Removal of Tetracycline Antibiotic as a Hospital Waste by pH-Sensitive Degradable Composite Hydrogel Using Fenton-Like System

Fenton-like hydrogels crosslinked with imine bond were prepared for the removal of tetracycline. Initially, the oxidation process of carboxymethyl cellulose (CMC) was performed, and it was named OX-CMC. The confirmations were then obtained using NMR and FTIR analyses. The degree of CMC oxidation was investigated in relation to reaction time, and optimal time of 4 h was selected. In the second part, a pH-sensitive hydrogel with imine bond was prepared from the crosslinking reaction between OX-CMC and chitosan. The formation of the hydrogel through imine crosslinking was confirmed by FTIR spectroscopy. By increasing ratio of OX-CMC to chitosan, the swelling rate for the hydrogel decreased. Turbidity measurements showed that a higher OX-CMC to chitosan weight ratio resulted in slower hydrogel degradation in acidic environments. In the third part, Fe₃O₄ nanoparticles with concentrations of 5 and 10 wt% were incorporated into the hydrogel structure. TEM studies revealed a spherical morphology and uniform distribution of nanoparticles within the hydrogel network. SEM images revealed a porous structure which composed of interconnected pores in the hydrogel. The results of UV–visible spectroscopy indicated that the degradation of magnetic hydrogels would augment as magnetic nanoparticle content increases, pH decreases, and the hydrogen peroxide content increases.