【作者】 谢杰；

【导师】 庆承松；

【作者基本信息】 合肥工业大学 ， 环境工程， 2010， 硕士

【摘要】 稻壳发电作为一项成熟的稻壳资源利用技术,有着很好的发展前景。但稻壳发电留下的热解残渣——稻壳灰,如不加以处理和利用还会对环境造成一定的污染。目前虽然有不少学者就稻壳灰的应用作过研究,但这些研究大多偏重于稻壳灰样品的制备及其应用,而忽略了稻壳发电过程中产生的稻壳灰。由于稻壳发电过程中温度和时间等方面因素的限制,留下的热解稻壳灰在物理化学特性上与实验室可控条件下形成的稻壳灰样品有着较大的区别。本研究以稻壳热解后的稻壳灰为实验材料,研究其物理及化学特性,并对其吸附性能作探索研究。吸附实验以苯酚作为有机污染物,研究稻壳灰在不同条件下对苯酚的吸附作用。吸附实验的结果表明,未经处理的稻壳灰样品对有机污染物的去除率只有41.6%,吸附效果不够理想,而在经过碱洗处理后,其吸附性能有明显提高,有机物去除率提高至78.5%。碱溶液的用量越多,稻壳灰样品对有机污染物的吸附效果越好。实验结果表明当样品与碱液比达到1:7时,碱液用量的增加对吸附效果的改善不明显。通过仪器测定发现,碱处理前后,稻壳灰的表面基团的组成没有发生明显变化,但比表面积和总碳含量有明显的增加,通过对场扫描透射电镜照片的分析,稻壳灰中存在大量SiO2团块状粒子,这些粒子堵塞了稻壳灰中的孔道。经碱处理后,稻壳灰孔道中的SiO2粒子被浸溶出来,孔道结构有明显的改善。吸附实验发现,当溶液pH值小于7时,稻壳灰对有机污染物的吸附效果要好于pH值大于7时的吸附效果。通过吸附实验的拟合,发现稻壳灰对苯酚的吸附等温线模型同时符合Langmuir和Freundlich等温吸附线模型,这说明稻壳灰对有机污染物的吸附属于多种吸附作用共同作用的结果。从实验数据来看,稻壳灰样品对苯酚的吸附容量最高可以达到15.873 mg/g。通过动力学实验,确定了稻壳灰对苯酚的动力学模型属于准二级动力学模型和颗粒内扩散模型。从实验数据可以看出,稻壳灰对苯酚的吸附行为可分为三个阶段:开始是一个快速吸附过程,随后是一个速度渐缓的吸附阶段,最后达到平衡。根据动力学方程的拟合结果,可以推定稻壳灰对苯酚的吸附属于快速吸附过程,该吸附过程的主要控制步骤为液膜扩散或者颗粒内扩散,但颗粒内扩散控制不是唯一的速率控制步骤。更多还原

【Abstract】 Power generation from rice husk has a potential industrial value as a mature technology for recycling use. However, the residue of power generation, known as rice husk ash, needs to be carefully handled, or there is certain damage to our environment. The most of studied researches are based on the preparation of rice husk ash from rice husk under experimental condition. The rice husk ash left after the power generation has many differences in the physical and chemical nature with the prepared rice husk ash, because of the high temperature and long heat time in the power generation process.It is studied that the rice husk ash of power generation is used to deal with the deep treatment of water pollutants as absorbent. The removal efficiency of organic pollutants is studied under different experimental conditions, which give a result that the rice husk ash has bad removal efficiency in comparison with the samples treated by alkaline cleaning. The removal efficiency is improved with the increase of alkaline quality used in the alkaline treatment.The instrumental analysis give a series results of that no apparent difference of infrared spectrogram between the alkaline treated samples and the untreated sample. However, the total surface area and total carbon quality of rice husk ash determined by using relative instruments shows that they increased both after the alkaline cleaning. It is found from the scanning transmission electron microscope that the large amount of silicon dioxide particles filled in the pores of rice husk ash. The silicon dioxide decreased after alkaline cleaning for samples, which is supposed to be the result of chemical reaction of silicon dioxide and alkaline. The pH value show a strong influence on the removal results that when pH value is greater than 7 gives a better result than when the pH value less than 7.It was proved in the adsorption study that the absorption model fits Langmuir and Freundlich isotherm model both, which proved that the adsorption belong to the combined action of different effects. It is also known that the adsorption capacity of rice husk ash can reach the highest 15.873 mg/L.The experimental data proved that there were three progresses in the whole adsorption, with quick adsorption first and secondly the slowing down adsorption progress, and the last balance phase. It can be concluded as the phase of adsorption on surface, intra-diffusion phase, and the balance phase. The kinetic study showed that rice husk ash adsorption kinetic model belongs to pseudo second order kinetic model and intra particle diffusion model.更多还原