Developing a robust treatment of antibiotics removal using Bi2O3/Cdots synthesized via microwave-assisted precipitation optimized by central composite design

Abstract

This study aims to optimize the development process of bismuth oxide/carbon dots (Bi2O3/Cdots) using microwave-assisted precipitation for antibiotics removal. Experimental design and analysis of optimum formulation predictions is conducted using the response surface methodology-central composite design (RSM-CCD). Analysis of variance (ANOVA) is used for model development and the fit optimized model is validated through actual experiments considering error estimation metrics. Optimal synthesis conditions is achieved by developing Bi2O3/Cdots 13.31%wt under 780 W microwaves for 17.35 minutes. The analysis of optical properties and crystallinity shows that the composite has a narrow bandgap compared to Bi2O3 with a lattice spacing of 0.32 nm. The morphological and topographical profiles shows that the composite structure consists of Bi2O3 rods with wavy, irregular, and rough surfaces decorated with colonies of Cdots. The chemical state of the composite consists of Bi, O, and C which are distributed throughout the surface with a lower binding energy compared to Bi2O3. Through disc diffusion, composite reduced the inhibition zone, which means it is able to reduce the antibacterial activity and antibiotic efficacy. The optimized composite is able to degrade 76.6% ciprofloxacin (CIP), 73.3% cefadroxil (CEF), 54.4% amoxicillin (AMX), and 60.3% mixed antibiotics (MIX). Our findings indicated that the developed Bi2O3/Cdots is capable of robust removal in various antibiotic pollutants.