柠檬酸对含Fe(II)天然矿物去除地下水中六价铬的促进作用
- Effect of Citric Acid on The Performance of Iron Ore in Removing Hexavalent Chromium from groundwater
- 摘要：含Fe(II)矿物作为化学还原修复材料,具有费用低、原料易得和反应产物稳定等特点,已被广泛用于对Cr(VI)污染水体的修复.但是,固体表面生成的CrxFe1-x(OH)3和Cr(OH)3等氧化产物钝化层,往往会抑制含Fe(II)矿物对Cr(VI)的去除行为.通过批实验观测了典型天然有机酸柠檬酸对黄铁矿、菱铁矿和磁铁矿等含Fe(II)矿物去除地下水中Cr(VI)的影响.研究结果表明柠檬酸对含Fe(II)矿物去除地下水中Cr(Ⅵ)有显著的促进作用,并受pH值、Cr(VI)初始浓度、Ca2+、Mg2+和SO42-等因素影响.不同于黄铁矿和磁铁矿,柠檬酸对菱铁矿的促进作用随着柠檬酸浓度的增大,在柠檬酸浓度为7 mmol?L-1时菱铁矿对地下水中Cr(VI)的去除速率达到峰值.黄铁矿、菱铁矿和磁铁矿去除地下水中Cr(Ⅵ)的反应速率随pH值的升高而降低;黄铁矿、菱铁矿和磁铁矿对地下水中Cr(Ⅵ)的反应速率随Cr(Ⅵ)初始浓度的升高而降低;Ca2+、Mg2+和SO42-对柠檬酸促进含Fe(II)矿物去除地下水中Cr(Ⅵ)有明显的影响.本研究丰富了柠檬酸对含Fe(II)矿物去除地下水中Cr(VI)影响的认识,为Cr(VI)污染地下水修复提供新的思路和理论依据.
- Abstract：Fe(II)-containing minerals have been widely used as chemical reduction remediation materials for the remediation of Cr(VI)-contaminated waters because of their low cost, easy availability of raw materials, and stability of reaction products. However, the passivation layer of oxidation products such as CrxFe1-x(OH)3 and Cr(OH)3 generated on the solid surface tends to inhibit the removal behavior of Fe(II)-containing minerals for Cr(VI). In this study, the effect of citric acid, a typical natural organic acid, on the removal of Cr(VI) from groundwater by Fe(II)-containing minerals such as pyrite, rhodochrosite and magnetite was observed in batch experiments. The results showed that citric acid contributed significantly to the removal of Cr(VI) from groundwater by Fe(II)-containing minerals and was affected by pH, initial Cr(VI) concentration, Ca2+, Mg2+ and SO42-. Unlike pyrite and magnetite, the promotion effect of citric acid on rhodochrosite increased with the increase of citric acid concentration, and the removal rate of Cr(VI) from groundwater by rhodochrosite reached a peak at a citric acid concentration of 7 mmol?L-1. The reaction rates of pyrite, rhodochrosite and magnetite for the removal of Cr(VI) from groundwater decreased with the increase of pH, respectively; the reaction rates of pyrite, rhodochrosite and magnetite for the removal of Cr(VI) from groundwater decreased with the increase of the initial concentration of Cr(VI); Ca2+, Mg2+ and SO42- were more important to citric acid than citric acid; and the reaction rates of pyrite, rhodochrosite and magnetite for the removal of Cr(VI) in groundwater decreased with the increase of the initial concentration of Cr(VI); Ca2+, Mg2+ and SO42- were more important to citric acid. and SO42- had significant effects on the citric acid-promoted removal of Cr(Ⅵ) from groundwater by Fe(II)-containing minerals. The present study enriched the understanding of the effect of citric acid on the removal of Cr(VI) from Fe(II)-containing minerals, and provided new ideas and theoretical basis for the remediation of Cr(VI)-contaminated groundwater.
