Novel solar simulated photocatalytic heterolysis of pharmaceutical wastewater via slag nanocomposite immobilization: optimization using response surface methodology

This study converted slag from the steelmaking industry into a Fe2O3-rich nanocomposite using solvothermal technique for photodegradation of pharmaceutical wastewater in an immobilized mode. The nanocomposite was characterized using XRF, scanning electron microscope (SEM), EDX, TEM, FTIR, XRD, and UV-Vis spectrometer. The XRF analysis result reveals a significant increase in the weight percent of Fe2O3 and SiO2, with a decrease in CaO content. The SEM images revealed the spherical and heterogeneous nature of the nanocomposite in shape and structure, while the FTIR confirms the increase in the vibration band of Si-O-Si and Fe-O with a reduction in the wide stretch mode of Ca-O. The XRD result illustrated the crystalline peak of Fe2O3 with a nanoparticle crystal size of 15.17 nm. The slag nanocomposite was used for the photodegradation of Paracetamol. The optimum operating parameters were obtained using response surface methodology at an R-2 value of 0.99 and p-value < 0.05. The degradation efficiency obtained at the optimum value was 96.96%. The degradation efficiency of the fifth repeated cycle of the immobilized nanocomposite was 77.89%. The degradation mechanism revealed that OH center dot radical was the major species of the degradation process. This work showed that slag nanocomposite might be effectively used for pharmaceutical wastewater treatment.