Photocatalytic degradation of 4-chlorophenol on titanium dioxide modified with Cu(II) or Cr(III) ion under visible light irradiation
Photocatalytic degradation of 4-chlorophenol on titanium dioxide modified with Cu(II) or Cr(III) ion under visible light irradiation
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DOI：
10.1016/j.apcata.2016.09.001
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发表时间：
2016-10
影响因子：
5.5
通讯作者：
N. Nishiyama;Keisuke Kozasa;S. Yamazaki
中科院分区：
文献类型：
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作者：
N. Nishiyama;Keisuke Kozasa;S. Yamazaki
以Ti（OC 3 H7）4为原料，采用溶胶-凝胶法和浸渍法制备了Cu 2+或Cr 3+改性的TiO 2（M-TiO 2，M-接枝TiO 2）。在溶胶-凝胶法中，通过制备具有或不具有透析的TiO 2溶胶（分别为M-TiO 2（D）或M-TiO 2（ND））来改变M-TiO 2的Brunauer-Emmett-Teller（BET）表面积。即使通过使用溶胶-凝胶法，离子尺寸大于Ti4+的Cu 2+也不能被掺杂，而是由于相对弱的相互作用而被掺入到TiO 2中。当Cu-TiO 2（D）、Cu-TiO 2（ND）或Cu接枝TiO 2浸入0.1 mol dm-3 HCl的酸性溶液中时，观察到Cu 2+离子的溶解。在可见光照射下，对4-氯苯酚（4-CP）的光催化降解活性顺序为：Cu接枝TiO 2> Cu-TiO 2（ND）> Cu-TiO 2（D）。结果表明，Cu接枝TiO 2的光催化活性随表面Cu ~（2+）离子数密度的增加而线性下降。另一方面，当Cr ~（3+）离子的粒径与Ti ~（4+）离子的粒径相近时，通过溶胶-凝胶法将Cr ~（3+）掺杂到TiO_2中，可显著提高TiO_2的光催化活性。通过透析增加BET比表面积增强了光催化活性。从光催化活性和酸性条件下的化学稳定性两个方面论证了溶胶-凝胶法制备的Cr掺杂TiO 2在降解水中难降解有机污染物4-CP方面优于Cu接枝TiO 2。
TiO2modified with Cu2+or Cr3+ion (M-TiO2, M-grafted TiO2) was synthesized by a sol-gel method using Ti(OC3H7)4as a starting material or a graft method by impregnation of rutile TiO2. In the sol-gel method, the Brunauer-Emmett-Teller (BET) surface area of M-TiO2was varied by preparing with or without dialysis of TiO2sol (M-TiO2(D) or M-TiO2(ND), respectively). Even by using the sol-gel method, Cu2+whose ionic size is larger than Ti4+cannot be doped but is incorporated in TiO2due to relatively weak interaction. Dissolution of Cu2+ion was observed when Cu-TiO2(D), Cu-TiO2(ND) or Cu-grafted TiO2was immersed into the acidic solution of 0.1 mol dm−3HCl. The photocatalytic activity for the degradation of 4-chlorophenol (4-CP) under visible light irradiation was the following order: Cu-grafted TiO2> Cu-TiO2(ND) > Cu-TiO2(D). We have revealed that the photocatalytic activity of Cu-grafted TiO2decreases linearly with an increase in the number-density of Cu2+ion on the TiO2surface. On the other hand, in the case of Cr3+ion which has a similar size as Ti4+, the photocatalytic activity increased remarkably by doping Cr3+in TiO2by the sol-gel method. An increase in the BET surface area by conducting dialysis enhanced the photocatalytic activity. This paper demonstrates from the viewpoint of the higher photocatalytic activity as well as the chemical stability in acidic conditions that Cr-doped TiO2prepared by the sol-gel method gives an advantage over Cu-grafted TiO2for the degradation of 4-CP which is one of the non-degradable organic contaminants in water.