Evaluation of an Adsorbent Based on Agricultural Waste (Corn Cobs) for Removal of Tyrosine and Phenylalanine from Aqueous Solutions

Table 2

Pure Tyr equilibrium isotherm models and fitting parameters.

Model	Equation	Parameter values			𝑟^2			RMS (%)
		25°C	35°C	45°C	25°C	35°C	45°C	25°C	35°C	45°C
Langmuir	𝑞𝑒=𝑞𝑚𝐾𝐿𝐶𝑒1+𝐾𝐿𝐶𝑒	𝐾𝐿𝑞=0.164𝑚=14.19	𝐾𝐿𝑞=0.140𝑚=10.87	𝐾𝐿𝑞=0.106𝑚=11.33	0.992	0.996	0.995	8.443	3.605	4.226
Freundlich	𝑞𝑒=𝐾𝐹𝐶^𝑛𝑒	𝐾𝐹=2.398𝑛=1.777	𝐾𝐹=1.957𝑛=2.109	𝐾𝐹=1.619𝑛=1.922	0.984	0.959	0.970	15.514	12.140	11.239
Temkin	𝑞𝑒=(RT/𝑏)ln(𝐾𝑇𝐶𝑒)	𝐾𝑇=1.482RT/𝑏=1.422	𝐾𝑇=1.258RT/𝑏=1.080	𝐾𝑇=0.968RT/𝑏=1.124	0.991	0.994	0.999	3.350	4.291	1.417
Langmuir-Freundlich	𝑞𝑒=𝐾𝐿𝐹𝑞𝑚𝐶^𝑛𝑒1+𝐾𝐿𝐹𝐶^𝑛𝑒	𝐾𝐿𝐹𝑞=0.1672𝑚=10.41𝑛=1.527	𝐾𝐿𝐹𝑞=0.133𝑚=9.78𝑛=1.181	𝐾𝐿𝐹𝑞=0.103𝑚=10.1𝑛=1.144	0.998	0.998	0.996	1.763	2.766	3.722

𝑞_𝑒 (mg g⁻¹) is the equilibrium adsorption capacity; 𝐶_𝑒 (mg L⁻¹) is the solute concentration in the aqueous solution, after equilibrium; 𝑞_𝑚 (mg g⁻¹) is the maximum adsorption capacity; the remaining constants are empirical parameters associated to each specific model.