Effect of pyrolysis conditions on chemical properties of carbonized rice husks for efficient NH4+ adsorption

Applied Biological Chemistry

Table 3 Langmuir and Freundlich isotherm parameters for the sorption of NH₄⁺ onto the carbonized rice husks depend on the concentration of solution

Isotherm	Type	Parameters	pH 6.1	pH 7.1	pH 11.0
Langmuir	Type 1	q_m (mg/g)	7.262	10.460	31.546
		b (L/mg)	0.006	0.005	0.002
		R²	0.987	0.995	0.999
	Type 2	q_m (mg/g)	14.265	13.889	23.202
		b (L/mg)	0.002	0.003	0.003
		R²	0.856	0.929	0.900
	Type 3	q_m (mg/g)	11.016	13.107	21.324
		b (L/mg)	0.004	0.004	0.004
		R²	0.585	0.682	0.487
	Type 4	q_m (mg/g)	16.143	17.000	36.706
		b (L/mg)	0.002	0.003	0.002
		R²	0.585	0.682	0.487
	Type 5	q_m (mg/g)	7.642	10.761	31.400
		b (L/mg)	0.005	0.005	0.002
		R²	0.987	0.995	0.999
Freundlich	Type 1	K_F	0.068	0.094	0.111
		n	1.302	1.341	1.239
		R²	0.976	0.970	0.960

q_m dosage of NH₄⁺ adsorbed by the single layer of carbide, b binding capacity, R² coefficient of determination, K_F indicator of the carbide’s adsorption capacity, n adsorption strength of carbide