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Journal ArticleDOI

Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2.

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 ...
Topics: Parathion methyl (52%)
Citations
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Journal ArticleDOI
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.
Abstract: In recent years, the application of heterogeneous photocatalytic water purification processes 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 recent works on the titanium dioxide (TiO(2)) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and wastewater effluents The effects of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed Results reported here suggest that the photocatalytic degradation of organic compounds depends on the type and composition of the photocatalyst and, 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 calcination temperature in the water environment A substantial amount of research has focused on the enhancement of TiO(2) photocatalysis by modification with metal, non-metal and ion doping Recent developments in TiO(2) 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 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

617 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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Journal ArticleDOI
Abstract: Nitrogen doped titanium photocatalysts with different nitrogen containing organic compounds were prepared by sol–gel method in acidic media. Among different nitrogen containing organic compounds, triethylamine doped TiO2 showed better photocatalytic activity under visible light. XRD, SEM and TEM analyses showed that the crystalline size of N-doped TiO2 was in the range of 20–24 nm. XRD and Raman spectrum showed that all peaks of N-doped TiO2 correspond to anatase crystalline structure. The formation of O–Ti–N bond in N-doped TiO2 does not lead to any new Raman band. XPS study confirmed that N replaces the O in the lattice of TiO2 and is present in the form of O–Ti–N. The photocatalytic activity of doped TiO2 was measured under UV and visible light using lindane as a target pollutant. The photocatalytic activity of anatase TiO2 and N-doped TiO2 was compared with commercially available Degussa P-25 TiO2. Intermediates formed during the degradation of lindane were monitored by GC–MS analysis.

193 citations


Journal ArticleDOI
20 Jan 2016-
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.

165 citations


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Journal ArticleDOI
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.

139 citations


Journal ArticleDOI
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.
Abstract: Here we introduce a novel approach of preparing TiO 2 films on conductive substrates at low temperature by electrophoretic deposition method without successive calcinate treatment. The photocatalytic activity of the non-calcinated TiO 2 film was evaluated by degradation rate of methyl orange (MO). We 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. In addition, lower pH was more favorable for the degradation of MO. The photocatalytic degradation of MO could be described as pseudo-first order reactions. When the initial concentration of MO increased from 1 mg/L to 10 mg/L, the highest degradation rate was achieved at 5 mg/L. The apparent reaction rate constant was calculated to be 0.0098 min −1 .

113 citations


References
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Journal ArticleDOI
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 .

3,161 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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Journal ArticleDOI
01 Feb 2000-Water Research
Abstract: The various currently used chemical oxidation processes (AOPs), for pesticide elimination from wastewater are reported. Heterogeneous TiO 2 photocatalysis, ozonation and photo-Fenton's reagent are the most intensively investigated technologies. Theoretical and practical advantages and limitations of each method are discussed. Degradation mechanism and experimental conditions employed for the optimization of each technology are reviewed. Performances such as the achieved degree of mineralization and obtained degradation rates are detailed. The various analytical approaches for studying pesticide degradation by AOPs are also discussed. Formation of by-products is unavoidable during cost effective treatments. Their detection and identification are required in order to determine which kind of chemical structures are left at the end of the process. For this purpose, the crucial role of gas and liquid mass spectrometry is emphasized. The review reveals a general lack of data on kinetics of formation and disappearance of the major by-products. The efficiency of AOPs has scarcely been investigated at industrial scales, i.e. in presence of a mixture of active ingredients together with their formulating agents and at concentration levels above 10 mg/l. The more polar by-products are largely unknown and their toxicity is usually not addressed.

444 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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Journal ArticleDOI
01 Mar 2002-Chemosphere
TL;DR: It is concluded that solar light induced degradation of textile dye in wastewater is a viable technique for wastewater treatment.
Abstract: Aqueous solutions of reactive blue 4 textile dye are totally mineralised when irradiated with TiO2 photocatalyst. A solution containing 4×10−4 M dye was completely degraded in 24 h irradiation time. The intensity of the solar light was measured using Lux meter. The results showed that the dye molecules were completely degraded to CO2, SO42−, NO3−, NH4+ and H2O under solar irradiation. The addition of hydrogen peroxide and potassium persulphate influenced the photodegradation efficiency. The rapidity of photodegradation of dye intermediates were observed in the presence of hydrogen peroxide than in its absence. The auxiliary chemicals such as sodium carbonate and sodium chloride substantially affected the photodegradation efficiency. High performance liquid chromatography and chemical oxygen demand were used to study the mineralisation and degradation of the dye respectively. It is concluded that solar light induced degradation of textile dye in wastewater is a viable technique for wastewater treatment.

433 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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Journal ArticleDOI
TL;DR: The HCHs provide an elegant example of how hemispheric-scale solvent switching processes can alter the ocean into which an HCH congener partitions, how air-water partitioning controls the pathway for H CHs entering the Arctic, and how the various pathways impact spatial and temporal trends of HCH residues in arctic animals feeding out of marine and terrestrial foodwebs.
Abstract: Historical global usage and emissions for organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDT), toxaphene and endosulfan, are presented. Relationships between the air concentrations of these OCPs and their global emissions are also discussed. Differences between the pathways of alpha- and beta-HCH to the Arctic Ocean are described in the context of environmental concentrating and diluting processes. These concentrating and diluting processes are shown to control the temporal and spatial loading of northern oceans and that the HCH burdens in marine biota from these oceans respond accordingly. The HCHs provide an elegant example of how hemispheric-scale solvent switching processes can alter the ocean into which an HCH congener partitions, how air-water partitioning controls the pathway for HCHs entering the Arctic, and how the various pathways impact spatial and temporal trends of HCH residues in arctic animals feeding out of marine and terrestrial foodwebs.

364 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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Journal ArticleDOI
20 May 2004-Toxicology
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.
Abstract: Use of pesticides in India began in 1948 when DDT was imported for malaria control and BHC for locust control. India started pesticide production with manufacturing plant for DDT and benzene hexachloride (BHC) (HCH) in the year 1952. In 1958, India was producing over 5000 metric tonnes of pesticides. Currently, there are approximately 145 pesticides registered for use, and production has increased to approximately 85,000 metric tonnes. Rampant use of these chemicals has given rise to several short-term and long-term adverse effects of these chemicals. The first report of poisoning due to pesticides in India came from Kerala in 1958 where, over 100 people died after consuming wheat flour contaminated with parathion. Subsequently several cases of pesticide-poisoning including the Bhopal disaster have been reported. Despite the fact that the consumption of pesticides in India is still very low, about 0.5 kg/ha of pesticides against 6.60 and 12.0 kg/ha in Korea and Japan, respectively, there has been a widespread contamination of food commodities with pesticide residues, basically due to non-judicious use of pesticides. In India, 51% of food commodities are contaminated with pesticide residues and out of these, 20% have pesticides residues above the maximum residue level values on a worldwide basis. It has been observed that their long-term, low-dose exposure are increasingly linked to human health effects such as immune-suppression, hormone disruption, diminished intelligence, reproductive abnormalities, and cancer. In this light, 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.

358 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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