# Synergistic sonocatalytic degradation of carbamazepine and 17α-ethinylestradiol in the presence of carbon nanotube yarn

## TL;DR

A new method using carbon nanotube yarn and ultrasound effectively breaks down harmful pharmaceuticals in water.

## Contribution

A synergistic sonocatalytic system using carbon nanotube yarn is introduced for enhanced pharmaceutical degradation.

## Key findings

- The system achieved synergistic indices of 1.39 for carbamazepine and 1.73 for 17α-ethinylestradiol.
- The carbon nanotube yarn system retained over 90% efficiency after five treatment cycles.
- Radical amplification by the yarn was confirmed as the main degradation mechanism.

## Abstract

Pharmaceuticals such as carbamazepine and endocrine disruptors such as 17α-ethinylestradiol are persistently present in aquatic environments and pose serious ecological and human health concerns due to their chemical stability and limited removal efficiency by conventional wastewater treatment methods. In this study, a carbon nanotube yarn catalyzed high-frequency ultrasonic system was developed to synergistically enhance the degradation of carbamazepine and 17α-ethinylestradiol. carbon nanotube yarn, which is well known for its high surface area, chemical stability, and good electrical conductivity, was applied to a 970 kHz ultrasonic reactor to amplify acoustic cavitation and promote •OH generation. Kinetic analysis confirmed that the combined ultrasonic US-assisted catalytic system with carbon nanotube yarn process enhanced degradation performance, with synergistic indices of 1.39 for carbamazepine and 1.73 for 17α-ethinylestradiol, significant improvement over ultrasonic alone. Enhanced radical generation was validated using electron paramagnetic resonance spectroscopy. In addition, the ultrasonic-assisted catalytic system with carbon nanotube yarn system showed stable catalytic activity and good reusability with an efficiency decrease of less than 10 % over five consecutive treatment cycles. The excellent pharmaceutical removal performance and retention of carbon nanotube yarn under repeated ultrasonic exposure indicates good catalytic performance and durability. The main mechanistic insight shows that carbon nanotube yarn promotes oxidative degradation via radical amplification. These results highlight the significant potential of the ultrasonic-assisted catalytic system with carbon nanotube yarn system as an efficient and scalable advanced oxidation technology to remediate persistent organic contaminants in environmental water.