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Visible Light-activated TiO2 photocatalytic Films; Synthesis, Characterization and Environmental Application for the Destruction of Microcystin-LR
Citation:
Pelaez, M. A., A. A. DELACRUZ, AND D. D. Dionysiou. Visible Light-activated TiO2 photocatalytic Films; Synthesis, Characterization and Environmental Application for the Destruction of Microcystin-LR. Presented at 236th American Chemical Society National Meeting, Philadelphia, PA, August 17 - 20, 2008.
Impact/Purpose:
The objectives of this study are the following: 1) to determine passive binding of Dynal magnetic beads to natural organic matters 2) to characterize covalently coupled monoclonal antibodies against MC-LR with a solid phase matrix and determine reuse capability 3) to optimize binding and determine recovery rates of MC-LR in spiked water samples using different sample volumes 4) to determine loading capacity of individual variants of MC and mixture of MCs 5) to compare recovery rates of immunomagnetic beads (IMB) and traditional solid phase extraction (SPE) in drinking and surface waters by HPLC with PDA and MS detection
Description:
Titanium dioxide (TiO2) photocatalysis has become one of the most effective advanced oxidation technologies (AOTs) for the treatment of persistent organic contaminants. To generate hydroxyl radicals, a non-selective, reactive oxidizing species and responsible for the oxidation of pollutants, conventional TiO2 must be activated under UV light irradiation (<400nm). This represents a limitation for the use of sustainable technologies with renewable energy sources such as solar light, where only 5% of the total spectrum includes UV irradiance. Several techniques have been established and demonstrated some success to doped TiO2 with dye, metals and non-metals to shift the absorption spectrum towards the visible light [1, 2]. More recent studies dealing with anionic-doped TiO2 (i.e nitrogen-doped TiO2) catalyst have reported an improvement in the photocatalytic activity in the visible region (<500 nm) [3, 4]. A particular technique, sol-gel method, has shown promising results for the formation of nitrogen doped TiO2 from environmentally friendly molecular precursors via room temperature procedures [4]. However, most of the studies so far on the nitrogen doped TiO2 materials were not directed towards its application in engineered water treatment processes. For instance, an emerging group of contaminants of primary concern worldwide are the cyanobacteria toxins. These are released from cyanobacterial harmful algal blooms (Cyano-HABs) and are considered a serious health risk due to their high solubility in water, toxicity (i.e., hepatotoxicity, neurotoxicity) and chemical stability [5]. Microcystin-LR (MC-LR) is one of the most commonly detected cyanotoxin in Cyano-HABs and the most toxic derivative of the group of microcystins [6]. High degradation rates of MC-LR were recently obtained with nitrogen-doped TiO2 nanoparticles synthesized by sol-gel based methods [4]. An implication of using suspended TiO2 nanoparticles is their possible mobility and transport in the environment, representing a health risk and requiring an additional filtration step for removal in processed water. This study investigates immobilized TiO2 catalyst with visible light sensitization with enhanced structural properties using a novel sol-gel process. Results on the evaluation of the films on the destruction of MC-LR will be presented.