摘要
在一定条件下利用钠基蒙脱石(Na-Mt)合成了OH/Al比为1.6的聚合羟基铝-蒙脱石(HyAl-Mt)复合体,并研究了弱酸性和强酸化条件下HyAl-Mt与氟之间的相互作用及土壤环境意义。结果表明,pH在5.0～9.0之间时,HyAl-Mt对氟的吸附受pH影响小;当pH<4.5时,吸附能力随pH减小迅速增大。pH6.62时,HyAl-Mt对氟的吸附主要是络合交换机制,而pH3.02及高氟浓度条件下是表面吸附、矿物溶解及共沉淀-卷扫等协同作用机制,并使HyAl-Mt具有异常高的氟去除能力。与蒙脱石粘土相比,HyAl-Mt的氟吸附能力明显提高,土壤中的HyAl-Mt组分可有效地降低氟污染土壤中氟的迁移性并减少其生物有效性。在酸性氟污染的土壤中,氟与HyAl-Mt相互作用还可一定程度抑制土壤的酸化。土壤酸度越大,这种抑制作用越明显。施用合成的HyAl-Mt可作为酸性氟污染土壤修复并控制土壤酸化的有效途经之一。
Hydroxyaluminum-montmorillonite (HyAl-Mt) complexes with OH/Al ratio of 1.6 were synthesized by irreversible adsorption of polymeric hydroxyaluminum cations on Na-saturated montmorillonite (Na-Mt). The interactions of fluoride with the HyAl-Mt are investigated under weak acid and strongly acidified conditions, and the environmental implications for fluoride-contaminated soils are also addressed. The results indicate that the effects of pH on fluoride sorption on the HyAl-Mt are slight in the pH range of 5.0～9.0, while sorption increases rapidly with decreasing pH when pH is lower than 4.5. At initial pH 6.62, ligand exchange is the main mechanism of fluoride sorption on the HyAl-Mt; at initial pH 3.02, several mechanisms such as surface adsorption, mineral dissolution and coprecipitation-sweeping are involved in fluoride sorption, through which fluoride removal is greatly enhanced. Compared with the Na-Mt, the sorption capacities of the HyAl-Mt for fluoride are significantly enhanced at similar conditions. The presence of HyAl-Mt complexes in acidic soils may greatly decreases the mobility and bioavailability of fluoride in soil environments. The interactions of fluoride with HyAl-Mt complexes may mitigate acidificationof fluoride-contaminated acidic soils to some extent. Application of synthetic HyAl-Mt complexes is one of effective ways for remediation of acidic fluoride-contaminated soils.
出处
《地球化学》
CAS
CSCD
北大核心
2005年第3期278-284,共7页
Geochimica
基金
国家自然科学基金(49904005)~~
关键词
羟基铝-蒙脱石
氟污染
吸附
土壤酸化
土壤修复
hydroxyaluminum-montmorillonite
fluoride contamination
adsorption
soil acidification
soil remediation
