Kinetic Studies on the Dehydration of Calcium Oxalate Monohydrate

Abstract The dehydration of CaC 2 O 4 · H 2 O has been studied both isothermally and nonisothermally using thermogravimetric analysis. It was found that material which had aged for 1 year behaved differently from the original sample. Isothermal dehydration of the original material followed an R1 rate law and gave an activation energy of 60.1 ± 6.6 kJ mole -1 . The reaction appears to be independent of particle size. Analysis of the data from nonisothermal experiments gave about equally good results with R2 and R3 rate laws. The isothermal dehydration of aged CaC 2 O 4 · H 2 O followed R1, A2, or A3 rate laws and appears to have an activation energy of 118 ± 15 kJ mole -1 . Sample to sample variation between runs is similar to that of K 2 [Cu(C 2 O 4 ) 2 ] · 2H 2 O.