Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China.
Environ Sci Technol. 2012 Jan 3;46(1):419-25. doi: 10.1021/es202043u. Epub 2011 Dec 13.
We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr(VI), Cd(II), Cr(III), Cu(II), and Co(II) ions from simulated wastewater with a facile subsequent solid-liquid separation because of their large sizes. We chose Cr(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr(VI) from simulated wastewater containing 8.0 mg·L(-1) of Cr(VI) at pH = 2.0. The Cr(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr(VI) ions in the form of negatively charged HCrO(4)(-) by positively charged TiO(2) beads, accompanying partial reduction of Cr(VI) to Cr(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L(-1) of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid-liquid separation property for heavy metal ions removal.
我们通过海藻酸钠生物聚合物模板法合成了尺寸均匀（约 450μm）、比表面积高的介孔二氧化钛珠。由于其较大的尺寸，这些介孔二氧化钛珠可以有效地从模拟废水中去除 Cr(VI)、Cd(II)、Cr(III)、Cu(II) 和 Co(II)离子，并通过简单的固液分离实现。我们选择去除 Cr(VI)作为案例研究，发现每克这些二氧化钛珠可以在 pH = 2.0 时从含有 8.0mg·L(-1) Cr(VI)的模拟废水中去除 6.7mg 的 Cr(VI)。Cr(VI)去除过程符合 Langmuir 吸附模型，动力学遵循拟二级速率方程。二氧化钛珠的 Cr(VI)去除机制可能归因于带负电荷的 HCrO(4)(-)形式的 Cr(VI)离子通过带正电荷的 TiO(2)珠的静电吸附，以及二氧化钛珠表面的还原羟基部分将 Cr(VI)还原为 Cr(III)。用过的二氧化钛珠可以用 0.1mol·L(-1)的 NaOH 溶液回收。这项研究提供了一种具有良好固液分离性能的新型微/纳米结构吸附剂，可用于去除重金属离子。
