Degradation of ciprofloxacin antibiotic using photo-electrocatalyst process of Ni-doped ZnO deposited by RF sputtering on FTO as an anode electrode from aquatic environments: Synthesis, kinetics, and ecotoxicity study

Fluoroquinolone ciprofloxacin removal from synthetic and real wastewaters by single and combined electrochemical advanced oxidation processes. A review

Ciprofloxacin (CIP) is a widely prescribed fluoroquinolone antibiotic detected in the aquatic environment fostering the emergence of bacteria and posing risks the human health and ecosystem integrity. The present comprehensive critical review deals with CIP removal from synthetic and real wastewater by electrochemical advanced oxidation processes (EAOPs) up to 2024. Lower performance was obtained in real wastewaters than synthetic ones because their components scavenged-generated oxidizing agents. Anodic oxidation (AO) has been developed with active dimensionally stable anodes (DSA) and the non-active potent boron-doped diamond (BDD) one, where CIP solutions in chloride medium reached a maximal of 75 % mineralization. A more rapid CIP degradation and up to 96 % mineralization have been found for homogeneous electro-Fenton (EF) with Pt and Fe2+ catalyst. Heterogeneous Fenton with functionalized iron cathodes and solid iron catalysts, and heterogeneous EF-like with non-ferrous catalysts gave worse results. Novel modified EF processes with dual cathodes for direct.•OH production after H2O2 electrogeneration allowed up to 96 % mineralization. Photoelectro-Fenton (PEF) with UVA light and solar PEF (SPEF) can yield overall mineralization by the rapid photolysis of final Fe(III)-carboxylate species formed. Photoelectrocatalysis (PEC) with new photoanodes like FTO/Ni-ZnO under UVA light yielded 87 % mineralization. Hybrid AO, EF, PEF, and PEC processes with persulfate, O3, ultrasounds, or photocatalysis were more powerful than their single EAOPs. The characteristics and performance of each method, the generation of oxidants (•OH, O2•-, and/or 1O2), its reusability, and the by-products produced are discussed. The loss of toxicity of the treated solutions by EAOPs is finally detailed.

Advanced oxidation process-mediated removal of pharmaceuticals from water: a review of recent advances

Pharmaceutical compounds have raised significant environmental concerns, due to their persistent and non-biodegradable nature. Addressing their presence in the environment has become a priority, leading to the application of various removal treatment techniques. Advanced oxidation processes (AOPs) undoubtedly have emerged as highly effective removal techniques, as evidenced by the growing body of work in this area. This review offers an overview of the recent advances in the development of AOPs for treating pharmaceuticals and their by-products. Current trends and discoveries reported in diverse AOP studies have been scrutinized and are presented. Furthermore, emphasis is placed on the use of TiO2-mediated photocatalysis, which stands out as one of the most explored AOPs for pharmaceutical remediation. Performance aspects of TiO2 photocatalytic treatment are explored and discussed encompassing both commercially available and synthesized TiO2, as well as engineered TiO2-based materials (e.g. activated carbon, polymers, metals and non-metals), all aimed at removal of pharmaceutical compounds from the environment. The review concludes by summarizing key findings and offers insights into directions for future research.

Complete abatement of the antibiotic ciprofloxacin from water using a visible-light-active nanostructured photoanode

The wide use of the fluoroquinolone antibiotic ciprofloxacin (CIP), combined with its limited removal in wastewater treatment plants, results in a dangerous accumulation in natural water. Here, the complete degradation of CIP by photoelectrocatalysis (PEC), using an FTO/ZnO/TiO2/Ag2Se photoanode that is responsive to blue light, has been investigated. A slow antibiotic concentration decay was found in 0.050 M Na2SO4 under the oxidizing action of holes and OH photogenerated at the anode surface. The degradation was strongly enhanced in 0.070 M NaCl due to mediated oxidation by electrogenerated active chlorine. The latter process became faster at pH 7.0, with total abatement of CIP at concentrations below 2.5 mg L-1 operating at a bias potential of +0.8 V. The performance was enhanced when increasing the anodic potential and decreasing the initial drug content. The use of solar radiation from a simulator was also beneficial, owing to the greater lamp power. In contrast, the electrochemical oxidation in the dark yielded a poor removal, thus confirming the critical role of oxidants formed under light irradiation. The generation of holes and OH was confirmed from tests with specific scavengers like ammonium oxalate and tert-butanol, respectively. The prolonged usage of the photoanode affected its performance due to poisoning of its active centers by degradation by-products, although a good PEC reproducibility was obtained upon surface cleaning.

Emerging aspects of metal ions-doped zinc oxide photocatalysts in degradation of organic dyes and pharmaceutical pollutants - A review

In recent periods, a broad assortment of continual organic contaminants has been released into our natural water resources. Indeed, it is exceedingly poisonous and perilous to living things; thus, the elimination of these organic pollutants before release into the water bodies is vital. A variety of techniques have been utilized to remove these organic pollutants with advanced oxidation photocatalytic methods with zinc oxide (ZnO) nanoparticles being commonly used as a capable catalyst for contaminated water treatment. Nevertheless, its broad energy gap, which can be only stimulated under an ultraviolet (UV) light source, and high recombination pairs of electrons and holes limit their photocatalytic behaviors. However, numerous methods have been suggested to decrease its energy gap for visible regions. Including, the doping ZnO with metal ions (dopant) can be considered as an effectual route not only the reason for a movement of the absorption edges toward the higher (visible light) region but also to lower the electron-hole pair (e--h+) recombination. This review concentrated on the impact of dissimilar types of metal ions (dopants) on the advancement in the degradation performance of ZnO. So, this work demonstrates a vital review of contemporary attainments in the alteration of ZnO nanoparticles for organic pollutants eliminations. Besides, the effect of doping ions including transition metals, rare earth metals, and metal ions (substitutional and interstitial) concerning numerous types of altered ZnO are summarized. The photodegradation mechanisms for pristine and metal-modified ZnO nanoparticles are also conferred.

ZnO/γ-Fe2O3/Bentonite: An Efficient Solar-Light Active Magnetic Photocatalyst for the Degradation of Pharmaceutical Active Compounds

For applications related to the photocatalytic degradation of environmental contaminants, engineered nanomaterials (ENMs) must demonstrate not only a high photocatalytic potential, but also a low tendency to agglomeration, along with the ability to be easily collected after use. In this manuscript, a two-step process was implemented for the synthesis of ZnO, ZnO/Bentonite and the magnetic ZnO/γ-Fe₂O₃/Bentonite nanocomposite. The synthesized materials were characterized using various techniques, and their performance in the degradation of pharmaceutical active compounds (PhACs), including ciprofloxacin (CIP), sulfamethoxazole (SMX), and carbamazepine (CBZ) was evaluated under various operating conditions, namely the type and dosage of the applied materials, pH, concentration of pollutants, and their appearance form in the medium (i.e., as a single pollutant or as a mixture of PhACs). Among the materials studied, ZnO/Bentonite presented the best performance and resulted in the removal of ~95% of CIP (5 mg/L) in 30 min, at room temperature, near-neutral pH (6.5), ZnO/Bentonite dosage of 0.5 g/L, and under solar light irradiation. The composite also showed a high degree of efficiency for the simultaneous removal of CIP (~98%, 5 mg/L) and SMX (~97%, 5 mg/L) within 30 min, while a low degradation of ~5% was observed for CBZ (5 mg/L) in a mixture of the three PhACs. Furthermore, mechanistic studies using different types of scavengers revealed the formation of active oxidative species responsible for the degradation of CIP in the photocatalytic system studied with the contribution of h⁺ (67%), OH (18%), and ·O₂⁻ (10%), and in which holes (h⁺) were found to be the dominant oxidative species.

Treatment of real wastewater by photoelectrochemical methods: An overview

An inadequate and inefficient performance ability of conventional methods to remove persistent organic pollutants urges the need of alternative or complementary advanced wastewater treatments methods to ensure the safer reuse of reclaimed water. Photoelectrochemical methods are emerging as promising options among other advanced oxidation processes because of the higher treatment efficiency achieved due to the synergistic effects of combined photochemical and electrolysis reactions. Synergistic effects of integrated photochemical, electrochemical and photoelectrochemical processes not only increase the hydroxyl radical production; an enhancement on the mineralization ability through various side reactions is also achieved. In this review, fundamental reaction mechanisms of different photoelectrochemical methods including photoelectrocatalysis, photo/solar electro-Fenton, photo anodic oxidation, photoelectroperoxone and photocatalytic fuel cell are discussed. Various integrated photochemical, electrochemical and photoelectrochemical processes and their synergistic effects are elaborated. Different reactor configurations along with the positioning of electrodes, photocatalysts and light source of the individual/combined photoelectrochemical treatment systems are discussed. Modified photoanode and cathode materials used in the photoelectrochemical reactors and their performance ability is presented. Photoelectrochemical treatment of real wastewater such as landfill leachate, oil mill, pharmaceutical, textile, and tannery wastewater are reviewed. Hydrogen production efficiency in the photoelectrochemical process is further elaborated. Cost and energy involved in these processes are briefed, but the applicability of photocatalytic fuel cells to reduce the electrical dependence is also summarised. Finally, the use of photoelectrochemical approaches as an alternative for treating soil washing effluents is currently discussed.