Development of a portable electrochemical sensor for real-time detection of heavy metals in water using a graphene-based modified electrode

Project Abstract

This study reports the development and validation of a portable electrochemical sensor employing a graphene-based modified electrode for real-time detection of heavy metals in water. The sensor integrates a screen-printed carbon electrode (SPCE) modified with reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) to enhance electron transfer, increase active surface area, and improve selectivity toward lead (Pb2+), cadmium (Cd2+), and mercury (Hg2+) ions. The fabrication process involves a straightforward drop-casting technique followed by electrochemical reduction to yield a stable rGO-AuNP composite on the electrode surface. The sensor’s analytical performance was characterized using anodic stripping voltammetry (ASV) and differential pulse voltammetry (DPV) under ambient conditions, with optimized parameters including deposition potential, deposition time, and scan rate to achieve lower detection limits and broad linear ranges suitable for regulatory thresholds. The linear dynamic ranges achieved were from 0.1 to 1000 µg L?1 for Pb2+, Cd2+, and Hg2+, with limits of detection down to the ng L?1 level for select metals, enabling trace analysis in diverse water matrices. Selectivity tests demonstrated minimal interference from common inorganic ions (Na+, K+, Ca2+, Mg2+) and organic matter, attributable to the affinity of the graphene-based surface and the preconcentration step inherent to ASV. A portable potentiostat with wireless data transmission was integrated with a lightweight, compact housing to enable on-site measurements, real-time data visualization, and automated calibration routines. The sensor’s robustness was evaluated through repeatability (n = 10 electrodes) and reproducibility (n = 6 devices), with relative standard deviations within acceptable ranges (<8% for all analytes). Real-world validation included analyses of river, lake, and tap water samples spiked with known concentrations of Pb2+, Cd2+, and Hg2+, achieving recoveries between 92% and 108% across matrices, indicating reliable performance in complex matrices. Temperature and pH effects were systematically studied to assess operational stability across typical environmental conditions, and a simple calibration model was developed to account for matrix effects, enabling rapid field deployment without extensive sample pretreatment. The device demonstrates rapid response times (<120 s per measurement), low power consumption, and the potential for multiplexed detection through differential pulse techniques and selective surface functionalization. Economic and life-cycle considerations were addressed by assessing material costs, scalability of electrode fabrication, and recyclability of sensor components. The study discusses challenges related to long-term stability of graphene composites, fouling in natural waters, and regulatory acceptance, and proposes strategies such as surface passivation, periodic regeneration, and integration with microfluidic modules for automated sampling. Overall, the developed graphene-based modified electrode-based sensor offers a portable, affordable, and sensitive platform for continuous monitoring of hazardous heavy metals in water, supporting environmental surveillance, public health protection, and compliance with water quality standards.

Project Overview

What This Project Is About

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A beginner-friendly look at building a simple, portable device that can detect tiny amounts of harmful metals dissolved in water in real time. The project focuses on a sensor made with graphene to improve sensitivity and a compact reader so measurements can be taken on-site rather than in a lab.

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The Problem It Addresses

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Water contamination by metals like lead, mercury, and cadmium is a serious health risk. Conventional testing is slow, expensive, and requires trained staff. This project aims to create a low-cost, easy-to-use sensor that delivers fast results in the field.

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Objectives of the Project

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1. Explain why heavy metals in water are dangerous and how sensors help.
2. Design a simple graphene-based electrode to detect metals.
3. Build a portable device to read sensor signals.
4. Test the device with water samples of known metal levels.
5. Evaluate accuracy, speed, and ease of use.

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What You Will Do Step by Step

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1) Learn basic concepts of electrochemical sensing and graphene.

2) Prepare or source a graphene-based electrode and assemble the sensor.

3) Calibrate the sensor using standard samples with known metal concentrations.

4) Build the portable reader and integrate data display.

5) Collect data from real water samples and compare with reference methods.

6) Analyze data to assess accuracy and reliability.

7) Discuss limitations and potential improvements.

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Expected Outcome

The project should yield a working, low-cost portable sensor capable of detecting select heavy metals in water with clear readings and an evaluation of its practicality for field use.