还原态蒙脱石有氧条件产生羟自由基降解有机污染物  

Organic Contaminant Degradation by Hydroxyl Radicals Produced from Reduced Montmorillonite Under Oxic Conditions

作　　者：袁松虎[1] 姚炜钰 张鹏[1] 刘细祥 YUAN Song-hu;YAO Wei-yu;ZHANG Peng;LIU Xi-xiang(State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)生物地质与环境地质国家重点实验室

出　　处：《矿物岩石地球化学通报》2019年第3期485-489,439,共5页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41830862)

摘　　要：近期见有含二价铁矿物可活化分子氧产生羟自由基而氧化污染物的报道。本文选用土壤/沉积物中的常见组分蒙脱石(含铁约2%),研究了还原态蒙脱石在不同条件下活化分子氧降解苯酚的效果。结果表明,20g/L还原态蒙脱石(还原程度为30%)在pH=6和有氧条件下,可通过产生羟自由基使11μM苯酚的降解率在6h内持续增加至59.1%。苯酚降解率对应的最佳pH为5,当pH>6时降解率则随着p H的升高而急剧降低;苯酚降解效果还随还原态蒙脱石剂量(0~40g/L)增加而提高;苯酚初始浓度为11μM降解率最高,增加或者降低初始浓度均使降解率降低。还原态蒙脱石铁含量低,活化分子氧时其八面体边缘配位和结构内部二价铁共同起作用,而受八面体层Al、Mg等惰性组分阻碍,其结构二价铁难以向边缘位置传递电子,这与前期报道的还原态绿脱石(含铁约20%)不同。Recent studies documented that Fe(Ⅱ)-bearing minerals could activate O2 to ·OH for contaminant oxidation.In this study,reduced montmorillonite( Fe content:~ 2%),a common component in soils and sediments,was chosen to active O2 for phenol degradation. In 20 g/L reduced montmorillonite [Fe(Ⅱ)/Fe( tot): 30%]suspension,59. 1% of 11μM phenol was progressively degraded by·OH within 6 h under oxic and weak acidic( pH = 6) conditions. The degradation efficiency was highest at pH 5,and decreased drastically at pH above 6. For tested montmorillonite dosage( 0-40 g/L),degradation efficiency increased with the increase of dosage. Degradation efficiency reached maximum at the initial phenol concentration of 11 μM,close to the cumulative·OH concentration produced. Compared with O2 activation by nontronite( Fe content:~ 20%) reported,montmorillonite contains a much lower Fe content,rendering different Fe(Ⅱ) entities for O2 activation. Fe(Ⅱ) in both edge and interior sites within the octahedral sheets of montmorllonite is most likely accountable for O2 activation,but electron transfer from interior to edge sites is difficult due to blockage by Al and Mg.

关 键 词：蒙脱石 二价铁 分子氧 羟自由基 有机污染物 

分 类 号：P578.967[天文地球—矿物学]