Degradation of sulfamethazine by persulfate activated with organo-montmorillonite supported nano-zero valent iron
Degradation of sulfamethazine by persulfate activated with organo-montmorillonite supported nano-zero valent iron
复制标题
有机蒙脱石负载纳米零价铁活化过硫酸盐降解磺胺二甲嘧啶
DOI：
10.1016/j.cej.2018.12.024
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发表时间：
2019-04-01
影响因子：
15.1
通讯作者：
Yu, Gang
中科院分区：
文献类型：
--
作者：
Wu, Junxue;Wang, Bin;Yu, Gang
磺胺乙嗪（SMZ）是应用最广泛的磺胺类化合物之一，在水资源中经常被检测到，对人类健康和生态健康构成威胁。为了解决这一问题，利用NaBH4还原Fe2+合成的有机蒙脱土（OMt）复合材料（nZVI/OMt）负载纳米级零价铁（nZVI）来激活过硫酸盐（PS），研究了SMZ的降解。在pH 6.8和25℃条件下，使用1.5 mm nZVI/OMt（质量/质量，3/1）和4mM过硫酸盐，在10 min内对20 mg/L SMZ的降解达到97%。实验结果表明，SMZ的降解符合准一级反应动力学，并且观察到nZVI/OMt活化PS工艺的准一级速率常数（k(obs)）是nZVI活化PS工艺的1.5倍。提高PS浓度和温度可以促进SMZ的转变。天然水体成分Cl-、NO3-和腐植酸对SMZ的降解有轻微抑制作用，而HCO3-对SMZ的转化有显著抑制作用。电子顺磁共振和自由基清除剂实验表明，(OH)- o中心点和SO4中心点-都参与了SMZ的降解；SO4中心点是主要的反应机理。通过UPLC-QTOF-MS对降解产物进行分析，确定了三种反应途径：S-N键断裂；smiles-type重排;然后是苯胺部分的氧化。综上所述，实验结果表明，nZVI/ omt活化的PS氧化是一种简单、低成本、高效的快速修复smz污染水体的方法。
Sulfamethazine (SMZ) is one of the most widely used sulfonamides and is frequently detected in water resources, posing threats to human and ecological health. To address this concern, SMZ degradation was investigated using nanoscale zero-valent iron (nZVI) supported on an organo-montmorillonite (OMt) composite (nZVI/OMt), which was synthesized by reduction of Fe2+ with NaBH4, to activate persulfate (PS). Up to 97% degradation of 20 mg/L SMZ was achieved within 10 min using 1.5mM nZVI/OMt (mass/mass, 3/1) and 4mM persulfate at pH 6.8 and 25 degrees C. Experimental results indicated that SMZ degradation obeyed pseudo-first-order reaction kinetics, and the observed pseudo-first-order rate constant (k(obs)) in the nZVI/OMt-activated PS process was 1.5 times that for the nZVI-activated PS process. SMZ transformation was improved by increasing the PS concentration and temperature. Natural water constituents, such as Cl-, NO3-, and humic acid, slightly inhibited SMZ degradation, whereas SMZ transformation was significantly reduced by HCO3-. Electron paramagnetic resonance and radical scavenger experiments demonstrated that both (OH)-O-center dot and SO4 center dot- participated in SMZ degradation; however, SO4 center dot- was the dominant reaction mechanism. Degradation products were analyzed by UPLC-QTOF-MS and confirmed three reaction pathways: cleavage of the S-N bond; smiles-type rearrangement; and, oxidation of the aniline moiety. Overall, the experimental results suggest that nZVI/OMt-activated PS oxidation is an easy, lowcost, and efficient method for rapid remediation of SMZ-contaminated water.