对预氯化和粉末活性炭(PAC)联合去除饮用水源中的嗅味物质2-MIB(2-Methylisobomeol)的影响因素进行了研究.利用静态试验考察PAC的吸附容量,同时采用比表面积仪、红外光谱等对氯化前后PAC的比表面积、孔径尺寸、官能团进行表征.结果表明,预氯化后,水中的2-MIB浓度降低很小,而余氯对后续PAC的进一步吸附去除2-MIB的影响很大.余氯的存在对等温吸附曲线影响较大,PAC对2-MIB吸附过程更接近于Freundich吸附等温式.氯化前后PAC的比表面积、孔径尺寸没有明显变化,但氯化后PAC表面的含氧官能团-COOH、-OH峰值明显增强.以松花江原水试验发现,余氯与水体其他有机物反应,降低了它们被PAC吸附,从而增加了2-MIB被PAC吸附的可能.余氯改变了活性炭吸附2-MIB的能力,同时也导致已被吸附的2-MIB重新解析.
The affecting factors of combining prechlorination with PAC to remove taste and odor compound, 2- methyliosborneol (2-MIB), were investigated. Results indicate that the concentrations of 2-MIB in drinking water change a little after preclorination, but the effect of residual chlorine on PAC adsorption of 2-MIB is substantial. Isothermal absorption curve is greatly affected by the presence of residual chlorine. The kinetic adsorption process of PAC to 2-MIB follows the isothermal equation of Freundich. The PAC adsorption of 2-MIB shows that the amount of PAC adsorption of 2-MIB decreases with the increase of residual chlorine, thus the adsorption capacity of PAC to 2-MIB is reduced. Experimental results from Songhua River show that residual chlorine reacts with other organic matters which have competitive effect on PAC adsorption of 2-MIB. The characterisations of PAC before and after chlorination show that the specific surface area and pore size have no obvious change. PAC analysis by FTIR indicates that the functional groups are changed. Oxygen functional groups of PAC, such as carboxyl and hydroxyl, are greatly increased after chlorination, which have resulted in the decrease of adsorption capacity of PAC to 2-MIB. The main reason for the reduction in the adsorption of 2- MIB in the presence of residual chlorine might be attributed to that chorine oxidizes PAC and changes the surface characteristics of PAC, which results in reduction of adsorption capacity of PAC to 2-MIB and the desorpion of the absorbed 2-MIB into water.