Efficient adsorptive removal of tetracycline from aqueous solution using phytosynthesized nano-zero valent iron

Recently, nano-zero valent iron (nZVI) has been identified as one of the most promising materials for the removal of a wide range of pharmaceuticals in water. However, nZVI effectiveness in aqueous media is dramatically reduced due to its aggregation and instability. To overcome these problems, castor oil (Ricinus communis Linn.) leaves aqueous extract has been used in this study as a reducing and stabilizing agent to increase the stability of nZVI. The fabricated RCL-nZVI was well characterized using several spectroscopic techniques, e.g., steady-state absorption and fluorescence, SEM, TEM, FTIR, EDS, XRD, XPS, and zeta potential. The green phytosynthesized RCL-nZVI was examined in the adsorptive removal of tetracycline (TC). It was interesting to see that the removal efficiency of TC by RCL-nZVI reached 98% at pH 6 and 25 °C. The efficient removal of TC from the aqueous solution was in accordance with the pseudo-second-order kinetic model and well fitted to Langmuir model with a maximum adsorption capacity of 72.64 mg. g⁻¹. In this study, a plausible removal mechanism was discussed, which primarily involves both adsorption and reduction pathways.     

离子刻蚀法制备具有高效催化性能的m-Bi2O4/BiOCl p-n异质结催化剂

光催化技术作为一种绿色的环境修复方法而备受关注,它直接利用太阳光作为能源,可有效地降解有机污染物.铋系化合物具有化学稳定性强、抑制光腐蚀、无毒和来源广泛等优点,被认为是一种环境友好的光催化剂,广泛用于降解染料、苯酚和其他有机污染物.BiOCl具有独特的内部结构,可形成内电场促进电子和空穴的移动,抑制其复合.但是BiOCl本身带隙能过大,只能被紫外光激发,对光的利用率较低,限制了其在环境治理中的应用.近两年来发现,m-Bi2O4带隙能小,可吸收大波长的可见光,催化性能好.为充分发挥m-Bi2O4的优异性质,改善BiOCl的性能,本文将BiOCl与m-Bi2O4复合制得新型催化剂,降低催化剂的带隙能,增强对光的吸收,提高量子效率,促进光生载流子的分离,抑制电子-空穴复合,从而提高催化剂性能,加速降解反应进程.本文通过离子刻蚀法制备具有p-n异质结的m-Bi2O4/BiOCl复合催化剂,通过调节HCl的加入量制得不同比例的催化剂,并考察了其在可见光下催化降解MO(甲基橙)的性能.结果表明,m-Bi2O4/BiOCl复合催化剂在可见光下表现出优异的光催化降解MO和四环素的性能,反应10内min可降解95％的MO,反应150 min内四环素的降解率为85.5％;该复合催化剂对MO和四环素的光降解效率分别是纯BiOCl的52.3和4.9倍.活性自由基捕获实验表明,空穴在光催化降解过程中起最主要的作用,其次是超氧自由基,羟基自由基对降解反应也起到一定的作用.采用XRD,SEM,EDS,TEM,SAED,FT-IR,Raman,XPS,BET,UV-vis和光电流等表征方法分析了催化剂的结构、形貌、化学组成、元素价态、孔结构、带隙能、光学性质和载流子复合效率.结果表明,与BiOCl的斜四方体相比,m-Bi2O4/BiOCl复合催化剂呈现纳米片状结构,氯离子进入晶格的内部,颜色也由BiOCl原来的深褐色变为黄色.m-Bi2O4/BiOCl为介孔结构,比表面积为112.90 m2/g,其吸收波长红移,由紫外光扩展至可见光区域,带隙能也由3.2降低为1.87 eV,能带弯曲形成p-n异质结,提高了电子-空穴的转移效率,抑制其复合;m-Bi2O4/BiOCl的光电流密度高于m-Bi2O4和BiOCl,电子-空穴的分离效率更高,因而其催化性能更优越.     

Preparation of high selective molecularly imprinted polymers for tetracycline by precipitation polymerization

High selective molecularly imprinted polymers(MIPs) for tetracycline have been prepared by precipitation polymerization. Effects of monomer and solvent,the ratio of monomer and template and the characterization of the polymer were investigated by frontal chromatography and selectivity experiment.The results clearly indicated that the polymer,which had the highest molecular recognition abilities for tetracycline antibiotics,had been received.     

高效液相色谱法快速测定蜂蜜中四环素族抗生素

建立了一种快速、准确、完善的测定蜂蜜中四环素族抗生素的反相高效液相色谱方法。研究了流动相配比、pH值、流速等因素对分离效果的影响，并且选出了它们的最佳值。试验和优化了两种蜂蜜样品的前处里方法，得到了满意的效果。灵敏度为4．8×10-8mol／L，回收率为96．18％。     

高效毛细管电泳-电导检测对四环素衍生物分离测定的研究

运用毛细管电泳-电导检测方法对4种四环素衍生物——土霉素(OTC)、金霉素(CTC)、强力霉素(DOC)和四环素(TC)的分离进行了研究。在3．5mmol/L三羟基氨基甲烷(Tris)-7．5mmol/L柠檬酸(Cit)pH4．0的运行缓冲液中，4种四环素衍生物在15min内获得完全分离。四环素衍生物的线性范围分别为5．0-500μg/mL OTC，3．6-420μg/mL CTC，4.5-470μg/mL DOC和2.5-400μg/mL TC。检测限(S／N＝3)分别为OTC2．0μg/mL，CTC 1．8μg／mL，DOC2．5μg/mL和TC1．0μg/mL。采用本法对实际样品强力霉素片中强力霉素和土霉素片中土霉素进行测定，回收率分别为97．2％和96.4％。     

Ligand exchange separation of metal ions on tetracycline hydrochloride sorbed on alumina

Summary The high sorption capacity of basic alumina for tetracycline hydrochloride is utilized for the separation of metal ions on the basis of ligand exchange. Tetracyclines are powerful chelating agents. Break-through capacity and rate of sorption have been studied. The distribution coefficients of 11 metal ions have been determined in demineralised water and in five different pH systems. On the basis of differences in Kd values some quantitative separations of metal ions have been achieved.     

场效应管药物传感器

将场效应管与药物敏感膜结合,以硅钨酸或四苯硼钠未转型的定域体试剂为电活性物质的药物传感器.该传感器制作简单,线性范围宽于或检测下限低于文献值.并对器件的影响因素进行了详尽的讨论.     

Synthesis and Application of Tetracycline Imprinted Polymer

Molecular imprinted polymer was synthesized by polymerization of methacrylate and ethylene glycol dimethacrylate in presence of tetracycline. The prepared polymer exhibited selectivity of 1.8 to 3.9 over non-imprinted polymer depending on nature of solvent. In water, 3.45 mg of tetracycline bind to 1 g of imprinted polymer. Non-covalent interactions between tetracycline and polymer provided selectivity to imprinted polymer. The polymer was evaluated in column chromatography and the bound tetracycline can be eluted with acetonitrile. Ciprofloxacin interacted with imprinted polymer, whereas amoxicillin did not. The feasibility of using MIP for concentrating tetracycline from milk has been demonstrated.     

Disposable amperometric magneto-immunosensor for direct detection of tetracyclines antibiotics residues in milk

The preparation and performance of a disposable amperometric magneto-immunosensor, involving the use of a selective capture antibody immobilized on the surface of protein G-functionalized magnetic beads (ProtG-MBs) and screen-printed carbon electrodes (SPCEs), for the specific detection and quantification of tetracyclines (TCs) residues in milk is reported. A direct competitive immunoassay using a tracer with horseradish peroxidase (HRP) for the enzymatic labeling was performed. The amperometric response measured at −0.2 V vs. the silver pseudo-reference electrode of the SPCE upon the addition of H₂O₂ in the presence of hydroquinone (HQ) as redox mediator was used as transduction signal. The developed methodology showed very low limits of detection (in the low ppb level) for 4 tetracycline antibiotics tested in untreated milk samples, and a good selectivity against other antibiotic residues frequently detected in milk and dairy products. The usefulness of the magneto-immunosensor was demonstrated by analyzing UHT whole milk samples spiked with 44 ng mL⁻¹ tetracycline (TC) as well as a reference milk containing a certified oxytetracycline (OTC) content. These features, together with the short analysis time (30 min), the simplicity, and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site analysis.     

rGO supported self-assembly of 2D nano sheet of (g-C3N4) into rod-like nano structure and its application in sonophotocatalytic degradation of an antibiotic

Graphitic carbon nitride (g-C₃N₄) is an analog of graphite due to its unique electronic structure. g-C₃N₄ based materials have been used in photocatalytic applications. However, pure g-C₃N₄ suffers from major shortcomings which include poor disparity, low surface area and a high recombination rate of photo generated electron-hole pairs that significantly reduce its photocatalytic activity. In this work, self-assembly of g-C₃N₄ sheet into rod shaped g-C₃N₄ was developed via a simple polymerisation method. A composite made of g-C₃N₄ nanorods and rGO (rGO-RCN) was also prepared. The band gap g-C₃N₄ was shifted from 2.77 to 2.6 eV evidented by UV-DRS data. As a result, rGO-RCN showed a relatively high absorption in the visible region. Moreover, a fast electron transfer rate was observed with rGO-RCN composite as conformed from PL analysis and photocurrent measurement. The formation of nanorod and sheet morphologies was confirmed via TEM analysis. The photocatalytic activities of prepared sheet-g-C₃N₄ (SCN)_, Rod g-C₃N₄ (RCN), reduced graphene oxide supported sheet-g-C₃N₄ (rGO-SCN) and reduced graphene oxide supported Rod-g-C₃N₄ (rGO-RCN) were evaluated using a commonly used antibiotic (tetracycline). Among these catalysts, rGO-RCN nanocomposite showed sonophotocatalytic activity 3 times higher compared to pure g-C₃N₄. This superior sonophotocatalytic activity could be due to enhanced visible light absorption of the material, active sites generated by ultrasound, and the high electron transport property of rGO.