UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids.

Area of Science:

• Environmental Science
• Polymer Chemistry
• Wastewater Treatment

Background:

• Wastewater bio-solids are a major source of microplastic (MP) pollution.
• Pre-environmental degradation of MPs can reduce ecological exposure.
• Understanding MP structural changes is crucial for mitigation strategies.

Purpose of the Study:

• To investigate the impact of UV-A and UV-C radiation at 70°C on common microplastics (polypropylene, polyethylene, polyethylene terephthalate) in bio-solid suspensions.
• To compare the degradation effectiveness of UV-A versus UV-C.
• To analyze the influence of MP shape (fibers, lines, granules) on degradation rates.

Main Methods:

• Microplastics (PP, PE, PET) were exposed to UV-A and UV-C in bio-solid suspensions, air, and water at 70°C.
• Structural changes were analyzed using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR).
• Surface morphology was examined using Scanning Electron Microscopy (SEM).

Main Results:

• UV exposure induced carbonyl and hydroxyl groups in polypropylene (PP), and in polyethylene (PE) and polyethylene terephthalate (PET) only within bio-solid suspensions.
• Formation of these functional groups increased with exposure time.
• UV radiation in bio-solid suspension showed the greatest impact, with fibers degrading more than other shapes due to higher surface-to-volume ratios. UV-A was slightly more effective than UV-C.

Conclusions:

• Ultraviolet radiation combined with elevated temperature alters polymer structure within wastewater bio-solids.
• This process can accelerate microplastic degradation, offering a potential pre-environmental mitigation strategy.
• MP shape significantly influences degradation rates, with fibrous forms being more susceptible.