Development and Characterization of Integrated Nano-Sensors for Organic Residues and pH Field Detection.

Itamar Chajanovsky,Sarah Cohen,Ran Yosef Suckeveriene,Giorgi Shtenberg

doi:10.3390/s21175842

Abstract

Meeting global water quality standards is a real challenge to ensure that food crops and livestock are fit for consumption, as well as for human health in general. A major hurdle affecting the detection of pollutants in water reservoirs is the lapse of time between the sampling moment and the availability of the laboratory-based results. Here, we report the preparation, characterization, and performance assessment of an innovative sensor for the rapid detection of organic residue levels and pH in water samples. The sensor is based on carbonaceous nanomaterials (CNMs) coated with an intrinsically conductive polymer, polyaniline (PANI). Inverse emulsion polymerizations of aniline in the presence of carbon nanotubes (CNTs) or graphene were prepared and confirmed by thermogravimetric analysis and high-resolution scanning electron microscopy. Aminophenol and phenol were used as proxies for organic residue detection. The PANI/CNM nanocomposites were used to fabricate thin-film sensors. Of all the CNMs, the smallest limit of detection (LOD) was achieved for multi-walled CNT (MWCNT) with a LOD of 9.6 ppb for aminophenol and a very high linearity of 0.997, with an average sensitivity of 2.3 kΩ/pH at an acid pH. This high sensor performance can be attributed to the high homogeneity of the PANI coating on the MWCNT surface.

Highlights

The half-oxidized state is known as the emeraldine base. It is capable of switching from the insulating state to the conductive state by protonating the imine nitrogen groups of the PANI backbone by strong acids (Figure 2b)
The films showed a higher sensitivity to aminophenol than phenol, resulting in a smaller limit of detection (LOD)
Each film showed a very high sensitivity in the range of ppb, regardless of the organic straightforward electrochemical pH-based nanosensor was designed for the deresidues

Summary

Introduction

There have been greater efforts to collect and store rainwater in reservoirs, in arid and semi-arid regions, given the massive variability in rainfall [3,4,5,6] This water management approach has enormous potential, since it is low-cost, reasonably simple to implement, and increases crop productivity [7]. The quality of rainwater from Polish reservoirs was shown to have a high salinity level, unacceptable phosphorus and chloride ion concentrations, and other pollutants in a lower load range, such as heavy metals [8]. Schets et al [12] showed that the fecal and coliform contamination of harvested rainwater resulted in the growth of extremely harmful bacteria in reservoirs

Methods

Results

Conclusion