TiO2 and Au-TiO2 Nanomaterials for Rapid Photocatalytic Degradation of Antibiotic Residues in Aquaculture Wastewater.

Antibiotic residues in aquaculture wastewater are considered as an emerging environmental problem, as they are not efficiently removed in wastewater treatment plants. To address this issue, we fabricated TiO2 nanotube arrays (TNAs), TiO2 nanowires on nanotube arrays (TNWs/TNAs), Au nanoparticle (NP)-decorated-TNAs, and TNWs/TNAs, which were applied for assessing the photocatalytic degradation of eight antibiotics, simultaneously. The TNAs and TNWs/TNAs were synthesized by anodization using an aqueous NH4F/ethylene glycol solution. Au NPs were synthesized by chemical reduction method, and used to decorate on TNAs and TNWs/TNAs. All the TiO2 nanostructures exhibited anatase phase and well-defined morphology. The photocatalytic performance of TNAs, TNWs/TNAs, Au-TNAs and Au-TNWs/TNAs was studied by monitoring the degradation of amoxicillin, ampicillin, doxycycline, oxytetracycline, lincomycin, vancomycin, sulfamethazine, and sulfamethoxazole under ultraviolet (UV)-visible (VIS), or VIS illumination by LC-MS/MS method. All the four kinds of nanomaterials degraded the antibiotics effectively and rapidly, in which most antibiotics were removed completely after 20 min treatment. The Au-TNWs/TNAs exhibited the highest photocatalytic activity in degradation of the eight antibiotics. For example, reaction rate constants of Au-TNWs/TNAs for degradation of lincomycin reached 0.26 min-1 and 0.096 min-1 under UV-VIS and VIS irradiation, respectively; and they were even higher for the other antibiotics. The excellent photocatalytic activity of Au-TNWs/TNAs was attributed to the synergistic effects of: (1) The larger surface area of TNWs/TNAs as compared to TNAs, and (2) surface plasmonic effect in Au NPs to enhance the visible light harvesting.

Analysis of alkaloids in Lotus (Nelumbo nucifera Gaertn.) leaves by non-aqueous capillary electrophoresis using ultraviolet and mass spectrometric detection.

Lotus leaves are a popular remedy in Asia to treat obesity, insomnia and mental impairment; alkaloids are considered most relevant for bioactivity. In this study the first CE method for the determination of all major alkaloids ((-)-nuciferine, (-)-nornuciferine, (-)-caaverine, (-)-armepavine, (+)-norarmepavine, (+)-isoliensinine and (+)-pronuciferine) in Nelumbo nucifera leaves was developed. The optimum buffer showed to be a solution of 100mM ammonium acetate in a mixture of methanol, acetonitrile and water, also containing 0.6% acid acetic. Applied voltage, temperature and detection wavelength were 25kV, 30°C and 225nm; the required analysis time was 15min. By CE-MS all standard compounds could be assigned in positive ESI mode, and two minor alkaloids were tentatively identified (n-nornuciferine and roemerine). A mixture of water, methanol and acetic acid served as sheath liquid in these experiments. The NACE assay was fully validated and utilized to analyze Lotus leaf samples collected in different parts of Vietnam. Respective results revealed significant qualitative and quantitative differences depending on growing area and season. Yet, in all samples (-)-nuciferine (0.34-0.63%), (-)-armepavine (0.13-0.20%), and (+)-isoliensinine (0.06-0.19%) were the most dominant alkaloids. The total alkaloid content varied from 0.72 to 1.41%.

Quantitative determination of phenolic compounds in lotus (Nelumbo nucifera) leaves by capillary zone electrophoresis.

The traditional use of lotus leaves as an anti-inflammatory remedy is associated with the occurrence of phenolic compounds. In this study the first CE method for the analysis of all major phenolic constituents in Nelumbo nucifera leaves is presented. It permits the separation of nine relevant markers in less than 10 min. The optimized procedure was fully validated and then used to analyze diverse samples collected in Vietnam. They revealed significant qualitative and quantitative differences depending on growing area and season. Yet, in all of them, quercetin-3-O-ß-D-glucuronide, hyperoside, and isoquercitrin were the most dominant flavonoids.