APPLICATION OF ADSORPTION THEORIES TO DESCRIBE CEFOPERAZONE PRECONCENTRATION USING AMINATED SILICA
Timofeeva A.A., Didukh-Shadrina S.L., Losev V.N.
Siberian Federal University
660041, Krasnoyarsk, Svobodny st., 79
The use of theoretical sorption models makes it possible to describe the equality in the system and calculate the physico-chemical characteristics to optimize the conditions and understand the mechanisms of interaction. In this work, the application of sorption theories to the preconcentration of cefoperazone (Cefoper) with silica modified with polydimethyldialammonium (PDDA), polyhexamethylene guanidine (PGMG) and polyethylenimine (PEI) was studied.
Cefoper is quantitatively (98%) extracted from aqueous solutions with sorbents SiO2-PDDA, SiO2-PGMG at pH 3-6. The experimentally determined sorption capacity of SiO2-PDDA, SiO2-PGMG, and SiO2-PEI according to Cefoper is 0.118, 0.087, and 0.104 mmol/g, respectively. The experimental sorption isotherms are satisfactorily described by the Langmuir model (see the table). The adsorption equilibrium constant KL decreases with the transition from SiO2-PDDA and SiO2-PGMG to SiO2-PEI, which is associated with the greater strength of the interaction of Cefoper with PGMG and PDDA, and this is confirmed by experimental data. The values of the coefficients RL of the Langmuir model and n of the Freundlich model indicate active sorption. The energy of interaction between Cefoper and sorbent polyamines decreases as the surface is filled. The free energy according to the Dubinin-Radostkevich model E < 8 kJ/mol indicates the physical mechanism of sorption, the energy according to the Temkin (B) model indicates the exothermic nature of the process.
Parameters of theoretical models of Cefoperazone sorption
| The sorption model | Parameter | SiO2- PDDA | SiO2- PGMG | SiO2- PEI |
|---|---|---|---|---|
| Langmuir | amax, mmol/g | 0.134 | 0.104 | 0.192 |
| KL, l/mmol | 11.0 | 9.28 | 1.91 | |
| RL | 0.1-0.9 | 0.1-0.9 | 0.3-1.0 | |
| R2 | 0.993 | 0.994 | 0.757 | |
| Freundlich | KF, mmol/g | 0.258 | 0.162 | 0.211 |
| 1/n | 0.662 | 0.617 | 0.888 | |
| R2 | 0.933 | 0.963 | 0.943 | |
| Dubinin-Radostkevich | amax, mmol/g | 0.129 | 0.098 | 0.121 |
| K, mol2/kJ2 | 0.017 | 0.017 | 0.032 | |
| Е, kJ/mol | 5.36 | 5.44 | 3.92 | |
| R2 | 0.984 | 0.987 | 0.995 | |
| Temkina | АТ, l/mg | 209 | 165 | 54 |
| B, kJ/mol | 23.5 | 18.4 | 27.7 | |
| R2 | 0.922 | 0.937 | 0.934 |