Research On Preparation Of Activated Carbon From Rice Husks And Surface Modification Of Activated Carbon

Activated carbon 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 husk is byproduct of rice processing .The rice husk resources are plentiful in our country, but most of them are discarded as waste material or burned out as fuel. The abundant rice husk as agricultural byproduct contains plentiful fixed carbon. It is significant to exploit the application of rice husk. The surface chemical properties of activated carbons are closely related to the functional groups on their surface,which further determine the chemical absorbing characteristic of the activated carbon..Surface modification can lead to substantial improvement in the activated carbon' ability to absorb specific absorbates.The activated carbon (AC) is prepared from rice husk by the activation of alkali metal hydroxide and phosphoric acid. The activated agent of different kinds and its ratio, 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 microcrystalline in AC. Utilizing the activated carbon from rice husk absorb Cr6+ in water, this paper does some study about Cr6+ removal sorption isotherm line and suitable terms of absorbing. In order to improve the carbon dioxide adsorption capacity on activated carbon, its oxidative treatment with nitric acid, sulphuric acid and ammonia water is carried out. The results show that surface modification has important effects on the carbon dioxide adsorption capacity and surface acid groups.The results of this paper are follows:(1)Experiment results show that the best technologic conditions of preparing AC with rice husk by the activation of KOH using muffle furnace in laboratory are the ratio of rice husk and KOH, activation temperature and activation time being 4,750 and 1 hour respectively. Its iodine adsorption value and methylene blue adsorption value are 1240 mg.g^-1and 150 mL.g^-1 respectively.(2)The catalysis activity of KOH is super to NaOH when single alkali metals hydroxide as activated agent.(3)The best technologic conditions of preparing AC with rice husk by the activation of...