纳米赤铁矿吸附剂吸附低浓度U(Ⅵ)的行为与机理

Adsorption Behavior and Mechanism of U (Ⅵ) by Nano Hematite from Low Concentration Wastewater

采用水热法制备了纳米赤铁矿吸附剂,对不同pH值、吸附剂用量、吸附时间和初始U(Ⅵ)浓度下纳米赤铁矿吸附剂吸附低浓度U(Ⅵ)的行为进行了研究,并采用XRD、SEM和EDS对纳米赤铁矿吸附剂吸附U(Ⅵ)前后的表面形貌进行了表征和分析,揭示了纳米赤铁矿吸附剂吸附低浓度U(Ⅵ)的动力学特征和吸附机理。结果表明,当温度为25℃、pH为7、吸附剂用量为0.4g/L、U(Ⅵ)的初始质量浓度为5mg/L时,在120min时吸附即达到了平衡;此时,吸附率最高,达到了92.62%;纳米赤铁矿吸附剂吸附低浓度U(Ⅵ)的过程是一个快速平衡的过程,其动力学过程符合准二级动力学模型,说明纳米赤铁矿吸附低浓度U(Ⅵ)的方式主要为化学吸附,其吸附等温线符合Freundlich吸附模型,表明纳米赤铁矿吸附低浓度U(Ⅵ)为多层吸附。

Nano-hematite adsorbent was prepared via hydrothermal synthesis.The effects of pH,adsorbent content,contact time and initial concentration of U(Ⅵ)on its adsorption of U(Ⅵ)in low concentration wastewater were investigated.The morphologies of nano-hematite adsorbents before and after adsorption of low concentration U(Ⅵ)were characterized by XRD,SEM and EDS.The adsorption kinetics and mechanism of the adsorbent for U (Ⅵ) in low concentration wastewater were determined.The results showed that when the temperature was 25 ℃,pH 7,dosage of nano hematite,0.4 g/L and the initial concentration of U(Ⅵ),5 mg/L,the adsorption reached equilibrium at 120 min.At this time,the adsorption effect was the best,and the removal rate reached 92.62%.The adsorption process of U(Ⅵ)in low concentration wastewater by the adsorbent was a rapid process for equilibrium.Its kinetic process was well fitted with the pseudo-second-order model,and the adsorption is mainly the chemical one.The adsorption isotherm for the adsorbent was consistent with the Freundlich adsorption model,and the adsorption of U(Ⅵ)by the adsorbent is mainly involved with multilayer adsorption.