【作者】 李燕；

【导师】 孙淑娟；

【作者基本信息】 山东农业大学 ， 环境工程（专业学位）， 2015， 硕士

【摘要】 本次研究选取四环素抗生素为研究对象,采用Ag/Bi VO4光催化剂对其光解进行催化,对四环素类抗生素在紫外、可见光下的光降解行为进行了研究。考虑到在实际废水处理中影响光降解的主要因素,着重研究了pH、Ca2+、Mg2+对Ag/BiVO4光催化降解盐酸四环素降解效率的影响,并且进行了分析。为达到更好的降解效果,利用Ag/BiVO4与过氧化氢联用降解水中盐酸四环素。同时,由于Ag/BiVO4光催化剂拥有可利用可见光的潜能,对其以可见光为光源光解抗生素进行研究,可对Ag/BiVO4光催化剂在实际生产应用中催化四环素类抗生素提供理论依据。通过研究表明:(1)UV-vis扫描图谱得出BiVO4主要吸收波长为445nm,Ag/BiVO4的主要吸收波长为540nm,Ag/BiVO4与BiVO4相比,能更好的利用可见光。(2)可见光照射条件下,由于负载Ag后的BiVO4能较好的吸收利用可见光,其对盐酸四环素的光降解效果较好。并通过对比不同载银量对光催化降解效率的影响,得出Ag负载量为2%的Ag/Bi VO4催化剂具有最佳的光催化降解盐酸四环素性能。紫外光照射条件下,盐酸四环素在BiVO4和Ag/BiVO4催化作用下并通过较长时间的光照均发生了氧化降解。但由于Bi VO4可以更好的利用紫外光,因而催化降解盐酸四环素的效果优于Ag/BiVO4催化剂。(3)适量催化剂可有效促进盐酸四环素光解,过量催化剂会堵塞电子空穴对,使其不能与溶解氧、水分子发生作用产生羟基自由基,阻碍了进一步的光催化降解,导致降解速率下降。当催化剂使用量由2g/L时,光催化效果最好。(4)弱酸性和中性环境有利于Ag/Bi VO4催化降解盐酸四环素;碱性环境盐酸四环素及催化剂均带负电荷,发生排斥反应,会抑制Ag/BiVO4催化活性,降低盐酸四环素光降解速率。(5)Ca2+和Mg2+会与盐酸四环素发生螯合反应,生成螯合物,不利于与Ag/BiVO4催化剂吸附结合,会降低Ag/BiVO4催化盐酸四环素降解速率。实验结果未添加金属离子的空白溶液光降解率为78.32%,而添加了钙离子、镁离子的溶液的光降解率分别为66.32%、62.21%。(6)过氧化氢联合Ag/BiVO4在紫外光及可见光条件下对盐酸四环素的光降解效果具有两重性。适量的过氧化氢会促进反应的进行,过量的过氧化氢会促使羟基自由基的转化,进而干扰光催化降解。随着过氧化氢体积分数的增加光降解率也逐渐增大,但过氧化氢体积分数超过1.2%时光降解率下降,当过氧化氢的体积分数为1.2%时,光催化降解效果最佳。更多还原

【Abstract】 This study selected tetracycline antibiotics as the research object, and Ag/BiVO4 as the photocatalyst, studying the behavior of tetracycline degradation under the ultraviolet, visible light. Taking into account the main factors in the actual wastewater treatment photodegradation, focusing on the pH, Ca2+, Mg2+ on Ag/BiVO4 photocatalytic degradation of tetracycline, and conducted a mechanism analysis. To achieve better degradation effect, the way that in combination of Ag/BiVO4 and hydrogen peroxide for the degradation of tetracycline hydrochloride.At the same time, because of the Ag/BiVO4 has the potential ability to using visible light, so studying the degradation of tetracycline under visible light may provide a theoretical basis on Ag/BiVO4 photocatalyst catalytic application in the actual production. According to the research, we can concluded that,(1)Scanning the UV-vis spectra we can obtained that the main absorption wavelength of Bi VO4 is 445 nm, and the main absorption wavelength Ag/BiVO4 is540 nm.Compared with BiVO4, Ag/BiVO4 can make better use of visible light.(2)Under visible light irradiation conditions, because BiVO4 loaded Ag can absorbed the visible light better, so the effect of degradation of tetracycline hydrochloride is better. Comparing the impact of different amounts of silver to the photocatalytic degradation efficiency, we can see that loading of 2% Ag/Bi VO4 catalyst has the best performance of the photocatalytic degradation of tetracycline hydrochloride. Under UV irradiation conditions, tetracycline hydrochloride have occurred slow oxidative degradation in BiVO4 and Ag / BiVO4 catalyzed by longer light irradiation. But because BiVO4 can make better use ultraviolet light, and thus the catalytic effect of the degradation of tetracycline hydrochloride is better than Ag/BiVO4 catalyst.(3)Photocatalytic degradation of tetracycline hydrochloride by BiVO4 and Ag/BiVO4 utilizing its unique photosensitivity as well, belonging to theheterogeneous photocatalytic degradation reactions. Processes in heterogeneous photocatalytic degradation reactions, relies mainly on a photosensitive material by absorbing light energy then exciting electron-hole pairs, generating adsorbed oxygen,water molecules on which play a role with the electron-hole pairs generated hydroxyl free radicals and other highly oxidizing free radicals then react with tetracycline hydrochloride to get degraded. Therefore, the amount of catalyst can effectively promote tetracycline hydrochloride photolysis, excess catalyst will plug electron-hole pairs, so it can not be dissolved, the role of water molecules to produce hydroxyl radicals, hindering further photocatalytic degradation, resulting in the degradation rate decreases.(4)pH play an influential role in the tetracycline hydrochloride and tetracycline photodegradation, as the performance of cationic form, anionic form, neutral ionic form related in different pH. Contains three different ionization tetracycline group,the ionization equilibrium constant pKa1, pKa2, pKa3 values in aqueous solution were 3.30,7.69,9.69. At pH 3.3 to 7.7, with tetracycline can be seen as a dimethylamino group and a phenolic hydroxyl group and the negatively charged ions(+-0), at a pH less than 3.3, can be seen as a cationic, pH greater than 7.7 can be seen as an anion. Weakly acidic and neutral environment conducive to Ag/BiVO4 catalytic degradation of tetracycline hydrochloride; alkaline environment tetracycline hydrochloride and catalyst are negatively charged, rejection, inhibits Ag/Bi VO4 catalytic activity, reduce light degradation rate of tetracycline hydrochloride.(5)Ca2 + and Mg2 + will happen to tetracycline hydrochloride chelation reaction of chelates, is not conducive to bind Ag/BiVO4 adsorption catalyst, will greatly reduce the Ag/BiVO4 catalytic degradation rate of tetracycline hydrochloride.(6)Hydrogen peroxide joint Ag / BiVO4 under UV and visible light conditions on the degradation of tetracycline hydrochloride has a duality. The right amount of hydrogen peroxide will promote the reaction, an excess of hydrogen peroxide will lead to the conversion of hydroxyl radicals, and thus interfere with the photocatalytic degradation.更多还原