Study On Preparation And Performance Of Activated Carbon From Rice Straw

Activated carbon( AC) is an important adsorbent, and is extensively used in industry such as environmental protection, chemical industry, food processing, pharmaceutical processing, and military chemistry etc. The rice straw is byproducts of rice processing. The rice straw resources are plentiful in our country, but most of them are discarded as waste material or burned out as fuel. The abundant rice straw as agricultural byproduct contains plentiful fixed carbon. It is significant to exploit the application of rice straw.The studies of sorbent were carried out on the preparation of activated carbon from rice straw with chemical abent including ZnCl₂, H₃PO₄, H₂SO₄, K₂CO₃ as activator. By single-factor test and orthogonal test, the activated agent of different kinds and its ratio, laying temperature,laying time,liquor concn,the activate temperature,the activate time,adsorption properties of AC have been investigated. Base on these, the technologic methods and conditions of controlling structure and properties of AC had been established. The morphology of AC is observed by scan electric microscope. X-ray diffraction analyzer analyzes the structure of microcrystal line in AC.Utilizing the activated carbon from rice straw absorb Cu²⁺,Ni²⁺ in water, and also doing some study about Cu²⁺,Ni²⁺ suitable terms of absorbing. The results of this paper are follows:The processing optimum conditions on preparation for activated carbon from rice straw with ZnCl2 chemical activation method were obtained, which was the laying time of 12h, laying temperature of 110℃, the material-to-solution ratio of 1:1, ZnCl₂ concentration of 55% ,activation temperature of 660℃and time of 60min.The yield of the product was to 34%, and the iodine value was to 810mg/g, the decolorant capacity for methylene blue was 90mg/g, caramel decolorizing capacity was 80%. There were great deals of big-and-small pores in the activated carbon with ZnCI2 as activator through electron-microscope observing. The results showed that the ZnCl₂ method to prepare activated carbon had better choiceness adsorbing capacity.Using H3P04 as activator soaking and carbonization-activation to rice straw to prepare activated carbon as sorbent,the optimum technique parameter was H₃PO₄ concentration of 30%,the activated temperature of 660℃and time of 30 min.The result showed that the iodine value and the yield of the product were 425mg/g and 65.4% respectively, the decolorant capacity for methylene blue was127mg/g, caramel decolorizing capacity was 87.5% , The yield of the product was to 52.1% and moisture was 3.2%. Pore-structure of the product was overmatch to the market activated carbon.The processing optimum conditions on preparation for activated carbon from rice straw with H₂SO₄ chemical activation method were obtained, which was the material-to-solution ratio of 1:3, H₂SO₄ concentration of 70%,activation temperature of 250℃and time of 65min.The yield of the product was to 52.4%, the iodine value was 357mg/g, moisture was 1.9%,the ash was 17.4% ,caramel decolorizing capacity was 80% and the decolorant capacity for methylene blue was up to 202.5mg/g which was overmatch to the market activated carbon obviously.The experiment studied the specialty of rice straw actived carbon with K2CO3 as an activator. The result showed that the iodine value and methylene blue value were up to 1033mg/g and 232.5mg/g respectively , caramel decolorizing capacity was 120%, moisture was 12.3%,the ash was 19.5% and The yield of the product was to 15.1%, under the condition of activation temperature of 840℃and time of 50 min, the ratio of K₂CO₃ to rice straw charcoal of 2.7:1, K₂CO₃ concentration of 55%.The product exceeded greatly the state best standards. Its microstructure was observed and found that there was abundance of board-layer frame in the product. It proved that the product had mightiness adsorbent capacity.The activated carbon from rice straw has good performance of ab sorbing to Cu²⁺ and Ni²⁺, especially the one which was on preparation for activated carbon from rice straw with K₂CO₃ as a activator, its absorbing effect was much better than commercial activated carbon.