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Adsorption and catalytic oxidation of arsenite on Fe-Mn nodules in the presence of oxygen.
Chemosphere ( IF 8.8 ) Pub Date : 2020-06-30 , DOI: 10.1016/j.chemosphere.2020.127503
Omar Rady 1 , Lihu Liu 2 , Xiong Yang 2 , Xianjin Tang 3 , Wenfeng Tan 2 , Guohong Qiu 2
Affiliation  

Fe-Mn nodules affect the speciation, transformation and migration of arsenic (As) via redox and adsorption reactions. However, few studies have been concerned with their interaction in the presence of dissolved oxygen. In this work, the interaction mechanism of As(III) and Fe-Mn nodules was studied in different atmospheres. The influence of pH, dissolved oxygen concentration and chemical composition of nodules on the reaction was also investigated. The results indicated that manganese oxides and iron oxides in nodules respectively contribute to As(III) oxidation and As(III,V) adsorption. Under oxic conditions, Fe-Mn nodules acted as a catalyst to accelerate the oxidation of Mn(II) to Mn(III,V) oxides, which significantly enhanced As(III) oxidation. In the system containing 10 mg L−1 As(III) and 1.0 g L−1 Fe-Mn nodules, the maximum oxidation capacity of As(III) reached 3.22, 3.48 and 3.71 mg g−1, and the corresponding As(III,V) adsorption capacity reached 2.49, 2.40, and 2.39 mg g−1 in nitrogen, air and oxygen atmosphere, respectively. The oxidation capacity of As(III) increased and decreased with increasing dissolved oxygen concentration and pH, respectively. This work clarifies the mechanism of As(III) oxidation by soil Fe-Mn nodules in various systems and contributes to a better understanding of the behaviors and fate of As in environments.



中文翻译:

在氧气存在下,Fe-Mn结核上砷的吸附和催化氧化。

铁锰结核通过氧化还原和吸附反应影响砷(As)的形态,转化和迁移。但是,很少有研究关注溶解氧存在下的相互作用。在这项工作中,研究了As(III)和Fe-Mn结核在不同气氛下的相互作用机理。还研究了pH,溶氧浓度和结核的化学组成对反应的影响。结果表明,结核中的锰氧化物和铁氧化物分别有助于As(III)的氧化和As(III,V)的吸附。在有氧条件下,Fe-Mn根瘤充当催化剂,促进Mn(II)氧化为Mn(III,V)氧化物,从而显着增强As(III)的氧化。在含有10 mg L -1 As(III)和1.0 g L的系统中-1铁锰结节,(III)由于最大氧化能力达到3.22,3.48和3.71毫克克-1,和相应的作为(III,V)的吸附容量达到2.49,2.40,和2.39毫克克-1在氮气,空气和氧气气氛。As(III)的氧化能力分别随溶解氧浓度和pH的增加而增加和降低。这项工作阐明了土壤铁锰结核在各种系统中氧化As(III)的机理,并有助于更好地理解环境中As的行为和命运。

更新日期:2020-07-06
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