Adsorption of nalidixic acid antibiotic using a renewable adsorbent based on Graphene oxide from simulated wastewater

Abstract Nalidixic acid is the first antimicrobial quinolone and today extensively applied in human and veterinary medicine. Recently, it is detected in the surface waters and is on the rise. In this study, the renewable adsorbent based on Graphene oxide (i.e., NiZrAl-layered double hydroxide-graphene oxide-chitosan (NiZrAl-LDH-GO-CS NC)), was synthesized and employed effectively for the adsorptive removal of Nalidixic acid (NA). The successful synthesis of the nanocomposite was evaluated using Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), X-ray powder diffraction (XRD), RAMAN spectroscopy, pHZPC and Barrett-Joyner-Halenda (BJH)/ Brunauer–Emmett–Teller (BET) analyses. The NiZrAl-LDH-GO-CS NC presented fast adsorption rates towards NA and maximum adsorption capacity on the basis of the pseudo-second-order (PSO) kinetic model reached 277.79 mg g−1, much higher than those reported by different nano-based adsorbents. The adsorption process was examined using the central composite design (CCD), adaptive network-based fuzzy inference system (ANFIS), and general regression neural network (GRNN) under various operational conditions of adsorbent dose, initial NA concentration, pH, temperature, and time. The comparison of the models revealed that ANFIS model outperformed compared to the others, with R2 = 0.9997, MSE = 0.0004, RMSE = 0.0082, and MAE = 0.0068, demonstrating that ANFIS is a powerful methodology for modeling NA adsorption by NiZrAl-LDH-GO-CS nanocomposite. Moreover, to express the most applicable conditions, RSM-GA and RSM-DFA based optimization is implemented and verified in practice (more than %92 NA removal is achieved). Further thermodynamic and kinetic assessments both signify the chemisorption mechanisms in this adsorption system. To sum up, LDH-GO-CS as a renewable adsorbent, will possibly have noteworthy effects on pharmaceutical wastewater remediation and can be considered for advanced researches as an efficient reagent for practicable remediation techniques.