'黑色'非晶形三价铁羟基氧化物及其对有害物质的吸附

摘要

利用硝酸铁与氨水之间的水解反应,生成了一种新的"黑色"非晶形三价铁羟基氧化物 (FeOOH).该物质在室温下稳定,有较高的硬度,其比表面积约为 300 m2/g,零电荷点 (PZC)在 pH 7～ 8之间.根据 M(o)ssbauer谱的鉴定,它具有四方纤铁矿(β-FeOOH)的结构特征. FeOOH和它与各溶质的表面配合物的 X射线光电光谱结果表明, FeOOH与 Pb、 Zn和GrO(4/2-)之间的反应是物理吸附,而与PO(4/3-)和AsO(4/3-)之间的反应是化学吸附. 3个阴离子及 2个阳离子的吸附等温式结果表明,该三价铁羟基氧化物的吸附能力比常见的铁羟基氧化物强 3倍.磷酸盐与砷酸盐之间的竞争反应结果表明,磷酸盐与 FeOOH的反应比砷酸盐强烈.%A novel form of amorphous black ferric oxyhydroxide (FeOOH) has been synthesized by hydrolysis of ferric nitrate with ammonia. This material is hard, stable at room temperature, has the local structure of akaganeite (β-FeOOH) according to conversion electron M(o)ssbauer results, fractures conchoidally, has a specific surface area around 300 m2/g and a point of zero charge at a pH around 7. X-ray photoelectron spectra of FeOOH and its surface complexes suggest that the interaction between FeOOH and two cations, Pb and Zn, and(CrO4/2-) constitutes physisorption, whereas that between FeOOH and two oxyanions,PO(4/3-) and AsO(4/3-) chemisorption. The adsorption isotherms of three oxyanions, chromate, phosphate, and arsenate and two cations lead and zinc indicate that the absolute adsorption characteristics are about three times higher than those of conventional ferric oxyhydroxides. Competitive experiments between phosphate and arsenate show that the phosphate-FeOOH substrate interaction is energetically favored over the arsenate one.