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

Applied Biological Chemistry

Table 4 Langmuir and Freundlich isotherm parameters for the sorption of NH₄⁺ onto the carbonized rice husks depend on the dose of absorbent

Isotherm	Type	Parameters	pH 6.1	pH 7.1	pH 11.0
Langmuir	Type 1	q_m (mg/g)	0.475	0.594	1.986
		b (L/mg)	0.008	0.008	0.007
		R²	0.972	0.964	0.933
	Type 2	q_m (mg/g)	0.475	0.596	1.846
		b (L/mg)	0.008	0.008	0.007
		R²	0.962	0.956	0.803
	Type 3	q_m (mg/g)	0.421	0.538	1.095
		b (L/mg)	0.008	0.008	0.008
		R²	0.999	0.999	0.996
	Type 4	q_m (mg/g)	0.425	0.538	1.117
		b (L/mg)	0.008	0.008	0.008
		R²	0.999	0.999	0.996
	Type 5	q_m (mg/g)	0.570	0.463	1.779
		b (L/mg)	0.008	0.008	0.007
		R²	0.964	0.972	0.933
Freundlich	Type 1	q_m (mg/g)	13.889	13.388	11.177
		K^F	0.000	0.000	0.000
		n	0.125	0.149	0.250
		R²	0.803	0.815	0.688

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