Preparation and Characterization of a New Chitosan–Iron–Cobalt Composite for Tetracycline Sorption

The environmental persistence of antibiotics such as tetracycline (TC) in water systems has raised serious ecological and public health concerns. In this study, a novel composite sorbent for tetracycline sorption, based on chitosan modified with iron and cobalt, was synthesized and characterized. The structural and morphological properties of the composite were investigated using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The FTIR spectrum revealed the presence of different functional groups on the sorbent surface, including -O-H, -N-H, -C-H, and -C-O. The successful incorporation of the metal oxides into the chitosan matrix was confirmed with the Me-O band at 554 cm^-1. The SEM images revealed a sorbent with heterogeneous morphology that is favorable for adsorption. EDX analysis verified the uniform distribution of Fe and Co within the composite. The point of zero charge (pH_PZC) was determined to assess the influence of the surface charge of the adsorbent. pH_PZC of 9.6 indicated optimal tetracycline sorption under slightly acidic to neutral pH conditions. Preliminary sorption tests were conducted at pH 5 with 1 g/L of sorbent material and an initial TC concentration of 50 mg/L. The obtained TC removal and uptake were 43.90% and 21.95 mg/g, respectively. These results suggest that the sorbent is a promising new material for further investigation and water treatment applications.