双金属和多金属系统对零价铁利用效率的改进

Improvement of Zero Valent Iron Efficiency by Bimetallic System and Multi-Metallic System

为解决Fe^0-PRB(零价铁-渗透反应格栅)中Fe0利用效率低、易板结堵塞的问题,分别采用粒径为0.074 mm的试剂铁粉和0.150~0.270 mm的工业铁粉为反应介质,在铁粉表面负载不同比例的Cu或Ni制备Cu/Fe、Ni/Fe双金属和Cu/Ni/Fe多金属颗粒,研究Fe^0、双金属和多金属系统去除Cr(Ⅵ)的性能、机制.结果表明:双金属和多金属系统的Cr(Ⅵ)去除率明显高于Fe^0,试剂铁粉的Cr(Ⅵ)去除率明显高于工业铁粉.反应8 h达到平衡后,试剂铁粉和工业铁粉的Cr(Ⅵ)去除率仅为45%和20%,Cu/Fe双金属、Cu/Ni/Fe多金属的Cr(Ⅵ)去除率均能达到90%以上,以试剂铁粉和工业铁粉制备的Ni/Fe双金属的Cr(Ⅵ)去除率最高分别为76.6%和44.0%.不同负载率的双金属和多金属系统反应过程中可溶的ρ〔Cr(Ⅲ)〕较低.反应后溶液的p H从反应前的5.0升至10.0左右.反应初期ρ(TFe)(TFe为总铁)超过了0.30 mg/L,其余时间均达标.反应过程中ρ(Cu^(2+))均在0.40 mg/L以下,均未检测出Ni^(2+).研究显示,双金属和多金属系统显著提高了Fe0利用效率.

To resolve the low zero valent iron （ Fe^0 ） use efficiency, barrier agglomeration and porous media blockage problems of Fe^0- PRB （ zero valent iron-permeable reactive barrier） , Cu/Fe, Ni/Fe bimetallic and Cu/Ni/Fe multi-metallic power were prepared by loading different small amounts of copper or nickel on the 8 g reagent grade Fe^0 powder （0. 074 mm） and industrial scrap Fe^0 powder （0. 150- 0. 270 mm） respectively, and Cr（ VI ） removal performance and mechanism were also investigated for Fe^0 , Cu/Fe, Ni/Fe bimetallic and Cu/Ni/Fe multi-metallic PRB systems. The results showed that Cr（VI） removal efficiency of bimetallic and multi-metallic PRB system were significantly higher than that of Fe^-PRB, while that of reagent grade Fe^0-PRB was obviously higher than that of industrial scrap Fe^0- PRB. When the reaction was balanced after 8h operation, Cr（ VI ） removals were above 90% for Cu/Fe bimetallic and Cu/Ni/Fe multi- metallic PRB system based on two grades of Fe^0 , and that of reagent grade and industrial scrap Ni/Fe were 76.6% and 44.0% , respectively. However, Cr（ VI ） removal of the reagent grade and industrial scrap Fe^0-PRB were only 45% and 20%. The dissolved Cr（ Ⅲ） concentration was very low during operation of the bimetallic and multi-metallic PRB with different metal loading ratio. The pH increased from 5.0 to 10.0 after their operation. The total iron concentration was above 0.30 mg/L at the initial state, but it could meetthe limited value of standards for drinking water quality at other stages. During the operation, the Cu^2＋ coneentration was less than 0.40 mg/L, while Ni^2＋ eoncentration was lower than its minimum detection limitation. Fe^0 efficiency was significantly improved by bimetallic system and multi-metallic PRB system.