Immobilization of heavy metals in soils amended by nanoparticulate zeolitic tuff: Sorption‐desorption of cadmium
Immobilization of heavy metals in soils amended by nanoparticulate zeolitic tuff: Sorption‐desorption of cadmium
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DOI：
10.1002/jpln.200900053
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发表时间：
2010-12
影响因子：
2.5
通讯作者：
A. Ghrair;J. Ingwersen;T. Streck
中科院分区：
文献类型：
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作者：
A. Ghrair;J. Ingwersen;T. Streck
污染土壤中Cd的固定化是一种改善土壤质量的技术。沸石是一种潜在的有用的重金属结合添加剂。研究了将天然沸石凝灰岩的粒度减小到纳米级对砂质土壤中Cd吸附-解吸等温线的影响。目的是评价纳米沸石凝灰岩作为土壤中Cd的固着剂的可行性。通过间歇实验研究了Cd在沸石纳米凝灰岩上的吸附和解吸行为。用沸石纳米凝灰岩、合成氧化铝纳米颗粒或原始沸石凝灰岩对沙质土壤进行改性。在48h的吸附步骤后，用顺序稀释法诱导出三个解吸步骤。测得的吸附-解吸数据符合Freundlich方程。实验测得的沸石纳米凝灰岩、粗沸石凝灰岩、氧化铝纳米颗粒和对照土壤对Cd的吸附-脱附等温线与非线性两阶段单速率模型吻合较好。批量实验表明，pH对Cd的吸附有很强的影响。沸石纳米凝灰岩的Zeta电位测量表明，静电相互作用是吸附的重要因素。根据吸附-解吸等温线对土壤吸附Cd量的不同，沸石纳米凝灰岩修饰的土壤表现出最低的滞后指数。该指数随金属浓度的增加而减小。纳米沸石凝灰岩改性土壤的Freundlich系数比对照土壤高4个数量级，比未改性沸石凝灰岩土壤高2个数量级。此外，与对照土壤和添加原始沸石凝灰岩的土壤相比，该脱附剂在三个解吸步骤后Cd的释放量分别减少了12倍和7倍。磨细生沸石凝灰岩对Cd吸附的影响明显大于磨细生沸石凝灰岩对Cd吸附的影响。
Immobilization of Cd in contaminated soil is a technique to improve soil quality. Zeolites are potentially useful additives to bind heavy metals. This study examines the influence of decreasing the grain size of raw zeolitic tuff to the nano-range on Cd sorption-desorption isotherms in a sandy soil. The aim was to evaluate the feasibility of using nanoparticulate zeolitic tuff as a sequestering agent for Cd in soil. Sorption and desorption of Cd on zeolitic nanotuff was investigated in batch experiments. The sandy soil was amended with zeolitic nanotuff, synthetic Al oxide nanoparticles, or raw zeolitic tuff. After a 48 h sorption step, three desorption steps were induced using the sequential dilution method. The measured sorption-desorption data were adequately described by the Freundlich equation. A nonlinear two-stage one-rate model matched well with measured Cd sorption-desorption isotherms of zeolitic nanotuff, raw zeolitic tuff, Al oxide nanoparticle, and control soil. The batch experiments demonstrated the strong influence of pH on Cd sorption. Zeta-potential measurements of zeolitic nanotuff indicated that electrostatic interaction was important for sorption. Soil amended with zeolitic nanotuff showed the lowest hysteresis index based on the differences obtained from sorption-desorption isotherms regarding the amount of Cd sorbed. The index decreased with increasing metal concentration. For soil amended with nanoparticulate zeolitic tuff, the estimated Freundlich coefficient was 4 orders of magnitude higher than in the control soil and 2 orders of magnitude higher than the soil amended with raw zeolitic tuff. In addition, this sorbent decreased the amount of Cd released after three desorption steps by up to 12 and 7 times compared to the control soil and the soil amended with raw zeolitic tuff, respectively. The effect on Cd sorption of grinding the raw zeolitic tuff to the nanorange was considerably more pronounced than the effect of raw zeolitic tuff.