Detection of low concentration microplastics in water based on the perturbation of the microwave resonance

Abstract

Pollution by plastic has become one of the most pressing problems threatening ecosystem and having potential risk to human health. However, a rapid method with accurate, sensitive, convenient properties and low detection concentration of microplastic (MP) particles still remains challenging. For this purpose, a method of MP concentration detection based on the perturbation of the microwave resonance is proposed. Through analyzing the received microwave signals, the MP concentration can be realized conveniently. Polypropylene (PP) and polyethylene (PE) with particle sizes of 200±30 μm, 250±30 μm, and 500±50 μm in distilled water and sewage (artificial sewage and urban lake water) are measured. The experimental results show that the proposed method has a good ability to distinguish low concentration microplastics (MPs) in water and the detection limit is in the range of tens to hundreds of parts-per-billion levels. The robust of the proposed method against variation in particle size and MP type is well. The error of repetitive measurement is less than 0.07 % in artificial sewage test samples and the measurement error of MP concentration is less than 2.70 %. The proposed method shows a good performance in the accurate, sensitive, and convenient detection of MP in water and sewage environment even with low concentrations.