Wang Yingcai, Wang Can, Shi Shuai, Fang Shuai
School of Environmental Science and Engineering, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin 300350, China.
Water Sci Technol. 2018 Jun;77(9-10):2509-2516. doi: 10.2166/wst.2018.208.
The effects of Mn(II) on Fenton system to treat papermaking wastewater and the mechanism of Mn(II) enhanced Fenton reaction were investigated in this study. The chemical oxygen demand (COD) removal efficiency was enhanced in the presence of Mn(II), which increased by 19% compared with that of the Fenton system alone. The pseudo-first order reaction kinetic rate constant of Mn(II)/Fenton system was 2.11 times higher than that of Fenton system. 67%-81% COD were removed with the increasing Mn(II) concentration from 0 to 0.8 g/L. COD removal efficiency was also enhanced in a wider pH range (3-7), which indicated the operation parameters of Fenton technology could be broadened to a milder condition. The study of the mechanism showed that Mn(II) participated in the oxidation and coagulation stages in Fenton system. In the oxidation stage, Mn(II) promotes the production of HO•/ O•, then HO•/ O• reacts with Fe(III) to accelerate the formation of Fe(II), and finally accelerates the production of HO•. Meantime MnMnO and Fe(OH) forms in the coagulation stage, facilitating the removal of suspended substances and a large amount of COD, which enhances the overall COD removal of papermaking wastewater. This study provided a detailed mechanism to improve practical applications of Fenton technology.
本研究考察了Mn(II)对芬顿体系处理造纸废水的影响及Mn(II)强化芬顿反应的机理。在Mn(II)存在的情况下，化学需氧量（COD）去除效率得到提高，与单独的芬顿体系相比提高了19%。Mn(II)/芬顿体系的准一级反应动力学速率常数比芬顿体系高2.11倍。随着Mn(II)浓度从0增加到0.8 g/L，COD去除率达到67%-81%。在较宽的pH范围（3-7）内，COD去除效率也有所提高，这表明芬顿技术的操作参数可以扩展到更温和的条件。机理研究表明，Mn(II)参与了芬顿体系的氧化和混凝阶段。在氧化阶段，Mn(II)促进HO•/O•的产生，然后HO•/O•与Fe(III)反应加速Fe(II)的形成，最终加速HO•的产生。同时，在混凝阶段形成MnMnO和Fe(OH)，促进悬浮物和大量COD的去除，从而提高造纸废水的整体COD去除率。本研究为改进芬顿技术的实际应用提供了详细的机理。
