CAJ | 학술논문

采用搅拌流动法研究了酸性水钠锰矿及水羟锰矿2种δ-MnO2矿物氧化As(Ⅲ)的动力学过程,构建了可用于多相体系的搅拌-流动氧化还原反应动力学模型.经过As吸附量的校正后,该模型对酸性水钠锰矿及水羟锰矿氧化As(III)动力学数据拟合度分别为0.980和0.951,模型拟合得到pH 7时2种矿物单位比表面上氧化As(III)的初始反应速率常数k分别为0.131,0.014min-1?m-2.相比而言,该速率常数明显高于批量法得到的表观速率常数kobs,0.021,0.001min-1?m-2更接近真实的化学动力学参数.搅拌流动法与批量法得到的不同矿物的速率常数大小趋势一致,即尽管酸性水钠锰矿对 As(III)的氧化率低于水羟锰矿,单位比表面上酸性水钠锰矿氧化 As(III)初始反应速率却远高于水羟锰矿.反应过程分析表明,反应初始阶段,As(III)的吸附为主要限速步骤；而随着反应的进行,矿物表面反应位点逐渐钝化或减少,反应位点数量成为限速步骤.
채용교반류동법연구료산성수납맹광급수간맹광2충δ-MnO2광물양화As(Ⅲ)적동역학과정,구건료가용우다상체계적교반-류동양화환원반응동역학모형.경과As흡부량적교정후,해모형대산성수납맹광급수간맹광양화As(III)동역학수거의합도분별위0.980화0.951,모형의합득도pH 7시2충광물단위비표면상양화As(III)적초시반응속솔상수k분별위0.131,0.014min-1?m-2.상비이언,해속솔상수명현고우비량법득도적표관속솔상수kobs,0.021,0.001min-1?m-2경접근진실적화학동역학삼수.교반류동법여비량법득도적불동광물적속솔상수대소추세일치,즉진관산성수납맹광대 As(III)적양화솔저우수간맹광,단위비표면상산성수납맹광양화 As(III)초시반응속솔각원고우수간맹광.반응과정분석표명,반응초시계단,As(III)적흡부위주요한속보취；이수착반응적진행,광물표면반응위점축점둔화혹감소,반응위점수량성위한속보취.
In this study, As (III) oxidation at the surfaces of two δ-MnO2 minerals, birnessite and vernadite, was investigated using stirred-flow technique, and the corresponding model was established to describe the kinetics of the redox reactions in the stirred-flow heterogeneous system. Following correction of As adsorption, the degree of fitting of the stirred-flow kinetic data of As (III) oxidation by birnessite and vernadite using the established model was 0.980and 0.951, respectively. The obtained initial rate constants (k) per unit specific area at pH 7were 0.131 and 0.014min-1m-2, respectively, which were much greater than apparent initial rate constant (kobs), 0.021min-1m-2 and 0.001min-1m-2, derived from the batch experiments. This indicated that rate constant (k) is much closer to the real chemical kintics that could be obtained using the stirred-flow technique. Both stirred-flow and the batch experiments showed that birnessite exhibited the greater reaction rate on a per surface area basis in As (III) oxidation than on vernadite, although birnessite had a relatively lower suface area and As (III) oxidation capacity. Analysis of the reaction process suggested that As (III) absorption was the rate determining step in the initial stage, and then the number of suface Mn reactive sites gradually became the rate determining step with the passivation and decrease of the sites.