A novel biocompatible environment friendly nanosilver Nafion®/nanoTiO2 Nafion® modified glassy carbon electrode was prepared by a simple procedure and characterized. This modified electrode was used as a sensing electrode for the detection of imidacloprid. Cyclic voltammetry, differential pulse voltammetry and amperometry were used in this work. The reduction potential of imidacloprid on this electrode is lower compared to other electrodes reported in the literature. The LOD and LOQ values obtained for the sensing of imidacloprid on this modified electrode are comparable to the values reported in the literature. 相似文献
The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors (CPCs) specially designed for solar photocatalytic applications. Experimental conditions allowed disappearance of pesticide and degree of mineralisation achieved in the two photocatalytic systems to be compared. In order to assure that the photocatalytic results are consistent, hydrolysis and photolysis tests have been performed with the four pesticides. The initial concentration tested with imidacloprid, formetanate and methomyl was 50 and 30 mg/l with diuron, and the catalyst concentrations were 200 mg/l and 0.05 mM with TiO2 and iron, respectively. Total disappearance of the parent compounds and 90% mineralisation have been attained with all pesticides tested, methomyl being the most difficult to be degraded with both treatments. First-order rate constants, initial rate, time necessary for mineralising 90% of the initial TOC and hydrogen peroxide consumption were calculated in all cases, enabling comparison both of treatments and of the selected pesticide reactivity. 相似文献
Effective design and fabrication of novel visible light-oriented photocatalysts is an existing challenging task that requires further dedicated efforts, and it has been always a main concern among the scientific community. This study deals with the design and fabrication of an extremely active and ultrafast ternary photocatalyst based on Ag nanoparticles, polypyrrole doped carbon black (PPy-C) and mesoporous TiO2 (m-TiO2). Sol-gel methodology along with sonication and photodeposition routes have been employed for the successful creation of the ternary framework. Ternary photocatalyst composed of uniform spherical titania nanoparticles (10–15 nm in size) perfectly intermingled with the polymeric linkage of PPy-C. Fruitful creation of unique trio photocatalyst between AgNPs, PPy-C and m-TiO2 was confirmed by XPS and XRD. FTIR analysis further supports the development of nanocomposite photocatalyst. TEM analysis showed uniform spherical m-TiO2 nanoparticles (10–15 nm in size) covered by PPy-C with compact nodes like appearance interlocked very well among each other. The newly developed Ag@PPy-C/m-TiO2 ternary photocatalyst exhibited band gap energy in desired visible range of spectra. The photocatalytic efficiency for all created photocatalysts has been evaluated taking Imidacloprid (insecticide derivative) and methylene blue (MB) dye as target pollutants. The novel Ag@PPy-C/m-TiO2 photocatalyst produced astonishing results with ultrafast removal of both Imidacloprid as well MB dye under visible light irradiation. The newly created ultrafast Ag@PPy-C/m-TiO2 photocatalyst has removed 96.0% of the insecticide Imidacloprid in only 25 min with almost ? 2.65 times more efficient than bare m-TiO2 towards the removal of insecticide derivative. The present report offers a highly encouraging and vastly talented Ag@PPy-C/m-TiO2 ternary photocatalyst, enabling the ideal management of extremely lethal and notorious chemicals. 相似文献
This paper presents experimental results on the imidacloprid removal from wastewater using homogeneous photo-Fenton reactions illuminated with black light lamps. Multivariate experimental design was used to identify the effect of initial Fe(II) and H2O2 concentrations on process performance. The initial iron concentration played a key role in the process kinetics, whereas hydrogen peroxide concentration directly affected the extent of the oxidation process.
Imidacloprid degradation proceeded via two distinctive kinetics regimes, an initial stage of rapid imidacloprid reduction, followed by a slower oxidation process until complete removal. Under optimal conditions, more than 50% imidacloprid degradation was observed after less than 1 min treatment, and TOC and COD removal up to 65% and 80%, respectively, were measured after all hydrogen peroxide was consumed.
Raw imidacloprid samples presented significant acute toxicity to Daphnia magna and genotoxic effects on Bacillus subtilis sp. Such toxic effects remained detectable even after significant pesticide removal had been achieved, due to the presence of toxic by-products. Both acute toxicity and genotoxicity disappeared after considerable mineralization resulting in final low molecular weight by-products. Results obtained here confirm that design and operation of photo-Fenton processes should focus on toxicity removal rather than on specific target pollutants. 相似文献
A new granulated version of the well-known P-25 titanium dioxide (VP AEROPERL® P-25/20 (Aeroperl)) has been tested to determine whether its photocatalytic efficiency is good enough for use in photocatalytic water purification and to find out if it can be separated from water more easily than its well-known homologue, powdered Degussa P-25, a significant technical improvement that might eliminate the tedious final filtration necessary with a slurry. Furthermore, a new commercial catalyst (PC-100 from Millennium Inorganic Chemicals), having a surface area and structure that are both different from Degussa P-25, has also been studied. All the experiments were carried out in sunlight in the pilot compound parabolic collector (CPC) plant at the Plataforma Solar de Almería. Three different substrates were chosen as model molecules for this study: dichloracetic acid, phenol and the pesticide imidacloprid. Results show that Degussa Aeroperl is not a good alternative to powdered Degussa P-25 because of its spontaneous sedimentation during photocatalysis. Millennium PC-100 efficiency seems to be in the same range as that of Degussa P-25. In this work we also attempt to demonstrate that the comparison of efficiencies of different photocatalysts is not a trivial matter. Many factors are involved and interfere in the testing of photocatalyst behaviour during the degradation of a contaminant. A thorough comparison of photocatalyst activity should include reactions with several different substrates under varied experimental conditions. 相似文献