abstract
New sorbents based on magnetite particles coated with siliceous shells were synthesized and tested in the removal of mercury ions from aqueous solutions by magnetic separation. Atomic fluorescence spectroscopy studies performed on water samples treated with these sorbents have shown that the metal ion concentration decreased to values lower than the guideline values for drinking water. The high adsorption affinity for mercury ions in these materials was attributed to dithiocarbamate groups grafted over the siliceous domains using a new surface modification method. Hence, the magnetic particles have been coated with amorphous silica shells that include thiolate moieties via a hydrolytic co-condensation process using tetraethoxysilane (TEOS) and siloxydithiocarbamate (SiDTC) as the sol-gel precursors. This one-step method for the surface modification of magnetite particles led to sorbents with extensive thiolate moieties that can be then collected by applying an external magnetic field.
keywords
HEAVY-METAL IONS; AQUEOUS-SOLUTION; NANOPARTICLES; WATER; SURFACE; PARTICLES; GEL; NANOMATERIALS; REMEDIATION; NANOCOMPOSITES
subject category
Chemistry; Energy & Fuels; Materials Science
authors
Tavares, DS; Daniel-da-Silva, AL; Lopes, CB; Silva, NJO; Amaral, VS; Rocha, J; Pereira, E; Trindade, T
our authors
Ana Luísa Daniel da Silva
Principal Researcher
Cláudia Batista Lopes
Assistant Researcher
Daniela Soraia dos Santos Tavares
PhD Student
João Rocha
Full Professor
Nuno João Silva
Principal Researcher
Tito Trindade
Full professor
Vitor Brás Sequeira Amaral
Full professorProjects
acknowledgements
The authors thank Fundacao para a Ciencia e a Tecnologia (FCT) (PTDC/CTM-NAN/120668/2010; Pest-C/CTM/LA0011/2011), FSE and POPH for funding. The NMR spectrometer is part of the National NMR Network (RNRMN), supported with funds from FCT.