Chemical Characteristics of Ciprofloxacin and Its Degradation Products: On the Road to Understanding Its Potential Hazards

Sep 29, 2026

Antibiotics such as ciprofloxacin (CIP) function as emerging contaminants due to extensive use in human and veterinary medicine, environmental persistence, and incomplete removal during wastewater treatment. Photocatalytic degradation can mitigate pollution, yet some degradation products may pose greater hazards than the parent compound. This investigation combines density functional theory with theoretical and experimental UV/visible spectra to characterize main photodegradation products and assess their chemical reactivity.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages15

Reading Time38 min

AccessFree to download

Abstract

Introduction

Photocatalytic degradation and identification of products

Electron transfer capacity and oxidative stress implications

Fukui functions and reactive atom analysis

Risk evaluation for mineralization and hazard mitigation

This article is licensed under CC-BY 4.0 [http://pubs.acs.org/journal/acsodf](http://pubs.acs.org/journal/acsodf) Article Chemical Characteristics of Ciprofloxacin and Its Degradation Products: On the Road to Understanding Its Potential Hazards Alexis Caballero, Emiliano Perez-Sanchez, Amauri Serrano-Lázaro, Monserrat Bizarro, and Ana Martínez * Cite This: ACS Omega 2025, 10, 58656−58670 Read Online | | | | | | | | --- | --- | --- | --- | --- | --- | | ACCESS | Metrics & More | | Article Recommendations | | *sı Supporting Information | ABSTRACT: Antibiotics such as ciprofloxacin (CIP) are considered emerging contaminants because of their widespread use inhuman and veterinary medicine, their persistence in the environment, and their incomplete removal during wastewater treatment. To mitigate pollution, the photocatalytic degradation of antibiotics is an available option. However, some of the degradation products could be more harmful than the original compound. The main idea of this investigation is to determine the chemical properties of the main photodegradation products of CIP to understand the positive or negative consequences of degrading CIP. Density functional theory calculations were performed to investigate the electron transfer capacity of CIP and 20 selected degradation products. Fukui functions were also calculated to determine the reactive atoms. To identify the degradation products, this investigation presents theoretical and experimental ultraviolet (UV)/visible spectra of the photocatalytic degradation of CIP using zinc oxide nanowires (ZnO NW). The 3 h photocatalytic reaction showed an 89% of CIP degradation, indicating the effectiveness of ZnO NW photocatalyst. The agreement between the experiment and theory indicates that two degradation products (B5 and B8) are formed during the photocatalytic experiment. Concerning the electron transfer capacity, B8 is a better electron donor and could help to prevent oxidative stress by donating electrons to free radicals. B5 is a better electron acceptor, but it is not as good as •OOH, and therefore, it is not expected that this molecule will oxidize other molecules. Fukui functions reveal that B5 and B8 have more reactive atoms than CIP, and this could have consequences for health and the environment. With this information on the chemical characteristics of the degradation products, it is possible to determine whether or not it is advisable to degrade the CIP using this photocatalytic degradation procedure, and the risks of not achieving its complete mineralization. Understanding the chemical reactivity from these theoretical results facilitates the analysis of the potential hazards in subsequent studies. ■ INTRODUCTION The enormous amount of antibiotics currently consumed to prevent and treat infections in humans and animals is beginning to represent a serious contamination problem. This is because antibiotics are not fully metabolized and consumers excrete both intact and metabolized pharmaceuticals, many of which are water-soluble. 1−8 These compounds can reach aquatic environments, increasing the number of contaminants in the surface and groundwater, as well as in sewage treatment plant effluents.3,7,8 These residues are not easily eliminated in most wastewater treatment processes and, in fact, these compounds are beginning tobe considered as emerging pollutants.5 An example of a widely used antibiotic is ciprofloxacin (CIP), presented in Figure 1, which belongs to the fluoroquinolone family. Specifically, CIP is a broad-spectrum antibiotic used to treat various bacterial infections. Its mechanism of action is to inhibit bacterial DNA replication.9, 10 There are several methods to remove CIP from water, such as adsorption, electrochemical, membrane separation, phytoremediation, and advanced oxidation processes. 11−21 Figure 1. Photodegradation sites of ciprofloxacin (CIP) with free radicals. | Received: July 14, 2025
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FAQs

Why are ciprofloxacin and similar antibiotics considered emerging contaminants?

Ciprofloxacin persists in the environment, is not fully metabolized, and many residues pass into aquatic systems and wastewater effluents while remaining difficult to eliminate in many treatment processes.

How does the study identify ciprofloxacin photodegradation products?

It uses theoretical UV/visible spectra from photocatalytic degradation combined with experimental measurements using zinc oxide nanowires (ZnO NW) and compares the results to determine formed products.

What do the results suggest about the potential hazards of degradation products?

The study indicates that reactive atoms in certain products (B5 and B8) exceed those in CIP, which may have consequences for health and the environment, and it supports evaluating whether degradation is advisable when complete mineralization is not guaranteed.

Sep 29, 2026

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