Novel solid-state compounds of heavy rare-earth (III) picolinates. A pyrolytic study using: TG-DSC-IR, HSM-MS and GC-MS

Autor(es)

Nascimento, A. L. C. S. ^{[1, 2]} ; Ashton, G. P. ^[2] ; Parkes, G. M. B. ^[2] ; Ekawa, B. ^[1] ; Fernandes, R. P. ^[1] ; Carvalho, A. C. S. ^[1] ; Ionashiro, M. ^[1] ; Caires, F. J. ^{[3, 1]}

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, Inst Quim, CP 355, BR-14801970 Araraquara, SP - Brazil

^[2] Univ Huddersfield, Thermal Methods Res Unit, Sch Appl Sci, Huddersfield HD1 3DH, W Yorkshire - England

^[3] Univ Estadual Paulista, UNESP, Fac Ciencias, Dept Quim, Campus Bauru, BR-17033260 Bauru, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS; v. 144, NOV 2019.
• Citações Web of Science: 0

Resumo

Heavy trivalent lanthanides and yttrium picolinates were synthesized by complexation of basic rare-earth metal carbonates with an aqueous solution of picolinic acid. The novel compounds were obtained with the general formula Ln(L)(3).nH(2)O, where L is picolinate and n = 1.5 H2O (Dy, Ho, Yb, Lu and Y), 2 H2O (Tb and Tm) and 2.5 H2O (Er). The stoichiometry of the complexes was calculated through mass losses found using thermogravimetry (TG), complexometry and elemental analysis (EA). The thermal behavior in oxidative and pyrolytic atmospheres of the compounds was analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC). The gaseous products of the pyrolysis were determined throughout by monitoring the evolved species using TG-DSC couple to Fourier transform infrared spectroscopy (TG-DSC-IR), hot-stage microscopy mass spectrometry (HSM-MS), and gas chromatography-mass spectrometry (GC-MS). The obtained results validated mass loss assignments made using the TG curves. However, gaseous product analysis indicates the degradation processes are more complex than the thermoanalytical techniques suggest alone. This study used a GC-MS technique to identify the condensed gaseous products obtained during the second step of thermal degradation of the picolinate complexes. The analysis of the symmetric and asymmetric stretching frequencies of the carboxylate group in the IR spectra showed a monodentate bonding mode. The compounds were obtained in the amorphous state, as indicated by the powder x-ray diffractometry (PXRD) data. (AU)

• Processo FAPESP: 18/24378-6 - Síntese, caracterização e estudo termoanalítico de cocristais de Valsartana, Candesartana Cilexetila e Olmesartana medoxomila
• Beneficiário: Flávio Junior Caires
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/14936-9 - Preparação, caracterização e estudos termoanalíticos de catalisadores heterogêneos de selenatos duplos de Mg/Co e Mg/Cu na produção de biodiesel a partir de diferentes óleos
• Beneficiário: Massao Ionashiro
• Modalidade de apoio: Auxílio à Pesquisa - Regular