Exploring the use of Magnetic Nanoparticles (MNPs) for the remediation of environmental contaminants

Abstract

The use of magnetic nanoparticles (MNPs) for the remediation of environmental contaminants was explored throughout this thesis. MNPs were exposed to varying compositions of aqueous solutions, including synthetic and natural samples.
Both 1 and 5 g L-1 of MNPs were added to varying concentrations of Co(II), Ni(II) and Zn(II) in single and mixed metal experiments at circumneutral pH. 5 g L-1 of MNPs removed all metals from both systems to low concentrations with Zn singularly having the highest partition coefficient value (Kd values: Zn: 0.07 L g-1 ; Co: 0.02 L g-1; and Ni: 0.01 L g-1). Transmission Electron Microscopy (TEM) and X-ray Absorption Spectroscopy (XAS) confirmed a uniform coverage of metals on the MNP surface, with interactions between the metals and MNPs occurring via coordinate bonding (Fe-O).

Advancing upon this, four Zn bearing mine water samples from two geographical locations were treated with MNPs. Removal increased with increasing MNP concentration with Zn preferentially sorbed over competing ions at the highest MNP concentration (Zn > Na > Ca > Mg). Combining data from both synthetic and natural samples enabled the determination of the maximum sorption capacity (Qmax) which was 27 mg g-1 for Zn.

Additionally, three types of MNPs were synthesised (unmodified, functionalised with Al(OH)3 in batch and scaled up) and characterised using TEM and X-ray Diffraction (XRD). These were used to remove Dissolved Organic Carbon (DOC) from reservoir drinking water. Functionalised MNPs had the highest removal efficiency (MNPs = 1%, MNPs-AlContinuous Reactor (CR) = 77%, MNPs-AlBatch (B) = 87%). Attenuated Total Reflectance – Fourier Transform Infrared Spectroscopy (ATR-FTIR) identified aldehyde and carboxylic groups on DOC interacting with MNP surfaces, indicating removal by ligand exchange and the formation of co-ordination complexes.

Overall, the findings from this thesis demonstrate that MNPs are effective in removing contaminants from both synthetic and natural water samples, supporting their potential application in resource recovery and sustainable water treatment.

Date of Award	9 Dec 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	James M Byrne (Supervisor), Jagannath Biswakarma (Supervisor) & Richard Crane (Supervisor)