Development of SPEEK-Coated IrO Sensor for High-Biomass Aquatic pH Monitoring.

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Monitoring

Background:

• pH sensors face instability issues in complex aquatic environments with high biomass and redox substances.
• Existing sensors struggle with drift and interference, limiting their practical application.
• Robust and stable pH monitoring is crucial for understanding aquatic ecosystems.

Purpose of the Study:

• To develop a novel, highly stable pH sensor for challenging aquatic environments.
• To mitigate drift and interference issues common in current pH sensing technologies.
• To validate the sensor's performance in real-time measurements across diverse aquatic settings.

Main Methods:

• Fabrication of a novel sensor using an Iridium Oxide (IrO2) sensing layer.
• Envelopment of the sensing layer in a composite film of sulfonated poly(ether ether ketone) (SPEEK) doped with a silicon-stabilized ionic liquid (SP-IrO2).
• Testing sensor robustness under reducing conditions (S2-, I-, ascorbic acid) and real-time validation in algal culture, sediment, and mussel aquaculture areas.

Main Results:

• The SP-IrO2 sensor demonstrated robustness against common interfering substances.
• Real-time pH measurements in demanding aquatic environments showed sustained accuracy and stability over 6-8 days.
• Minimal deviations from reference electrodes were observed: <0.03 pH units in mussel aquaculture and <0.07 pH units in algal culture.

Conclusions:

• The developed SP-IrO2 sensor offers a stable and accurate solution for pH monitoring in challenging aquatic environments.
• Its solid-state, potentiometric design is compact, energy-efficient, economical, and low-maintenance.
• This technology is suitable for precise pH monitoring in diverse environments with high biomass and turbidity.