Preparation Of Activated Carbon From The Desilicon Rice Husk By Mixed Alkali Activation

Activated carbon is commonly used as a kind of adsorbent and plays an important role in treatment of waste water and waste gas pollution. Raw material of activated carbon was coal in the past, but now we prepared it mostly comes from the wood, in this experiment, we used grass biomass-rice husk to produce the activated carbon. Every year, there are a great amount of rice husk has an abundant yield, which was cheap and easy to get. The preparation of activated carbon from rice husk can increase the added value of agricultural products, solve the waste pile of environmental pollution problems, and achieve the comprehensive utilization of biomass resources.The desilicon rice husk has been used to prepare activated carbon by mixed alkali activation at the first time. We systematically studied various influence factors in the activation process. The activated carbon products were characterization.At first, the effect of single factor on mixed alkali activation process was studied. Through the materials ratio experiments of four single activators, we think the best material ratio is13. We designs experiments with different mixed activation ratios, the experimental results show that the iodine adsorption value and methylene blue adsorption may be the best, when NaOH&Na2CO3and KOH&K2CO3mixed ratio is2.5:0.5. Consequently, adding the auxiliary activator can effectively improve the adsorption value of rice husk activated carbon. Under the established conditions, three single fector experiments of the mass fraction of the impregnating solution, the activation temperature and activation time were done. Results showed that:the iodine value can up to the best, under the conditions of the mass fraction of the impregnating solution with30%, the activation time for40min, the activation temperature at500℃. Based on the single factor experiments, L934orthogonal experiment with four factors and three levels was carried out, analysis the influence of different factors on the iodine adsorption value by range:activation temperature> mixed ratio> activation time> the mass fraction of the impregnating solution; methylene blue adsorption value:activation temperature> the mass fraction of the impregnating solution> mixed ratio> activation time.Secondly, the effects of different factors on the interaction of mixed alkali activation process were studied. Through four factors (activation temperature, activattion time, mixed ratio,the mass fraction of the impregnating solution) and three levels of response surface method determining the optimization process, results shows:the activation temperature of633.75℃,the activation time of35.5min, the mixing ratio of3.96, the mass fraction of the impregnating solution of40.06%, iodine adsorption value can be the best, the validation experiments average were1383.46mg/g, consistent with the predicted values, the pore regularity was analyzed with methylene blue adsorption value and the yield as response value; the activator was recovery at various concentrations, By two ways (supplement use and concentrated use) to reuse the recovery activator, results showed:supplement use way was the best when the material ratio was1：3, can has a further discussion.Finally, the activated carbon from desilicon rice husk was characterized. Mainly relates to the thermo-gravimetric analysis, specific surface area and pore size distribution SEM, XRD, FTIR of activated carbon raw materials and finished products. Through the study, the effect of mixed activation in the preparation of activated carbon from desilicon rice husk was obtained. Through the microscopic point of view we can analyze the laws and features of pore-creating, this can provide certain theoretical guidance for the preparation of activated carbon from rice husk. The theory can facilitate the application of the future development of activated carbon based on rice husk.