Surfactant recovery from mesoporous metal-modified materials (Sn-, Y-, Ce-, Si-MCM-41), by ultrasound assisted ion-exchange extraction and its re-use for a microwave in situ cheap and eco-friendly MCM-41 synthesis

TitleSurfactant recovery from mesoporous metal-modified materials (Sn-, Y-, Ce-, Si-MCM-41), by ultrasound assisted ion-exchange extraction and its re-use for a microwave in situ cheap and eco-friendly MCM-41 synthesis
Publication TypeJournal Article
Year of Publication2014
AuthorsGonzález-Rivera, J, Tovar-Rodríguez, J, Bramanti, E, Duce, C, Longo, I, Fratini, E, Galindo-Esquivel, IR, Ferrari, C
JournalJournal of Materials Chemistry A
Volume2
Pagination7020–7033
ISSN20507488 (ISSN)
KeywordsCerium, Environmental impact, Environmental protection, Extraction, Hexagonal structures, Hydrothermal synthesis, Ion exchange, Ion exchange process, Materials, Mesoporous materials, Metal recovery, Metals, Microwave-assisted hydrothermal synthesis, Organic solvents, Salt concentration, Silicon, Surface active agents, Surfactant extraction, Surfactant recovery, Surfactant removal, Tin, Ultrasonics, Ultrasound amplitude
Abstract

Different metal substituted (Y, Sn and Ce) MCM-41 materials were synthesized and detemplated by a low temperature surfactant removal methodology. All metal substituted materials showed an increase in the d100 lattice parameter compared to the parent MCM-41 matrices. The increase depends on both the metal type and amount that is successfully incorporated by direct conventional hydrothermal synthesis. The metal modified MCM-41 materials were detemplated by an ultrasound assisted (US) ion-exchange process using methanol as the solvent (NH4NO3/US/MeOH). The effect of the ultrasound amplitude, extraction time and salt concentration were explored, and optimal values were determined for Y-MCM-41 detemplation (40 mM of NH 4NO3, 60% of US amplitude and 15 min of adiabatic treatment). The removal percentage achieved with these values was in the following order: Y (97.7%) > Ce (94.4%) > Sn (92.1%) > Si (90.3%). Several techniques (SAXS, FTIR, TGA, 1H MAS, 29Si HPDEC MAS NMR and N2 physisorption) demonstrated that the mesoporous materials keep their hexagonal structure and high surface area after the NH 4NO3/US/MeOH surfactant extraction. Moreover, the thermal shrinkage of the structure was reduced in the following order: Si (0.6%) < Sn (4%) < Ce (5%) < Y (9%) < calcined samples (from 9 to 15%). The surfactant recovered was successfully recycled in a consecutive microwave assisted hydrothermal synthesis cycle (MW-HT). The synergy of different strategies (MW-HT synthesis, NH4NO3/US/MeOH surfactant removal and surfactant recovery) produces considerable time, energy and cost abatement, environmental impact reduction and promising scale up projections in the eco-friendly synthesis of MCM-41 materials. © 2014 the Partner Organisations.

URLhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84898867835&partnerID=40&md5=b3e277816bfc2e7a2705bd434b544395
DOI10.1039/c3ta15078j