Abstract: The adsorption behavior of arsenite (As(Ⅲ)) and arsenate (As(Ⅴ)) by Fe-Mn binary oxide (FMBO) was studied. The results indicated that FMBO had strong adsorption ability to both As(Ⅲ) and As(Ⅴ) and the maximum adsorption capacity was 111.10, 71.40 mg·g^-1 respectively. As(Ⅲ) and As(Ⅴ) were adsorbed on FMBO surface through forming inner-sphere surface complexes by ligand exchange with hydroxyl groups, and As(Ⅲ) removal by FMBO was through an oxidation and adsorption combined process. In addition, the influences of co-existing substances generally present in biogas slurry were examined. Zinc ion could promote As(Ⅲ) and As(Ⅴ) adsorption on FMBO and the adsorption capacity increased with increasing zinc ion concentration. Phosphate had significant effect on As(Ⅲ) and As(Ⅴ) removal. When P/As ratio was equal to 1, the adsorption capacity of As(Ⅲ) and As(Ⅴ) was reduced by 34.70%, 31.50%, respectively. However, organics, such as humic acid, animal protein and carbamide had no significant effect on As(Ⅲ) and As(Ⅴ) removal. Moreover, FMBO as adsorbent for removal arsenic of actual biogas slurry was investigated. The average removal rate of arsenic of actual biogas slurry was about 65%, decreasing the arsenic concentration of some biogas slurry to the drinking water and surface water discharge standard. Therefore, FMBO could be an attractive adsorbent for both As(Ⅴ) and As(Ⅲ) removal from biogas slurry.

Key words: Fe-Mn binary oxide, arsenic, adsorption, oxidation, biogas slurry

摘要： 研究了铁锰复合氧化物（FMBO）吸附去除As（Ⅲ）、As（Ⅴ）的性能。结果表明FMBO对As（Ⅲ）、As（Ⅴ）均具有较好的吸附能力，其饱和吸附量分别为111.10、71.40 mg·g^-1。As（Ⅲ）和As（Ⅴ）是通过与FMBO表面的Fe—OH基团进行交换并形成内层络合物的形式被FMBO吸附，且As（Ⅲ）的吸附是吸附和氧化共同作用的结果。另外，沼液中共存离子对As（Ⅲ）和As（Ⅴ）的吸附有不同的影响。Zn²⁺能够增加FMBO对As（Ⅲ）、As（Ⅴ）的吸附量，且增加幅度随着Zn²⁺浓度的增加而增加；磷酸根对As（Ⅲ）、As（Ⅴ）的吸附有明显的抑制作用，当磷与砷的分子摩尔比为1时，FMBO对As（Ⅲ）、As（Ⅴ）的吸附量分别降低了34.70%、31.50%；但是有机物（腐殖酸、动物蛋白及尿素）对FMBO吸附As（Ⅲ）、As（Ⅴ）的影响不大。利用FMBO对实际沼液中的砷进行吸附，结果表明砷的去除率平均达到65%左右，使吸附后某些沼液中砷的浓度达到生活饮用水标准和地表水排放标准。因此，将FMBO用于砷污染的沼液及水体的治理具有很好的应用前景。

关键词: 铁锰复合氧化物, 砷, 吸附, 氧化, 沼液