A POC device for on-the-spot detection of hexavalent chromium in wastewater

What is it about?

This research introduces a new, useful handheld device for detecting chromium in wastewater on the spot. It can determine not only whether chromium is present (qualitative detection) but also how much is there (quantitative detection). You can see if chromium is present just by looking, but for exact measurements, the device uses a built-in colorimetric sensor. The device includes a light source, a sample holder, a detector, and a microcontroller with a display. It works by detecting hexavalent chromium (Cr(VI)) in water using citrate-capped silver nanoparticles (C-AgNPs). These nanoparticles help convert Cr(VI) to the less harmful trivalent chromium (Cr(III)), making it easier to detect. The silver nanoparticles were carefully made and studied using techniques like UV-Vis spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The device's performance is reliable even when other metals are present in the water. To ensure accuracy, the device's results were compared with those from atomic absorption spectroscopy (AAS), a standard lab method. The device showed consistent results for chromium concentrations ranging from 0.01 to 0.7 parts per million (ppm) in spiked wastewater samples. It can detect chromium levels as low as 26 parts per billion (ppb) and measure up to 79 ppb accurately. This low-cost and easy-to-use colorimetric device highlights the practical use of this method for on-site testing, making it a valuable tool for environmental monitoring and ensuring water safety.

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Photo by Accuray on Unsplash

Photo by Accuray on Unsplash

Why is it important?

Detecting chromium in wastewater is crucial due to its toxic effects on human health and the environment. Hexavalent chromium (Cr(VI)) is highly carcinogenic and can contaminate drinking water sources, posing serious health risks. Traditional lab methods for detecting chromium are often expensive and time-consuming. The development of a portable, affordable device allows for quick, on-site detection, enabling immediate action to prevent exposure and contamination. This helps in monitoring industrial discharge, ensuring compliance with environmental regulations, and protecting public health by providing a rapid response to potential water pollution.

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