Synthesis and Physicochemical Characterization of Anion Exchanger Based on Green Modified Bottle Gourd Shell

Table 4

Expressions of isotherm models and nonlinear regression parameters for phosphate and nitrate biosorption onto CALV.

Models	Expressions and isotherm parameters		Statistics
			R^2	χ^2
Phosphate biosorption
Langmuir		Qmax (mg·g^−1) = 16.608	0.8899	4.1923
		KL (dm^3·mg^−1) = 0.249
Freundlich		KF (mg·g^−1) (mg·dm^−3)^1/n = 5.728	0.9955	0.1693
		1/nF = 0.244
Nitrate biosorption
Langmuir		Qmax (mg·g^−1) = 16.532	0.9839	0.7641
		KL (dm^3·mg^−1) = 0.169
		RL = 0.05−0.54
Freundlich		KF (mg·g^−1) (mg·dm^−3)^1/n = 3.957	0.9712	1.3327
		1/nF = 0.341

: equilibrium solid phase concentration (mg·g⁻¹); : equilibrium liquid phase concentration (mg·dm⁻³); Q_max: maximum biosorption capacity; : Langmuir constant related to the energy of biosorption (dm³·mg⁻¹); : Langmuir separation factor; : Freundlich constant characterizing biosorption capacity ((mg·g⁻¹) (mg·dm⁻³)^1/n); : Freundlich parameter related to energy or intensity of biosorption.