Application of RSM and ANN modelling techniques in the removal of Cr (VI) from aqueous solution using PANI@ Fe3O4@green moringa leaves biomass, a hybrid magnetic nanocomposite

Abstract

This study examines how a hybrid magnetic nanocomposite polyaniline@ iron oxide @ moringa leaves biomass (PANI@Fe 3 O 4 @ML) can be applied to remove hexavalent chromium (Cr (VI)) from water. The hybrid nanocomposite was prepared vi a ultrasound-assisted polymerization technique in a short period of time. Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, and Brunauer–Emmett–Teller techniques were used to characterize the hybrid nanocomposite. Isotherm analysis revealed that Cr (VI) adsorption by PANI@Fe 3 O 4 @ML followed the Langmuir model, indicating monolayer adsorption with a maximum capacity of 50.8 mg/g. Kinetic studies showed the best correlation with the pseudo-second-order model (R² = 0.999981). Thermodynamic analysis confirmed that the adsorption process was both endothermic and spontaneous (∆H =10.71 kj.mol −1 , ΔG=-4.36 kJ.mol −1 at 50℃), respectively for PANI@Fe 3 O 4 @ML. The ΔG◦ values ranging from −0.87 to −3.02 kJ/mol confirmed that the adsorption process occurred spontaneously and was primarily governed by physisorption. Additionally, the data was analyzed using response surface methodology (RSM) and artificial neural network (ANN). The ANN model demonstrated a good fit (R 2 = 0.9742) against RSM with (R² = 0.9567). The optimization results revealed that the ideal conditions for achieving 96.43% removal efficiency of Cr (VI) with PANI@Fe 3 O 4 @ML were a pH of 2.27, an adsorbent dosage of 0.0488 g/L, a concentration of 26.7416 mg/L, and a temperature of 43.7747 °C. Under these conditions, the overall desirability value reached 1, indicating the most favorable outcome. These findings suggest that PANI@Fe 3 O 4 @ML is a promising adsorbent for Cr (VI) removal from water.