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The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes

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Journal of Environmental Sciences 2016年第7期28卷 115-123页

作者： nasr bensalah Sondos Dbira Ahmed Bedoui Department of Chemistry and Earth Sciences College of Arts and Sciences Qatar University Department of Chemistry Faculty of Sciences of Gabes University of Gabes

In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond（BDD） anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in Na Cl;however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and Na Cl O4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine（Cl2, HCl O, Cl O-）electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density（≤ 10 m A/cm2） and neutral medium（p H in the range 6–9） should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate.

关键词： Electrolytic degradation Diamond anode Supporting electrolyte Mediated oxidation Cyanuric acid

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Fenton treatment of olive oil mill wastewater—applicability of the method and parameters effects on the degradation process

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Journal of Environmental Sciences 2004年第6期16卷 942-944页

作者： bensalah nasr Bedoui Ahmed Gadri Abdellatif Institut Supérieur des Sciences Appliquées et Technologie de Gabès Rue Amor Ibn Elkhattab Zrig 6072 Gabès TunisiaFaculté des Sciences de Gabès Cité Erriadh Zrig 6072 Gabès TunisiaEcole Nationale d'Ingénieurs de Gabès Zrig 6029 Gabès Tunisia

The low biodegradability of polyphenolic compounds typically found in olive processing indicated that biological treatment is not always successful in the treatment of olive oil mill wastewater in term of COD removal. In this study the results of investigations on the applicability of Fenton's reagent in the treatment of this effluent were discussed. The efficiency of this method was determined. 86 % of removal COD was obtained using 5 mol H 2O 2 and 0.4 mol Fe 2+ per liter of crude OMW. The main parameters that govern the complex reactive system, i.e., time, pH, [H 2O 2] and [Fe(II)] were studied.

关键词： olive oil mill wastewater Fenton's reagent organic compounds removal COD

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Investigations on the Degradation of Triazine Herbicides in Water by Photo-Fenton Process

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American Journal of Analytical Chemistry 2014年第8期5卷 500-517页

作者： Sondos Dbira Ahmed Bedoui nasr bensalah Department of Chemistry and Earth Sciences College of Arts and Sciences Qatar University Doha Qatar Department of Chemistry Faculty of Sciences of Gabes University of Gabes Gabes Tunisia

In this work, the degradation of 2-chloro-4,6-diamino-1,3,5-triazine in aqueous solutions by photo-Fenton process has been investigated. The preliminary results have shown that the degradation of 2-chloro-4,6-diamino-1,3,5-triazine by photo-Fenton process is more rapid and more effective than Fenton and UV/H2O2 processes. The effects of certain experimental parameters on kinetics and efficiency of the degradation of 2-chloro-4,6,-diamino-1,3,5-triazine by photo-Fenton process, have been evaluated. Under optimal conditions, photo-Fenton process achieved more than 90% of chloride release and about 30% of nitrate formation. The results of total organic carbon (TOC) and total Kjeldahl nitrogen (TKN) analyses have shown that no carbon dioxide and ammonia are formed during photo-Fenton treatment of aqueous solutions containing 40 mg/L triazine. These results indicate that only substituent groups of triazine ring are released;however, nitrogen atoms of triazine ring remain unaffected. A simple mechanism of degradation of 2-chloro-4,6-diamino-1,3,5-triazine has been proposed. The degradation starts by a rapid release of chlorine atoms as chloride ions to form 2-hydroxy-4,6-diamino-1,3,5-triazine. The amino groups of 2-hydroxy-4,6-diamino-1,3,5-triazine undergo are oxidized into nitro groups by hydroxyl radicals to form 2-hydroxy-4,6-dinitro-1,3,5-triazine which undergoes a slow release of nitro groups and their substitution with hydroxyl groups to form cyanuric acid and nitrate ions. The degradation of cyanuric acid by photo-Fenton process has also been investigated. The results of TOC and TKN analyzes show that no carbon dioxide is formed during the treatment.

关键词： Photo-Fenton Process Hydroxyl Radicals s-Triazine Herbicides Degradation Cyanuric Acid

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Formation of Trihalomethanes during Seawater Chlorination

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Journal of Environmental Protection 2010年第4期1卷 456-465页

作者： Ahmed Abdel-Wahab Ahmed Khodary nasr bensalah 不详

The use of seawater for industrial cooling is a vital technology that poses some of the most profound environmental impact on the water quality in the Arabian Gulf. Biocide (chlorine) is added to the seawater to control biofouling of the cooling system. This added chlorine reacts with bromide and other chemicals naturally exist in the water to form a wide range of oxidants. Regrettably, reactions between the residual oxidants and natural organic matter in the water lead to formation of toxic halogenated organic compounds that have detrimental effects on the environment when they are discharged into the Gulf. This paper describes the formation of trihalomethanes (THMs) in seawater cooling systems. Results of kinetic experiments have shown that concentrations of THMs increased rapidly with time during the first half hour. Chlorination of seawater has shown significant increase in total THMs (TTHMs) and in bromoform concentrations. Rapid decrease of UV absorbance at 254 nm was also observed during seawater chlorination which is indicative of natural organic matter degradation into small organic molecules including THMs and other by-products. The increase in chlorine dose was accompanied with an increase in TTHMs and bromoform concentrations. Linear relationships between total chlorine concentration and both final TTHMs and bromoform concentrations were established. First order exponential decay and exponential associate functions were developed to correlate chlorine dose with formed THMs.

关键词： Chlorination by-Products Seawater Cooling Biocides Trihalomethane Bromoform

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