Performance of Goethite Surface-mediated Ferrous Iron Aerobic Oxidation to Generate Hydroxyl Radicals and Its Application
By externally adding Fe(Ⅱ)and Fe(Ⅲ)to the reaction system,this study focuses on investigating the production of reactive oxygen species(ROS)mediated by the surface of goethite and its enhancement mechanism for the oxidation and transformation of As(Ⅲ).The analyses with XRD,ESR,and XPS indicated that ROS gener-ated in the oxidation of the ferrihydrite/Fe(Ⅱ)system under weakly acidic pH conditions includes hydroxyl radical·OH,singlet oxygen 1O2,and superoxide radical·O2-,while the Fenton like reaction for the·OH production is a single electron transfer process.Approximately 364.82 μmol/L H2O2 can be generated during the oxidation reaction of ferrihydrite/Fe(Ⅱ)system for 120 min,and the presence of O2 highly determined the generation of H2O2.The·OH cumulative concentration in the above ferrihydrite/Fe(Ⅱ)system is positively correlated with the amount of Fe(Ⅱ)to be oxidized.A weak weak acidic condition at pH 6 is more favorable for the ferrous oxygenation reaction system to produce OH,wherein the OH cumulative concentration is about 30.69 μmol/L.Moreover,the oxida-tion of As(Ⅲ)by ROS such as·OH species mainly occurs on mineral surfaces.The presence of Fe(Ⅱ)is condu-cive to the occurrence of As(Ⅲ)oxidation to form As(V)in the system,but due to competitive adsorption,the Fe(Ⅱ)adsorption may not be conducive to both the adsorption of As(Ⅲ)and its subsequent interfacial oxidation in the system.As a result,this study will contribute to well-understanding of the synergistic mechanism of Fe(Ⅱ)reactivity mediated by mineral surfaces coupling with the enhancement in arsenic pollution environmental purifica-tion,and thus may provide the experimental and theoretical bases for practical arsenic contaminated soil environ-mental remediation.
ferrihydriteferrous iron oxygenationhydroxyl radicalArseniteoxidative transformation
万方数据
维普
