王俊伟,杜俊逸,桂梦瑶,吴代赦.氧化环境中FeS修复重金属的稳定性变化与机制[J].环境科学学报,2020,40(2):563-573
氧化环境中FeS修复重金属的稳定性变化与机制
- Variation in stability of FeS-immobilized heavy metal in oxidizing environments and the mechanism
- 基金项目：国家重点研发计划（No.2017YFD0800900）
- 王俊伟
- 1. 南昌大学资源环境与化工学院, 南昌 330031;2. 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 杜俊逸
- 1. 南昌大学资源环境与化工学院, 南昌 330031;2. 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 桂梦瑶
- 1. 南昌大学资源环境与化工学院, 南昌 330031;2. 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 吴代赦
- 1. 南昌大学资源环境与化工学院, 南昌 330031;2. 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 摘要：硫化亚铁（FeS）是良好的重金属修复剂，但它对氧化环境敏感.当环境氧气浓度升高时，FeS对重金属的固定效果可能发生改变.本研究考察了氧化环境中FeS与重铬酸根、铅和镉离子的反应规律和结合机制变化.结果表明，环境氧气浓度升高可促进Fe2+的释放，且增加FeS表面S（-II）氧化态的比例（与Pb2+反应：从24%增加到44%，与Cd2+反应：从60%增加到78%）.延长反应时间至30 d，虽然PbS和CdS结晶度提高，但两者表面出现Pb-O和Cd-O氧化形态，预示着重金属再释放的风险.有氧干燥条件下FeS表面矿物相转变为纤铁矿，对Cr（VI）的还原能力大幅下降.与未干燥FeS（FeS-Cr-3h）相比，当有氧干燥的FeS与Cr（VI）反应时，总铬的去除量下降约96%（由约100 mg·g-1降至（3.74±1.12）mg·g-1），Cr（VI）去除量下降约57%（由约100 mg·g-1降至（43.28±0.46）mg·g-1）.FeS及重金属硫化物的氧化显然不利于重金属的长期稳定.如何延缓或抑制FeS与重金属硫化物的氧化因此成为未来研究需回答的问题.
- Abstract：Ferrous sulfide (FeS) is one of the most favorable agents for heavy metal remediation, yet it is sensitive to the oxidizing environment.As the oxygen concentration in the remediation environment increases, the ability of FeS to immobilize heavy metal may change.This study thus investigated the variations of FeS with dichromate (Cr(VI)), lead (Pb2+), and cadmium (Cd2+) ions in reactions and binding mechanisms in oxidizing environments.An increased dissolved oxygen concentration accelerated the release of Fe2+ and boosted the proportion of S(-II)-oxidized state on the surface of FeS(Reaction with Pb2+:from 24% to 44%;reaction with Cd2+:from 60% to 78%).Extending the reaction time to 30 days was conducive to the crystallization of PbS and CdS.Nevertheless,the oxidized species, Pb-O and Cd-O, appeared on the surface of samples after 30 days, predicative of a risk of heavy metal re-mobilization. After drying in an oxygen-containing environment, the surface FeS transformed into lepidocrocite, which led to lower Cr(VI) removal than undried FeS. Specifically, the total chromium and the Cr(VI) removal of dried FeS decreased by about 96% from 100 mg·g-1 to (3.74±1.12) mg·g-1, and 57% from 100 mg·g-1 to (43.28±0.46) mg·g-1, respectively.The oxidation of FeS and heavy metal sulfides obviously affected the long-term stability of heavy metals in the remediation environment.How to mitigate the oxidation of FeS and heavy metal sulfides will be a question to be answered in our future research.
