Synthesis of silica-chitosan nanocomposite for the removal of pharmaceuticals from the aqueous solution

Diclofenac, ibuprofen, and carbamazepine are commonly used in medicine, and they have been frequently detected in aquatic environments. Since they cannot be fully treated in treatment plants and can threaten the lives of aquatic life, effective treatment methods are needed to remove they from wastewater and contaminated waters. The removal of these compounds from synthetic seawater was investigated by utilizing the super adsorbent property of silica-chitosan nanocomposite material synthesized using domestic chitosan. 1.25% (w/w), 2.5% (w/w), and 5% (w/w) silica-chitosan nanocomposite were prepared by the sol–gel method. Silica-chitosan nanocomposites were characterized by Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-Ray Fluorescence Spectrometer (XRF), thermogravimetric analyses (TGA), and Brunauer–Emmett–Teller (BET) surface area analysis. FTIR and XRF spectrums show that silica-chitosan composite formation has successfully been obtained since Si% is measured 77.26 in XRF and Si–O-Si groups on 1100 cm⁻¹ in FTIR. The most successful synthesized nanocomposite was 2.5% (w/w) silica-chitosan aerogel. The adsorbent capacities were demonstrated at pH 5, 7, and 8.5 of 1561, 1445, and 1610 mg/g for carbamazepine; 395, 340, and 390 mg/g for diclofenac; 1649, 1553, and 1773 mg/g for ibuprofen, respectively. The ideal pH for the simultaneous removal of these three compounds in water was 8.5. Among these three pharmaceutical compounds, carbamazepine is the most efficiently (89.3%) removed from synthetic seawater. Adsorption isotherms were suitable with Langmuir and Freundlich isotherm models and adsorption kinetics proceeds were fitted well with a pseudo-second-order kinetic model of silica-chitosan nanocomposite for all pharmaceutical compounds (R² > 0.9742).