Kong Xiangke, Huang Guoxin, Han Zhantao, Xu Youming, Zhu Ming, Zhang Zhaoji
Institute of Hydrogeology and Environmental Geology, CAGS, Shijiazhuang, 050061, China.
Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, No. 268, North Zhonghua Street, Shijiazhuang, 050061, China.
Environ Sci Pollut Res Int. 2017 May;24(15):13837-13844. doi: 10.1007/s11356-017-8974-9. Epub 2017 Apr 13.
A new composite adsorbent, zeolite-supported microscale zero-valent iron (Z-mZVI) was evaluated as a potential adsorbent for the removal of Cd and Pb from aqueous solution using batch and column experiments. Adsorption isotherms were well fitted by Langmuir model, and the maximum adsorption capacity was 63.14 mg/g for Cd and 154.61 mg/g for Pb, respectively. Both adsorption processes followed the pseudo-second-order model which indicated that the rate-limiting step for different initial concentration was dominated by chemical adsorption process. The coexistence of Cd and Pb caused the reduction of Cd removal efficiency, but not for Pb. Z-mZVI has a high removal capacity for Cd and Pb over a wide pH range (3.0-6.8) as well as in the presence of competitive Ca or Mg ions (<2 mmol/L). Moreover, Z-mZVI shows a high immobilization capacity for the adsorbed Cd and Pb products, even at the acid solution (pH = 3.95). Column experiment confirmed that Z-mZVI could simultaneously remove Cd and Pb from solution efficiently. Thomas model can simulate the equilibrium adsorption capacity of Cd and Pb of the Z-mZVI column well. This study demonstrates that Z-mZVI is an efficient and promising reactive material in permeable reactive barriers for Cd and Pb removal from aqueous solution.
一种新型复合吸附剂，即沸石负载的微尺度零价铁（Z-mZVI），通过批次实验和柱实验被评估为从水溶液中去除镉（Cd）和铅（Pb）的潜在吸附剂。吸附等温线很好地符合朗缪尔模型，Cd的最大吸附容量分别为63.14 mg/g，Pb的最大吸附容量为154.61 mg/g。两种吸附过程均遵循准二级模型，这表明不同初始浓度下的限速步骤由化学吸附过程主导。Cd和Pb的共存导致Cd去除效率降低，但对Pb没有影响。Z-mZVI在较宽的pH范围（3.0 - 6.8）以及存在竞争性Ca或Mg离子（<2 mmol/L）的情况下，对Cd和Pb具有较高的去除能力。此外，即使在酸性溶液（pH = 3.95）中，Z-mZVI对吸附的Cd和Pb产物也表现出较高的固定能力。柱实验证实Z-mZVI可以有效地同时从溶液中去除Cd和Pb。托马斯模型可以很好地模拟Z-mZVI柱对Cd和Pb的平衡吸附容量。本研究表明，Z-mZVI是一种用于从水溶液中去除Cd和Pb的渗透反应屏障中高效且有前景的活性材料。
