Chemical oxygen demand determination in well and river waters by flow-injection analysis using a microwave oven during the oxidation step

Balconi, M.L.; Borgarello, M.; Ferraroli, R.; Realini, F.

doi:10.1016/0003-2670(92)80205-l

Cited by 68 publications

(30 citation statements)

References 12 publications

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“…Chemical oxygen demand (COD) is one of the most widely used metrics in the field of water-quality analysis in many countries, and is frequently used as an important index for controlling the operation of wastewater treatment plants, wastewater effluent monitoring, and taxation of wastewater pollution. [14] or ultrasound-assisted oxidation.[15]Other alternative assays have also been developed such as electrocatalytic determination using PbO 2 or Cu sensors in thin-cell reactors, [16,17] and photocatalytic and photoelectrocatalytic methods based on TiO 2 nanomaterial sensors. [18,19] However, all these modified K 2 Cr 2 O 7 methods are still plagued by the secondary pollution caused by highly toxic Cr(VI) ions, and moreover, the PbO 2 sensors pose the risk of the potential release of hazardous Pb during the preparation and disposal of the active material of the sensors.…”

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confidence: 99%

Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

et al. 2008

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The principal impetus for the fabrication of functional nanotube materials comes from the promise of discovering unique structure-dependant properties and superior performance that are derived from their intrinsic nanotubular architecture. [1][2][3][4] 1D TiO 2 nanotube arrays prepared by the electrochemical anodization of self-organized porous structures on Ti foil [5][6][7] have attracted great research interest in recent years owing to their peculiar architecture, remarkable properties, and potential for wide-ranging applications. Uniform TiO 2 nanotubes are quite remarkably different in structure from other forms of TiO 2 , and are highly ordered, high-aspect-ratio structures with nanocrystalline walls perpendicular to electrically conductive Ti substrates, thereby naturally forming a Schottky-type contact. Moreover, these structures can be directly used as electrodes for photoelectric applications since the size of the nanotubes is very precisely controllable. The technological applications of TiO 2 nanotube arrays are still at an early stage, but these remarkable structures have already been shown to be very promising for applications in sensing, [8] catalysis, [9] photovoltaics, [10] photoelectrolysis, [11] and nanotemplating. [12] The electrical resistance of the TiO 2 nanotubes changes by almost 7 orders of magnitude upon exposure to 1000 ppm H 2 , [13] the largest ever reported sensitivity of a material to a gas. Furthermore, the H 2 evolution rate of TiO 2 nanotube arrays has been reported to be 76 mL hw -1 , [11] which is the highest reported H 2 generation rate for any oxide system upon photoelectrolysis. TiO 2 nanotube arrays have also attracted great interest for enhancing the photocatalytic degradation of various organics, which makes them promising materials for the detection of pollutants. Given the increasing quantities of pollutants that are being dumped into water bodies, environmental monitoring and control have become issues of global concern. Chemical oxygen demand (COD) is one of the most widely used metrics in the field of water-quality analysis in many countries, and is frequently used as an important index for controlling the operation of wastewater treatment plants, wastewater effluent monitoring, and taxation of wastewater pollution. [14] or ultrasound-assisted oxidation.[15]Other alternative assays have also been developed such as electrocatalytic determination using PbO 2 or Cu sensors in thin-cell reactors, [16,17] and photocatalytic and photoelectrocatalytic methods based on TiO 2 nanomaterial sensors. [18,19] However, all these modified K 2 Cr 2 O 7 methods are still plagued by the secondary pollution caused by highly toxic Cr(VI) ions, and moreover, the PbO 2 sensors pose the risk of the potential release of hazardous Pb during the preparation and disposal of the active material of the sensors. As compared to traditional analytical methods, photoelectrocatalytic approaches are more promising because of the superior oxidative abilities of illuminated TiO 2 . Furthermore, TiO 2 ...

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Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

et al. 2008

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“…The bubbles that were formed under the effect of heating could cause the signal to be unstable. 31 A degasser made of a porous Teflon tube (i.d. 1 mm × 5 cm, Sumitomo Electric Engineering) was used to separate the bubbles from the solution.…”

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A 3-Step Chemiluminescence Method for Chemical Oxygen Demand Measurement

et al. 2017

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Direct chemiluminescence emission from the reaction of acidic permanganate and organic compounds was employed for determining the chemical oxygen demand (COD) in water (1-step CL COD). Due to the diversity of organic pollutants in water, there are no standards for COD measurements, and many compounds do not show any chemiluminescence signal in the 1-step CL COD method. As a result, this method shows a low correlation with the conventional CODMn method. In this study, a new 3-step CL COD method was developed to overcome these drawbacks. The basic principle of the 3-step CL COD method is based on the principle of "back titration" in the CODMn method: (i) the sample is treated with permanganate under heating, (ii) the excess permanganate is treated with pyrogallol, and (iii) the excess pyrogallol is measured by the chemiluminescence reaction with permanganate. The reagent concentration, sample volume, and heating temperature were optimized, and the 3-step CL COD method successfully obtained the signal from some samples that cannot be detected by 1-step CL COD method. The calibration graph is linear in the range of 0 -12.86 mg/L with a detection limit of 0.082 mg/L. This method is continuous, sensitive and low cost compared with the conventional method, and is applicable for on-site monitoring. The effect of the chloride ion was investigated, and showed an insignificant effect after two-times dilution of high-salinity samples. The correlation with the CODMn method for various organic compounds showed a good coefficient of determination, R 2 = 0.9773 (n = 16).

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“…[13][14][15][16] Chemical oxygen demand is widely used as an important parameter in assessing the extent of water pollution and it is the regular item for detection of water quality. [17][18][19] In procedures of conventional evaluation of COD methods, a known amount of oxidant (such as dichromate, permanganate) is added to the sample and the mixture is boiled. After the oxidation has proceeded for a finite period of time, the initial concentration of organic species can be calculated by determining the amount of the remaining oxidizing agent.…”

Section: Introductionmentioning

confidence: 99%

Study on Determination of Chemical Oxygen Demand in Water with Ion Chromatography

et al. 2007

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A new method for determining chemical oxygen demand (COD) value in water using ion chromatography coupled with nano TiO 2 -K 2 S 2 O 8 co-existing system was described. The photocatalytic oxidation system and nano TiO 2 -K 2 S 2 O 8 co-existing system could degrade the organic compounds in water. All sulfur-containing species in the reactive solution were eventually transformed to sulfate which could be determined by conductivity detector in ion chromatography. The change of conductivity of sulfate was proportional to COD value. The optimal experimental conditions and the mechanism of the detection were discussed. The application range was 10.0-300.0 mg•L -1 and the lowest limit of detection was 3.5 mg•L -1 . It was considered that the value obtained could be reliably correlated with the COD value obtained using the conventional methods.

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Chemical oxygen demand determination in well and river waters by flow-injection analysis using a microwave oven during the oxidation step

Cited by 68 publications

References 12 publications

Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

A 3-Step Chemiluminescence Method for Chemical Oxygen Demand Measurement

Study on Determination of Chemical Oxygen Demand in Water with Ion Chromatography

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Chemical oxygen demand determination in well and river waters by flow-injection analysis using a microwave oven during the oxidation step

Cited by 68 publications

References 12 publications

Self‐Organized TiO2 Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

Self‐Organized TiO2 Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

A 3-Step Chemiluminescence Method for Chemical Oxygen Demand Measurement

Study on Determination of Chemical Oxygen Demand in Water with Ion Chromatography

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Product

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Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand