臭氧/沸石工艺处理水中硝基苯的机理探讨

考察了臭氧在H型沸石上吸附与分解情况,发现臭氧在H型沸石上发生了吸附与分解,并且吸附过程与脱附过程是不可逆的,其脱附速率很快.在吸附分解平衡后,臭氧在H型沸石上的吸附分解量与进水臭氧浓度成正比.而在1×10^-3 mol/L Na⁺存在条件下,被Na⁺交换的H型沸石基本不吸附分解臭氧.考察不同阳离子和不同型号沸石对臭氧/沸石工艺去除硝基苯的影响,发现Ca²⁺的影响最大,另外Na型沸石和NH₄型沸石在降解硝基苯的过程中,硝基苯的去除效率逐渐提高,并且Na型沸石中的Na⁺发生溶出,表明盐析效应影响臭氧扩散进入沸石孔道进行自分解和催化分解的能力.脱铝后的H型沸石没有体现降解硝基苯的效果.最后在pH 3.0时,H型沸石也能吸附分解一部分臭氧,说明H⁺的影响不如其它阳离子.

Mechanism of Degradation of Nitrobenzene by Ozone/Zeolite Process

Adsorption and desorption of ozone on H-form zeolite was investigated in solution. The results showed that ozone could be adsorbed on H-form zeolite, and finally decomposed. And the process of adsorption and desorption was irreversible. After equilibrium of adsorption and desorption, the relationship of the amount of adsorbed ozone with the influent ozone concentration was linear. However, exchanged H-form zeolite by sodium ion at the concentration of 1×10^-3 mol/L did not adsorb any ozone. By investigating the effect of cation and zeolite type on ozone/zeolite process oxidizing nitrobenzene, it was investigated that the nitrobenzene removal rate was significantly inhibited by calcium ion. Additionally, during the ozonation of nitrobenzene by ozone/Na-form zeolite and ozone/NH₄-form zeolite process individually, the removal rate of nitrobenzene by ozone/Na-form zeolite process was gradually improved as the sodium ion dissolved in solution. It was verified that cations affected ozone diffusing into the pore of zeolite and then self-decomposition and catalysis decomposition. After dealuminated, the ozone/H-form zeolite process did not show any efficiency on nitrobenzene removal. In the end, ozone also can be adsorbed and decomposed at pH 3.0 in zeolite, which showed that the effect of hydrogen ion was not as well as other cations.