改性凹凸棒土吸附剂去除水中的Cr(VI)

以凹凸棒土为载体，合成了乙二胺(EDA)改性凹凸棒土(ATP)吸附剂EDA/ATP复合材料。采用FTIR、TGA对吸附剂进行表征，同时将其应用于对水中Cr(VI)的吸附，研究了溶液初始浓度、吸附时间、溶液pH、Cl?与PO₄3?阴离子浓度对吸附的影响。FTIR和TGA结果表明乙二胺已成功接枝到凹凸棒土表面。吸附实验表明，25℃时EDA/ATP复合材料对Cr(VI)的最大吸附容量为153.78 mg·g?1，吸附在800~900 min内达到平衡，吸附符合Freundlich吸附等温模型和拟二级动力学模型；在初始溶液pH为2~10条件下，随着pH的增加，吸附量先增加再降低，pH为3时，吸附量最大；Cl?对吸附影响较小，PO₄3?对吸附的影响较大，当PO₄3?浓度达到20 mmol·L?1时，Cr(VI)最大吸附量下降了83 mg·g?1；实验表明EDA/ATP可作为一种潜在处理水中Cr(VI)的吸附剂。 

Removal of Cr(VI) from water by modified attapulgite adsorbent

Ethylenediamine modified attapulgite(EDA/ATP) adsorbent was synthesized by using clay-based adsorbent ATP as carrier. The EDA/ATP composite adsorbent was characterized by FTIR and TGA. The adsorbent was applied to the adsorption of Cr(VI) in aqueous. The effects of initial concentration of Cr(VI) solution, adsorption time, solution pH and the anion concentration Cl? and PO₄3? on the adsorption of Cr(VI) were studied. The FTIR and TGA results show that EDA has been successfully grafted onto the surface of ATP. The adsorption experimental results show that at 25℃ the maximum adsorption capacity of EDA/ATP composite for Cr(VI) is 153.78 mg·g?1, and the adsorption reaches equilibrium within 800~900 min. The adsorption experimental data conform to Freundlich adsorption isotherm model and the pseudo-second-order kinetics. The initial pH of solution is ranging from 2 to 10. With the increase of pH, the adsorption capacity first increases and then decreases. When the pH is 3, the adsorption capacity reaches the maximum adsorption amount. PO₄3? has greater effect on the adsorption than Cl?, and the maximum adsorption capacity decreases by 83 mg·g?1 when the concentration of PO₄3? is 20 mmol·L?1. The experimental results show that EDA/ATP composite can be used as a potential adsorbent for Cr(VI) in water treatment.