# The removal of Zn from complex circumneutral pH mine waters using magnetic nanoparticles (MNPs)

## TL;DR

This study shows that magnetic nanoparticles effectively remove zinc from mine water, even at low concentrations, making them a promising solution for water treatment.

## Contribution

The study demonstrates the effectiveness of magnetic nanoparticles for zinc removal from real mine water samples at low dosages.

## Key findings

- Magnetic nanoparticles removed zinc from mine water samples within 48 hours.
- At 5 g L−1, zinc concentrations were reduced to near-zero levels in some samples.
- Zinc removal increased with higher MNP doses, with over 1 g L−1 needed for trace-level removal.

## Abstract

Mine water discharges pose a significant environmental challenge due to elevated metal concentrations, which can be detrimental to aquatic ecosystems and water quality. In this study, four circumneutral-pH mine water samples were treated with different magnetic nanoparticle (MNP) concentrations (0.1 g L−1, 1 g L−1, and 5 g L−1) to assess their efficacy for Zn removal. Sorption of Zn to all MNP systems tested, occurred within 48 hours. At 5 g L−1, MNPs removed Zn from all mine waters tested, reducing concentrations to 0.09, 0.66, 0.0 and 0.0 mg L−1 for the River Ystwyth, Cwmystwyth adit, River Nent and Haggs adit respectively. A clear positive correlation was recorded for Zn removal as a function of MNP dose, with MNP concentrations >1 g L−1 required for Zn removal to below trace concentrations. Analysis of competing ions (e.g., Ca2+, Mg2+, Na+) showed that a decrease in concentration followed the order Zn > Na+> Ca2+ > Mg2+. These findings confirm that MNPs are effective for the removal of Zn from real mine water samples even when applied at low dosages, suggesting that they are a highly promising water treatment technology for such applications.

Mine water discharges pose a significant environmental challenge due to elevated metal concentrations, which can be detrimental to aquatic ecosystems and water quality.