Table: 4.

Thermodynamic parameters of madder dye at different heating rate at temperature 250 °C.

S. No.	Heating rate	Stage	Temp.	Ea (kJ mol−1)	ΔS (kJ mol−1)	ΔH (kJ mol−1)	ΔG (kJ mol−1)
1	10 °C/min.	2	250	20.6469	−0.2427	16.2985	143.2168
2	20 °C/min.	2	250	11.1980	−0.2777	6.8497	152.0953
3	30 °C/min.	2	250	24.6638	−0.2347	20.3154	143.0738
4	40 °C/min.	2	250	25.8167	−0.2356	21.4684	144.6755
5	50 °C/min.	2	250	32.3961	−0.2205	28.0477	143.3729

The Thermodynamic parameter at 450 °C are shown in Table 5. The positive ΔG value are observed in the range from 178.0351 to 197.5309 kJ mol⁻¹ at heating rate 40° and 10 °C per minute, which is confirm the thermally non-spontaneous process. The negative ΔS value observed in the range from −0.2030 to −0.2583 kJ mol⁻¹ at heating rate 40° and 10 °C per minute respectively. The positive ΔH values are obtained in the range between 10.81374 and 31.29486 kJ mol⁻¹ at heating rate 10° and 40 °C per minute respectively. The maximum and minimum Ea value are observed of 37.306 and 16.825 kJ mol⁻¹at heating rate 40° and 10 °C respectively.