Potoccatalytic oxidation of oganophosphorus pesticides using zinc oxide

Abstract In recent years, the application of heteroge-neous photocatalytic water treatment processses has gained wide attention due to its effectiveness in degra-ding and mineralizing the pesticides. These pesticides are often found in many surface and groundwater sources and their concentration levels often exceed the drinking water permissible limits recommended by Iran and European drinking water standards. The aim of the present study was to investigate the influence of various parameters such as initial malathion and diazinon concentration catalyst amount, initial pH of the reaction medium and pesticide types on the photocatalytic decomposition of pesticides in the presence of ZnO using an ultraviolet lamp as the light source. The best conditions for the photocatalytic degradation of pesticides were obtained. Results showed that the optimal concentration of catalyst was found to be 100 mg. L -1 . The photodegradation efficiency of pesticides increases with the increase of the illumination time. The photodegradation rate of pesticides was higher in alkaline than in acidic conditions. The photocatalytic degradation rate of the malathion was more than diazinon. The photodegradation efficiency decreases with the increase in the initial concentration of pesticides. The photocatalytic system afforded the highest removed percentage at initial concentration for diazinon and malatlion were 100 and 200 mg.L-1 respectivel

Photocatalytic Oxidation of Carbofuran Pesticide Using Zinc Oxide

In recent years, the application of ultraviolet irradiation and zinc oxide (UV/ZnO) process water and wastewater treatment has gained removal activity of the persistence organic compounds. The degradation of carbofuran pesticide was investigated under ultraviolet irradiation and zinc oxide (UV/ZnO) process. Likewise, the effect of the operational parameters such as reaction volume, initial concentration of catalyst, initial carbofuran concentration, light intensity and pH were studied. In this study the (UV/ZnO) process at different initial concentrations (50-250 mg/L), 5 different initial pH and 5 different initial concentration of catalyst was investigated. Analyses were performed by gas chromatography mass spectroscopy. Results showed that the carbofuran initial concentration of 50 mg/L, ZnO concentration of 300 mg/L, pH of 8, light intensity of 125 watts and reaction volume of 150 mL, were the optimum condition for degradation of carbofuran by UV/ZnO system. This study demonstrated that carbofuran could be effectively degraded by ultrasonic irradiation

The role of the global cryosphere in the fate of organic contaminants

The cryosphere is an important component of global organic contaminant cycles. Snow is an efficient scavenger of atmospheric organic pollutants while a seasonal snowpack, sea ice, glaciers and ice caps are contaminant reservoirs on time scales ranging from days to millennia. Important physical and chemical processes occurring in the various cryospheric compartments impact contaminant cycling and fate. A variety of interactions and feedbacks also occur within the cryospheric system, most of which are susceptible to perturbations due to climate change. In this article, we review the current state of knowledge regarding the transport and processing of organic contaminants in the global cryosphere with an emphasis on the role of a changing climate. Given the complexity of contaminant interactions with the cryosphere and limitations on resources and research capacity, interdisciplinary research and extended collaborations are essential to close identified knowledge gaps and to improve our understanding of contaminant fate under a changing climate

Evaluación de procesos de oxidación avanzada para la eliminación de contaminantes emergentes en efluentes de aguas residuales

[Abstract]: The increasing industrialization in agriculture supposed an increase in the use of pesticides and other health-threatening substances. Different advanced oxidation processes (direct photolysis, photosensitization, photocatalysis, photo-Fenton and ozonation) for a family of pesticides, the neonicotinoids, will be discussed. Different factors, such as pH, concentration of scavengers, inorganic species, auxiliary oxidants and dissolved organic matter or temperature will be taken in consideration. Methods will be assessed in terms of effectivity, rate and prize.[Resumo]: A crecente industrialización da agricultura supuxo un incremento no uso de pesticidas e outras substancias perigosas para a saúde do ser humano. Diferentes procesos de oxidación avanzada (fotólise directa, fotosensibilización, fotocatálise, método photo- Fenton e ozonización) foron avaliados para unha familia de pesticidas, os neonicotinoides. Factores como o pH, a concentración de eliminadores de radicais libres, especies inorgánicas e materia orgánica disoluta ou a temperatura foron considerados. A avaliación dos métodos levouse a cabo tendo en conta a súa efectividade, a súa rapidez e o seu prezo.[Resumen]: La creciente industrialización de la agricultura supuso un incremento en el uso de pesticidas y otras sustancias perjudiciales para la salud del ser humano. Diferentes procesos de oxidación avanzada (fotólisis directa, fotosensibilización, fotocatálisis, método photo-Fenton y ozonización) fueron evaluados para una familia de pesticidas (los neonicotinoides). Factores como el pH, la concentración de eliminadores de radicales libres, especies inorgánicas y materia orgánica o la temperatura fueron considerados. La evaluación de estos métodos se llevó a cabo teniendo en cuenta su efectividad, su rapidez y su precio.Traballo fin de grao (UDC.CIE). Química. Curso 2019/202

UV induced photolysis of fructose: Generation of reactive oxygen species and their application in photo-degradation of pesticides

Exposure to UV-light at 254 nm has shown to induce photolysis of fructose present in the open chain form, generating reactive oxygen species (ROS). The objective of this study was to identify these ROS and evaluate whether fructose can be used as a photosensitizer for accelerated photodegradation of recalcitrant organic compounds such as the pesticides chlorpyrifos and diuron and the organic contaminant pentachlorophenol found in flowback water resulting from the hydraulic fracturing process. Using fluorescein as reactive oxygen species probe, I demonstrated that ROS such as hydrogen peroxide and acidic photolysis products were generated during UV exposure of fructose. Hydrogen peroxide generation from UV exposed fructose solution was investigated using ferrous sulfate- xylenol orange (FOX) assay. After 7 minutes of UV exposure, 63.7±1.11, 52.91±1.07 and 67.08±1.08 μM hydrogen peroxide was generated in 500 mM fructose solution prepared in distilled water and buffer solutions of pH 4.5 and 6.7, respectively. Generation of singlet oxygen was identified using Singlet Oxygen Sensor Green (SOSG) probe which forms fluorescent endoperoxides (EP) upon reaction with singlet oxygen. Approximately 20-fold increase in fluorescence from SOSG-EP was observed in 500 mM fructose solution after 1 minute of UV exposure, indicating generation of singlet oxygen. The degradation rate of chlorpyrifos and diuron was accelerated by approximately two-fold when comparing 500 mM fructose as a photosensitizer to UV-alone. Likewise, the presence of 500 mM fructose in water and 10% saline solution increased the rate of PCP degradation by 2.3 and 6.3 times respectively compared to the control (UV exposure alone). These results highlight the use of fructose as a photosensitizer for photo-catalytic degradation may be particularly attractive to food and beverage processing industry where the effluents typically contain high amount of fructose and possibly high amounts of pesticide residues. In addition, the results demonstrate the potential of fructose as a photosensitizer to treat organic contaminants in highly saline solutions, such as flowback water produced during hydraulic fracturing.M.S., Food Science -- Drexel University, 201

Literature Review: Global Neonicotinoid Insecticide Occurrence in Aquatic Environments

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, neonicotinoids have been detected in rivers and streams across the world. Determining and predicting the exposure potential of neonicotinoids in surface water requires a thorough understanding of their fate and transport mechanisms. Therefore, our objective was to provide a comprehensive review of neonicotinoids with a focus on their fate and transport mechanisms to and within surface waters and their occurrence in waterways throughout the world. A better understanding of fate and transport mechanisms will enable researchers to accurately predict occurrence and persistence of insecticides entering surface waters and potential exposure to non-target organisms in agricultural intensive regions. This review has direct implications on how neonicotinoids are monitored and degraded in aquatic ecosystems. Further, an improved understanding of the fate and transport of neonicotinoids aide natural resource practitioners in the development and implementation of effective best management practices to reduce the potential impact and exposure of neonicotinoids in waterways and aquatic ecosystems