Effect of FeS Colloids on Desorption of As(Ⅴ) Adsorbed on Ferric Iron
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摘要: 地下水中的含铁胶体颗粒会携带污染物如砷等运移，但人们对该过程中的机理缺乏认识.通过群组静态吸附解吸模拟实验, 探究FeS胶体对吸附在覆Fe2O3石英砂上As(Ⅴ)的解吸作用, 以及腐殖酸(HA)、H2PO4-和HCO3-对解吸的影响.实验结果表明，室内合成的FeS胶体具有纳米级粒径和较大的比表面积，且能均匀稳定存在于水溶液中.低浓度的FeS胶体主要通过竞争覆Fe2O3石英砂表面的吸附点位将As(Ⅴ)解吸，而高浓度的FeS胶体主要通过与覆Fe2O3石英砂竞争对As(Ⅴ)的吸附而导致解吸.HA、H2PO4-和HCO3-对As(Ⅴ)的竞争解吸作用降低了FeS胶体导致的解吸效率.Abstract: The iron colloids in groundwater are associated with contaminants such as arsenate in transport processes, but the mechanism underlying the process is not clear. In this study, batch static adsorption and desorption experiments were conducted to investigate the effect of FeS colloids on desorption of As(Ⅴ) adsorbed on Fe2O3-coated sand, as well as the influences of HA, H2PO4- and HCO3- on the desorption. Results show that FeS colloids at low concentrations desorbed As (V) mainly by competing adsorption sites on the surface of Fe2O3-sand, while desorption at high concentrations is mainly due to the competitive adsorption for As (V) with Fe2O3-sand. As HA (humic acid), H2PO4- and HCO3- could desorb As (V) from Fe2O3-sand, As (V) desorption by FeS colloids was reduced. The results may better our understanding of the mechanisms of the arsenate release from sediments into groundwater.
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Key words:
- FeS colloids /
- sediment /
- As(Ⅴ) /
- groundwater
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图 1 FeS胶体对水溶液中As(Ⅴ)的吸附时间曲线
Fig. 1. Time profiles of As (V) adsorption by FeS colloids in aqueous solution
图 2 FeS胶体对As(Ⅴ)的解吸时间曲线(a)，以及溶液中FeS浓度随时间的变化(b)
Fig. 2. Time profiles of As(Ⅴ) desorption by FeS colloids (a), the change of FeS concentration by time in the solution (b)
图 4 不同浓度H2PO4-对FeS胶体解吸As(Ⅴ)的影响(a)，以及对溶液中H2PO4-浓度的变化(b)
Fig. 4. Effects of H2PO4- on As (V) desorption by FeS colloids (a), and the change of H2PO4- concentration in the solution (b)
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