金属有机框架材料UTSA-74高效去除水溶液中的砷

利用水热法合成金属有机框架材料UTSA-74,并用它同时去除水中的As(Ⅴ)和As(Ⅲ)。 批次实验结果表明,在低质量浓度情况下(~1 mg/L),UTSA-74对As(Ⅴ)的去除率高达95%。 对As(Ⅲ)的去除率达85%。 经拟合,本实验符合拟二级动力学及Freundlich等温吸附模型。 本文还探究了共存离子(如Cl^-、NO₃^-、PO₄^3-)干扰影响,结果表明PO₄^3-的存在会抑制吸附的进行,可能是由于竞争吸附位点所致。 此外,本文对吸附后的材料进行洗脱(0.1 mol/L NaOH),将洗脱后的UTSA-74材料再次进行吸附探究,反复3次,其去除率仍可达70%左右。 为探究其中机理,本文通过X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)对吸附前后材料进行表征,结果表明吸附过程中可能形成了Zn—O—As,以此促进吸附反应的进行。 综上所述,UTSA-74可以作为一种处理砷的新型吸附剂,具有一定的实用价值。

Efficient Removal of Arsenic by Metal Organic Framework UTSA-74 from Aqueous Solutions

Metal organic framework UTSA-74 synthesized via hydrothermal method could efficiently remove both arsenate and arsenite from water. A batch test with aqueous solutions was performed, and 95% of As(Ⅴ) and 85% of As(Ⅲ) removal was obtained with the lower concentration of arsenic(~1 mg/L). This experiment data matched the pseudo-second-order model and Freundlich model. In addition, when Cl^-, NO₃^- and PO₄^3- all existed in solutions, PO₄^3- affected the adsorption of arsenic obviously. After adsorption, we eluted UTSA-74@arsenic by 0.1 mol/L NaOH, the removal rate of arsenic was still up to around 70% after three cycles. XRD, SEM and IR analyses showed that the excellent adsorption capacity was due to the reformed Zn—O—As bond between arsenic and adsorbent. In a word, UTSA-74 can be the candidate for removing arsenic.