臭氧氧化对天然有机物在氧化铝表面吸附行为的影响

为进一步明确臭氧预氧化对颗粒的脱稳作用,选用氧化铝（α-Al₂O₃）作为悬浮颗粒,考察了臭氧氧化后天然有机物（natural organic matters,NOM）特性及吸附行为的变化.结果表明,臭氧氧化能够破坏NOM的芳香结构,SUVA值降低25%～35%,氧化后酸性官能团含量增多,总酸度增加0.3～1.4 mmol·g^-1,分子量和极性的变化与NOM的性质有关;有机物初始浓度相对于臭氧投量较低时,NOM的溶解性增强,与其酸性官能团增加产生的吸附促进作用相抵消,因而吸附性能出现不变甚至降低的现象;有机物初始浓度较高时,臭氧能够起到强化NOM吸附的作用.采用2.5　mg·L^-1臭氧进行氧化后,以商用腐殖酸为代表的NOM的吸附形貌,由密集分布的球形对称聚集结构向网状结构过渡,分子之间的交联作用十分明显,吸附高度低于其氧化处理前,云母的表面覆盖率较氧化前略有提高.

Effect of Preozonation on the Adsorption Behaviors of NOM on Alumina

In order to understand the mechanisms of "ozone-induced particle destabilization", the effect of preozonation on the adsorption behaviors of natural organic matters (NOM) on alumina (alpha-Al2O3) was investigated. Besides, the characteristic transformation of NOM after ozonation was also evaluated. The results revealed that ozone will destroy the aromatic structures of NOM and increase the content of the acidic functional groups. The SUVA value decreased 25% - 35% and the total organic acidity increased 0.3 - 1.4 mmol x g(-1). The transformation of molecular weight and polarity after ozonation was affected by the characteristics of NOM. The solubility of NOM increased after ozonation at a low organic carbon concentration, which counteracted the enhanced adsorption caused by the increased acidic functional groups. At a high organic carbon concentration, the adsorption capacity of NOM on alumina was enhanced after ozonation. Taken CHA as an example, the adsorbed CHA displayed a well-proportioned spheric aggregates structure. After CHA was oxidized by ozone at a dosage of 2.5 mg x L(-1), the microtopography transformation of CHA was observed. The adsorption height of CHA was decreased prominently, while the coupling among CHA molecules and the surface coverage of mica was increased slightly. The integral microtopography presented a network structure.