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 is evident from the literature survey that photocatalysis has good potential to remove a variety of organic pollutants, however, there is still a need to determine the practical utility of this technique on a commercial scale.
711 citations
Cites background from "Removal of mixed pesticides from dr..."
...Photocatalytic degradation of methyl parathion, dichlorvos and lindane in aqueous medium were investigated with suspended and immobilized system (Senthilnathan and Philip 2009)....
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TL;DR: In this article, Nitrogen doped titanium photocatalysts with different nitrogen containing organic compounds were prepared by sol-gel method in acidic media and XRD and Raman spectrum showed that all peaks of N-doped TiO2 correspond to anatase crystalline structure.
225 citations
TL;DR: In this paper, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed, and the existing challenges and strategies to improve the photocATalytic efficiency are discussed.
Abstract: Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.
205 citations
20 Jan 2016
TL;DR: In this paper, a review summarizes the recent research in the field of inorganic engineered nanoparticles development with direct or potential interest for drinking water treatment. But, despite early encouraging results, nanoparticles meet a number of limitations to get promoted and become part of large-scale water treatment plants.
Abstract: This review summarizes the recent research in the field of inorganic engineered nanoparticle development with direct or potential interest for drinking water treatment. The incorporation of engineered nanoparticles into drinking water treatment technologies against the removal of heavy metals, microorganisms and organic pollutants appears as a very dynamic branch of nanotechnology. Nanoparticles owe their potential to the high specific surface area and surface reactivity compared to conventional bulk materials. Depending on the mechanism of uptake, nanoparticles can be designed to establish high selectivity against specific pollutants and provide the required efficiency for application. However, despite early encouraging results, nanoparticles meet a number of limitations to get promoted and become part of large-scale water treatment plants. The most important is their availability in the required large quantities and their efficiency to fulfil the strict regulations for drinking water consumption and environmental safety. Both deal with the particle preparation cost and the cost of treatment operation with respect to the increase in supplied water price for the consumers. Under this view, this work attempts to evaluate reported studies according to their possibility to meet the reliable requirements of water technology and also suggests an experimental approach to allow validation of tested nanoparticles.
190 citations
02 Jan 2020
TL;DR: Pesticides and organic waste constitute a group of environmental pollutants that are widely distributed in our environment due to various human activities as discussed by the authors. Adsorptive removal and photocatalization can be used to remove these pollutants.
Abstract: Pesticides and organic waste constitute a group of environmental pollutants that are widely distributed in our environment due to various human activities. Adsorptive removal and photocatal...
165 citations
Cites methods from "Removal of mixed pesticides from dr..."
...Suspended and immobilized TiO2-based catalysts were used to remove various P-based pesticides including lindane, methyl parathion, quinalphos, diazinone, and dichlorovos from water bodies.([243-248]) Besides nonmetallic immobilization, immobilization of transition metals is effective in enhancement of TiO2 photocatalysis in visible light....
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References
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TL;DR: In this article, the photocatalytic degradation of an organophosphorous insecticide, dichlorvos, using two different photocatalyststs (TiO 2 and ZnO) has been investigated.
Abstract: In the present study, the photocatalytic degradation of an organophosphorous insecticide, dichlorvos, using two different photocatalysts (TiO 2 and ZnO) has been investigated. The blank experiments for either illuminated dichlorvos solution or the suspension containing TiO 2 or ZnO and dichlorvos in the dark showed that both illumination and the catalyst were necessary for the destruction of the pesticide. Dichlorvos disappearance is achieved in ∼20 min when treated with illuminated TiO 2 and in ∼120 min with illuminated ZnO. The degradation of the organic molecule follows first-order kinetics according to the Langmuir–Hinshelwood model. It was observed that the initial rate increases linearly with an increase in the amount of catalyst up to a level where it reaches a plateau. Temperature and pH also affect the rate of the reaction. The addition of an oxidant (H 2 O 2 or K 2 S 2 O 8 ) to the TiO 2 suspensions leads to an increase in the rate of photooxidation. On the contrary, the addition of hydrogen peroxide in ZnO suspensions caused a decrease in the reaction rate. Moreover, illuminated TiO 2 suspensions were proved to be quite effective in mineralizing dichlorvos. Measurements of chlorine and phosphate ions gave valuable information about how this process is achieved. On the other hand, ZnO suspensions could not lead in complete mineralization of the insecticide. Addition of the oxidants enhances mineralization for both photocatalytic systems. Finally, toxicity measurements showed that toxicity increases during treatment independently from the type of catalyst or the oxidant that has been used, indicating the inefficient detoxification capacity of the processes.
292 citations
TL;DR: A survey undertaken in Kanpur, northern India, has shown the presence of high concentrations of both organochlorine and organophosphorous pesticides in the surface and ground water samples, with the concentration of malathion finding to be much higher than the EC water quality standards.
243 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...Organochlorine pesticides are known to resist biodegradation and therefore can be concentrated through the food chain.[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....
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TL;DR: In this paper, anatase thin films were used as an efficient form of deposited TiO 2 for the photocatalytic degradation of 4-chlorophenol, a priority pollutant commonly used as a model in photocatalysis, and for carbaryl, a carbamic pesticide.
Abstract: Photocatalytic degradation of water pollutants using TiO 2 and solar light has been proposed as an effective alternative of treatment. Usually, TiO 2 as a finely divided powder is added to polluted water forming a suspension, which is then irradiated under sunlight to conduct photochemical reactions. Although the literature frequently points out the minor efficiency of immobilized systems, it is desirable to look for a fixed catalyst to avoid wastes of time and materials during separation of the powder at the end of the treatment. This paper presents results that show the use of anatase thin films as an efficient form of deposited TiO 2 for the photocatalytic degradation of 4-chlorophenol, a priority pollutant commonly used as a model in photocatalysis, and for carbaryl, a carbamic pesticide. The thin films were deposited over small cylindrical pieces of glass, using a sol–gel technique, the average thickness being 600 nm, and having a band gap of 3.28 eV. The anatase TiO 2 -covered glasses were used to fill a cylindrical photoreactor located at the focus of a parabolic solar collector able to concentrate up to 41 suns. Results show that the films are an effective catalyst in photodegradation, under solar irradiation, and conduct to similar values as those for TiO 2 in suspension. The photoefficiency obtained is similar to that obtained using powder suspension. These results compel us to the continued pursuit of TiO 2 immobilization.
154 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...in suspension form such as exponential decrease of the available light with distance from a light source due to the absorbance of UV light and requirement of extensive solidliquid separation process to separate the nano sized TiO2 particles.[14] Immobilizing TiO2 on suitable support and employing this coated surface as the photocatalyst may be a promising solution for the above mentioned problem....
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TL;DR: Although complete mineralization is hard to accomplish, and large amounts of the oxidant are required to lower the organic content of the solutions, the possibility of ozonation cannot be ruled out if partial degradation is the final goal wanted.
141 citations
"Removal of mixed pesticides from dr..." refers background in this paper
...Maldonado et al.[21] reported that during the photo degradation of five different pesticides (alachlor, atrazine, chlorfenvinphos, diuron and isoproturon), complete mineralization was hard to accomplish....
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TL;DR: In this paper, the physicochemical properties, the photocatalytic activities in aqueous solution and the adhesion properties of supported TiO2 films prepared by different sol-gel methods have been studied.
Abstract: The physicochemical properties, the photocatalytic activities in aqueous solution and the adhesion properties of supported TiO2 films prepared by different sol–gel methods have been studied. The thickness, the TiO2 loading and the photocatalytic activities are influenced by the nature of the stabilising agent. By contrast, the nature of the organic titanium precursor, as well as the solvent and the absence of stabilising agents are determining for the resulting photocatalytic activities. Titania-sol generated by non-controlled hydrolysis of titanium isopropoxide was used to determine the influence (i) of number of coating, (ii) of the calcination temperature and (iii) of the nature of support on the photocatalytic activity under direct and backside irradiation. The higher the coating number, the thicker the TiO2-film and the higher the photocatalytic efficiency. the optimum calcination temperature was found to be 400 °C. Migration of cationic species into TiO2-films and the decrease of thickness at higher temperatures lead to the decline of activity.
118 citations
"Removal of mixed pesticides from dr..." refers methods in this paper
...[ 18 ] For effective degradation, TiO 2 should cover the entire area of the exposed reaction surface (Pyrex glass tube)....
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