Ecologically sustainable removal of pharmaceuticals: A mechanistic study of bismuth sulfide-graphene oxide/silver nanocomposite

Abstract

Bismuth sulfide nanoparticles (BiS NPs) were synthesized via the hydrothermal method, and reduced graphene oxide(rGO) and silver nanoparticles (Ag), which acted as substrates, have prepared using the chemical reduction method. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectroscopy, and photoluminescence spectroscopy. Commercially available paracetamol-500 mg (PAM) and aspirin-300 mg (ASP) were selected for photodegradation under visible light using the as-prepared composites in an aqueous solution. Photoluminescence spectroscopy was used to detect PAM and ASP using the photo-excited electron transfer (PET) process, and the limit of detection (LOD) has obtained for PAM(8.70 ppm) and ASP(4.43 ppm) with a sensitivity of 0.9954 and 0.8002, respectively. Fourier transform infrared spectroscopy (FTIR) was used to analyze the before and after degradation products and to confirm the disintegrated products such as –COOH and –CH– both before and after disintegration.. The experimental data were found to fit well with the Freundlich isotherm, suggesting that the as-prepared nanocomposites exhibited a heterogeneous nature for PAM (5119 mg/L), and the pseudo-first-order kinetic model suggests ASP (1030 mg/L) with R2 values of 0.9119 and 0.7075. The risk assessment analysis of PAM was 9.823 μg/L(RQ > 1) and that of ASP was 0.2106 μg/L(RQ < 1), indicating that PAM has a higher potential risk than ASP. The demographic data of the participants indicated that PAM was the most stockpiled medicine at home; this work also encompasses the action of a single PAM and ASP tablet toward the environment, if it is accidently disposed of improperly could create massive water/soil pollution; hence, the care/duty of each person should follow the proper disposal of medical waste because we cannot replace this environment.