葫芦6脲对印染废水中染料曙红的吸附特性及影响因素
Adsorption characteristics and influencing factors of cucurbit6 uril for dye eosin Y from printing and dying wastewater
-
摘要: 考察了葫芦6脲(CB6)对印染废水中典型染料曙红的吸附特性,研究了初始pH、吸附剂投加量、共存离子等对吸附效果的影响,并探讨了吸附机理。结果表明:在温度为25 ℃,曙红初始浓度为20 mg/L条件下,CB6投加量为0.5 g/L时,2 h吸附去除率为79.5%,吸附动力学特征符合准二级动力学方程;Langmuir等温模型拟合结果比Freundlich模型具更高的相关系数,由Langmuir 模型计算得出的最大吸附容量为413.05 mg/g,且随温度升高,最大吸附容量下降,表明CB6对曙红的吸附过程为放热过程;随溶液初始pH由3增至11,吸附容量从33.28 mg/g降至9.14 mg/g;共存阴离子对CB6吸附的不利影响顺序为PO3-4>CO2-3>NO-2>NO-3;CB6具有重复利用性,利用芬顿试剂3次再生后仍保持了原始材料84.9%的吸附容量。通过比表面积、核磁共振氢谱红外图谱和扫描电镜对样品进行表征,采用密度泛函理论计算的静电势分布图分析,揭示了CB6可能的吸附原理是其“腰部”与阴离子形式的曙红水解产物产生静电吸引,从而形成超分子外包结构组装体。Abstract: The adsorption characteristics of cucurbit6uril (CB6) for the typical dye eosin in printing and dyeing wastewater were investigated. The effects of initial pH, adsorbent dosage and co-existing ions on the adsorption effect were studied, and the adsorption mechanism was discussed. The results showed that the adsorption removal efficiency was 79.5% after 2 hours when the initial concentration of eosin Y (EY) was 20 mg/L at 25 ℃ and the dosage of CB6 was 0.5 g/L, and the adsorption kinetics characteristics was consistent with the pseudo-second-order kinetic equation. The Langmuir isotherm model had higher correlation coefficient than Freundlich model. The maximum adsorption capacity calculated using Langmuir model was 413.05 mg/g, and with the increase of the temperature, the maximum adsorption capacity of CB6 decreased, indicating that the adsorption process of CB6 was exothermic. As the initial pH of the solution increased from 3 to 11, the adsorption capacity decreased from 33.28 mg/g to 9.14 mg/g. The adverse effects of coexisting anions on adsorption were in the order of PO3-4>CO2-3>NO-2>NO-3. CB6 was recyclable and retained 84.9% adsorption capacity of the original material after 3 times of regeneration using Fenton reagent. The samples were characterized by BET,1H NMR, IR and SEM. The electrostatic potential distribution map of CB6 was analyzed by the density functional theory (DFT), which revealed that the possible adsorption principle of CB6 was that the “waist” of CB6 and the hydrolysate of EY in the form of anions generated electrostatic attraction, thus forming a supramolecular outsourcing package.