Background: Wastewater with dyes pollutes the environment and causes serious risk to human health and aquatic biota. Gentian violet (GV) belongs to typical triphenylmethane dyes and is difficult to be degraded. Calcium bismuthate nanoflakes possess good photocatalytic activity toward GV under solar light irradiation.

Objective: The aim of the study was to prepare calcium bismuthate nanoflakes by the hydrothermal method and research on the solar light photocatalytic performance of the calcium bismuthate nanoflakes for GV degradation.

Methods: Calcium bismuthate nanoflakes were synthesized via a facile hydrothermal route assisted by cetyltrimethylammonium bromide (CTAB) based on the reaction of sodium bismuthate and calcium chloride. The calcium bismuthate products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy and solid UV-vis diffuse reflectance spectrum.

Results: The calcium bismuthate nanoflakes possess single crystalline monoclinic CaBi2O4 phase. The size of the whole nanoflakes is about 10 μm and the thickness of the nanoflakes is about 40 nm. The morphology, size and phase of the products are closely relative to CTAB concentration, reaction temperature and reaction time. The bandgap of the calcium bismuthate nanoflakes is 2.21 eV. The photocatalytic activity of the calcium bismuthate nanoflakes is high enough to completely degrade GV under solar light irradiation for 6 h.

Conclusion: The photocatalytic performance for the removal of GV is dependent on the irradiation time, dosage of the calcium bismuthate nanoflakes and initial GV concentration. The calcium bismuthate nanoflakes exhibit great promising activity for the removal of organic pollutants.

背景：含染料的废水污染了环境，对人类健康和水生生物造成了严重的风险。龙胆紫（GV）属于典型的三苯甲烷染料，很难降解。铋酸钙纳米片在日光照射下对GV具有良好的光催化活性。

目的：以水热法制备铋酸钙纳米片，研究其在光催化下降解GV的性能。

方法：在铋酸钠与氯化钙反应的基础上，通过十六烷基三甲基溴化铵（CTAB）辅助的水热法合成铋酸钙纳米片。铋酸钙产品通过X射线衍射（XRD），扫描电子显微镜（SEM），透射电子显微镜和固体UV-vis漫反射光谱进行了分析。

结果：铋酸钙纳米片具有单晶CaBi2O4单晶相。整个纳米薄片的尺寸为约10μm，并且纳米薄片的厚度为约40nm。产物的形态，大小和相与CTAB浓度，反应温度和反应时间密切相关。铋酸钙纳米薄片的带隙为2.21 eV。铋酸钙纳米薄片的光催化活性足够高，可以在太阳光照射6小时后完全降解GV。

结论：去除GV的光催化性能取决于照射时间，铋铋酸钙纳米薄片的剂量和初始GV浓度。铋酸钙纳米片在去除有机污染物方面显示出巨大的前景。