Electrochemical Nanocomposite-Derived Sensor for the Analysis of Chemical Oxygen Demand in Urban Wastewaters

Abstract

This work reports on the fabrication and comparative analytical assessment of electrochemical sensors applied to the rapid analysis of chemical oxygen demand (COD) in urban waste waters. These devices incorporate a carbon nanotube-polystyrene composite, containing different inorganic electrocatalysts, namely, Ni, NiCu alloy, CoO, and CuO/AgO nanoparticles. The sensor responses were initially evaluated using glucose as standard analyte and then by analyzing a set of real samples from urban wastewater treatment plants. The estimated COD values in the samples were compared with those provided by an accredited laboratory using the standard dichromate method. The sensor prepared with the CuO/AgO-based nanocomposite showed the best analytical performance. The recorded COD values of both the sensor and the standard method were overlapped, considering the 95% confidence intervals. In order to show the feasible application of this approach for the detection of COD online and in continuous mode, the CuO/AgO-based nanocomposite sensor was integrated in a compact flow system and applied to the detection of wastewater samples, showing again a good agreement with the values provided by the dichromate method.

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

“…So far, number of novel electrode materials have been utilized to oxidize organic compounds. For instance, the following electrodes were reported for the electrochemical detection of COD: copper electrode modified with copper nanoparticles ; activated copper electrode ; glassy carbon electrode (GCE) coated with Ni nanoparticles , (NiCu) alloy , or cobalt oxide film ; boron‐doped diamond electrode (BDD) ; Pt electrodes modified with PbO 2 , or F‐PbO 2 ; Ti electrodes coated with nano‐TiO 2 , Rh 2 O 3 , or TiO 2 /PbO 2 ; carbon nanotube‐polystyrene composite electrode containing CuO/AgO ; gold electrode coated with micro‐nano structured Cu−Co film .…”

An online surface water COD measurement method based on multi-source spectral feature-level fusion

“…The correlation coefficient is dened as the degree of correlation between sample true value (obtained by standard COD measurement) and model output. 7 The formula of the correlation coefficient is shown as eqn (9).…”

“…The proposed method can realize an online COD measurement and is not sensitive to white Gaussian noise (AWGN), but failed to offer enough precision compared with the standard method. Concerning the technology based on electrochemical sensors, Gutierrez et al 9 successfully applied electrochemical sensors to realize rapid COD measurement in urban waste water. Although showing easy measurability and continual detection, the method does not have good performance for surface water detection with low COD.…”

Development of a Three-Dimensional Structured Carbon Fiber Felt/β-PbO2 Electrode and Its Application in Chemical Oxygen Demand Determination

“…The standard COD determination method is dichromate titration [3], which involves toxic (Cr 6+ , Hg 2+ ) and expensive (Ag 2 SO 4 ) chemicals [1][2][3] and is difficult to realize in situ monitoring. Among the alternative methods, such as electrochemical oxidation method [1,[3][4][5], photocatalytic oxidation method [6][7][8][9] and photoelectrocatalytic oxidation method [10][11][12], electrochemical oxidation method has been proposed as the most potential manner for COD in situ detection.…”

“…For electrochemical detection of COD, the adsorbed hydroxyl radicals (·OH) which are electro-generated on the anode at an appropriate potential react with the organic compounds in electrolyte [13,14], and the current response to electrochemical regeneration of ·OH radicals is proportional to the concentration of the organic compounds in electrolyte [1,[3][4][5][13][14][15][16][17][18]. Several kinds of electrochemical sensors for the determination of COD, such as AgO/CuO [15], PbO 2 [13,16], Rh 2 O 3 /Ti [17], Cu/CuO [18] and boron-doped diamond (BDD) [3] electrodes, have been developed in recent years.…”