RESUMO
A composite of chitosan-supported ZnO nanoparticles (ZnO/CS) was green-synthesized via an easy and cost-effective method using Chicory (Cichorium intybus) plant extract. The synthesis was confirmed using uv-vis spectrometry at a λmax of 380 nm, and the surface of the material was characterized via FT-IR spectroscopy, and finally via SEM, which confirmed the distribution of ZnO nanoparticles on the surface of chitosan biopolymer (CS). The synthesized material was applied in the adsorptive removal of residues of the pyridoxine hydrochloride (vitamin B6) pharmaceutical drug from aqueous media using the batch technique. The material's removal capacity was studied through several adjustable parameters including pH, contact time, the dose of the adsorbent, and the capacity for drug adsorption under the optimal conditions. Langmuir and Freundlich isotherms were applied to describe the adsorption process. The removal was found to obey the Freundlich model, which refers to a chemisorption process. Different kinetic models were also studied for the removal process and showed that the pseudo-second-order model was more fitted, which indicates that the removal was a chemisorption process. Thermodynamic studies were also carried out. The maximum removal of vitamin B6 by the nano-ZnO/CS composite was found to be 75% at optimal conditions. The results were compared to other reported adsorbents. Reusability tests showed that the nano-ZnO/CS composite can be efficiently reused up to seven times for the removal of PDX drugs from aqueous media.