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环境化学  2015 

钛酸盐纳米片光催化-吸附协同去除水中Cr(Ⅵ)和Cr(Ⅲ)

Keywords: 钛酸盐纳米片,协同,光催化,吸附,

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Abstract:

以锐钛型纳米TiO2为原材料,采用水热法合成了钛酸盐纳米片(TNS),系统研究了Cr(Ⅵ)和Cr(Ⅲ)在TNS上的吸附行为,以及不同pH下TNS光催化协同吸附对水体中Cr(Ⅵ)和Cr(Ⅲ)的同步去除.TEM及XRD表征结果表明,制备的TNS呈现出锐钛矿与钛酸盐混合晶相,这对于其光催化和吸附性能的发挥极为重要.吸附实验证实,TNS对Cr(Ⅵ)和Cr(Ⅲ)的吸附显著受pH影响,高pH利于Cr(Ⅲ)的吸附,而Cr(Ⅵ)在低pH下吸附量更大.Cr(Ⅵ)和Cr(Ⅲ)在TNS上的吸附速度较快,吸附动力学符合准二级动力学模型(R2>0.99).吸附等温线结果符合Langmuir方程(R2>0.99),pH5时,Cr(Ⅲ)的最大吸附量(13.19mg·g-1)远大于Cr(Ⅵ)(0.63mg·g-1),因此,单一吸附不是有效处理Cr(Ⅵ)的手段,光催化还原是必要的.光催化-吸附实验表明,随着pH的增加,TNS光催化还原Cr(Ⅵ)反应速率逐渐降低,但产生的Cr(Ⅲ)在TNS表面的吸附量显著增加.综合可知,光催化-吸附协同反应最佳pH值为5,Cr(Ⅵ)和总Cr的去除率可达97.6%,且体系中无Cr(Ⅲ)的积累.该研究为同步有效去除水体中的Cr(Ⅵ)和Cr(Ⅲ)提供了一种新的可参照的途径.

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