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Enhanced photocatalytic degradation of perfluorooctanoic acid using carbon-modified bismuth phosphate composite: Effectiveness, material synergy and roles of carbon
Chemical Engineering Journal ( IF 15.1 ) Pub Date : 2020-04-08 , DOI: 10.1016/j.cej.2020.124991
Tianyuan Xu , Yangmo Zhu , Jun Duan , Yabei Xia , Tianyi Tong , Lizhi Zhang , Dongye Zhao

Per- and polyfluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) are recalcitrant to conventional wastewater treatment processes. In search for a more effective technology, we prepared a carbon sphere (CS) modified bismuth phosphate composite photocatalyst (BiOHP/CS) through a hydrothermal process. BiOHP/CS was able to adsorb > 99% of PFOA in 2 h (dosage = 1.0 g/L, initial PFOA = 200 µg/L, pH = 7.0), and subsequently, in situ decompose adsorbed PFOA nearly completely in 4 h of UV irradiation. The PFOA degradation rate was ~18 times greater than that by neat BiOHP. Advanced spectroscopic analyses and density functional theory calculations revealed that the carbon modification not only enhances the PFOA adsorption capacity, but also facilitates a side-on adsorption configuration of PFOA on the photoactive sites. While only the head carboxylate group was involved in PFOA adsorption on neat BiOHP, both the CF2/CF3 entities and the head carboxylate group participated in adsorption of PFOA on BiOHP/CS, which facilitates the subsequent photocatalytic cleavage of the CF bonds. Photoluminescence emission analysis and density of states calculations confirmed the CS-facilitated side-on adsorption mode and CS-enhanced separation of electrons and holes. In addition, the CS modification facilitates activation of PFOA by changing the electron distribution of the C-F bond, and enhances the stability and reusability of BiOHP by preventing photo-corrosion of the composite material. Overall, the findings provide important insights into the roles of carbonaceous modification and adsorption configurations in enhanced photocatalytic destruction of PFOA, which may guide future design and fabrication of environment-friendly adsorptive photocatalysts.



中文翻译:

碳改性的磷酸铋复合物增强的全氟辛酸光催化降解:有效性,材料协同作用和碳的作用

全氟和多氟烷基物质(PFAS),例如全氟辛酸(PFOA),对常规废水处理工艺不利。为了寻求更有效的技术,我们通过水热法制备了碳球(CS)改性的磷酸铋复合光催化剂(BiOHP / CS)。BiOHP / CS能够吸附> PFOA的99%在2小时(剂量= 1.0克/升,初始PFOA = 200微克/升,pH值= 7.0),接着,在原位在紫外线照射4小时后几乎完全分解了吸附的PFOA。PFOA的降解率比纯BiOHP高约18倍。先进的光谱分析和密度泛函理论计算表明,碳改性不仅增强了PFOA的吸附能力,而且还促进了PFOA在光敏位点上的侧向吸附构型。虽然仅头部羧酸酯基团参与纯净BiOHP上PFOA的吸附,但CF 2 / CF 3实体和头部羧酸酯基团均参与BiFOP / CS上PFOA的吸附,这促进了C的后续光催化裂解。F键。光致发光发射分析和状态密度计算证实了CS促进的侧面吸附模式以及CS增强的电子和空穴分离。另外,CS改性通过改变CF键的电子分布而促进了PFOA的活化,并且通过防止复合材料的光腐蚀而增强了BiOHP的稳定性和可重复使用性。总体而言,这些发现为碳质修饰和吸附构型在增强PFOA的光催化破坏中的作用提供了重要的见识,这可能会指导未来设计和制造环境友好的吸附性光催化剂。

更新日期:2020-04-21
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