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Title: Developing materials and methods for remediation of metaldehyde from drinking water
Author: Tao, Bing
ISNI:       0000 0004 5347 4584
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2014
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Metaldehyde contamination of drinking water across the United Kingdom has raised extensive public attention since 2007. There is still no effective solution for this issue, despite all of the steps taken by different concerned parties. The proposed methods of removing metaldehyde either suffer from prohibitive energy costs and/or the by-product issue. In this project, adsorption, ion-exchange and heterogeneous catalysis were evaluated and employed to address the metaldehyde contamination issue. Detailed investigation of metaldehyde sorption onto different activated carbons showed that the low adsorption capacity and high leaching tendency are the main reasons why the current method employed in water treatment works failed. The detailed investigation of metaldehyde removal by granular activated carbon (GAC), MN200 and S957 confirmed that strong acid functionalities (e.g. sulfonic acid) are desirable for metaldehyde removal. The non-functionalised MN200 or GAC both suffered high leaching tendency, which is the result of weak affinity between adsorbent and metaldehyde. The sulfonic and phosphonic acid functionalised S957 was showed to exhibit high adsorption capacity and no leaching at all, except suffering poor kinetics. Sulfonic acid functionalised silica samples (SA-SBA-15) were synthesised to improve the kinetic performance. The nuclear magnetic resonance (NMR) study indicated that the mechanism of sulfonic acid functionality removing metaldehyde is a heterogeneous catalysis process, and acetaldehyde is the only by-product, with further confirmation by quantification study. A variety of polymeric Macronets with tuneable sulfonic acid functionality and porosity were manufactured to optimize the materials development. Results showed that sample MN502 exhibits the best degrading performance and is also the most cost-effective one. Therefore, a novel dual-stage method was developed using MN502 as a heterogeneous catalyst to degrade metaldehyde into acetaldehyde. Experimental demonstrations showed that acetaldehyde can be completely removed by amine functionalised ion-exchanger A830. The bench-scale column tests using both synthetic and real surface water confirmed that the developed dual-stage method is promising and of practical interest since it can adapt the current facilities in water treatment works, making the actual application easy to employ, and most importantly very cost-effective.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available