Determination of Low Chemical Oxygen Demands of Surface Waters by Dichromate Oxidation

Moore, Wendy; Walker, W. W.

doi:10.1021/ac60110a005

Cited by 21 publications

(6 citation statements)

References 12 publications

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“…Nevertheless, the environmentally more friendly method is favored in some states for waters of low COD value, for example, for drinking waters and surface waters where more reproducible results are obtained. At present, the method predominantly applied is the dichromate method published as early as 1926 by Adeney (Adeney and Dawson, 1926) and improved by Muers (1936) and Moore (Moore et al, 1949(Moore et al, , 1951Moore and Walker, 1956). Jirka and Carter (1975) are regarded as the founders of this semimicro method.…”

Section: Introductionmentioning

confidence: 99%

Semimicro Determination of COD Employing Microwave Digestion

Houser

2003

Environmental Engineering Science

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A modified semimicro method is described for determining chemical oxygen demand (COD) employing microwave (MW) digestion (0.5 min exposure at 1,000 W power, and 10 min exposure at 250 W power) with a titration assessment. Composition of reaction mixture was the same as that of the usual reflux method. Determination was performed in glass vessels of original tetrafluoromethoxil containers. Under given conditions dichromate autoreduction was low. A good agreement with the usual reflux method was obtained with selected substances (potassium hydrogen phthalate, glutamic acid, glucose, dodecyl sulphate, where COD-MW/ThOD is 98.9-101.5%). With real samples (municipal sewage, mixed tanning and chemical wastewaters, and treated wastewater from biological treatment plants) the obtained results were also satisfactory (88.0-111.9%).

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Section: Introductionmentioning

confidence: 99%

Semimicro Determination of COD Employing Microwave Digestion

Houser

2003

Environmental Engineering Science

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“…Reaction kinetics of the oxidant reagents with some organic or inorganic contaminants affecting the COD values of a given water system is quite slow. As a consequence, with classic methods, such as oxidation by permanganate or dichromate [3], the oxidation efficiency for some compounds is low or inclusive nil. This results in COD determinations which are not representative of the real contamination of the samples being analyzed.…”

Section: Introductionmentioning

confidence: 99%

A Nafion Film Cover to Enhance the Analytical Performance of the CuO/Cu Electrochemical Sensor for Determination of Chemical Oxygen Demand

Carchi

Lapo

Alvarado

et al. 2019

Sensors

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We modified and evaluated the performance of a CuO/Cu electrochemical electrode for chemical oxygen demand (COD) determination by covering it with a Nafion (Nf) film. The resulting modified CuONf/Cu electrode sensor was used for the electrochemical determination of COD in river, slaughterhouse and estuarine water samples in order to evaluate its performance for this particular task. It was compared with the CuO/Cu sensor with no Nafion. The main electrochemical characteristics of interest, resistance, sensitivity, accuracy and reproducibility, were assessed by means of Linear Sweep Voltammetry using glucose as a standard. Results of these essays indicate that the procedure used produced smooth and firmly attached Nf films covering the whole copper surface. This sensor was shown to be resistant to interferences and effective in electro-oxidation of a wide range of organic compounds and therefore very useful for COD determination. Using the newly developed CuONf/Cu electrode an analytical linear range of 50 to 1000 mg·L−1 COD, with a detection limit of 2.11 mg·L−1 (n = 6) COD was achieved. The comparison shows that the CuONf/Cu sensor is more appropriate for COD determination than its counterpart with no Nafion.

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“…COD is defined as the number of oxygen equivalents consumed in the oxidation of organic compounds using strong oxidizing agents. Conventional method evaluates COD by the oxidative degradation of organic compounds present in water or waste water with strong oxidizing agents such as permanganate or dichromate . Unfortunately, this method involves several disadvantages, such as: low sensitivity, low precision, large sample volume, and high consumption of expensive (e. g. Ag 2 SO 4 ), corrosive (concentrated H 2 SO 4 ) and toxic (e. g., HgSO 4 ) chemicals.…”

Section: Introductionmentioning

confidence: 99%

Sensitive and Green Method for Determination of Chemical Oxygen Demand Using a Nano‐copper Based Electrochemical Sensor

et al. 2017

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Copper nanoparticles (nano‐Cu) were electrodeposited on the surface of glassy carbon electrode (GCE) potentiostatically at −0.6 V vs. Ag/AgCl for 60 s. The developed nano‐copper modified glassy carbon electrode (nano‐Cu/GCE) was optimized and utilized for electrochemical assay of chemical oxygen demand (COD) using glycine as a standard. The surface morphology and chemical composition of nano‐Cu/GCE were investigated using scanning electron microscope (SEM) and energy dispersive X‐ray spectrometer (EDX), respectively. The electrochemical behavior was investigated using linear sweep voltammetry (LSV) which is characterized by a remarkable anodic peak at ∼0.6 V, compared to bare GCE. This indicates that nano‐Cu enhances significantly the electrochemical oxidation of glycine. The effect of different deposition parameters, such as Cu2+ concentration, deposition potential, deposition time, pH, and scan rate on the response of the developed sensor were investigated. The optimized nano‐Cu/GCE based COD sensor exhibited a linear range of 15 to 629.3 ppm, and a lower limit of detection (LOD) of 1.7 ppm (S/N=3). This developed method exhibited high tolerance level to chloride ion (0.35 M chloride ion has minimal influence). The analytical utility of the prepared COD sensor was demonstrated by investigating the COD recovery (99.8±4.3) and the assay of COD in different water samples. The results obtained were verified using the standard dichromate method.

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Determination of Low Chemical Oxygen Demands of Surface Waters by Dichromate Oxidation

Cited by 21 publications

References 12 publications

Semimicro Determination of COD Employing Microwave Digestion

Semimicro Determination of COD Employing Microwave Digestion

A Nafion Film Cover to Enhance the Analytical Performance of the CuO/Cu Electrochemical Sensor for Determination of Chemical Oxygen Demand

Sensitive and Green Method for Determination of Chemical Oxygen Demand Using a Nano‐copper Based Electrochemical Sensor

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