Separation of Spherical Nanosilica from Agricultural Wastes in Vietnam via Ultrasonic-Assisted Precipitation and Application for Effective Removal of Methylene Blue from Aqueous Solution

Table 6

Thermodynamic parameters of MB adsorption onto BA-SiO₂, RHA-SiO₂, and pure-SiO₂.

Temperature (K)		283		293	303		313	323	333
Parameters	Materials
ΔH° (kJ·mol^−1)	BA-SiO2	−58.98
	RHA-SiO2	−51.95
	Pure-SiO2	−59.41
ΔS° (J·mol^−1)	BA-SiO2	−185.57
	RHA-SiO2	−164.20
	Pure-SiO2	−187.07
ΔG° (kJ·mol^−1)	BA-SiO2	−5.60	−5.01			−3.93	−0.93	0.75	3.57
	RHA-SiO2	−4.71	−4.19			−3.52	−0.33	1.75	2.72
	Pure-SiO2	−6.94	−6.01			−5.07	−1.31	−0.008	1.64