Abstract:
A mixed oxidant of chlorine dioxide (ClO2) and NaClO was often used in water treatment. A novel UVA-LED (365 nm)-activated mixed ClO2/NaClO process was proposed for the degradation of micropollutants in this study. Carbamazepine (CBZ) was selected as the target pollutant. Compared with the UVA365/ClO2 process, the UVA365/ClO2/NaClO process can improve the degradation of CBZ, with the rate constant increasing from 2.11×10-4 sec-1 to 2.74×10-4 sec-1. In addition, the consumption of oxidants in the UVA365/ClO2/NaClO process (73.67%) can also be lower than that of UVA365/NaClO (86.42%). When the NaClO ratio increased, both the degradation efficiency of CBZ and the consumption of oxidants can increase in the UVA365/ClO2/NaClO process. The solution pH can affect the contribution of NaClO in the total oxidant ratio. When the pH range of 6.0-8.0, the combination process can generate more active species to promote the degradation of CBZ. The change of active species with oxidant molar ratio was investigated in the UVA365/ClO2/NaClO process. When ClO2 acted as the main oxidant, HO• and Cl• were the main active species, while when NaClO was the main oxidant, ClO• played a role in the system. Both chloride ion (Cl-), bicarbonate ion (HCO3-), and nitrate ion (NO3-) can promote the reaction system. As the concentration of NaClO in the reaction solution increased, the generation of chlorates will decrease. The UVA365/ClO2/NaClO process can effectively control the formation of volatile disinfection by-products (DBPs), and with the increase of ClO2 dosage, the formation of DBPs can also decrease.
摘要:
二氧化氯(ClO2)和NaClO的混合氧化剂通常用于水处理。提出了一种新型的UVA-LED(365nm)激活的ClO2/NaClO混合工艺用于降解微污染物。选择卡马西平(CBZ)作为目标污染物。与UVA365/ClO2工艺相比,UVA365/ClO2/NaClO工艺可以改善CBZ的降解,速率常数从2.11×10-4sec-1增加到2.74×10-4sec-1。此外,UVA365/ClO2/NaClO工艺中氧化剂的消耗量(73.67%)也可以低于UVA365/NaClO的消耗量(86.42%)。当NaClO比例增加时,在UVA365/ClO2/NaClO工艺中,CBZ的降解效率和氧化剂的消耗都会增加。溶液pH可以影响NaClO在总氧化剂比例中的贡献。当pH范围为6.0-8.0时,组合过程可以产生更多的活性物种以促进CBZ的降解。在UVA365/ClO2/NaClO工艺中研究了活性物种随氧化剂摩尔比的变化。当ClO2作为主要氧化剂时,HO•和Cl•是主要的活性物种,而当NaClO是主要氧化剂时,ClO•在系统中发挥了作用。氯离子(Cl-),碳酸氢根离子(HCO3-),和硝酸根离子(NO3-)可以促进反应体系。随着反应溶液中NaClO浓度的增加,氯酸盐的产生将减少。UVA365/ClO2/NaClO工艺可有效控制挥发性消毒副产物(DBPs)的形成,随着ClO2用量的增加,DBPs的形成也会减少。