Tetracycline removal by a natural biosorbent: optimization by response surface methods employing DOE/FFD design of the experiment

ABSTRACT

This study utilised activated carbon, synthesised with H₃PO₄ as an active agent (referred to as C-H₃PO₄), as an adsorbent for the removal of tetracycline (TC), a commonly used pharmaceutical compound. The activated carbon underwent characterisation through SEM-EDS, FTIR, and XRD analyses. The C-H₃PO₄ particles were found to range in size from 63 to 50 µm and possessed acidic functions within a surface area of 590 mmol/g. To assess the adsorptive performance of C-H₃PO₄ in relation to tetracycline, several operational parameters were investigated, including contact time, temperature, pH, concentration of the pharmaceutical compound, and C-H₃PO₄ dosage. Optimal conditions were determined as follows: a pH of 2.8, a TC concentration of 15 mg/L, a temperature of 308 K, and an adsorbent dosage of 90 mg, utilising the design of experiments (DOE/FFD) for parameter optimisation. In addition, the analysis of variance (ANOVA) and three-dimensional surface plots were created to evaluate the interaction between the factors and the ideal conditions for removing tetracycline. The maximum adsorption capacity of C-H₃PO₄ onto TC was found to be 7.41 mg/g. The experimental data were best fitted using the pseudo-second-order and Freundlich models, suggesting a multilayer physisorption phenomenon.

KEYWORDS:

• Water treatment
• pharmaceutical compound
• DOE/FFD
• kinetic
• pH effect

Acknowledgments

The authors wish to express their gratitude to the chemical analysis center at university of Cadi Ayyad Marrakesh.

Disclosure statement

No potential conflict of interest was reported by the author(s).