144-6 Microplastic-Hematite Interactions: Implications for Arsenate Fate and Transport in Saline Aquatic Systems

Session: Microplastics in the Environment (Posters)

Poster Booth No.: 39

Presenting Author:

Wei Ren

Authors:

Bawa, Maxwell Mutala¹, Ren, Wei², Cai, Rui³, Xu, Tingying⁴, Gonzalez-Estrella, Jorge⁵

(1) Oklahoma State University, Stillwater, OK, USA, (2) Oklahoma State University, Stillwater, OK, USA, (3) School of Civil and Environmental Engineering, Oklahoma State University, Stillwater, OK, USA, (4) Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK, USA, (5) School of Civil and Environmental Engineering, Oklahoma State University, Stillwater, OK, USA,

Abstract:

Arsenic contamination in aquatic systems poses significant environmental and public health risks, originating from both geogenic and anthropogenic sources. While previous research has examined arsenate interactions with individual sorbents, the complex behavior of arsenate in systems containing both mineral phases and emerging contaminants like microplastics remains poorly understood. This study elucidates the coupled effects of microplastics and iron oxides on arsenate mobility in saline environments through systematic adsorption experiments. Our results demonstrate that hematite exhibits substantially higher arsenate adsorption capacity than microplastics across all tested conditions. In binary systems containing both sorbents, total arsenate removal increased by 25-80% compared to single-sorbent systems, indicating synergistic removal mechanisms. Arsenate adsorption onto hematite remained invariant across ionic strength conditions (0.1-0.5 M), consistent with inner-sphere surface complexation. Conversely, microplastic adsorption capacity increased from 0.98 ± 0.12 to 2.11 ± 0.06 µmol g⁻¹ with increasing ionic strength, attributed to reduced electrostatic repulsion between negatively charged surfaces. Spectroscopic analysis using ATR-FTIR revealed distinct surface functional group modifications on hematite following arsenate adsorption, while microplastics showed negligible spectral changes, confirming physisorption as the dominant mechanism. SEM-EDS mapping corroborated preferential arsenate association with hematite surfaces in all experimental configurations. These findings highlight the critical role of mineral-microplastic interactions in controlling arsenate biogeochemistry in high-salinity environments. The enhanced removal efficiency observed in mixed systems has important implications for understanding natural attenuation processes and developing effective remediation strategies for arsenic-contaminated waters. Our work provides fundamental insights into contaminant fate and transport in complex environmental matrices increasingly impacted by microplastic pollution.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9397

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.