Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2.
11 Mar 2009-Journal of Environmental Science and Health Part B-pesticides Food Contaminants and Agricultural Wastes (Taylor & Francis)-Vol. 44, Iss: 3, pp 262-270
TL;DR: During mixed pesticides degradation, the degradation pattern was not similar to that of single pesticide and there was not much change in the rates of degradation in both suspended and immobilized TiO2 systems irrespective of the pesticide.
Abstract: Lindane (1α, 2α, 3β, 4α, 5α, 6β-hexachloro cyclohexane), methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are removed from water individually and as a mixture by photo degradation using suspended and immobilized forms of TiO2 (Degussa P-25). Studies were conducted to optimize the coating thickness of immobilized photo catalyst. The rate of degradation of pesticides was compared in both suspended and immobilized TiO2 systems. Degradation studies of mixed pesticides were carried out with low concentrations (1.0 and 2.5 mg/L) of pesticides. Only three intermediate byproducts such as methyl paraoxon, O,O,O-trimethyl phosphonic thionate and p-nitrophenol were observed during the methyl parathion degradation in suspended, immobilized TiO2 systems and mixed pesticides degradation studies. At the end of the reaction methyl parathion and its by-products were completely degraded. During lindane degradation hexachloro cyclohexane, pentachloro ...
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TL;DR: It was found that the degradation rate of MO increased with the amount of TiO(2), and it was higher in both acidic and alkaline media than under neural condition, and lower pH was more favorable for the degradation of MO.
135 citations
01 Jan 2011
TL;DR: In this article, the effect of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed, including the type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcinations temperature in water environment.
Abstract: In recent years, the application of heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works on the titanium dioxide (TiO2) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and waste water effluents. The effect of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggested that the photocatalytic degradation of organic compounds depends on the type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcinations temperature in water environment. A substantial amount of research has focused on the enhancement of TiO2 photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO2 photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has shown good potential for the removal of various organic pollutants. However, still there is a need to find out the practical utility of this technique on commercial scale.
91 citations
TL;DR: In this paper, a literature search using the keywords "titanium dioxide", "photocatalysis", "advanced oxidation processes", "pharmaceuticals", and "degradation" were used in the ISI Web of Knowledge TM, Scopus TM and ScienceDirect TM databases up to and including articles published on 23 November 2011.
Abstract: Pharmaceutical compounds have been detected in the environment and potentially arise from the discharge of excreted and improperly disposed medication from sewage treatment facilities. In order to minimize environmental exposure of pharmaceutical residues, a potential technique to remove pharmaceuticals from water is the use of an advanced oxidation process (AOP) involving titanium dioxide (TiO2) photocatalysis. To evaluate the extent UV/TiO2 processes have been studied for pharmaceutical degradation, a literature search using the keywords ‘titanium dioxide’, ‘photocatalysis’, ‘advanced oxidation processes’, ‘pharmaceuticals’ and ‘degradation’ were used in the ISI Web of Knowledge TM, Scopus TM and ScienceDirect TM databases up to and including articles published on 23 November 2011. The degradation rates of pharmaceuticals under UV/TiO2 treatment were dependent on type and amount of TiO2 loading, pharmaceutical concentration, the presence of electron acceptors and pH. Complete mineralization under particular experimental conditions were reported for some pharmaceuticals; however, some experiments reported evolution of toxic intermediates during the photocatalytic process. It is concluded that the UV/TiO2 system is potentially a feasible wastewater treatment process, but careful consideration of the treatment time, the loading and the type of TiO2 (doped vs. undoped) used for a particular pharmaceutical is necessary for a successful application (198 words).
88 citations
TL;DR: In this paper, the photocatalytic degradation of Monocrotophos (MCP) and chlorpyrifos (CPS) was carried out using prepared TiO 2 photocatalyst irradiated with 16 W UV light source.
Abstract: Monocrotophos (MCP) and chlorpyrifos (CPS) are most popular and broadly used organophosphorous pesticides owing to its low cost and high efficiency in controlling pests in agriculture. Presence of pesticides in aquatic environments causes serious problems to human beings and other organisms. Photocatalytic degradation has been proved to be a promising method for the treatment of water. In view of this, TiO 2 photocatalyst was prepared by sol–gel method and characterized by SEM with EDAX, XRD, BET and FTIR. The photocatalytic degradation of MCP and CPS was carried out using prepared TiO 2 photocatalyst irradiated with 16 W UV light source. The effect of various parameters, i.e., photocatalyst concentration, pesticide concentration and pH of the solution on the percentage of degradation of selected pesticides had been examined. The kinetic analysis of photodegradation of MCP and CPS under different initial concentration followed the Langmuir–Hinshelwood model. TiO 2 found to be an excellent photocatalyst for the degradation of MCP and CPS under UV light irradiation.
75 citations
TL;DR: In this paper, the surface decoration of CoO nanoparticles was used to degrade paraoxon and achieved a degradation performance of 11 to 24 times that of pure TiO2 or Rh2O3-TiO2 under white light (natural sunlight and fluorescence light).
Abstract: We report the enhanced photocatalytic activity of TiO2 by the surface decoration of CoO nanoparticles to degrade paraoxon. The CoO nanoparticles are precipitated in situ during heat treatments of Co doped amorphous TiO2 and enhance the degradation by 11–24 times that of pure TiO2 or Rh2O3–TiO2 or the oxide nanoparticles under white light (natural sunlight and fluorescence light). The enhanced activity is a combined result of visible light absorption by CoO and effective electron-hole separation at the CoO–TiO2 interfaces.
62 citations
References
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TL;DR: An overview of the field of semiconductor photocatalysis can be found in this paper, where a brief examination of its roots, achievements and possible future is presented, and the semiconductor titanium dioxide (TiO 2 ) features predominantly in past and present work.
Abstract: The interest in heterogeneous photocatalysis is intense and increasing, as shown by the number of publications on this theme which regularly appear in this journal, and the fact that over 2000 papers have been published on this topic since 1981. This article is an overview of the field of semiconductor photocatalysis : a brief examination of its roots, achievements and possible future. The semiconductor titanium dioxide (TiO 2 ) features predominantly in past and present work on semiconductor photocatalysis; as a result, in the most of the examples selected in this overview to illustrate various points the semiconductor is TiO 2 .
3,245 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...[4] Degussa P-25 TiO2 photo catalyst has become a research standard because of its welldefined nature and higher photocatalytic activity compared to most of the other available photo catalysts.[5] Many researchers have reported the photo catalytic degradation of methyl parathion in aqueous TiO2 suspensions....
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TL;DR: It is concluded that solar light induced degradation of textile dye in wastewater is a viable technique for wastewater treatment.
480 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...The rate of degradation is related to the formation of OH radical which is a critical species in the degradation process.[19] The equilibrium adsorption of pesticide on the catalyst surface and the rate of reaction of OH radicals with other chemicals are also significant in the rate of degradation....
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TL;DR: In this article, various currently used chemical oxidation processes (AOPs) for pesticide elimination from wastewater are reported, including Heterogeneous TiO 2 photocatalysis, ozonation and photo-Fenton's reagent.
457 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...Among these techniques, advanced oxidation technique (AOP) such as photo oxidation is most effective because it does not leave any byproducts and pesticide residue in the system.[4] Degussa P-25 TiO2 photo catalyst has become a research standard because of its welldefined nature and higher photocatalytic activity compared to most of the other available photo catalysts....
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TL;DR: Problems of pesticide safety, regulation of pesticide use, use of biotechnology, and biopesticides, and use of pesticides obtained from natural plant sources such as neem extracts are some of the future strategies for minimizing human exposure to pesticides.
400 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...[1] Even when present in small quantities their variety, toxicity and persistence have an adverse effect on ecological systems such as birds, fish and trees with which human welfare is inseparably bound.[2] They are ubiquitous and found even in the most remote areas, far from any industrial activity....
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391 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...[2] They are ubiquitous and found even in the most remote areas, far from any industrial activity.[3] Direct applications of insecticides,...
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