst carrier. In recent years, with the expanding of application fields of activated carbons and worsening of energy problems, more and more researches have been made to seek abundant and renewable raw materials. Jute fibers, which have porous and hollow structure as well as higher lignin content, are promising raw materials for preparing activated carbons. In addition, the use of jute fibers in activated carbons production can not only increase the added value of the jute industry chain, but also save valuable timber and coal resources, thus it has an important economic significance. China is the third largest producer of jute in the world and has abundant jute resources, however, few reports have been made on the use of jute resources in activated carbons production. In this study, different jute resources were used as raw material to prepare activated carbons, aiming to fill the research gap on preparation and adsorption properties of jute-based activated carbons.In this study, various jute-based activated carbons were prepared by using fully degummed jute fibers, half degummed jute fibers or jute sticks as raw materials and phosphoric acid as activating agent. A tube type resistance furnace and a microwave oven were used as the activation apparatus, respectively. The effects of several main factors namely concentration of activating agent, activation temperature and activation time on the yield and adsorption properties of active carbon fibers were investigated by adopting single factor analysis method. Results showed that with the increase of the phosphoric acid concentration, activation temperature or microwave power as well as activation time, the yield decreased, while the iodine adsorption value, methylene blue adsorption value, benzene adsorption rate, carbon tetrachloride adsorption rate firstly increased and then decreased. Compared with the activated carbons prepared on a microwave oven, the activated carbons prepared on a tube type resistance furnace had better adsorption properties. However, the microwave heating method can obviously shorten the activation time and save energy.The preparation parameters of jute-based activated carbons were optimized via orthogonal experiments to obtain optimum adsorption properties. Besides, specific surface area and pore structure of jute-based activated carbons were analyzed using an automatic adsorption analyzer via t-plot and BJH methods. Moreover, the morphology, surface chemical structure and thermal properties of jute-based activated carbons were analyzed using scanning electron microscope (SEM) observation, FT-IR analysis and thermogravimetric analysis, respectively.The adsorption behaviors of fully degummed jute fiber activated carbons prepared under optimized conditions on methylene blue (MB) and methyl orange (MO) dye solutions were studied and emphases were laid on the effects of the initial concentration and initial pH value of the dye solutions, the dosage of activated carbons, adsorption time and the temperature of the dye solutions on the adsorption properties of jute fiber-based activated carbon. Besides, adsorption kinetics of fully degummed jute fiber activated carbons on the two dye solutions were further investigated. Results showed that the adsorption behaviors of fully degummed jute fiber activated carbons on both MB and MO fitted well with Pseudo-second-order kinetic model.