Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065, PR China.
J Hazard Mater. 2010 Jan 15;173(1-3):33-9. doi: 10.1016/j.jhazmat.2009.08.003. Epub 2009 Aug 8.
This study describes a new approach for the preparation of tannin-immobilized adsorbent by using mesoporous silica bead as the supporting matrix. Bayberry tannin-immobilized mesoporous silica bead (BT-SiO2) was characterized by powder X-ray diffraction to verify the crystallinity, field-emission scanning electron microscopy to observe the surface morphology, and surface area and porosity analyzer to measure the mesoporous porous structure. Subsequently, the adsorption experiments to Cr(III) were applied to evaluate the adsorption performances of BT-SiO2. It was found that the adsorption of Cr(III) onto BT-SiO2 was pH-dependent, and the maximum adsorption capacity was obtained in the pH range of 5.0-5.5. The adsorption capacity was 1.30 mmol g(-1) at 303 K and pH 5.5 when the initial concentration of Cr(III) was 2.0 mmol L(-1). Based on proton nuclear magnetic resonance (HNMR) analyses, the adsorption mechanism of Cr(III) on BT-SiO2 was proved to be a chelating interaction. The adsorption kinetic data can be well described using pseudo-first-order model and the equilibrium data can be well fitted by the Langmuir isothermal model. Importantly, no bayberry tannin was leached out during the adsorption process and BT-SiO2 can simultaneously remove coexisting metal ions from aqueous solutions. In conclusion, this study provides a new strategy for the preparation of tannin-immobilized adsorbents that are highly effective in removal of heavy metals from aqueous solutions.
本研究描述了一种新的方法，即用介孔硅珠作为支撑基质制备单宁固定化吸附剂。杨梅单宁固定化介孔硅珠（BT-SiO2）通过粉末 X 射线衍射进行了表征，以验证其结晶度，用场发射扫描电子显微镜观察其表面形态，并用比表面积和孔隙率分析仪测量其介孔多孔结构。随后，应用吸附实验对 Cr(III)进行了评估，以评价 BT-SiO2 的吸附性能。结果表明，Cr(III)在 BT-SiO2 上的吸附是 pH 值依赖性的，在 pH 值为 5.0-5.5 的范围内获得了最大吸附容量。当 Cr(III)的初始浓度为 2.0 mmol L(-1)时，在 303 K 和 pH 5.5 下，吸附容量为 1.30 mmol g(-1)。基于质子核磁共振（HNMR）分析，证明了 Cr(III)在 BT-SiO2 上的吸附机理是螯合相互作用。吸附动力学数据可以很好地用拟一级模型描述，平衡数据可以很好地用 Langmuir 等温模型拟合。重要的是，在吸附过程中没有杨梅单宁浸出，BT-SiO2 可以同时从水溶液中去除共存的金属离子。总之，本研究为制备高效去除水溶液中重金属的单宁固定化吸附剂提供了一种新策略。
