ZnAl hydrotalcites modified with nanocomposites nZVI–PAA for environmental remediation

NIETO-ZAMBRANO, SORELIS; RAMOS-RAM?REZ, ESTHELA; TZOMPANTZI MORALES, FRANCISCO; BOFFITO, DARIA CAMILLA; NACCACHE, RAFIK; GUTIÉRREZ ORTEGA, NORMA L.; LITTER, MARTA I.; CIPAGAUTA-D?AZ, SANDRA; BARBOSA-LÓPEZ, AIDA LILIANA

Journal of Materials Research and Technology

ELSEVIER SCIENCE SA

Año: 2021 vol. 14 p. 2243 - 2256

2238-7854

Diffraction patterns of polyacrylic acid (PAA) encapsulated-(Fe)-modified ZnAl hydrotalcite(ZnAlH) showed the integration of Fe in the H lattice, resulting in a hybrid nanocomposite(Fe-PAA-ZnAlH), which was mainly verified with the characteristic shift in the 59e63 (2q)region of the ZnAlH (110) reflection plane. The rise in the unit cell parameters (c and a) asthe Fe % incremented, denoted incorporation of Fe in the ZnAlH red. Nonetheless, changesin the immobilizer molecular weight (PAA MW) from 1250 kDa to 5.1 kDa did not cause adifference in the distance between layers (c parameter) but in the cation-cation separation(a parameter), which meant that the nanoparticle was not located between layers, but inthe lattice. The resulting band gap energies of the calcined hybrid nanocomposites wereamong 1.07e1.21 eV, which is an additional support of Feþ3 integration, suggesting insertionof Feþ3 3d orbitals between the valence and the conduction band of ZnO. Furthermore,nZVI were prepared through a pre-agglomeration reduction method, where COOH-groupswere bound to metal cations. Initially, aqueous Feþ2 was bound to PAA [Feþ2-PAA], thenreduced to obtain enclosed hybrid (nZVI-PAA). Less stability and more aggregation wereobserved with the lower molecular weight PAA. Additionally, PAA dissociation caused bypH changes affected the clustering of the nZVI particles. At higher MW, the hydrodynamic diameter and size distribution become smaller and tighter, respectively, allowing a moremonodispersed population with sphere shape and organized in coreeshell beads chains.