A multivariate modeling and experimental realization of photocatalytic system of engineered S-C3N4/ZnO hybrid for ciprofloxacin removal: Influencing factors and degradation pathways

Bramha Gupta; Ashok Kumar Gupta; Chandra Sekhar Tiwary; Partha Sarathi Ghosal

doi:10.1016/j.envres.2020.110390

A multivariate modeling and experimental realization of photocatalytic system of engineered S-C₃N₄/ZnO hybrid for ciprofloxacin removal: Influencing factors and degradation pathways

Environ Res. 2021 May:196:110390. doi: 10.1016/j.envres.2020.110390. Epub 2020 Oct 28.

Authors

Bramha Gupta¹, Ashok Kumar Gupta², Chandra Sekhar Tiwary³, Partha Sarathi Ghosal⁴

Affiliations

¹ School of Water Resources, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India. Electronic address: guptabramha@iitkgp.ac.in.
² Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India. Electronic address: agupta@civil.iitkgp.ac.in.
³ Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India. Electronic address: chandra.tiwary@metal.iitkgp.ac.in.
⁴ School of Water Resources, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India. Electronic address: psghosal@swr.iitkgp.ac.in.

PMID: 33129859
DOI: 10.1016/j.envres.2020.110390

Abstract

Ciprofloxacin, a pharmaceutically active compound, is present as a micropollutant in wastewater, which cannot be removed by conventional techniques due to its recalcitrant nature. Therefore, in the present study, the photocatalytic degradation of this bio-toxic compound was demonstrated using a three-dimensional sulfur-doped graphitic-carbon nitride/zinc oxide hybrid, with enriched oxygen vacancies. The influence of various water matrices and experimental conditions on the ciprofloxacin degradation was optimized. The hybrid material showed 98.8% and 75.8% degradation efficiency under optimum experimental conditions (i.e., catalyst dose: 1 g/L; pH: 5; initial ciprofloxacin concentration: 20 mg/L; temperature: 27 °C) under ultraviolet (UV) and visible light, respectively. A neural-network-based multivariate approach was used to predict a significant model considering the experimental conditions that showed adequate statistical significance (R²: 0.992 and F-value: 8707.1). The relative significance of the experimental conditions was assessed, suggesting that the initial ciprofloxacin concentration has a more significant effect on the degradation efficiency than the other factors. The rate kinetics and reaction mechanisms for ciprofloxacin degradation were demonstrated, and the driving radicals involved were identified. A higher rate of reaction was found under UV irradiation (0.01702 min^-1) than under visible light (0.00802 min^-1). Superoxide radicals were identified as the main driving radicals, which caused substantial photocatalytic reactions among the hybrid and ciprofloxacin molecules. Microscopic and macroscopic analyses of the used hybrid were conducted, which confirmed the presence of higher defect concentrations, crystallinity, and interlinked stacked structure in the hybrid. Hence, the 3D hybrid can be efficiently used and reused for ciprofloxacin degradation. This advanced photocatalytic system can be widely used to remediate emerging contaminants in wastewater treatment.

Keywords: Artificial neural network; Microscopy; Photocatalysis; Spectroscopy; Water matrices.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Catalysis
Ciprofloxacin
Wastewater
Water Purification*
Zinc Oxide*

Substances

Waste Water
Ciprofloxacin
Zinc Oxide