Abstract
Water pollution can cause significant depletions of dissolved oxygen (DO) in water systems with serious environmental and economic consequences. Online and continuous monitoring of DO can help prevent or minimise the risks associated with low DO values in water. Current DO sensors are, however, expensive and not suitable for continuous and autonomous in-field operation. In this study, we propose a novel and affordable Ceramic Soil Microbial Fuel Cell (CSMFC) for in situ, continuous and autonomous monitoring of DO in water. The system consists of a submersible ceramic vessel containing a soil-based anodic chamber, while the cathode, wrapped around the vessel, is used as the DO probe. The sensor signal, in terms of output voltage, correlates with the DO in water up to a saturating value of 4.5 ± 1.2 mg L−1, at a maximum voltage output of 321 ± 29 mV (20 ̊C, pH=7, 1.65 mS cm−1) with a sensitivity in the linear range of 53.3 ± 22.6 mV L mg−1. A factorial Design of Experiments (DoE) on pH, conductivity, DO and temperature, shows that the response of the sensor is mainly affected by temperature and DO, as well as by their mutual interaction. The calibration model is normalised by the output voltage baseline, thus accounting for any variability in performance, within the same device during long-term performance and from one device to another, which is a challenge in microbial-based systems. As such, this work not only reports an innovative microbial fuel cell-based DO sensor, but also demonstrates the necessity of a DoE to effectively calibrate the sensor.
Original language | English |
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Article number | 137108 |
Journal | Electrochimica Acta |
Volume | 362 |
Early online date | 28 Sept 2020 |
DOIs | |
Publication status | Published - 1 Dec 2020 |
Funding
This work was supported by the UK Engineering and Physical Sciences Research Council ( EP/L016214/1 ) and the Society of Spanish Researchers in the United Kingdom (SRUK). The authors thank Laura Forfar (Paul Murray Catalysis Consulting) for the support on the experimental design and Andrew Chapman (University of Bath) for the support in statistical analysis.
Keywords
- Design of experiments
- Dissolved oxygen sensor
- Soil ceramic microbial fuel cell
- Water quality
ASJC Scopus subject areas
- General Chemical Engineering
- Electrochemistry