Preparation Of Activated Carbon From Typha Orientalis And Its Application For Dyes Removal

An activate carbon (TOC) was prepared from a perennial aquatic plant, Typha orientalis by H3PO4 activation and then characterized and tested for its dye adsorption capacities. Mn-impregnated activated carbons (TOC-Mn) were prepared by dipping and heating methods and used for the removal of Netrual Red from aqueous solutions. The effects of modification on carbon surface properties and adsorption capacities were analyzed and batch experiments were carried out to investigate their adsorption progresses and mechamisms. Dye-exhausted carbon was regenerated by thermal treatment and its regeneration efficiencies were studied.The preparation condition of TOC was at a H3PO4 concentration of 40%, an impregnation ratio of 2.5:1, an impregnation time of 12 h, an activated temperature of 450℃, and an activated time of 1 h. A heterogeneous structure in terms of both size and shape was highly developed and widely distributed on the carbon surface. The Brunaue-Emmett-Teller surface area and average pore size of the activated carbon were 1279 m2/g and 5.585 nm, respectively. Some functional groups were formed on the carbon surface. The result of adsorption experiment showed that TOC could effectively remove Neutral Red and Malachite Green, with the adsorption capacities of 194.88 mg/g and 197.94 mg/g, respectively.Three modified activated carbons (TOC-Mn), TOC-MnCl2, TOC-MnSO4 and TOC-Mn(NO3)2 were prepared by dipping and heating methods. The amount of Mn impregnated in the activated carbon was influenced by the anion species. Impregnation with Mn decreased the surface area, changed the pore size and crystal structure, introduced more acidic functional groups such as carboxyl, lactone and phenol groups, and improved the adsorption capacities of carbon. Batch experiments were carried out to further investigate NR adsorption onto TOC-Mn. The results showed that the optimum carbon dose was 0.1 g/100 ml, and the adsorption progresses were not affected by pH except for minor variations over the pH range of 2-6. The adsorption isotherms fit the Langmuir isotherm equation. The maximum monolayer adsorption capacities at 45℃were obtained as 285.71 mg/g from TOC-Mn(NO3)2. Kinetic studies showed that the adsorption reached equilibrium at about 4.5 h and the data followed the pseudo-second-order model. Intraparticle diffusion was not the only rate-limiting step and other processes may affect the adsorption.Dye-exhausted carbon could be effectively regenerated by thermal treatment, and the regenerated carbon still has greater adsorption capacities.