Design of pH Responsive Textile as a Sensor Material for Acid Rain

Area of Science:

• Materials Science
• Environmental Science
• Textile Chemistry

Background:

• Rainwater's chemical composition indicates acidifying air pollutants like sulfur dioxide and nitrogen oxides.
• Acid rain is defined as rainwater with a pH below 5.6.
• Developing functional textiles as sensors for environmental monitoring is an emerging area.

Purpose of the Study:

• To design a halochromic textile sensor for detecting air pollutants.
• To tailor a polyamide 6 fabric with Bromocresol green dye for visual pH indication.
• To evaluate the performance and durability of the functional textile.

Main Methods:

• Polyamide 6 fabric dyed with Bromocresol green (pH-sensitive dye).
• Fabric treated with water/oil repellent finish.
• Spectrophotometric analysis (CIELAB) of color change in buffer solutions.
• Assessment of color fastness (rubbing, washing, light) and repellency (SIST EN ISO standards).

Main Results:

• Unfinished dyed fabric showed faster, clearer reversible color change compared to finished fabric.
• The dyed fabric exhibited good color fastness to rubbing and laundering but poor light fastness.
• The textile remained pH-sensitive despite dye degradation under xenon light.

Conclusions:

• The Bromocresol green-dyed polyamide 6 fabric functions as a pH-sensitive sensor for air pollutants.
• The unfinished textile offers superior color change performance for sensing applications.
• Further research may be needed to improve light fastness for long-term outdoor use.