College of Food and Chemical Engineering, Shaoyang University, No. 28, Lane 3, Shaoshui West Road, Shaoyang, 422000, Hunan, China.
College of Food and Chemical Engineering, Shaoyang University, No. 28, Lane 3, Shaoshui West Road, Shaoyang, 422000, Hunan, China.
Water Res. 2019 Sep 15;161:439-447. doi: 10.1016/j.watres.2019.06.021. Epub 2019 Jun 11.
Vacuum ultraviolet/ultraviolet/chlorine (VUV/UV/chlorine) is considered a novel advanced oxidation process (AOP), but little is known about its kinetics for pollutant degradation in water treatment. This study investigated the degradation of six typical pesticides, namely dimethoate (DMT), atrazine (ATZ), prometon (PMT), propoxur (PPX), bromacil (BRM) and propachlor (PPC), by VUV/UV/chlorine. The results show that all pesticides were rapidly degraded by VUV/UV/chlorine with a high removal efficiency of over 95% after 60 s. The pesticide degradation fitted well with pseudo-first-order reaction kinetics and a significant synergistic effect was observed during the VUV/UV/chlorine process. The synergistic factor (F) for DMT, ATZ, PMT, PPX, BRM and PPC were determined to be 1.75, 1.70, 2.06, 1.57, 2.84 and 1.61, respectively, indicating a synergistic improvement of 57%-184% for all pesticides. As hydroxyl radical (HO) transformed into reactive chlorine species (RCSs), the contribution ratio of RCSs for the pesticide degradation was much higher than that of HO in the VUV/UV/chlorine process, thus causing the synergistic effect. Solution pH ranging from 5.0 to 10.0 had various influence on the pesticide degradation by VUV/UV/chlorine. As initial concentration of free chlorine increased from 0 to 0.25 mM, the apparent rate constants of the pesticides kept on increasing while the F first increased and reached the highest value, and decreased afterwards. The formation of nitrite was significantly inhibited during the degradation of all pesticides by VUV/UV/chlorine. It suggests that VUV/UV/chlorine is a promising AOP for the pesticide degradation in water treatment.
真空紫外线/紫外线/氯气（VUV/UV/氯气）被认为是一种新型的高级氧化工艺（AOP），但对于其在水处理中污染物降解的动力学知之甚少。本研究考察了 VUV/UV/氯气对六种典型农药（乐果（DMT）、莠去津（ATZ）、扑灭津（PMT）、残杀威（PPX）、溴麦隆（BRM）和丙草胺（PPC））的降解作用。结果表明，所有农药在 60s 内均能迅速被 VUV/UV/氯气降解，去除率超过 95%。农药降解符合准一级反应动力学，VUV/UV/氯气过程中观察到显著的协同作用。DMT、ATZ、PMT、PPX、BRM 和 PPC 的协同因子（F）分别确定为 1.75、1.70、2.06、1.57、2.84 和 1.61，表明所有农药的协同提高了 57%-184%。由于羟基自由基（HO）转化为活性氯物种（RCSs），RCSs 对农药降解的贡献比例远高于 VUV/UV/氯气过程中的 HO，从而产生协同效应。溶液 pH 值在 5.0 至 10.0 范围内对 VUV/UV/氯气处理农药降解有不同的影响。随着自由氯初始浓度从 0 增加到 0.25mM，农药的表观速率常数不断增加，而 F 值先增加达到最高值，然后降低。在 VUV/UV/氯气降解所有农药的过程中，亚硝酸盐的形成明显受到抑制。这表明 VUV/UV/氯气是一种很有前途的水处理中农药降解的 AOP。
