Algae based green biocomposites for tetracycline removal from aqueous solutions: kinetic, equilibrium and thermodynamic studies

This study aimed to develop beads from biomass and evaluate their adsorbent potential for tetracycline removal from water. For this purpose, a green synthesis of the biocomposite was made and characterized. In the removal studies carried out in the batch system; the effects of solution pH, amount of biocomposite, contact time, and different initial pollutant concentrations at different temperatures on the efficiency of tetracycline removal were studied. Langmuir, Freundlich, and D-R isotherms were applied to the data obtained from isotherm studies. Qm values obtained from Langmuir isotherm for 25, 35 and 45 oC were found to 108.95 mg/g, 191.25 mg/g and 404.75 mg/g, respectively. The resulting biocomposite had hydrophobicity and various functional groups (CH2, CN, CO, CO3-2 vb.), which may be associated with high tetracycline biosorption. The high Qm values of the biocomposite are due to the ir-ir electron-donor-acceptor interaction and complex formation between functional groups and tetracycline molecules. Considering the determination coefficients for tetracycline biosorption, the pseudo-second order model was found suitable. From the thermodynamic data; the increase in tetracycline biosorption with increasing temperature indicates that the biosorption process has an endothermic and spontaneous nature. As a result; it has been demonstrated that the synthesized algae-based green biocomposite can be used to successfully remove tetracycline from water.