Hybrid organic-inorganic nanotubes effectively adsorb some organic pollutants in aqueous phase

Roberto Nasi (1) , Filomena Sannino (2) , Pierre Picot (1) , Antoine Thill (1) , Olimpia Oliviero (3) , Serena Esposito (3) , Marco Armandi (4) , Barbara Bonelli (4)

1 LIONS - Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire
2 Department of Agricultural Sciences, Division of Grape and Wine Sciences
3 Department of Neuroscience and Reproductive and Odontostomatologic Sciences
4 DMSCE - Department of Materials Science and Chemical Engineering

Methylimogolite nanotubes (Me-IMO NTs, chemical composition (OH)3Al2O3SiCH3) are characterized by having an inner hydrophobic (fully-methylated) surface. Conversely, the outer surface is hydrophilic and positively charged below the point of zero charge (at pH = 8.6), due to the Al(OH)Al + H+ = Al(OH)2+Al equilibrium occurring at the outer surface of the NTs when they are dispersed in water.In this work, adsorption of MCPA (2-methyl-4-chlorophenoxyacetic acid) and of dichloromethane (DCM) on Me-IMO NTs was studied by means of both adsorption/desorption measurements in batch conditions (at room temperature and at different pH value) and Small Angle X-rays Scattering (SAXS).MCPA, which partially dissociates in water (pKa = 2.90), is mainly adsorbed at the outer surface of the NTs, although measurements in batch conditions show that other types of interaction occur (i.e. H-bond) at higher MCPA concentration. SAXS measurements confirm that MCPA has not entered the NTs inner pores.Interaction of the NTs with DCM, instead, is more complex: SAXS measurements show that DCM molecules interact with the NTs inner surface, whereas batch experiments indicate that additional interactions take place with the outer surface of the NTs.

Domains: Material chemistry

Roberto Nasi, Filomena Sannino, Pierre Picot, Antoine Thill, Olimpia Oliviero, et al.. Hybrid organic-inorganic nanotubes effectively adsorb some organic pollutants in aqueous phase. Applied Clay Science, 2020, 186, pp.105449. ⟨10.1016/j.clay.2020.105449⟩. ⟨cea-02458782⟩