Abstract:

Fluorine-doping of TiO₂ (F-TiO₂) was prepared by using solvothermal method and subsequent soaking in KF solution, and hierarchical porous carbon foam (CCF) was prepared by using coal loose medium component as raw material. A composite photocatalyst F-TiO₂/CCF was then prepared by impregnating F-TiO₂ onto CCF. With phenol as the target pollution, the effects of F ion concentration, soaking time and activation time of CCF on the catalytic performance of the catalysts were studied. The samples were characterized by using XRD, XPS, SEM, N₂ adsorption, UV-Vis-DRS, etc. The results showed that the optimized preparation conditions of F-TiO₂/CCF were 0.1 mol/L of KF concentration, 24 h of soaking time, and 1 h of steam activation of CCF. The prepared composite catalyst had a photodegradation rate of 76% for phenol under 6 h of simulated sunlight which was 2.7 times higher than that of F-TiO₂ nanoparticles, and a total removal rate of 89%. After four consecutive degradation cycles, the removal rate of phenol remained around 84%. The strong electronegativity of doped fluorine atoms make the Ti in F-TiO₂ more positive, which is more conducive to coordinate with oxygen atoms in phenol. While the CCF support not only promotes the separation of photoexcited carriers, but also ensures the effective use of light and the rapid adsorption and diffusion of phenol due to its macro/meso/micro porous structure. All these factors contribute to the significant improvement of the photocatalytic performance of F-TiO₂/CCF.

Key words: coal-based carbon foam, TiO₂, F doping, photocatalytic degradation, phenol

摘要：

采用溶剂热法及随后的KF溶液浸泡制备了氟掺杂TiO₂（F-TiO₂），以煤疏中质组为原料制备多级孔泡沫炭（CCF），采用浸渍法将F-TiO₂负载于CCF上制得复合型光催化剂F-TiO₂/CCF。以苯酚溶液为目标降解物，研究了氟离子浓度、浸泡时间以及泡沫炭活化时间对催化剂催化性能的影响。分别采用XRD、XPS、SEM、N₂吸附、UV-Vis-DRS等对样品进行表征。结果表明，F-TiO₂/CCF的最佳制备条件为KF溶液浓度0.1 mol/L、浸泡时间24 h、泡沫炭水蒸气活化时间1 h。由此制得的复合催化剂在模拟太阳光下6 h对苯酚的光降解率达76%，总脱除率达89%，比F-TiO₂纳米颗粒的光催化活性提高了2.7倍。4次连续降解循环实验后对苯酚的脱除率仍维持在84%左右。掺杂氟原子的强电负性使F-TiO₂上的Ti化合价更正，更有利于与苯酚上的氧原子进行吸附配位。而泡沫炭载体不仅促进了光生载流子的高效分离，其大/中/微孔的共同作用保证了光的有效利用和苯酚的快速吸附扩散，使F-TiO₂/CCF光催化性能得到了显著的提高。

关键词: 煤基泡沫炭, TiO₂, F掺杂, 光催化降解, 苯酚