An Optical Fiber Sensor for Uranium Detection in Water.

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Uranyl (UO2^2+) detection is crucial for environmental monitoring and nuclear safety.
• Existing methods for uranyl detection can be complex and time-consuming.
• Development of sensitive and selective sensors for uranyl is an ongoing challenge.

Purpose of the Study:

• To develop and characterize a novel optical sensor for the detection of uranyl ions.
• To investigate the interaction mechanism between uranyl and the sensor's receptor molecule.
• To evaluate the sensor's performance in real-life water samples.

Main Methods:

• Fabrication of a gold-plated D-shaped plastic optical fiber (POF) sensor.
• Immobilization of 11-mercaptoundecylphosphonic acid (MUPA) as a molecular layer on the gold surface.
• Characterization of sensor response to varying uranyl concentrations in different aqueous matrices.
• Investigation of uranyl-MUPA interaction mechanisms and selectivity against competing ions (Ca^2+, Mg^2+).

Main Results:

• The sensor demonstrated a high affinity for uranyl ions, with affinity constants around 10^7 M^-1 in the presence of competing ions.
• Selective detection of uranyl was achieved, with reduced affinity in the presence of Mg^2+ (around 10^6 M^-1).
• A low detection limit of a few μg L^-1 was achieved directly in natural water samples (tap water, seawater).

Conclusions:

• The developed optical sensor based on MUPA-functionalized POF is effective for rapid and in situ uranyl detection.
• The sensor exhibits high affinity and selectivity for uranyl, even in complex matrices.
• This sensor offers a promising tool for environmental monitoring and water quality assessment.