Metal-Organic Framework-Based Fiber Optic Sensor for Chromium(VI) Detection.

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.
• Accurate and rapid detection methods for Cr(VI) are crucial for water quality monitoring.
• Existing detection methods can be time-consuming or lack selectivity.

Purpose of the Study:

• To develop a novel fiber optic sensing strategy for selective and rapid detection of Cr(VI) ions.
• To utilize a metal-organic framework (ZIF-67) for enhanced adsorption and detection sensitivity.
• To evaluate the sensor's performance for real-world water sample analysis.

Main Methods:

• Fabrication of U-bent fiber optic sensor (U-FOS) probes coated with zeolitic imidazolate framework (ZIF-67) via in situ deposition and heat treatment.
• Utilizing evanescent wave-based absorbance sensitivity for Cr(VI) detection at 395 nm.
• Testing selectivity against 14 other heavy metals and interfering ions.
• Evaluating sensor performance using a compact light-emitting diode-photodetector setup.

Main Results:

• The developed FOS/ZIF-67 probes demonstrated high sensitivity and selectivity for Cr(VI).
• Achieved a low limit of detection (LOD) of 1 ppb and a wide linear dynamic range (0.005–100 ppm).
• Exhibited a rapid response time of 5–10 minutes and good recovery rates in real water samples.
• The sensors maintained a shelf-life of at least 4 weeks under ambient conditions.

Conclusions:

• The novel fiber optic sensor (FOS/ZIF-67) provides a viable platform for selective and rapid Cr(VI) detection.
• The sensor's performance indicates its potential for practical environmental monitoring applications.
• This approach offers an efficient method for assessing water contamination by Cr(VI).