Non-isothermal decomposition of Al- , Cr- and Fe- cross-linked trivalent metal-alginate complexes

Abstract

ABSTRACT

The thermal decomposition of Al^III, Cr^III and Fe^III metal-alginate complexes have been investigated thermogravimetrically using (TG) and (DTG) techniques in static air. However, the TG curves showed three stages of weight loss, the DTG curves indicated the presence of a series of thermal peaks associated with the TG curves. The thermal dehydration of the coordinated water molecules was found to occur in the first stage, whereas the decomposition of the dehydrated complexes were occurred in the second and third stages, respectively. The results revealed the formation of hydroxide, oxalate and carbonate intermediates for the cross-linked Al^III, Cr^III and Fe^III metal–alginate complexes, respectively, followed by decomposition of these intermediates to the corresponding metal oxides as final products. These complexes have been characterized by FTIR and chemical analysis. A tentative mechanism for decomposition has been suggested and discussed in terms of the strength of chelation and the structure geometry.

 Abstrak

Penguraian terma AlIII, alginat logam CrIII and FeIII kompleks-kompleks telah disiasat thermogravimetrically menggunakan (TG) dan (DTG) teknik-teknik dalam udara statik. Bagaimanapun , TG lengkung menunjukkan tiga peringkat-peringkat kehilangan berat, DTG lengkung menunjukkan kehadiran satu siri puncak terma dikaitkan dengan TG lengkung. Penyahhidratan terma molekul-molekul air terselaras telah didapati untuk terdapat dalam peringkat pertama, manakala penguraian dinyahhidratkan kompleks-kompleks terjadi dalam kedua dan peringkat-peringkat ketiga, masing-masing. Keputusan didedahkan pembentukan hidroksida, perantaraan oksalat dan karbonat untuk salib mengaitkan AlIII, logam CrIII and FeIII–alginat.