【作者】 陈志华；

【导师】 王栋；

【作者基本信息】 大连理工大学 ， 环境工程， 2012， 硕士

【摘要】 为了消除染料废水的环境污染,本研究选用亚甲基蓝模拟染料废水,对亚甲基蓝(Methylene Blue trihydrate,MB)在曝气塔环境中的降解过程进行了实验研究。采用臭氧氧化技术,考察了pH值、活性炭、改性活性炭以及自由基捕获剂对MB脱色行为的影响,并给出了可能的反应过程机理分析。研究表明,颗粒状活性炭(GAC)与臭氧的曝气量存在最佳比例,在本研究体系中,GAC的最佳投放量为6g/L；单独的臭氧体系中,在pH=12.7时,曝气时间20min,脱色率达到100%,在pH=2.5时,用时32min,脱色率仅为86%,表明,在碱性条件下,有利于臭氧的氧化作用。通过浸渍法制备四种不同铈(Ce)负载量的改性活性炭(Ce/GAC)催化剂通过XRD表征,其表面都存在CeO2立方形晶体,经X射线光电子能谱仪(XPS)表征,Ce负载量分别为0.12%、0.23%、0.56%和1.12%；观察扫描电镜图(SEM)得知,随着Ce负载量的增大,Ce/GAC的比表面积、孔容和孔径变小。在pH=2.5的缓冲体系中,Ce/GAC的投加量为6g/L时,Ce的负载量为0.23%,降解效果最佳；考察不同Ce负载量的Ce/GAC/O3体系在26min的TOC去除率和溶液体系中的电导率,以TOC去除率为纵坐标、电导率为横坐标拟合曲线,发现,TOC/电导率成一元线性相关(R2=-0.99575)。在pH=12.7的环境体系中,比较O3、GAC、0.23%Ce/GAC/O3体系的降解效果,当脱色率达到100%,用时分别为20min、18min、16min,此时,TOC的去除率分别为8.3%、20.3%、28.0%,推测0.23%Ce/GAC/O3对中间产物有明显的降解和吸附作用。经全自动物理吸附仪(BET)监测孔容和比表面积得知,实验使用前的0.23%Ce/GAC (0.5076cc/g、779.278m2/g)>未经任何处理的GAC (0.4670cc/g、751.288m2/g)>实验使用后的0.23%Ce/GAC’(0.3808cc/g、603.344m2/g),表明活性炭在臭氧氧化过程中,表面结构有明显变化。在pH=12.7的缓冲体系,添加叔丁醇·OH捕获剂或碳酸氢根阴离子·OH捕获剂,O3的氧化能力下降,表明体系中确实存在·OH,同时,比较强酸(pH=2.5)、添加HCO3-、添加叔丁醇条件下的反应速率常数,碳酸氢根的捕获效果强于叔丁醇,表明叔丁醇作为·OH捕获剂具有一定的局限性。更多还原

【Abstract】 The degradation of Methylene Blue trihydrate (MB) in a bubble column was studied to eliminate the environmental pollutions produced by dye wastewaters. Using ozone oxidation technique, the effects of granular activated carbon (GAC), granular modified activated carbon, pH and hydroxyl radical scavengers on decolorization of MB were investigated, where the possible mechanism of reaction process was analyzed.The four different weight of cerium(Ce) supported on GAC, which are prepared by dipping method, are characterized by XRD, XPS and SEM. CeO2cubic crystal is deposited on GAC. The content of Ce (W/W) is0.12%、0.23%、0.56%and1.12%respectively. At higher Ce on GAC, the surface area and microporous volume on GAC decrease. In pH=2.5buffer system with the dose of Ce/GAC at6g/L, the degradation of MB reaches optimal when0.23%Ce is attached to GAC; at26min, studying TOC removal ration and conductance ration in the four different laden Ce’s Ce/GAC/03systems, there obtains linear correlation between TOC removal ration and conductance ration(R2=-0.99575).In pH=12.7buffer system with the dose of Ce/GAC at6g/L or not, comparable date of degradation with O3,GAC/O3and0.23%Ce/GAC/O3systems, reaction time attains20min,18min,16min respectively when decolorization ration reaches100%, meanwhile, TOC removal ration reaches8.3%,20.3%and28%respectively. Through characterized by BET, the microporous volume and surface area of the new preparation0.23%Ce/GAC (0.5076cc/g^779.278m2/g) increase comparing with original GAC (0.4670cc/g、751.288m2/g), but the used0.23%Ce/GAC decrease (0.3808cc/g,603.344m2/g).It is validated that surface of0.23%Ce/GAC changes during ozonation process.Added HCO3" or tert-butyl alcohol(TBA)? OH radical scavengers in pH=12.7buffer system results in droping the ability for O3. It indicates that there exist? OH in systems. At the same time, compared the rate constants under acidic(pH=2.5), added HCO3-and added TBA conditions, this finding confirms that HCO3" is more stronger than tert-butyl alcohol(TBA). Therefore, it is demonstrated that the power of TBA as scavenger is characterized with limitation.更多还原