N/La-TiO_(2)的制备及光催化降解水杨酸的研究

Preparation of N/La-TiO and Photocatalytic Degradation of Salicylic Acid

该文以尿素和硝酸镧为前驱体,采用溶胶-凝胶法制备N、La共掺杂TiO_(2)光催化剂,以水杨酸为目标污染物,研究了N、La不同配比、反应体系等因素对水杨酸降解率的影响,并采用XRD、XPS、UV-Vis、BET等表征手段分析其材料性能。结果表明,500℃下煅烧2 h的N/La-TiO_(2),掺杂比N∶La为40∶0.1时,紫外光下反应60 min后对水杨酸的去除率最高达98.18%,而此时TiO_(2)的去除率仅为50%,掺杂N/La后去除率提高了近2倍;p H 4为N/La-TiO_(2)降解水杨酸的最佳反应pH值;活性物种淬灭实验中证明,紫外光下N/La-TiO_(2)催化剂去除水杨酸占主要作用的是h+和·OH。N/La-TiO_(2)中N置换了TiO_(2)晶格中的O形成O-Ti-N结构并在TiO_(2)中形成了独特的杂质能级,La进入TiO_(2)晶格中产生更多的晶格缺陷,N、La共掺杂减小了TiO_(2)的平均粒径,使比表面积增大2.1倍、孔容体积增大2.2倍,禁带宽度窄化至3.06 eV,N、La协同增强了TiO_(2)光催化活性。

TiO_(2)photocatalyst co-doped with N and La was prepared via sol-gel method using urea and lanthanum nitrate as precursors.The salicylic acid was used as the target to degrade the pollutants.The effects of N,La ratio,reaction system on the degradation rate of salicylic acid were studied.XRD,XPS,UV-Vis,BET and other characterization tests were used to analyze the properties of the materials.The results showed that the highest removal rate of salicylic acid by N/La-TiO_(2),which the doping ratio N∶La=40∶0.1,reached 98.18%under 60 min UV light.The photocatalyst calcination temperature was 500℃and the calcination time was 2 h.The removal rate of TiO_(2)reached only 50%.After doping N/La,the removal rate increased by nearly 2 times.p H=4 was the best reaction pH for degradation of salicylic acid by N/La-TiO_(2).Experimental quenching of active species proved that the main action of the degradation of salicylic acid by N/La-TiO_(2)catalyst under UV light was h+and·OH.N in the N/La-TiO_(2)substituted for O in TiO_(2)lattic,which could form O-Ti-N and cause unique doping energy levels.La entered TiO_(2)lattice to produce more lattice defects.N,La co-doping reduced the average particle size,increased surface area by 2.1 times,increased pore volume by 2.2 times,and narrowed the band gap energy to 3.06 e V.N,La synergistically enhanced TiO_(2)photocatalytic activity.