Kinetic Model for pH Variation Resulted from Interaction of Aqueous Solution Contaminated with Nickel Ions and Cement Kiln Dust

Table 2

Selected approximations for constants of kinetic models for numerical approach.

Model	Equation	Type of model for
		k	qc
Model 1		Exponential	Without modification
Model 2		Exponential	Exponential
Model 3		Exponential	Exponential based on (e) constant
Model 4		Exponential based on (e) constant	Without modification
Model 5		Exponential based on (e) constant	Exponential
Model 6		Exponential based on (e) constant	Exponential based on (e) constant

is the quantity of solute removed from the aqueous solution at time t (mg/g), is the numerical constant (mg/g min^α), and is the quantity of solute removed from the aqueous solution at equilibrium (mg/g); ,, z, and α are numerical constants (-), are also numerical constants (1/min), and is the numerical constant (1/min^b).