Rapid Potentiometric Detection of Chemical Oxygen Demand Using a Portable Self-Powered Sensor Chip

Abstract

Chemical oxygen demand (COD) is an important indicator of organic pollutants in water bodies. Most of the present testing methods have the disadvantages of having complicated steps, being time-consuming, and using toxic and hazardous substances. In this work, rapid potentiometric detection of chemical oxygen demand (COD) using a portable self-powered sensor chip was successfully developed. The indium tin oxide (ITO) electrode was etched by laser, and the photocatalytic materials TiO2/CuS and Pt were modified onto the photoanode and the cathode to prepare the sensor chip. Based on the principle of photocatalytic degradation, organic pollutants can be oxidized by TiO2/CuS, and the concentration will affect the generated voltage. The quantitative detection of COD in the range of 0.05–50 mg/L can be rapidly achieved within 5 min by a miniature device. Besides good portability and sensitivity, the proposed sensor also has the advantages of environmental friendliness and ease of use, which is an ideal choice for the on-site detection of water pollution.

A Portable Self-Powered Electrochemical Sensor Based on Zinc-Air Battery for Detection of Hydrogen Sulfide

“…1,2 The self-powered electrochemical sensor (SPES), a detection device without external power supply, has received extensive attention and indepth research, which will be a new development model for electrochemical sensors in the future. 3−5 Since first coined by Willner's group in 2001, 6 SPESs have shown broad applications in early disease diagnosis, 7,8 environmental monitoring, 9,10 body fluid testing, 11,12 rapid determination, 13,14 and the like. Among a variety of SPESs, biofuel cell-based SPESs possess advantages in terms of outstanding biocompatibility, low cytotoxicity, welldefined catalytic mechanism, and excellent selectivity, facilitating their translation to an application-type device for early disease diagnosis and real-time monitoring.…”

Compact fluidic electrochemical sensor platform for on-line monitoring of chemical oxygen demand in urban wastewater

“…The organic load of wastewater influents is treated in WWTPs to avoid possible contamination and eutrophication processes of the receiving water bodies [4]. Chemical oxygen demand (COD) is one of the reference parameters for determining the water organic load [5] and is defined as the mass concentration of oxygen consumed for oxidizing the organic matter of a liquid sample. It is calculated from the amount of the strong oxidant dichromate anion (Cr 2 O 7 -) consumed for fully oxidizing organic matter in a titration analysis (1 mol of Cr 2 O 7 is equivalent to 1.5 mol of O 2 ) [6,7].…”

“…An important limitation of the standard analytical technique based on dichromate titration is that it does not allow on-site measurements. Indeed, since it makes use of hazardous chemicals that require careful handling and controlled disposal by trained personnel, water sampling and transportation to centralized laboratories are required, thus increasing the cost and turnaround time of the analysis [5,6,10].…”

“…Several devices mainly based on electrocatalytic and photoelectrocatalytic mechanisms have been reported as promising solutions for implementing COD analysis on-site [1,5,11,12]. These have been summarized in Table S1 (Supporting Information, SI).…”

“…These have been summarized in Table S1 (Supporting Information, SI). In order to be massively deployed for water monitoring purposes, they had to be implemented on compact, affordable, user-friendly devices that required low-power electronics and enabled automatic sampling and analysis [1,5].…”