生物炭载硫化铁对2,4-二氯苯氧乙酸的催化氧化降解

Oxidative degradation of 2,4-dichlorophenoxyacetic acid catalyzed by the biochar supported iron sulfide

以木质生物炭为载体制备了负载型硫化铁(FeSx/BC),采用扫描电镜/能量色散X射线光谱(SEM/EDX)、X射线粉末衍射(XRD)和X射线光电子能谱(XPS)对其结构进行了表征分析.然后将其用于催化除草剂2,4-二氯苯氧乙酸(2,4-D)的类Fenton氧化降解,并与市售硫化亚铁(c-FeS)进行对比.结果表明,生物炭可以提高硫化铁分散性,炭载催化剂中的Fe主要以Fe3S4形式存在.与c-FeS相比,采用FeSx/BC催化降解2,4-D的反应速率常数(kobs)提高了约20倍.降解反应速率随催化剂、H2O2用量增加而提高,但是随初始pH(2.0—9.0)上升而下降.机理研究表明,生物炭作为电子穿梭体有助于提高·OH的生成量,促进2,4-D降解中间产物转化、并使脱氯反应更完全.

The supported iron sulfide(FeSx/BC)was prepared by loading on a wood biochar,and then characterized by SEM/EDX,XRD and XPS.It was used for catalyzing the Fenton-like oxidation of herbicide 2,4-dichlorophenoxyacetic acid(2,4-D),and compared with the commercial ferrous sulfide(c-FeS).The results indicated that the biochar improved the dispersion of iron sulfide,which existed mainly in the form of Fe3S4.The reaction rate constant(kobs)for 2,4-D degradation catalyzed by FeSx/BC was nearly 20 times that using the c-FeS.The degradation reaction was accelerated by increasing the dosages of catalyst and H2O2,while the reaction rate dropped with the rising initial pH(2.0—9.0).The mechanism studies showed that the biochar acting as the electron shuttle enhanced the production of·OH,which in turn promoted the transformation of degradation intermediates and facilitated the more complete dechlorination of 2,4-D.