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: In this paper, reduced graphene oxide (RGO) and PbS nonoparticles (NPs) were simultaneously modified by a simple one-step electrodeposition process, and the photocatalytic activity of the ternary RGO/PbS-TiO 2NTs photocatalyst far exceeds those of bare TiO 2 NTs.
Abstract: TiO 2 nanotube arrays (TiO 2 NTs) were simultaneously modified by reduced graphene oxide (RGO) and PbS nonoparticles (NPs) through a simple one-step electrodeposition process. RGO film is formed on the top surface of TiO 2 NTs and PbS NPs showing size less than 20 nm are intercalated within the RGO sheets and also dispersed inside/outside walls the TiO 2 NTs. Resulting from the synergetic effect of RGO and PbS, the photocatalytic activity of the ternary RGO/PbS-TiO 2 NTs photocatalyst far exceeds those of bare TiO 2 NTs, the binary RGO-TiO 2 NTs and PbS-TiO 2 NTs photocatalysts in the degradation of pentachlorophenol (PCP) under simulated solar light. After 120-min irradiation, almost 100% PCP removal is obtained on the RGO/PbS-TiO 2 NTs, compared to 61% on bare TiO 2 NTs, 76% on RGO-TiO 2 NTs, and 86% on PbS-TiO 2 NTs. Because the PbS NPs were covered by the RGO sheets, to a certain extent the photocorrosion of PbS was suppressed, and therefore the RGO/PbS-TiO 2 NTs photocatalyst shows a good stability relative to the PbS-TiO 2 NTs without RGO. This study will inspire better design of advanced photocatalysts with high visible-light photocatalytic activity, easy recovery, and good stability.
51 citations
TL;DR: The photocatalytic degradation of 2,4-dicholorophenoxyacetic acid showed 92% degradation for TiO2/chitosan beads in UV light, and the kinetics and stability of the TiO 2/ chitOSan beads were monitored for their feasibility.
46 citations
TL;DR: In this article, a modified TiO2 with band gap excitations in visible light was used for the degradation of carbamazepine and diclofenac under visible light.
Abstract: The present paper deals with photocatalytic degradation of carbamazepine and diclofenac by using a modified catalyst with band gap excitations in visible light. The C-doped TiO2 was synthesized using a microwave digestion method from titanium oxyacetylacetate with glucose as the carbon source. The synthesized catalyst was then characterized using Scanning Electron microscopy (SEM), X-ray Diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and UV-VIS-NIR spectrophotometer. The TiO2 present was in anatase phase and showed significant absorption in visible region. The catalyst was tested for the degradation of carbamazepine and diclofenac under visible light, where complete removal was achieved and the reaction followed first order kinetics. System parameters like catalyst and pollutant concentration, light intensity and time of reaction, were optimized using response surface methodology. In optimum conditions (catalyst concentration of 244 mg/L and light intensity of 7715 lx) 99% removal was achieved.
43 citations
TL;DR: This work has developed an unprecedented reliable, clean, nontoxic, eco-friendly, and cost-effective biological method for the synthesis of uniformly distributed FeNPs, which were used for the catalytic degradation of dichlorvos in aqueous medium.
Abstract: The removal of dichlorvos contamination from water is a challenging task because of the presence of direct carbon to phosphorous covalent bond, which makes them resistant to chemical and thermal degradation. Although there have been reports in the literature for degradation of dichlorvos using nanomaterials, those are based on photocatalysis. In this paper, we report a simple and rapid method for catalytic degradation of dichlorvos using protein-capped zero valent iron nanoparticles (FeNPs). We have developed an unprecedented reliable, clean, nontoxic, eco-friendly, and cost-effective biological method for the synthesis of uniformly distributed FeNPs. Yeast extract was used as reducing and capping agent in the synthesis of FeNPs, and synthesized particles were characterized by the UV-visible spectroscopy, $X$ -ray diffraction, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). TEM micrographs reveal that the nanoparticles size is distributed in the range of 2–10 nm. Selected area electron diffraction pattern shows the polycrystalline rings of FeNPs. The mean size was found to be 5.006 nm from ImageJ. FTIR spectra depicted the presence of biomolecules, which participated in the synthesis and stabilization of nanoparticles. As synthesized, FeNPs were used for the catalytic degradation of dichlorvos in aqueous medium. The degradation activity of the FeNPs has been investigated by the means of incubation time effect, oxidant effect, and nanoparticle concentration effect. The ammonium molybdate test was used to confirm the release of phosphate ions during the interaction of dichlorvos with FeNPs.
42 citations
Cites background from "Removal of mixed pesticides from dr..."
...Some reports have been cited in the literature for the degradation of insecticide using ZnO, TiO2 and Mg2+ doped TiO2 nanomaterials [12], [28]....
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01 Jan 2020
TL;DR: In this article, the authors reviewed the effectiveness of different physicochemical technologies for removing high-risk pollutants from wastewater, including adsorption, advanced oxidation processes, membranes, combination process, and emerging technologies.
Abstract: In recent years, various high-risk pollutants (HRPs) widely present in wastewater have received global attention, because HRPs can pose serious impacts on human health and ecological security. However, traditional wastewater treatment technologies have limited effect on HRPs removal. Therefore, development of cost-effective technologies for removal of HRPs from wastewater has become a research hotspot in the current scientific community. Physicochemical technologies are considered to have great potential in dealing with HRPs. In this chapter, adsorption, advanced oxidation processes, membranes, combination process, and emerging technologies are deeply reviewed to assess their efficiency and safety in the elimination of HRPs from wastewater. The principle and current application of each technology are briefly introduced. Most of the lab-scale experiments have shown that each of the physicochemical technologies can effectively remove certain HRPs and control their risk, but it should be noted that information regarding the performance of these technologies in practical applications is limited. In addition, more attention should be paid to the cost and effectiveness evaluation for the materialization technologies, which is of great importance for wastewater treatment plants to choose appropriate technologies.
41 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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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.
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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