酸性水钠锰矿掺杂钛离子强化重金属锑的氧化和吸附

Enhanced Removal of Sb(III)and Sb(V)by Acid Birnessite with Doped Titanium Ions

酸性水钠锰矿对于重金属Sb(III)表现出优越的氧化性能,但是在吸附方面特别是对于Sb(V)的吸附效果并不理想。本研究通过掺杂四价钛离子改善水钠锰矿的晶体结构、比表面积和等电点,从而来提高其对于工业废水中锑的吸附能力,特别是提高对于Sb(V)的吸附。结果表明,掺杂钛离子后的水钠锰矿对于Sb(V)最大吸附量可达474 mg/g,较不掺杂时几乎不吸附有了极大的提升。掺钛水钠锰矿对于Sb(III)和Sb(V)的吸附等温线符合Langmuir模型,而动力学曲线符合假一级动力学模型。机理研究发现,掺钛水钠锰矿在去除Sb(III)的动力学过程反映出吸附-脱附-再吸附过程,这与酸性水钠锰矿与Sb(III)的氧化反应促使材料结构改变有关。而且,掺钛水钠锰矿在吸附重金属Sb(V)时材料的晶格扭曲度降低,有序度提高,这也再一次证实锑离子的吸附影响了材料本身的晶体结构。本研究提供了简便高效的改性方式,从而改善了水钠锰矿在含锑工业废水处理时的应用。

Acid birnessite(AB)shows superior oxidation performance for Sb(Ⅲ),but its adsorption capacity especially for Sb(Ⅴ)is not ideal.Here,we doped tetravalent titanium ion in AB for adjusting the crystal structure,specific surface area and isoelectric point to improve the adsorption capacity for antimony,especially for Sb(Ⅴ).The maximum adsorption capacity for Sb(Ⅴ)of Ti doped AB reached 474 mg/g,greatly higher than that of without Ti doping,almost no adsorption of Sb(Ⅴ).The adsorption isotherms of Sb(Ⅲ)and Sb(Ⅴ)on Ti doped AB fitted the Langmuir model,while the kinetic curves agreed well with the pseudo-first-order kinetic model.Moreover,the mechanism study found that the kinetic process of Sb(III)removal by Ti doped AB reflected the adsorption-desorption-re-adsorption process,which was related to the oxidation reaction between AB and Sb(Ⅲ)to change the material structure.In addition,the lattice distortion of the material decreased and the order degree increased during the adsorption of Sb(Ⅴ),which confirmed once again that the adsorption of Sb(Ⅴ)affected the crystal structure of the material itself.This study provided a simple and efficient modification method for AB and extended the application of AB in the treatment of antimony containing wastewater.