铬酸根离子在羟基铁离子—蒙脱石体系中的吸附行为研究

廖立兵; FraserDonald G.

铬酸根离子在羟基铁离子—蒙脱石体系中的吸附行为研究

廖立兵^{1, 2},
FraserDonald G.²

1.
中国地质大学材料科学与工程学院, 北京 100083
2.
牛津大学地球科学系, Parks Road, Oxford OX1 3PR, UK

基金项目:

国家自然科学基金 49973028

详细信息

作者简介:
廖立兵(1963-), 男, 矿物学博士, 教授, 博士生导师, 主要从事矿物表面、矿物材料学研究

中图分类号: P579;P578.8
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出版历程
- 收稿日期: 2002-06-11
- 刊出日期: 2002-09-25

Adsorption of Chromate in System Hydroxy-Fe-montmorillonite

LIAO Li-bing^{1, 2},
Fraser Donald G.²

1.
School of Material Science and Engineering, China University of Geosciences, Beijing 100083, China
2.
Department of Earth Sciences, Oxford University, Parks Road, Oxford OX1 3PR, UK

摘要

摘要: 采矿、电镀、制革等行业废物排放及含Cr矿物风化可造成一些地区土壤和地下水的Cr污染.Cr主要以三价和六价形式存在, 其中Cr (Ⅵ) 有强的迁移能力, 对动植物均有很强的毒害性.研究了在氧化、酸性条件下, 土壤及土壤溶液中的蒙脱石和羟基铁离子共存时对铬酸根离子(主要以HCrO₄^2-和CrO₄^2-等Cr (Ⅵ) 形式存在) 的吸附行为.进行了蒙脱石、羟基铁离子、Cr (Ⅵ) 离子添加顺序不同的3个系列的实验, 重点研究了Cr的初始质量浓度、溶液pH值、环境温度、吸附时间、溶液离子强度对3个系列Cr吸附行为的影响, 并与羟基铁离子体系进行了对比.结果表明, 蒙脱石-羟基铁离子体系的Cr吸附能力明显强于蒙脱石而低于羟基铁离子, 其Cr吸附率随Cr初始质量浓度、温度的升高和吸附时间的延长而降低, 随离子强度的升高而升高, 而pH值对不同系列的Cr吸附率有不尽相同的影响.
- 蒙脱石 /
- 羟基铁离子 /
- 铬酸根 /
- 吸附
Abstract: Chromate ions have high affinity for soluble hydroxy-Fe species and for Fe-oxyhydroxide precipitates. The hydrolysis of Fe (Ⅲ) and the growth of initially precipitated Fe (Ⅲ) phases is, in turn, strongly affected by montmorillonite. In this paper, the adsorption of Cr (Ⅵ) in the system hydroxy-Fe-montmorillonite was studied. Four series of batch experiments were conducted by mixing montmorillonite, hydroxy-Fe and chromate in the following order: (1) Montmorillonite+hydroxy-Fe before addition of chromate; (2) Hydroxy Fe+chromate before addition of montmorillonite; (3) Montmorillonite+chromate before addition of hydroxy-Fe; (4) Hydroxy-Fe+chromate. For each series, the effects of pH, ionic strength, temperature, initial Cr concentration and adsorption duration on the overall uptake of Cr in the system hydroxy-Fe-montmorillonite were studied.Resultsshow that the uptake of Cr increases with the increase in ionic strength and decreases with the increases in temperature, initial Cr concentration and adsorption duration. Optimum pH values exist for Series 2, 3 and 4, but not for Series 1. These effects occur, to different extents, in the four series. On all experimental conditions, the hydroxy-Fe-montmorillonite system displayed very strong affinity for Cr with Series 3 containing the highest Cr adsorption capacity and Series 1 the lowest. The authors attribute this to the difference in mixing order adopted, resulting in more hydroxy-Fe (the main adsorbent for Cr) being adsorbed onto montmorillonite for Series 1 before the hydroxy-Fe is able to adsorb Cr, that is the case for Series 2 and 3. Discussions and explanations have been given to these experimental phenomena.
- hydroxy-Fe /
- montmorillonite /
- chromate /
- adsorption.

HTML全文

图 1 羟基铁离子—蒙脱石体系中Cr吸附率随Cr初始质量浓度(a)、pH值(c) 的变化以及Cr吸附量随Cr加入量(b) 的变化

Fig. 1. Percentage adsorption of Cr as functions of initial Cr concentration (a) and pH (c), and total amount of adsorbed Cr as a function of initial amount of Cr in hydroxy-Fe-montmorillonite system

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图 2 羟基铁离子—蒙脱石体系的Cr吸附率随离子强度(a)、温度(b) 和吸附时间(c) 的变化

Fig. 2. Percentage adsorption of Cr in hydroxy-Fe-montmorillonite system as functions of ionic strength (a), temperature (b) and adsorption time (c)

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图 3 羟基铁离子—蒙脱石体系吸附Cr后溶液中的剩余Fe浓度随吸附时间的变化(只显示系列2, 4)

Fig. 3. Fe remained in solution after adsorption of Cr by hydroxy-Fe-montmorillonite system for different adsorption duration (only series 2 and 4 shown)

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表 1 蒙脱石用量对羟基离子-蒙脱石体系Cr吸附率的影响

Table 1. Influence of montmorillonite dosage on the percentage adsorption of Cr in hydroxy-Fe-montmorillonite system

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