Preparation And Application Of The Activated Carbon From The Residue Of Desilicication Rice Husk

Activated carbon has a large specific surface area and rich pore structure, whichis widely used in important fields such as chemical engineering, environmentalprotection, medicine, defense, food industry and so on. At present, coal is the mainsources for the production of activated carbon. As is known that coal is anon-renewable fossil oil resource and the price of coal is continually rising, the coalwould be replaced by the renewable and low-cost materials to prepare activatedcarbon. It is one of the hottest issues studied in this field.Because of the high silica contents Rice husk is used to produce silica white. Ifthe residue of desilication rice husk which was left to produce silica white is notutilized properly, it will become to be a tremendous waste. Activated carbon could beprepared from residue of rice husk using physical activation with the steam asactivating agent. This study not only solves the pollution which was caused by wastestacking and broadens the materials to prepare activated carbon, but also realizesmultilevel utilization of resources.Firstly, activated carbon has been prepared from the residue of desilicication ricehusk (DRH) using steam as activating agent. The important parameters, which greatlyaffect the iodine sorption value of activated carbon, such as activation temperature,activation time and the amount of steam, were investigated. Response surfacemethodology (RSM) was applied to optimize processing parameters and the optimumconditions have been identified. The theoretical model is credible by the analysis ofvariance and correlation coefficient. The optimal conditions of activated carbon wereactivation temperature of946℃, activation time of31.2min and the ratio of waterwhich changed to steam by heating and DRH was3：1(g/g), which resulted in970.06mg/g of iodine adsorption capacity and31.36%of activated carbon yield.Secondly, the adsorption characteristic of indigo and aniline using activatedcarbon was studied. Experiments were conducted to study the factors affecting the adsorption process such as the contact time, the initial pH, the dosage of adsorbent,the initial concentration and temperature. The results indicated that300min and100min were seen as the adsorption equilibrium time for adsorption of indigo and aniline,respectively. The maximum monolayer adsorption capacity of activated carbon forindigo and aniline were1.05and1.14mmol/g at298K, respectively. The adsorptionof indigo is favorable at high temperatures, but the adsorption of aniline is favorableat low temperatures.According to the Langmuir, Freundlich, Koble-Corrigan, Temkin andRedlich-Peterson isotherm models, the non-linear regressive analysis of theequilibrium adsorption data was conducted, respectively. The results indicated thatthe adsorption of indigo onto activated carbon follows Koble-Corrigan and Temkinisotherm models well, moreover, the adsorption of aniline onto activated carbonfollows Langmuir and Temkin isotherm models well. The kinetic studies for indigoand aniline indicated that adsorption process followed the pseudo second-order model.The adsorption process was found to be controlled by both film diffusion andintra-particle diffusion.In the binary system, indigo and aniline exhibited competitive adsorption.The adsorption isotherm of binary system indicated that the Freunlich isotherm modeldescribed well the process of adsorption competition.Multiple analytical techniques such as specific surface area analysis, FTIR andSEM were employed to examine the micro-structure of the activated carbon derivedfrom the residue of desilicication Rice Husk. The surface area of activated carbon wasestimated to be1004.30m2/g, while total pore volume was0.9388cm3/g.