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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），pH 5时，Cr（Ⅲ）的最大吸附量（13．19 mg·g－1）远大于Cr（Ⅵ）（0．63 mg·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．

Titanate nanosheets ( TNS) were prepared using hydrothermal method via anatase TiO2 as raw material. The adsorption processes of Cr(Ⅵ) and Cr(Ⅲ) onto TNS were thoroughly studied, and simultaneous removal of Cr (Ⅵ) and Cr (Ⅲ) by synergetic photocatalysis and adsorption at various pHs was investigated. TEM and XRD analysis indicated that the as?prepared TNS exhibited multiple phases of anatase TiO2 and titanate, which were important for their photocatalysis and adsorption performance. Batch adsorption experiments depicted that pH significantly affected Cr(Ⅵ) and Cr(Ⅲ) adsorption onto TNS. The adsorption capacity of Cr(Ⅲ) was enhanced with increasing pH, while that of Cr(Ⅵ) was decreased. Both Cr(Ⅵ) and Cr(Ⅲ) were adsorbed rapidly by TNS, with the adsorption kinetics fitted well with the pseudo?second model (R2>0.99). In addition, the Langmuir model can describe well the adsorption isotherms of both Cr (Ⅵ) and Cr (Ⅲ) ( R2>0.99), and the saturated adsorption capacity of Cr(Ⅲ) (13.19 mg·g-1) was much larger than that of Cr(Ⅵ) (0.63 mg·g-1). Therefore, adsorption alone is not an effective method for removal of Cr(Ⅵ) and photocatalysis is needed. Synergetic experiments of photocatalysis and adsorption suggested the apparent rate constant of Cr(Ⅵ) photocatalysis decreased dramatically with increase pH, while the adsorption of Cr(Ⅲ) was obviously facilitated. Taken together, the optimal pH for the synergy of photocatalysis and adsorption was pH 5, at which the removal efficiency of Cr(Ⅵ) and total Cr reached as high as 97. 6%, and Cr (Ⅲ) was not detected in the solution. This study has provided a promising method for simultaneous removal of Cr(Ⅵ) and Cr(Ⅲ) from the wastewater.