Preparation and applications of catalytic magnetic nanoparticles

It is critical to decontaminate organophosphate compounds in large scale economically, including OP pesticides in groundwater system and chemical nerve agents on the battle field. Homogeneous or micellar decomposition systems with various nucleophiles improve reaction rates significantly without affording the recovery and reuse of the nucleophiles. This research focuses on developing functional magnetic particles to carry strong [alpha]--nucleophilic groups, which are able to catalyze the decomposition reaction and can be recycled and reused.The amidoxime modified magnetic particles were prepared first. The original particles were synthesized with the two-step procedure to obtain average particle size of around 80nm for effective capture by high gradient magnetic separation (HGMS). The precursor molecule cyanoacetohydrazide reacted with the free carboxyl groups on the particle surfaces and subsequently the nitrile groups were transformed into amidoxime groups. The modified particles were of similar average hydrodynamic diameter as the original ones and colloidally stable over a wide range of solutin pH. The amidoxime-modified particles accelerated the hydrolysis reaction of p-nitrophenyl acetate (PNPA). They were easily recycled by HGMS without loss of reactivity. Higher reactivity of the particle system than homogenous amidoxime systems was attributed to the increased concentration of the substrate on the particle surface due to the presence of hydrophobic centers using pseudo-phase exchange model.Stronger nucleophilic groups, hydroxamic acid, were then attached on the particle surfaces. Original particles were prepared with unsaturated carboxylic acid as the second coating in the two-step procedure. The acrylamide monomers were copolymerized with the second coating and the attached amide groups were converted into the hydroxamic acid groups.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Zhang, Huan, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• T. Alan Hatton and Kenneth A. Smith.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46672

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46672