Issue 6, 2023

Ferrihydrite coating reduces microplastic induced soil water repellency

Abstract

Addition of microplastics (MP) to soil has the potential to increase soil water repellency. However, coating of MP with soil abundant substances e.g., iron compounds, can reduce this effect. Here, we tested if pre-coating or in situ coating of MP with ferrihydrite (Fh) reduces soil water repellency. We applied hotspots of pristine and coated MP (20–75 μm, PS and PET) to sand and imaged capillary rise via neutron radiography. Capillary rise experiments in wetting–drying cycles were conducted using water and Fh suspension. Pristine MP hotspots were not wettable. Capillary rise of water into coated MP hotspots differed in wettability depending on polymer type. While coated PS was still non-wettable, water imbibed into the coated PET hotspot. Capillary rise of Fh suspensions in wetting and drying cycles also showed varying results depending on polymer type. MP hotspots were still non-wettable and local water content increased only marginally. Our results indicate that Fh coating of MP changes MP surface wettability depending on polymer type and therefore counteracts the hydrophobic properties of pristine MP. However, MP coating is likely to be slowed down by the initial hydrophobicity of pristine MP. Dynamics of MP coating and increasing wettability are key factors for biotic and abiotic degradation processes.

Graphical abstract: Ferrihydrite coating reduces microplastic induced soil water repellency

Supplementary files

Article information

Article type
Paper
Submitted
22 Feb 2023
Accepted
02 May 2023
First published
10 May 2023
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Processes Impacts, 2023,25, 1094-1101

Ferrihydrite coating reduces microplastic induced soil water repellency

A. Cramer, J. Schmidtmann, P. Benard, A. Kaestner, M. Engelhardt, S. Peiffer and A. Carminati, Environ. Sci.: Processes Impacts, 2023, 25, 1094 DOI: 10.1039/D3EM00077J

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