Adsorptive ozonation using high silica zeolite adsorbents and its application for drinking water treatment.

研究了水溶性臭氧在高硅沸石上的吸附性能。吸附的臭氧几乎可逆地解吸。吸附平衡关系可用线性方程q = βC表示，其中q为吸附量，C为平衡浓度，B为平衡常数。β值还与SiO_2/Al_2O_3（mol/mol）比和高硅沸石的孔结构有关。SiO_2/Al_2O_3比值越大，B值越大。ZSM-5（SiO_2/Al_2O_3比为3000）对水中溶解的臭氧具有最高的吸附容量，能使水中溶解的臭氧高度富集在吸附剂上。研究了吸附态臭氧的分解行为。臭氧在高硅沸石上的吸附比臭氧在水体中的吸附稳定。在SiO_2/Al_2O_3比为30-3000范围内，分解速率与溶液pH值无关。 关于我们 在此基础上，我们开发了一种新的臭氧化水处理工艺，采用高硅沸石作为水中溶解的臭氧和有机污染物的吸附浓缩剂，使反应速率显著提高。在管式流动反应器中进行的三氯乙烯（TCE）分解实验中，ZSM-5（SiO_2/Al_2O_3 =3000）对TCE的分解率明显高于无ZSM-5时的分解率，这可能是由于吸附剂中臭氧和TCE的浓度较高所致。实验中TCE的转化率达到了理论上的最大值，并考察了该工艺在饮用水处理中的适用性。研究了USY（SiO_2/Al_2O_3 =70）催化分解2-甲基异山梨醇（MIB）的效果。这种分解能力在含有天然有机物（NOM）的天然水中也得到了证实。少

The adsorption properties of water-dissolved ozone on high silica zeolites were investigated. Adsorbed ozone was desorbed almost reversibly. The adsorption equilibrium relations were described by a linear expression written as q = βC, where q is the amount adsorbed, C is the equilibrium concentration and b is the equilibrium constant. Also, the β values were strongly dependent on the SiO_2/Al_2O_3 ratio (mol/mol) and on the pore structure of the high silica zeolites. The larger the SiO_2/Al_2O_3 ratio, the larger the value of b. ZSM-5 (SiO_2/Al_2O_3 ratio : 3000), which gave the highest adsorption capacity of water-dissolved ozone, was able to highly concentrate water-dissolved ozone on the adsorbent. The decomposition behavior of adsorbed ozone was also investigated. Ozone adsorbed on high silica zeolite was observed to be a little more stable than ozone existing in bulk water. The decomposition rate was independent of SiO_2/Al_2O_3 ratios in the range of 30-3000 or a solution pH in t … More he range of 4-6.On the basis of the upper mentioned results, we developed a novel ozonation process for water treatment using high silica zeolites as an adsorptive concentrator of water-dissolved ozone and organic pollutants, resulting in a significant increase in reaction rate. In experiments involving trichloroethene (TCE) decomposition using a tubular flow reactor, TCE decomposition was much greater in the presence of ZSM-5 (SiO_2/Al_2O_3 ratio=3000) than in its absence, possibly due to the high concentrations of ozone and TCE inside the adsorbent. The TCE conversion obtained in our experiments was found to reach its theoretically maximum limit.Furthermore, the applicability of the process on drinking water treatment was also investigated. The effectiveness of the process using USY (SiO_2/Al_2O_3 ratio=70) for 2-methylisoborneol (MIB) decomposition with preventing bromate formation was clarified. This decomposition ability was also demonstrated in natural water containing natural organic matter (NOM). Less