Author(s): Lan T. N. Pham; Van T. Nguyen
Linked Author(s): Van-Thanh-Van Nguyen
Keywords: Ctivated carbons; Agricultural wastes; Pyrolysis; Wastewater treatment; Heavy metals
Abstract: Production of activated carbons (activated charcoal) from agricultural wastes is one of the good methods to solve the environmental problems caused by burning and getting rid of the crop wastes: emission of CO 2 into the atmosphere-the main reason of the global climate change, pollution of air and inhibition of the vision, etc. . . Besides, there is a great economical value of recycling the corn cob and rice straw to produce activated carbons which have many applications for treatment industrial wastewaters. In this study, a series of activated carbons experiments were done from the agricultural waste corn cob and rice straw by the chemical activation using phosphoric acid, sulfuric acid, zinc chloride and potassium hydroxide as activating agents. Many factors affecting the process have been studied such as the pyrolysis temperature, soaking time and chemical treatment of the raw materials through the impregnation ratio of the production of adsorbent in order to determine the optimal conditions. As the results, the important parameters in the chemical activation of corn cob and rice straw with ZnCl 2, KOH, H 3 PO 4, H2SO4 are the impregnation ratio and the pyrolysis temperature. Under the experimental conditions in the laboratory, the temperature of 350oC for pyrolysis process and of 550oC for activation during 120 minutes with phosphoric acid and sulfuric acid were found to be the optimal condition for producing high surface area carbons in the range of 982-1234 m 2 /g. The activated carbons produced in this work were used as an excellent sorbent to remove color and heavy metals: copper (Cu 2+), iron (Fe 2+), zinc (Zn 2+), Chromium trivalent (Cr 3+) from various wastewaters such as: as metal plating, mining, tanneries.