| 二胺基改性有序多孔SBA-15对溶液中Cd2+离子的吸附研究 |
| 摘要点击 2694 全文点击 1649 投稿时间：2012-10-10 修订日期：2013-01-15 |
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| 中文关键词 胺基改性 SBA-15 吸附 有序介孔材料 Cd2+ 热力学特征 |
| 英文关键词 amino-modified SBA-15 adsorption ordered mesoporous material Cd2+ thermodynamic |
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| 中文摘要 |
| 具有高度有序孔道结构的SBA-15是一种广受关注的新型吸附材料,为增加其对溶液重金属离子的吸附性能,选用水热-后期接枝的合成方法,制备出二胺基改性多孔二氧化硅2N-SBA-15,并用透射电镜、X射线衍射、氮气吸附-解吸和红外光谱等手段对其结构进行了表征. 并以其为吸附剂,通过批实验的方法讨论了吸附时间、体系初始pH值、吸附剂用量和温度等因素对水溶液中Cd2+吸附的影响,同时结合Zeta电势和XPS分析对其吸附机制进行了探讨. 结果表明,合成的SBA-15具有规则多孔特征,SBA-15对Cd2+的吸附受体系pH控制; 未改性的SBA-15对Cd2+的吸附量较小,胺基改性可以显著增强SBA-15对Cd2+的吸附能力. 在100 mL 25 mg·L-1的Cd2+溶液中,2N-SBA-15的用量在7.5~20 mg之间均能对Cd2+的吸附能力约达95%左右. 2N-SBA-15对溶液中Cd2+的吸附很迅速,并在30 min内达到吸附平衡; 随着体系温度从25℃增加到35℃,2N-SBA-15对溶液中Cd2+的吸附率从94.73%增加到98.22%. 吸附等温线可用Langmuir模型描述,在 298 K 时Cd2+的最大吸附量为0.9 mmol·g-1, 0.1 mol·L-1 HCl溶液对Cd2+的洗脱率接近93%. 结合pH、温度、Zeta电势和XPS分析结果,可以推测出2N-SBA-15对Cd2+的吸附机制是包含物理吸附、离子交换和络合反应等的复杂吸附过程. 2N-SBA-15是一种对水体Cd2+具有较好吸附能力的吸附材料. |
| 英文摘要 |
| Highly ordered channel structure SBA-15 was widely concerned as new adsorbents in environmental protection, in order to increase its heavy metal ions adsorption ability from aqueous solution, the diamine -modified porous silicate SBA-15 was synthesized by a hydrothermal grafting method and characterized by TEM,X-ray diffraction,FTIR and N2 adsorption-desorption.The SBA-15 and modified SBA-15 samples were used as sorbents to adsorb Cd(Ⅱ) ions from aqueous solution. The effect of experimental parameters,such as pH,contact time, sorbent dosage and temperature were examined, and the maximum adsorption amount was also calculated.The results showed that under same conditions,the Cd(Ⅱ) removal rate was higher for 2N-SBA-15 than that of the unmodified SBA-15.The adsorption process was controlled by system pH. The highest removal rate could reached about 95% after pH was higher than 4. Adsorption equilibrium was reached within 30 minutes,and more than 95% Cd2+ was adsorbed when 7.5-20 mg sorbent was added into 100 mL solution contained 25 mg·L-1 Cd2+.The adsorption capacity increased from 94.73% to 98.22% with temperature increased from 25℃ to 35℃. The Langmuir model can be used to describe adsorption isotherms.The adsorption capacity of Cd2+ was 0.9 mmol·g-1 which is comparable to the adsorption capacity of various adsorbents reported in the literature, and 0.1 mol·L-1 HCl could remove nearly 93% Cd2+ from 2N-SBA-15 particles.Based on the thermodynamic, pH, XPS and Zeta potential analysis results in this study, it could be concluded that the adsorption process was an endothermic and spontaneous reaction which contained physical adsorption, ion exchange and chelating reaction etc. The study indicated that the diamine -modified ordered mesoporous material SBA-15 is a potential sorbent which could be used for the aqueous Cd2+ removal. |
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