Sensitivity Enhancement of Pb(II) Ion Detection in Rivers Using SPR-Based Ag Metallic Layer Coated with Chitosan-Graphene Oxide Nanocomposite.

Nurul Fariha Lokman,Ahmad Ashrif A Bakar,Fatihah Suja,Norhana Arsad,Nur Hidayah Azeman

doi:10.3390/s19235159

Nurul Fariha Lokman, Ahmad Ashrif A Bakar + Show 3 more

Open Access

https://doi.org/10.3390/s19235159

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Abstract

The detection of Pb(II) ions in a river using the surface plasmon resonance (SPR)-based silver (Ag) thin film technique was successfully developed. Chitosan–graphene oxide (CS-GO) was coated on top of the Ag thin film surface and acted as the active sensing layer for Pb(II) ion detection. CS-GO was synthesized and characterized, and the physicochemical properties of this material were studied prior to integration with the SPR. In X-ray photoelectron spectroscopy (XPS), the appearance of the C=O, C–O, and O–H functional groups at 531.2 eV and 532.5 eV, respectively, confirms the success of CS-GO nanocomposite synthesis. A higher surface roughness of 31.04 nm was observed under atomic force microscopy (AFM) analysis for Ag/CS-GO thin film. The enhancement in thin film roughness indicates that more adsorption sites are available for Pb(II) ion binding. The SPR performance shows a good sensor sensitivity for Ag/CS-GO with 1.38° ppm−1 ranging from 0.01 to 5.00 ppm of standard Pb(II) solutions. At lower concentrations, a better detection accuracy was shown by SPR using Ag/CS-GO thin film compared to Ag/CS thin film. The SPR performance using Ag/CS-GO thin film was further evaluated with real water samples collected from rivers. The results are in agreement with those of standard Pb(II) ion solution, which were obtained at incidence angles of 80.00° and 81.11° for local and foreign rivers, respectively.

Highlights

The contamination of Pb(II) in the rivers is deteriorating due to the rapid industrial development nearby the river areas [1], such as agriculture, mining activities [2], and textile industries [3]
The surface plasmon resonance (SPR) performance using Ag/Chitosan–graphene oxide (CS-graphene oxide (GO)) thin film was further evaluated with real water samples collected from rivers
We report on the proof of concept for Pb(II) ion sensing using an SPR-based Ag metallic layer integrated with a CS-GO nanocomposite thin film and the application of the developed SPR sensors on real water samples collected from the contaminated rivers to validate the SPR performance

Summary

Introduction

The contamination of Pb(II) in the rivers is deteriorating due to the rapid industrial development nearby the river areas [1], such as agriculture, mining activities [2], and textile industries [3]. Rivers are contaminated by Pb(II) either by the direct discharge of waste or through the leaching of Pb(II) from the soil into the rivers [3,4]. It is reported that the accumulation of Pb(II) is found in marine organisms, especially fish that live in the contaminated rivers [4]. Humans become contaminated with Pb(II) via the consumption of seafoods such as fishes, shrimps, and crabs, where Pb(II) is highly accumulated in these living organisms [5]. Pb(II) is toxic to humans even at low concentration levels where it leads to serious illnesses such as chronic inflammation of the kidney and heart, inhibited brain development, poor

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