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绿锈与As(V)可共存于土壤、沉积物和地下水等缺氧环境,但As(V)如何影响绿锈转化过程和机制了解甚少.本工作通过溶液化学和光谱学方法,系统研究了As(V)浓度、pH、温度和空气流速对硫酸盐绿锈(GR)转化的影响.GR转化过程中通过吸附和共沉淀作用对As(V)有极强的去除能力,同时As(V)增强了GR的稳定性,显著影响转化产物的结晶度、矿物类型和生成机制.随As(V)浓度增加,GR氧化转化由溶解-氧化-沉淀机制向固态氧化机制过渡,产物由针铁矿和纤铁矿混合相向纯纤铁矿向纤铁矿、水铁矿和高铁绿锈混合相转变;高As(V)浓度时形成无定形FAsO_4表面沉淀.Fe/As=24时,pH 6.5~9、温度(5~45℃)和空气流速(0~0.05 m3/h)条件下纤铁矿均为主要产物,随pH和空气流速增加或温度减小纤铁矿结晶度逐渐减弱;高pH或高空气流速或低温有利于高铁绿锈和水铁矿形成,高温有利于针铁矿形成.上述结果对深入理解环境中各种铁氧化物的形成转化机制和As(V)的环境行为有重要意义.
Green rust and As (V) can coexist in anoxic environments such as soil, sediments and groundwater, but little is known about how As (V) affects the process and mechanism of green rust transformation.This work was studied systematically by solution chemistry and spectroscopy The effect of As (V) concentration, pH, temperature and air velocity on the conversion of sulfate green rust (GR) was studied.As (V) was strongly removed by adsorption and coprecipitation during the process of GR conversion, As (V) V) enhanced the stability of GR and significantly affected the crystallinity, mineral type and formation mechanism of the conversion products.With the increase of As (V) concentration, the GR oxidation conversion from the dissolution-oxidation-precipitation mechanism to the solid state oxidation mechanism, the product from the needle The mixed phases of iron ore and lepidocrocite transformed into mixed phases of lepidocrocite, ferrihydrite and high-iron-iron, and formed amorphous FAsO_4 surface precipitates at high As (V) concentration. When Fe / As = 24, The results show that the leaching rate of lepidocrocite increases with the increase of pH and air velocity or the decrease of the crystallinity of lepidocrocite at the temperature of 6.5 ~ 9 (5 ~ 45 ℃) and air velocity (0 ~ 0.05 m3 / h) High pH or high air velocity or low temperature is beneficial to the formation of high-iron green rust and water iron ore, high temperature is conducive to goethite formation. The transformation mechanism is formed appreciated that the environment of various iron oxides and As (V) environmental behavior is important.