Investigations on dehydration processes of trisodium citrate hydrates

The dehydration processes of trisodium citrate (Na₃C₆H₅O₇) hydrates were investigated using thermogravimetry (TG), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). It was found that the temperature of dehydration of trisodium citrate dihydrate was at 430.99 K. For trisodium citrate pentahydrate, there is a two-step dehydration process and the endothermal peaks appear at 337.23 K and 433.83 K, respectively. During the first step of dehydration process, the structure of trisodium citrate pentahydrate changed into the structure of trisodium citrate dihydrate. In addition, the kinetics of dehydration for trisoidum citrate hydrates was also investigated using TG data. According to the activation energies of dehydration calculated by Ozawa equation, it was found that the dehydration mechanisms of the two hydrates were different.