Thermal behavior of alginic acid and its sodium salt

Abstract

An evaluation of hydration and thermal decomposition of HAlg and its sodium salt isdescribed using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG curves inN 2 and air, were obtained for alginic acid showed two decomposition steps attributed to loss of waterand polymer decomposition respectively. The sodium alginate decomposed in three steps. The firstattributed to water loss, followed by the formation of a carbonaceous residue and finally the Na 2 CO 3 .DSC curves presented peaks in agreement with the TG data. In the IR alginic acid presented bands at1730 and 1631 cm -1 , while sodium alginate presented a doublet at 1614 e 1431 cm -1 , evidencing thepresence of salified carboxyl groups.