Adsorption Of 2,4,6-trichlorophenol From Aqueous Solution Onto Activated Carbon Derived From Loosestrife

An activated carbon was prepared from the stalk of the scrap aquatic plant loosestrife employing H3PO4 as activator Physical structure and chemical properties were evaluated from specific surface area, pore size distribution, Fourier-transform infrared spectroscopy (FTIR) and Boehm titration. Then, its ability to adsorb 2,4,6-trichlorophenol (2,4,6-TCP) was also appraised. The effects of solution pH, agitation time,2,4,6-TCP initial concentration, and temperature on 2,4,6-TCP adsorption were investigated. The activated carbon was regenered by alcohol to study the recycling rate. On the basis of adsorption properties, adsorptive mechanism was futher discussed.The optimum conditions for producing the activated carbon were as follows. H3PO4 solution 40 wt.%, loosestrife to H3PO4 2.5:1, Soaking time 12h, heating rate 18℃/min, activation temperature 450℃, activation time 1h. The results of Brunauer-Emmett-Teller surface area and average pore size showed that the activated carbon had 1255.75m2/g of surface area and 1.20cm3/g of total pore volume. The functional groups were formed on the carbon surface, and the carboxyl group and phenolic hydroxyl group were the major oxygen-containing group. The results of adsorption experiment suggested that 2,4,6-TCP could be effectively removed with high adsorption capacities.The results also showed that the optimum dosage was 0.1g/100ml. The adsorption capacity was not affected by pH from 2～natural value, and at the range of natural～12, the adsorption capacity was decreased. Kinetic researches indicated that the adsorption equilibrium time was obtained about 5～6h. Other kinetic processes were also occurring and contributed to the adsorption properties. Compared.to the Freundlich and Langmuir isotherm model, the Temkin isotherm equation is more appropriate to the adsorption data. The adsorption is considered to be an exothermic (△H<0) process.Spent activated carbon could be regenerated effectively by alcohol. The regenerated carbon still has greater adsorption capacities, and it is a promising adsorbent for water treatment.