纳米零价铁去除冶炼废水中砷和硒:固相形态分析

Removal of Arsenic and Selenium From Smelting Waste water with Nanoscale Zero-valent Iron(nZVI):Solid State Speciation Analysis

采用序批式化学提取法对纳米零价铁与冶炼废水反应后固相中砷和硒的形态进行了测定分析,并与去离子水系统中砷/硒固相形态进行了比较,探讨了纳米零价铁去除冶炼废水中As/Se的反应机制。结果表明:序批式化学提取法可有效用于确定反应后固相中砷和硒的形态;纳米零价铁去除冶炼废水中硒的机制主要以还原反应为主,固相中硒形态主要为还原态的Se(0)和Se(-Ⅱ),Se(0)含量随初始pH值的增加而增加,随反应时间的延长、纳米零价铁投加量的增加而减少,Se(0)被进一步还原为Se(-Ⅱ);纳米零价铁去除冶炼废水中砷的机制主要以共沉淀反应为主,固相中共沉淀As的含量随反应时间的延长、pH值的升高而增加,随纳米零价铁投加量的增加而减少。

In this study,nanoscale zero-valent iron(nZVI)was used to treat the real smelting wastewater and solid一state speciation of arsenic and selenium was determined by sequential batch chemical extraction.The arsenic and selenium speciation were compared with that of deionized water system.The removal mechanisms of arsenic and selenium from smelting wastewater were also investigated.The results showed that the solid-state arsenic and selenium speciation can be efficiently determined by sequential batch chemical extraction method.The main mechanism of Se removal from smelting wastewater with nZVI was reduction and Se in smelting wastewater was mainly reduced to Se(0)and Se(—Ⅱ)by nZVI.The content of Se(0)increased as pHini increased,while decreased with increasing reaction time and nZVI dosage.The elemental Se could be further reduced to Se(—Ⅱ).The main mechanism of As removal from smelting wastewater with nZVI was coprecipitation with iron corrosion products and metal hydroxide.The content of As—coprecipitated increased with increasing reaction time and pHini,while decreased as nZVI dosage increased.