Phenol degradation in waters with high iodide level by layered double hydroxide-peroxodisulfate:Pathways and products  

作　　者：Qingqing Su Peiyue Gao Ning Li Feifei Wang Xin Huang 

机构地区：[1]School of Environmental and Chemical Engineering,Shanghai University,Shanghai 200444,China [2]Shanghai National Engineering Research Center of Urban Water Resources Co.,Ltd.,Shanghai 200082,China

出　　处：《Journal of Environmental Sciences》2022年第6期14-24,共11页环境科学学报（英文版）

基　　金：partially supported by National Science Foundation Project of China(No.51678351);Research and demonstration on key technology of direct drinking guarantee of municipal water in Shanghai(No.19DZ1204400);State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF19003)。

摘　　要：Recently, layered double hydroxide-peroxodisulfate(LDH-PDS) as an advanced oxidation system can effectively remove organics by the pathway of free radical. However, little has been known if there is a potential risk regarding the formation of high toxic iodine byproducts through another pathway when LDH-PDS is used in high iodide waters at coastal areas.Therefore, this study investigated phenol degradation pathways and transformation products to evaluate both removal mechanism and potential risk by LDH-PDS in high iodide waters. The results showed that in LDH-PDS system, with the degradation of PDS, phenol degraded till below detection limit in 1 hr in the presence of iodide, while PDS and phenol were hardly degraded in the absence of iodide, indicating iodide accelerated the transformation of PDS and the degradation of phenol. What is more, it reached the highest phenol removal efficiency under the condition of 100 mg/L LDH, 0.1 mmol/L PDS and 1.0 mmol/L iodide. In LDH-PDS system, iodide was rapidly oxidized by the highly active interlayer PDS, resulting in the formation of reactive iodine including hypoiodic acid, iodine and triiodide instead of free radicals, which contributed rapid degradation of phenol. However, unfortunately toxic iodophenols were detected. Specifically, 2-iodophenol and 4-iodophenol were formed firstly,afterwards 2,4-diiodophenol and 2,6-diiodophenol were produced, and finally iodophenols and diiodophenols gradually decreased and 2,4,6-Triiodophenol were produced. These results indicated that LDH-PDS should avoid to use in high iodide waters to prevent toxic iodine byproduct formation although iodide can accelerate phenol degradation.

关 键 词：IODIDE Layered double hydroxide(LDH) Non-radical pathway Peroxodisulfate(PDS) Synergic activation 

分 类 号：X703[环境科学与工程—环境工程]